A New Class of Nuclear Reactors

prunedude tips this quote from a post at Freakonomics about Japan's nuclear crisis: "The folks over at IV Insights, the blog associated with Nathan Myhrvold's Intellectual Ventures, point out that it was the complete loss of power that disabled the cooling systems protecting the plant's reactors. Which raises the question: Is there nuclear technology that could withstand such a catastrophe? Possibly. TerraPower, an Intellectual Ventures spin-off that also boasts Bill Gates as an investor, is working on a new reactor design called a traveling wave reactor that uses fast reactor technology, rather than the light water technology used at the Fukushima Daiichi plant. The two biggest advantages of the fast reactor design is that it requires no spent fuel pools and uses cooling systems that require no power to function, meaning the loss of power from the tsunami might not have crippled a fast reactor plant so severely."

Comments

If Bill Gates is involved . . .

[drsmack1]

Does that mean he had previously dismissed it as a bad idea and then after someone else made progress he jumped aboard?

Just saying' . . .

Re:If Bill Gates is involved . . .

[WrongSizeGlass]

Does that mean he had previously dismissed it as a bad idea and then after someone else made progress he jumped aboard?

No ... though it sure could offer new meaning to 'Blue Screen of Death'.

Re:If Bill Gates is involved . . .

[MobileTatsu-NJG]

Does that mean he had previously dismissed it as a bad idea and then after someone else made progress he jumped aboard?

No ... though it sure could offer new meaning to 'Blue Screen of Death'.

Only if it's a hardware problem, yeesh.

NUKE EM !! DUKE EM ??

[Anonymous Coward]

What in the world is this about then?

Um, don't safe reactors already exist?

[DurendalMac]

My understanding is that breeder reactors and pebble bed reactors wouldn't have had the problem that hit the plant in Japan. That and breeder reactors have the added benefit of eating nuclear waste over and over until whatever is left might make you sneeze. Maybe I'm completely off on that, but why do we need a new design on this kind of reactor unless it's relatively simple to retrofit older reactors?

Re:Um, don't safe reactors already exist?

[Surt]

Indeed, this was what came to mind immediately to me as well.
http://en.wikipedia.org/wiki/Pebble_bed_reactor

Re:Um, don't safe reactors already exist?

[skylerweaver]

According to TFA, a travelling wave reactor is a type of breed-burn reactor.

http://www.terrapower.com/Technology/Timeline.aspx

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Germany ran a pebble bed reactor at the Nuclear Research Facility at Juelich. The Juelich post-mortem report concluded that pebble bed reactors have severe problems in practice (at least some of them base design flaws), in the specific case of the Julich AVR reactor leading to Strontium-90 contamination of the soil and aquifer beneath the reactor.

The post-mortem report is posted here http://www.eskom.co.za/content/AVR-Report-Press.PDF

Some interesting bits from the report:

The AVR primary circuit is heavily contaminated with metallic fission products (Sr-90, Cs-137) which create problems in current dismantling. The amount of this contamination is not exactly known, but the evaluation of fission product deposition experiments indicates that the end of life contamination reached several percent of a single core inventory, which is some orders of magnitude more than precalculated and far more than in large LWRs.
[...]
It leads to the conclusion that the AVR contamination was mainly caused by inadmissible high core temperatures, increasing fission product release rates, and not - as presumed in the past - by inadequate fuel quality only.

From the conclusions:

As outlined above there exist unresolved safety problems in pebble bed reactors for design basis accidents, as for beyond design basis accidents like severe air ingress with graphite burning. Previously a superior safety behaviour of pebble bed reactors was claimed compared to other nuclear systems including an allegedly catastrophe free design. According to the above presents arguments there are doubts, whether this depicts reality.

So while pebble bed reactors have some advantages over traditional designs, they are by no means the silver bullet that some people make them to be.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Your exactly right. The plants in Japan are using 30+ year old designs. Modern plants would most likely been fine.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

One instance of that design is 20 miles from here. It is only a small reactor built to study this type of reactor. It has contaminated the soil and groundwater beneath it. It has been very close to exceeding the worst case scenario for this type of reactor and only luck prevented a catastrophe. It is unclear if the dismantling of the reactor is technically possible in the planned timeframe because the containment is much more radioactive than expected. Scientists working at the institute which operated the reactor have studied the failure modes exhibited by this reactor. They deem the design unsafe. A commercial scale implementation of the same type has exhibited additional problems.

There is no inherently safe nuclear reactor design. The energy densities involved are too high to be inherently safe. The hubris and conflicts of interest surrounding nuclear energy will always create potential for disaster.

Re:Um, don't safe reactors already exist?

[Locutus]

Microsoft people are best known for reinventing what others have already done and selling as their invention. These "New Class of Nudlear Reactors" can only be run using Microsoft Windows. Does that answer your question as to why we need a new design as the OP mentioned?

LoB

Re:Um, don't safe reactors already exist?

[blair1q]

All they needed was a backup supply of water that would be gravity-fed. One big tank on that big hill behind the plant, with a nice, flexible hose leading to a fat, manual valve behind enough shielding to protect someone even if the reactor was breached.

But no. GE sells generators, and that's what Fukushima Daichii got. Fucked by GE.

Re:Um, don't safe reactors already exist?

[no-body]

Please note:

The premise "that it was the complete loss of power that disabled the cooling systems protecting the plant's reactors" in the original post is incorrect.
Causes for failures on the JA plants were many.
Besides being under-designed for a 9 earthquake (7.? designed) and a too low tsunami wall to hold up the one occurred, there were failures in maintenance/upkeep/supervision.

Any plant can have those "failures" and the "uups, we did not think of that ever happening" is too costly and will happen again. IMO - get rid of that stuff asap!

And yeah, let that pebble core get compromised and the graphite fuel balls in there start burning... PU-239 is not your friend.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Unfortunately Jimmy Carter shut down the only breeder reactors that were operating in the United States

Re:Um, don't safe reactors already exist?

[dgatwood]

Most of those problems are about shielding and disposing of the plant when you shut it down. The remainder can be solved by using a moderator that doesn't burn. You don't have to use graphite. You could, for example, use beryllium....

Re:Um, don't safe reactors already exist?

[Martin Blank]

Fukushima Daiichi was built to withstand a 5.7m tsunami, as required by Japanese regulators. It was hit with a 10m tsunami, though, which is why the generators were knocked offline.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

There's always something, isn't there? The design is inherently safe, if you don't use graphite. The design is inherently safe if you manage not to crack the reflector. No! The design is NOT inherently safe. Inherently safe means that you won't need less than obvious tweaks to make it safe. The people who built the existing reactors thought they were building safe reactors. It turns out they were wrong. How can anyone believe that that is the exception, not the rule? Do we really have to keep watching reactors fail in unexpected ways because some people can't control their optimism?

Re:Um, don't safe reactors already exist?

[divisionbyzero]

My understanding is that breeder reactors and pebble bed reactors wouldn't have had the problem that hit the plant in Japan. That and breeder reactors have the added benefit of eating nuclear waste over and over until whatever is left might make you sneeze. Maybe I'm completely off on that, but why do we need a new design on this kind of reactor unless it's relatively simple to retrofit older reactors?

Like most engineering problems there are always trade-offs. So while pebble-bed reactors don't have the same problems that the ones in Japan do they have their own problems. Other people have taken the time to post them.

Re:Um, don't safe reactors already exist?

[Hartree]

That's not quite true. The Integral Fast Reactor was also a type of sodium cooled breeder though with much less waste and much harder for proliferation purposes. The prototype was working up at Argonne National Labs.

Carter didn't shut that one down. The congress did in the 90s and Bill Clinton mentioned it in his state of the union speech as one of his administrations achievements. He said it was a waste of money, since we would never need it.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Ditto on the pebble bed. As I understand it, the type of problems seen are not possible with pebble bed technology. Unfortunately 1d10ts seem to go for the nuclear = bad * always formula

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Do we really have to keep watching reactors fail in unexpected ways

That's the way progress works. Bridges, for example, used to collapse often enough that it was obvious we didn't yet know enough about building bridges. Engineers learned from their mistakes, and now bridges are reasonably safe.

Civilization needs power. All forms of producing it have risks and benefits. Nuclear power generation suffers from the fact that its disasters are obvious. The risks from coal-generated power is are so easily measured, and so they are more easily swept under the rug. But putting in the effort clearly shows that coal is much more harmful that nuclear.

Humans are lazy. They want easily quantifiable comparisons, even when they are not valid.

Re:Um, don't safe reactors already exist?

[dave420]

I'd be more worried about the water-soluble uranium getting everywhere.

Re:Um, don't safe reactors already exist?

[Microlith]

get rid of that stuff asap

Very well. Oh by the way, starting next week a coal power plant is going in near next to your neighborhood, the fly ash is going to be stored in retention ponds on the hill above your property.

At least it's not Nuclear!

Re:Um, don't safe reactors already exist?

[CapOblivious2010]

If only there were some way that a nuclear power plant could generate electricity, then external power failures wouldn't be a problem... nah, that could never work... oh well, it was a nice thought. Maybe some day....

Re:Um, don't safe reactors already exist?

[maxume]

And all the (apparently) corrupt regulators. And Toshiba and Hitachi.

I don't mean to defend GE (I'm not terribly sold on the utility of megacorporations), but you sure are painting a nice simple picture of things.

Re:Um, don't safe reactors already exist?

[Khyber]

"All forms of producing it have risks and benefits."

Power itself is a risk. You can kill yourself, others, or the entire planet with it.

Even simple solar panels on the desert ground will cause ecological damage.

Barring that caveat, I would be inclined to argue that solar power (the ultimate power source in the system) is the best and safest means of acquiring/generating/tweaking power to our needs. Right now, using 1/10th the power that the sun shines upon every square meter on a cloudless summer day at noon, I can produce 5-8x the amount of lettuce or spinach in the same space with LED. If we can even hit 50% PV efficiency, feeding the world for the next century - including any unexpected catastrophic population burst - is almost zero problem.

Though, I'd almost expect enforced population control to come into effect before that, or at least human expansion into space.

Re:Um, don't safe reactors already exist?

[Korin43]

Wouldn't it have to be a really big tower to get the pressure high enough?

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Well, let's discuss it that way then. Who wants nuclear technology if we have to admit that we do not know how to use it safely? Apparently there aren't many people who do, because there appears to be a strong urge to belittle people's worries and tell them that there are safe designs, which we know is a big fat lie. I suspect that the difference between collapsing bridges and out of control nuclear reactors is the area which becomes uninhabitable for hundreds or thousands of years as a result.

Re:Um, don't safe reactors already exist?

[Mspangler]

"One big tank on that big hill behind the plant,"

(Pardon my English Engineering units)
Let's see, 2.3 feet per psi, 1000 psi steam pressure (According to wikipedia, sounds a bit high to me) so we are looking at a 2300 foot high hill. If it's 600 psi steam, at least after shutdown, then it's only about 1700 feet of hill.

And the big tank has to still be there after the 9.0 earthquake. There is more complication in "All they needed" than you think.

The basic design is supposed to have a steam powered feed pump with a source of makeup water. Whether it broke, was never there, or the source of makeup water was a condenser that was mudded out by the tsunami, I don't know. And I would like to know. I used to serve on an SSN, so I have a certain professional curiosity.

Re:Um, don't safe reactors already exist?

[Khyber]

"Causes for failures on the JA plants were many.
Besides being under-designed for a 9 earthquake (7.? designed)"

AND IT HELD

"and a too low tsunami wall to hold up the one occurred,"

BUILT TO STANDARDS MADE BY PREVIOUS RECORD TSUNAMIS

"there were failures in maintenance/upkeep/supervision."

And *THIS* matters not when #2 was an unforeseen consequence, and is therefore moot.

"And yeah, let that pebble core get compromised and the graphite fuel balls in there start burning... PU-239 is not your friend."

You assume that's the only way to run a pebble-bed reactor. Whooo you're way off, and there are other materials that would pretty much make it nearly-bulletproof unless someone were to purposely start an out-of-control nuclear reaction inside the core.

Part of the 50's generation, are we?

Re:Um, don't safe reactors already exist?

[Khyber]

At least the radiation coming from the fly ash can be handled with thin layers of gold and lead sandwiching liquid mercury.

Re:Um, don't safe reactors already exist?

[peragrin]

large windfarms would kill off massive bird populations, and large solar farms will deprive the ground of sunlight. Tide farms will disrupt fish swimming.

The only answer is to kill off everyone but me and the 50 hottest models on the planet. I will keep them alive and we can restart the human population safely.

Re:Um, don't safe reactors already exist?

[DurendalMac]

Solar power still has a long way to go before it's viable, both as a power source and as an economical power source. I sure as hell hope it gets there soon (I keep seeing stories about breakthroughs in solar, but have yet to see these seriously materialize in the market), but it isn't there yet and we can't say when it will be.

And quite frankly, if what I hear about breeder reactors is true, I'm surprised that the US hasn't build one at Hanford and fed all that leaking nuclear waste to it. Power and disposal all in one.

Re:Um, don't safe reactors already exist?

[CrazyDuke]

Interesting. Just a guess, but, I take it the problem is the containment is breached due to a combination of thermal stress and the molecules and/or lattice being disrupted by neutron absorption and secondary decay? I have seen this in mildly radioactive geological samples, where the isotope bearing crystal irradiates the surrounding rock over millions of years, wreaking it, leaving a tell-tale star-burst pattern. Or, perhaps the high energy neutrons are making it out of the bed and into the surroundings, inducing new radioisotopes outside of containment? I suppose the saving grace of the second one would be the short half life of the created material.

Do you have any links to any academic research, studies, or articles on the subject?

Re:Um, don't safe reactors already exist?

[mcguiver]

A lot of the safety of the pebble bed design comes from the TRISO fuel particles that it uses. In the even of an accident like the one at Fukushima there would be no concern over the fuel melting down since the power density is so low and the melting point of graphite is so high there is no possible way for the fuel to melt down. These particles can be used in any sort of a Very High Temperature Gas Cooled Reactor, of which the gas cooled pebble bed and prismatic designs are both very attractive options. The helium atmosphere in the core cools and helps to inhibit the ignition of a graphite fire.

The problem with the pebble bed reactors of releasing Cs and Sr are both due to the design of the TRISO particle. The TRISO particle has a silicon carbide (SiC) layer that provides structural stability as well as stopping for most fission products. Unfortunately there are a few fission products (Cs, Sr, Ag especially) that are able to pass through the SiC in significant quantities. There is research going on to investigate the use of zirconium carbide (ZrC) in addition to SiC in the TRISO particle. The addition of this layer provides many benefits, including the ability to stop fission products that SiC can't stop.

As a side note, TRISO particles also make a great waste form. Graphite doesn't dissolve readily in any natural environment and would be able to remain intact for millions of years.

Re:Um, don't safe reactors already exist?

[Graff]

If we can even hit 50% PV efficiency, feeding the world for the next century - including any unexpected catastrophic population burst - is almost zero problem.

Of course, photovoltaics are in the neighborhood of 7% - 17% right now so we have a LONG way to go.

Solar cells are a technology still in its infancy and it will be years before it actually outperforms coal for power/pollution. It may never be able to compete with nuclear fission for that ratio.

Overall we are best off building fission plants and spending our R&D money on perfecting fusion technology. That's the real ultimate power source in the system, being able to control nuclear fusion directly instead of needing to collect a fraction of the energy thrown at us by the sun.

Re:Um, don't safe reactors already exist?

[Sulphur]

Fit the diesels with a snorkel. Two pipes supported by the containment building: One for air, and the other for exhaust.

From time to time, start the diesels and later add steam to get white smoke to remind everyone that you are thinking of safety.

Either design the backup power building to run 10m underwater or move it up.

Re:Um, don't safe reactors already exist?

[bmo]

>The only answer is to kill off everyone but me and the 50 hottest models on the planet.

You want 50 wives?

Are you insane?

Obviously, you have never been married.

--
BMO

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

To the OP :

Your points are well taken, but if the Slashdot editors thought like you do
this would obviate the chance for that fat prick and his company Intellectual
Vultures to get a free advertisement.

Re:Um, don't safe reactors already exist?

[no-body]

> You assume that's the only way to run a pebble-bed reactor.

No - but do you know of one running in production, smartypants?

Re:Um, don't safe reactors already exist?

[Redlazer]

There's also the Canadian built CANDU Reactor, known for its safety, flexibility, and efficiency:

http://en.wikipedia.org/wiki/Candu

Re:Um, don't safe reactors already exist?

[thebigmacd]

I have read that these reactors never had steam powered pumps.

Re:Um, don't safe reactors already exist?

[Hadlock]

Regan shut down the last breeder reactor in the US based on fears that it could be used by terrorists to create weapons grade plutonium, or something equally ridiculous. I think the Japanese and French are using breeder reactors these days.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Canada hasn't been in the bomb building business since the Manhattan Project Treaty was signed in Quebec City in 1943, (and Canada provided Plutonium for Britains first bomb, and sold a reactor to India, which they used to build a bomb). Canada has been building heavy water reactors for 60 years. Power loss (for example: an Ohio power company fails to trim trees in the middle of a heat wave in the middle of the summer. The load on the power grid is incredible due to temperatures over the entire North American Eastern Seaboard. The high current load causes power lines to heat up, causing them to droop. The heat from the ambient temperature has them sagging already, and when they make contact with the un-trimmed trees, and electrical ground fault occurs, causing the plant to shut down. The sudden loss of power and a software flaw in power routing and distribution computers creates a situation where power stations begin shutting down before lines can be disconnected. The final result is that all power plants in the North East United States stop producing power, creating a blackout. Several Canadian nuclear reactors are connected to the grid, and they shutdown. New York State Governor Hillary Clinton, upon finding that Canadian power plants are connected to the grid, promptly blames Canada for the problem. Due to the physics of the Canadian reactors, they are unable to restart for several days (power loss causes neutron absorbing rods to be inserted in the calandria fuel rods, disrupting neutron flux for several days, making the plant unable to restart for several days). You must electrically move the neutron dampers out of the calandria (fuel rods) in order for the reactor to start, and it takes several days for neutron density to build in order to create power. Its acts like an electric lock acting like a solenoid against a spring. Loss of power causes an immediate shutdown. If a spring should break, gravity will pull it down.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Don't be daft...you only marry 1 or 2 of them. The rest are just there to make the 1-2 you do choose feel insecure enough so that they'll really take care of you.

Re:Um, don't safe reactors already exist?

[tronbradia]

My understanding is that they are describing a fast breeder reactor, one of the two major types of breeder reactor. https://secure.wikimedia.org/wikipedia/en/wik/Breeder_reactor

Breeder reactors are not a mature technology and have not been put to widespread commercial use, so the field is pretty much wide open as far as which design should be adopted on a large scale. As far as I can tell, they are simply pushing this particular design as a way to get the ball rolling on wider adoption of breeder technology.

Re:Um, don't safe reactors already exist?

[davester666]

And don't the higher-efficiency photovoltaics depend on very rare elements, for which China is the primary source...

Re:Um, don't safe reactors already exist?

[uvajed_ekil]

There is more complication in "All they needed" than you think.

Not if you do it right. For example: all they need is unicorn-powered backup cooling pumps, and a 50m sea wall all up and down the coast. And maybe some ice-nine. Or alien technology. But that's it.

Re:Um, don't safe reactors already exist?

[lennier1]

A Nuclear reactor controlled by Windows systems. Sounds like a reliable approach!

Re:Um, don't safe reactors already exist?

[Khyber]

"Solar power still has a long way to go before it's viable, both as a power source and as an economical power source."

Forgive me for asking, but what cave have you been in? Producing 5-8x the crop with 1/10th the power the sun irradiates a square meter of earth, with 25% (and rapidly rising) efficiency (with LED tech RIGHT BEHIND it in generations improvements,) means that with current solar and LED tech I could produce possibly 15x what any natural-sun crop on the ground will EVER yield.

I already have several solar-powered sheds installed globally. They push a few million count per year of whichever vegetative crop you're after, lettuce, cilantro, parsley, spinach, in just under half an acre.

I think your 'Potential Solar Power Applications' list is too narrow-minded.

Re:Um, don't safe reactors already exist?

[Khyber]

Not even close, we've got 30% efficient solar cells using newer laser tech to etch more micro-channels into the silicon substrate. That alone generates a HUGE improvement in efficiency as surface area for photon capture is dramatically increased.

And that story was on slashdot a couple of days ago with DEMOS TO BOOT.

I'd ask the redundant DYRTFA? but this is /. after all so even the summary was likely never seen in the first place and was relegated to firehose history.

Re:Um, don't safe reactors already exist?

[Khyber]

"Of course, photovoltaics are in the neighborhood of 7% - 17% right now"

This isn't the '80s anymore, and I have plenty of those era panels still pushing about 15-17% efficiency.

We're at 30% minimum, now. They're what power my solar-powered rapid crop production sheds. Lettuce in the winter time usually takes 90 days to produce any usable crop. Current solar tech means a lettuce crop in winter is harvestable and in 19 days (versus 17 from natural sunlight) we can have that lettuce crop ready to go with full elemental and nutritional content of soil/sun-grown produce.

I think you're behind the times.

Re:Um, don't safe reactors already exist?

[BlueParrot]

The problem with pebble bed reactors is that even thou a thorium cycle could in principle be used to make them breeders, it is a royal pain to try to reprocess the spent fuel for recycling. It involves combustion of large quantities of radioactive carbon, which then has to be scrubbed out of the resulting exhaust. In general carbon is a problem in reprocessing operations because it forms a large variety of compounds and allotropes that are resistant to dissolution in nitric acid as well as molten salts ( the two type of solvents favored for reprocessing).

The corollary is that such reactors would be highly unsuitable for making weapons grade plutonium. It just isn't practical to run them on a short refueling cycle, which would be necessary for producing weapons material.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

out of control nuclear reactors is the area which becomes uninhabitable for hundreds or thousands of years as a result.

For example?

Re:Um, don't safe reactors already exist?

[stevelinton]

The basic design is supposed to have a steam powered feed pump with a source of makeup water. Whether it broke, was never there, or the source of makeup water was a condenser that was mudded out by the tsunami, I don't know. And I would like to know. I used to serve on an SSN, so I have a certain professional curiosity.

Ny understanding is that the pumps were there but the battery power for the controls of the pumps ran out.

Re:Um, don't safe reactors already exist?

[lisp-hacker]

These are reactors that (again) are called safe by their inventors, as the light water reactors before.
Of course these had some advantages over graphite moderated types, but are they safe in the sense that you press the red button an all problems stop?

For breeders, well you woudn't have the water-steam pressure problem, but without active cooling you get a temperature problem probably even quicker (high concentrations, high power densities). And yes of course you have fission products in the system, generating heat. I don't even want to know what happens if you reach 900 Degrees and the Natrium evaporates.

Besides the problem that Natrium cooling erodes the steel of every tank and tube around it, which is the main reason why most breeders are no longer running (outside of Russia, which does not care for safety). I wouldn't trust the stability of a 40 year old breeder.

For pebble beds: these are a German invention and they did long therm reasearch on that, the pebbles are called safe because the *should* withstand 2500+ Degrees and this temperature is inhibiting the nuclear chain reaction (negative temp coefficient). There was also the idea around that you could leave the reactor without active cooling -- this is releasing heat just by radiation. In practice this would mean, that a larger volume reactor reaches some 3000 Degrees inside, which melts down pretty much everything.

In practice the pebbles have also problems with high temps above 1500 Degs (breakage) and apparently release fission products as well (diffusion problem, loads of radioactive dust in the primary gas cooling). And there is a really dangerous situation, if the hot reactor gets in any water or normal air. The latter is not uncommon: there is a gas-water heat exchanger (which became dripping in the Test Reactor in Juelich) as well as they had problems with the air locks (for feeding/withdrawing pebbles).

The Reactors in Japan are apparently no longer intact, which probably means that a breeder or pebble bed would simply be burning now, due to the contact with water or air.

Re:Um, don't safe reactors already exist?

[hey!]

Sure, but let's not forget that what's causing the biggest concern at Fukushima right now is something that is supposed to be "walk away safe": the spent fuel pools. Which is not to say that "walk away safe" designs aren't worth pursuing. It just means our model for how something reacts to unusual circumstances is probably no reliable.

In a perfect world, we'd react to the prospect of peak oil by becoming more energy efficient, allowing our economy to grow as it transitions to sustainable energy sources (which will take a long time). I the world we actually live in, people will wait, demanding somebody to fix the problem of rising oil prices, and when it becomes absolutely clear even to people who haven't thought through the problem that it's not going to happen they'll demand a crash program of building nuclear plants. The anti-nuke crowd will point to the known inadequacies of the old boiling and pressurized water reactors, the pro-nuke crowd will get behind one of the new, walk-away-safe designs and we'll end up building lots of those and learning *that* design's unexpected inadequacies by experience.

What I think is we should start evaluating some of these new designs now and start building, not dozens of them, but one or two of the new designs. The important thing is that this will mobilize the anti-nuke people. Not the *dumb* ones, because they don't add to the process. The *smart* ones. We wouldn't *have* better designs if there weren't intelligent critics of LWR and PWR designs. The result will be another less than perfect world where peoples' pet ideas are shot down, nobody gets their way in entirety, at least right away, and we're forced to pay attention to a debate that feels like it will last forever because it's gone on for years. In other words a world that's much better prepared to go on a crash nuclear build-up if that's what's needed, and has thoroughly hashed over alternatives to that.

Re:Um, don't safe reactors already exist?

[jez9999]

You want 50 wives?

Are you insane?

No, just a mormon.

Re:Um, don't safe reactors already exist?

[AlienIntelligence]

Most of those problems are about shielding and disposing of the plant when you shut it down. The remainder can be solved by using a moderator that doesn't burn. You don't have to use graphite. You could, for example, use beryllium....

Brilliant!
I'll gladly trade Beryllium poisoning http://en.wikipedia.org/wiki/Beryllium_poisoning
for strontium and cesium contamination.

Is a sarc tag required here?

-AI

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Hömma kommse auch aus'n Tropen?

Re:Um, don't safe reactors already exist?

[TheTurtlesMoves]

You mean highly toxic beryllium, that also burns in air. Not really an improvement over graphite.

Re:Um, don't safe reactors already exist?

[TheTurtlesMoves]

If you are going to push a design that is "safe" and "this" and "that can't happen". Then you can't really start saying, "well that demonstrator didn't work because the pebbles are designed wrong". Your back at square one. Its not safe if you didn't think of everything. In particular pebble bed reactors are useless for anything but once through cycles, and quite frankly if we really are going to go nuclear, that's silly.

They had serious problems in plant that didn't have a earthquake and a tsunami.

Oh and when the earthquake cracks the main coolant loop and your helium leaks out? Then you have a nice graphite fire...

Re:Um, don't safe reactors already exist?

[TheTurtlesMoves]

It is also a different way of doing nuclear. Lots of smaller self contained plants that come and go as a single unit. This removes the massive capitol cost with nuclear that dominates the cost of energy from a plant. You also get economies of scale, because you are building the same design many times.

Re:Um, don't safe reactors already exist?

[Magada]

The TRISO particle is mostly a lump of charcoal. With the pebble bed design, you can get one of two major issues:
a. oxygen (i.e. outside air) incursion - obviously, results in a fire
b. water (i.e. secondary coolant) incursion -results in at least a steam explosion, if not explosion+fire, if not even a (localized?) power excursion from the temperature drop and additional moderation.

This, for a design that proposed doing away with containment vessels.

Smaller issues include: pebble cracking from thermal stress, pebble erosion, densification of the pebble bed above design density resulting in localized hotspots, lack of control over cycle length for a given pebble, impossibility to recycle pebbles.

Compare and contrast with, for instance, the CANDU design, where each rod can be manipulated separately and breach of the primary coolant loop results in your heavy water leaking into, well, heavy water.

Re:Um, don't safe reactors already exist?

[lisp-hacker]

Beryllium is melting at about 1500 and will burn as all other metals in that group. And of course burning moderator that blows radioactive dust and aerosoles into the air is causing a problem. The most prominent example is 25 years old, in the Ukraine and still warm.

Re:Um, don't safe reactors already exist?

[lisp-hacker]

Do we really have to keep watching reactors fail in unexpected ways

That's the way progress works. Bridges, for example, used to collapse often enough that it was obvious we didn't yet know enough about building bridges. Engineers learned from their mistakes, and now bridges are reasonably safe.

Well, as usual for architectural and medical failures you can grow Ivy on the remains and forget about it.

You should still not grow anything useful in certain regions of Ukraina and Belorussia for a reason and this will be the case for a couple of generations. Ukraina is still spending 5% of their gross national product on the remains of the accident 25years ago. IMHO this should be a difference for anybody who is not extremely short-sighted.

Re:Um, don't safe reactors already exist?

[Electricity Likes Me]

Since people like you would stop even research reactors on the concept being constructed, what's your point?

The anti-nuclear lobbyists have a lot to answer for since they seem perfectly happy to just make developing technology impossible in the idiotic belief that they can choke the industry out of existence without hazard.

Re:Um, don't safe reactors already exist?

[fritsd]

Well, I'm not sure, but for example this waste pool B30 in Sellafield; according to the Wikipedia article it contains Plutonium (presumably Pu-239, half-life 24 200 years) and you can't stay for longer than 2 minutes next to it. That means in the year 244 011 you could stay for more than a day next to it (34 hours). Timespans so large are meaningless. 200 000 years ago was called the "Middle Pleistocene" when Fred Flintstone probably felt more at home than you (think: Smilodon, Mastodon (an uncle of mine once found a molar while fishing on the Oosterschelde), the Würm ice age covering Britain (incl. Sellafield) under 1 km of ice).
WHO is going to clean this mess up?!?? Do you volunteer to work there? Remember, radioactive elements can not be changed by any chemical process, they have to be transmuted in a nuclear reaction or you have to wait until they are naturally decayed.
Imagine good old Fred Flintstone leaving us this mess, I'd hate him for it despite his good-natured antics.
</long_incoherent_rant>
The gist of my incoherent ranting is: the kind of people who are in favour of nuclear fission energy have no concept of exponential processes or of time. There, I said it.
That means the onus of cleaning things up afterward falls on the taxpayer (our far descendants).
TMI, Pennsylvania, USA finished 1993 (14 years, $1 billion, yay!)
THTR-300 pebble bed thorium reactor, Germany 2027
Dodewaard, Netherlands 2045
AVR, Jülich, Germany late 21st century
Superphénix liquid Sodium breeder, France ???
Sellafield, UK ??? profit
Chernobyl, Ukraine ???

Re:Um, don't safe reactors already exist?

[no-body]

Since people like you would stop even research reactors on the concept being constructed, what's your point?

The anti-nuclear lobbyists have a lot to answer for since they seem perfectly happy to just make developing technology impossible in the idiotic belief that they can choke the industry out of existence without hazard.

Really, is that what's in your mind?

"pro-nuclear lobbyists" - About 5,080 results
"anti-nuclear lobbyists" - About 9,580 results --- Yess! we win!

"nuclear lobbyists" - About 12,700 results - oh shit - you win:

http://www.namavoice.org/index.php?ht=display/ContentDetails/i/4553081

Sure a lot of dough trying to make it right.

Re:Um, don't safe reactors already exist?

[MachineShedFred]

John Kerry played a big part in shutting it down too. You know, those Democrats that are championing global warming, Kyoto, and carbon trading schemes?

Re:Um, don't safe reactors already exist?

[diegocg]

That doesn't explain why it wasn't designed to replace generators or provide alternative power sources quickly. It amazes me that it took so many days to solve it, and they needed to install a new 1.5 kilometers long cable. Which was hard and took several days, because there was too many radiation in some reactors.

Why aren't all reactors required to have a 1.5 km emergency cable? Why they pretend that prevention will always work?

Re:Um, don't safe reactors already exist?

[Thelasko]

The thing that bothers me about pebble bed reactors is the graphite moderator. Graphite is combustible, and burning graphite is what caused the crisis at Chernobyl. I know they take precautions to make sure the graphite never comes in contact with oxygen, but that seems futile when it's present in so much of our world.

Personally, I favor passive cooling, like the AP1000.

Re:Um, don't safe reactors already exist?

[Ihlosi]

That doesn't explain why it wasn't designed to replace generators or provide alternative power sources quickly. It amazes me that it took so many days to solve it, and they needed to install a new 1.5 kilometers long cable.

Remember the 8.9 earthquake and the tsunami? Things like that can really mess up your reactor-saving efforts.

Re:Um, don't safe reactors already exist?

[mcguiver]

The Pebble Bed reactor design does have problems, that is why I am more of a fan of the prismatic VHTR design. With the prismatic design you have fuel stacked in long cylindrical compacts that can be placed in a reactor much like current fuel rods are packed and placed. Research is also being done on the VHTRs to allow them to use a Brayton cycle system to generate electricity. This allows the hot gas to directly turn the turbine. This means that there is no water to create steam and all associated problems with that. Air incursion creating fire is also not an issue. The thermal density is so low that the temperatures in an uncooled reactor will not get high enough to cause combustion, even in the presence of air. The single loop system does not pose the same contamination threat as BWRs since the helium does not carry any heavy fission products as well as water does.

Early US TRISO designs had problems with pebble cracking, erosion, densification, kernel migration, and a host of other problems. Manufacturing procedures have greatly improved and tests have shown that TRISO particles are capable of almost 20% burn up with virtually no failure (much less than 1 in a million). Is this design perfect and completely fool-proof? No. Anyone who claims that a design is fool-proof is either ignorant or a lier. However, with a prismatic VHTR reactor the probably of catastrophic failure is very remote.

Re:Um, don't safe reactors already exist?

[Dabido]

The Germans shut down their pebble bed reactor after releasing radiation to the atmosphere when one of the balls got caught (when being rotated through) and almost caught fire. A nearby earthquake could cause something like that to happen again. It might be immune to the same problem that Fukushima has, but it would still have a major problem. The reason for a new type of reactor is because there isn't a design yet which hasn't had a problem at some stage somewhere. Even the 'Advanced BWR (Boiling Water Reactors)' that the USA have now, have had problems. The Japanese Fukushima reactor was an old BWR that was only days away from being shut down (26th of March was the due date). Japan really should go Geothermal. But a new reactor design is sorely needed to get over the many problems with the other designs. Safe reactors don't exist yet, but pebble beds etc are safer than the BWR's a lot of places still have. This article is really just an advert for Terrapower to try and sell a new design. To use a car analogy, Fukushima is a like an old model T Ford, with all it's problems, the pebble beds are like car with crumple zones and the new design is like they've added some air bags.

Re:Um, don't safe reactors already exist?

[mcguiver]

Quick correction. I am not sure about shut-down temperatures in the Prismatic VHTR and if they are/are not high enough to cause graphite fires in the presence of oxygen. The statement I made came from looking at spent fuel (a project I am working on right now). Spent fuel in storage is safe from graphite fires and can be safely stored in oxygen environments.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

lettuce, cilantro, parsley, spinach

Is that what the kids call it these days? How do LEDs compare to other grow lamps?

Re:Um, don't safe reactors already exist?

[tehcyder]

Most of those problems are about shielding and disposing of the plant when you shut it down

Well solve those problems then. It's not like they won't still apply when you use them in a production environment.

Re:Um, don't safe reactors already exist?

[Magada]

Shut-down temperatures are exactly equal to the operating temperature, i.e. about 1270 K, at least immediately after a scram (or maybe I am misunderstanding your comment).

Frankly, I think graphite should have been abandoned for good after Chernobyl. I see some promise in modern molten lead reactors, although the Russian sub models from which they are derived don't exactly have a stellar safety record.

As for molten salt designs, especially the MOX-burning kind, they give me the nuclear heebie-jeebies. The piping corrosion issues are constantly downplayed, even after Superphenix and Dounreay PFR.

Re:Um, don't safe reactors already exist?

[tehcyder]

Fukushima Daiichi was built to withstand a 5.7m tsunami, as required by Japanese regulators. It was hit with a 10m tsunami, though, which is why the generators were knocked offline.

I'm not sure if you think that is an argument for or against nuclear reactors.

Re:Um, don't safe reactors already exist?

[tehcyder]

I'd be more worried about the water-soluble uranium getting everywhere.

It's perfectly safe as long as you don't drink it.

Re:Um, don't safe reactors already exist?

[tehcyder]

Yes, there is only a simple binary choice between nuclear or coal-fired power stations, well spotted.

Re:Um, don't safe reactors already exist?

[Khyber]

http://tinypic.com/r/2r5gleg/7 - does that look like marijuana to you?

LED wins hands down. The tech has matured enough. Watt for watt LED destroys all HID.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

Everybody keeps talking about pebble bed reactors. Where's the love for the energy amplifier? Basically, you stick a particle accelerator next to the reactor and feed the reaction with neutrons from spallation. Some of the energy acquired from fission can then be used to pay off the energy demands of the accelerator; and because the accelerator can be tuned, it can make use of ordinarily tricky fuel -- like thorium or what we call "nuclear waste". If it ever seems to be getting out of control, shut down the accelerator and everything stops.

Re:Um, don't safe reactors already exist?

[Martin Blank]

It's just a statement of fact. Any structure will be built with shortfalls. For whatever reasons, Japanese regulators figured that the highest tsunami within a given probability range was 5.7m or less. The odds of a tsunami of a given depth decrease markedly as that depth goes up. For sake of argument, let's say that the odds were given as 1% that a tsunami larger than that would hit. A 6m wall of water would fit that, but so would the 10m tsunami that actually hit. The difference is that the latter was even less likely. But sometimes luck isn't just against you, it comes backed by artillery.

Re:Um, don't safe reactors already exist?

[Karhgath]

Why does it have to be either an argument for or against? Can't it simply be a fact?

Since it's a pet peeve of mine, the following is a biased rant that I have to get out of my chest...

A fact shouldn't be encumbered by bias. The rest is up to you.

You can try to make one or many "general" conclusions(which are somewhat biased) based on the fact in the parent post :
- Regulation might be lacking
- They were short sighted and should have known better
- It was extraordinary circumstances and thus couldn't/wouldn't plan for it
- It is a design flaw/bad maintenance ... or more, any, none of the above

You can _then_ interpret it based on your views and bias and make it means whatever you want:
- Since nuclear power is unsafe and dangerous, it should never fail under any circumstances and thus shows why it is dangerous!
- It is perfectly safe since it needed an unlikely chain reaction of events led to this state, which is more than we can say about BP's Oil Rigs.
- Hey so let's plan against nuclear strike and alien invasion then!?
- It is just propaganda by the media and environmentalists to slander nuclear power's rock solid reputation! .. or whatever bias you want.

Why do you want someone else to interpret it for you? We can do that ourselves. ... Something the media should understand but obviously don't. (my biased conclusion)

Re:Um, don't safe reactors already exist?

[Martin Blank]

Ever seen what a landscape looks like after a major earthquake like that? It's really hard to get around. Drag in mud and debris from a tsunami, and it makes it even harder. Add in frigid temperatures that have been below freezing for at least parts of the day, and you have stagnant water and ice. That cable had to be brought in by truck, and the path for that truck had to be cleared by heavy equipment, and the fuel for that heavy equipment had to be brought on-site as well. It's a more complex job than it looks.

And all of that was before factoring in the radiation.

Re:Um, don't safe reactors already exist?

[Shotgun]

No there are several other choices. For instance, your backyard will be getting a windmill. That will give a nice short distance to power your electric vehicle. Your noise reducing earmuffs should be arriving by UPS, and do please do try to avoid the flying ice in winter.

Re:Um, don't safe reactors already exist?

[HungryHobo]

Forget the solar part, the high efficiency indoor growing looks far more interesting.
Are those LED's putting out light at a frequency the plants can absorb unusually well?

I imagine such tech could be very useful in colder climates where energy is cheaper like iceland.

Re:Um, don't safe reactors already exist?

[HungryHobo]

The gist of my incoherent ranting is: the kind of people who are in favour of nuclear fission energy have no concept of exponential processes or of time. There, I said it.

That's a great example of the fuckups with the early weapons programs, but that has nothing to do with power generation.

In practice most of the radiation from waste like that isn't due to their plutonium or uranium content but rather far shorter lived fission fragments.
The more radioactive it is the shorter lived it is.

if we're talking costs of energy production make sure to compare those figures to cleaning up the billions of tons of CO2 and the millions of tons of arsenic from coal, recycling the trillions of tons of solar pannels every 30 years with solar and all the industrial runoff producing them would cause if we were to power everything with solar, all the cleanup costs and environmental impacts from oil spills, the cleanup costs from steel foundries and mines for building millions of wind turbines.

etc
etc
etc
etc

Re:Um, don't safe reactors already exist?

[mcguiver]

Yes, the reactor temperature immediately after a scram is about 1270K, but I don't know how quickly that drops. I know that power levels drop quickly I just don't know what the heat profile does. I am not sure about the combustion danger in a prismatic VHTR (my area of interest is nuclear waste). From what I have read, combustion doesn't seem to be a major concern. When the reactor scrams the heat generation rate drops quickly. If depressurization occurs, indicating a breach in the reactor vessel, it seems that the failure mode would be to open up all the valves and allow the air to come in and let convective cooling happen. Graphite is thermally conductive and so I wouldn't expect the surface temperatures to remain above 850K for very long (I believe that 850K is the oxidation temperature of the graphite). You have me interested in this, I am going to have to do some research.

The major problem with Chernobyl was the combination of graphite and water. The using graphite seems to be a smart way to go. I really like it from a waste containment perspective, if SiC and ZrC are used in conjunction with it. I completely agree with you by being freaked out by the thought of molten salt reactors. I think that there are much better options available.

Re:Um, don't safe reactors already exist?

[mcguiver]

Pebble bed and prismatic reactors can incorporate a variety of fuels. I have read research papers where recycled LWR fuel has been used in them. It is true that the TRISO fuel is not easy to recycle, but it does make a great waste form. We could take all of our current waste, recycle it, and turn it into VHTR fuel. After this stuff is burned up then it is already in its final waste form.

I am not an expert on failure risk analysis on these reactors, but those that I have talked to don't seem concerned. If the helium leaks out you will not have a deflagration fire (the temperatures aren't high enough) but you could get oxidation. Oxidation of graphite is a problem since it produces CO2 and the carbon will gas itself away. If all the carbon were to do this, the fuel is still contained within a SiC core which will prevent release of major fission products. However, it is unlikely that all of the carbon will volatilize. If the reactor loses the helium then opening all the valves will allow for natural convection to cool the fuel. With all reactions stopped it won't take long for the reactor to cool below the graphite oxidation temperature. Thus it is unlikely that enough graphite will will lost to expose the SiC layer, let alone the fuel.

Re:Um, don't safe reactors already exist?

[Magada]

The heat profile does nothing much out of the ordinary. It takes hours (afaicr) to go down to manageable temps If you have cooling for the period it takes, all is fine and dandy. If not... as you note, oxidation temp is way below operating temp.

As for waste containment: why do we contain it when we can burn it further? Why more CANDU reactors aren't being built to at least partly deal with "spent" fuel from PWRs?

One other pet source of amazement for me is why the don't we take all this "spent" fuel we are currently assiduously not dealing with and arrange it, in small bundles, around some efficient neutron sources (fusors, maybe?) and then power Stirlings with the resulting heat.

I'm quite aware it wouldn't be thermodynamically very efficient. However, just cooling them down as we currently do has negative efficiency.

Maybe you know more about why dealing with the waste in these ways isn't feasible?

Re:Um, don't safe reactors already exist?

[fbjon]

Latest estimate is that the wave was 14m high when hitting the plant.

Re:Um, don't safe reactors already exist?

[Shotgun]

We're sort of experimenting with small nukes now. Just about every new large warship has one. They are designed to be used in a friggin' WARZONE. How does a ship getting hit by an enemy cruise missile compare to and earthquake and tsunami?

The anti-nuke people get just about zero input into what the military chooses to do.

Re:Um, don't safe reactors already exist?

[Anonymous Coward]

potato / potahto

Re:Um, don't safe reactors already exist?

[dgatwood]

I don't think the melting point of beryllium would be a problem. The moderator is inside the sphere, not on the surface. The outer shell is ceramic. Thus, even at maximum operating temperature, it shouldn't be an issue. Besides, the uranium itself is liquid at the specified maximum operating temperature. I'm not sure how much difference it makes for the moderator to also be liquid, so long as it is still able to adequately moderate neutron emissions. (This might require an extra layer of ceramic to separate the two. I'm not sure.)

Then again, the only time the graphite would be an issue would be if the ceramic cracks, so you'd still experience a serious failure under the same conditions, just without the same devastating result (nuclear fallout) under said conditions.

Re:Um, don't safe reactors already exist?

[dgatwood]

Um.... You're not supposed to swallow the balls of fuel....

Re:Um, don't safe reactors already exist?

[lisp-hacker]

I don't think the melting point of beryllium would be a problem. The moderator is inside the sphere, not on the surface. The outer shell is ceramic.

No, you misunderstood the nature of the pebbles:
In the current designs only the Thorium/Uranium mixed with some small amount of carbon is embedded into a ceramic shield with 0.5mm size (TRISO-Particle). 15000 of these tiny spheres are then embedded into graphite balls of about tennis ball size for mechanical handling.
The graphite in the outer ball is moderating the reactor and transfers the heat to the He-N Gas flow. Graphite is also meant to 'lubricate' the movement of balls inside the reactor, but apparently this does not work in the hot and dry atmosphere.
Therefore replacing graphite with a metal would leave you with a molten mess.

Re:Um, don't safe reactors already exist?

[hey!]

Well, I'm not sure the engineering trade-offs between a civilian nuke and civilian safety are the same as they are for nuclear powered warships. For one thing, the reactors on nuclear vessels are much smaller. Making a large civilian power plant as robust as a small military reactor might well mean it isn't economical. Capital ships tend to be cost-is-no-object items.

The worst case in a nuclear accident would be fire carrying radioactive material away from the reactor in a plume of smoke. In that worst case on a ship, you'd scuttle the ship. That's not environmentally desirable, of course, but it's better than letter her drift, uninhabitable and contaminating everything downwind. Chances are there would be no civilian casualties, and if it were in deep water no economic impact. The same accident on land would be an economic disaster.

The number of deaths due to a radiological accident after an attack have to be considered in light of the number of casualties from the attack per se, and then in the total strategic context. In other words, people die in attacks on warships, conventional or nuclear. The increased casualties due to radiological accidents have to be balanced against the overall reduction in casualties from the strategic benefits of powering capital ships with nuclear power.

So I don't think you can point to our choice of powering military vessels with reactors as proof that the technologies used in them is safe enough, cost effective, and scalable to civilian needs. We should be designing reactors specifically for the scale on which and the environment in which they'll be used.

Re:Um, don't safe reactors already exist?

[Martin Blank]

Wow... I just can't imagine having to deal with a wall of water that high. I've been trying here and there to find the rationale for the 5.7m protection, and learned that no evidence of a larger tsunami in that area in the last several centuries could be found. I believe I also heard this morning on NPR that seismologists believed that the maximum earthquake possibility along the fault that was responsible for the main quake was 7.8, some 60 times smaller than what actually hit.

Re:Um, don't safe reactors already exist?

[LandGator]

1) Breeders have no inherent safety; read up about the Enrico Fermi I partial meltdown in Monroe, MI. http://en.wikipedia.org/wiki/List_of_civilian_nuclear_accidents#1960s http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucacc.html 2) Pebble bed reactors are a nice idea, but the two actually made were leaky and contaminated the nearby area: The fuel temperature instabilities during operation with locally far too high temperatures, mentioned above in the criticism section, resulted in a heavy contamination of the whole vessel by Cs-137 and Sr-90. Some contamination was also found in soil/groundwater under the reactor, as the German government confirmed in January, 2010. http://en.wikipedia.org/wiki/Pebble_bed_reactor#AVR The release of radioactive dust was caused by a human error during a blockage of pebbles in a pipe. Trying to restart the pebble movement by increased gas flow led to mobilization of dust, always present in PBRs and—due to an erroneously open valve—to an unfiltered dust release into the environment. http://en.wikipedia.org/wiki/Pebble_bed_reactor#Thorium_High_Temperature_Reactor Anyone made a pebble bed reactor yet which was economically feasible as a power generator? Answer: No. 3) ..breeder reactors have the added benefit of eating nuclear waste over and over until whatever is left might make you sneeze. Answer: No.

Same as it ever was

[drsmack1]

Of course any new reactors designed will have safeguards against any previous disaster - it's the ones that never happened before that fuck us.

Re:Same as it ever was

[monkyyy]

now if only this applied to all parts of life

Re:Same as it ever was

[LordLucless]

The thing is, even prior to this disaster we had designs that would have safeguarded against it (Pebble Bed Reactors aren't new). It just cost too much to tear down the old ones and build nice safe ones. Well, now we have a nice, big example to point to of why fiscal conservativeness is not always the most effective long-term strategy.

Re:Same as it ever was

[blair1q]

Depends on who's doing the thinking and who's doing the spending.

The thinkers can only fuck us by lacking imagination, and the spenders can only fuck us by making sure the thinkers lack imagination.

Re:Same as it ever was

[ColdWetDog]

See above for the comments on Pebble Beds. It appears that even after decades of research and engineering into nuclear reactors, we still don't know enough to be confident that any particular design or implementation will behave the way the designers expect. Not exactly surprising since anything more complicated than a paper towel seems to have those same issues but it does mean that any progress will have to come slowly and hopefully carefully.

Just because it looks good in Autocad doesn't mean it will actually work correctly.

Re:Same as it ever was

[giorgist]

So now we have plannd for the 1/100 years event.
When the 1/1000 years event strikes, we will plan that as well.

For example spontaneous volcanism, 1000 tonne meteor strike.

G

Re:Same as it ever was

[LordLucless]

Well of course not; we're never really certain about designs until they're put into practice, and frequently not even then.

What I was arguing about was the GPs assertion that reactor design is only driven by our mistakes; that after this disaster we'll design for cooling failure, but not before. That's incorrect - we've designed (or attempted to design) for precisely this sort of disaster for decades. Our designs may not be perfect, but they show an awareness of the problem driven by something other than hindsight.

Re:Same as it ever was

[PeterBrett]

For example spontaneous volcanism, 1000 tonne meteor strike.

With a 1000 tonne meteor strike we'd have more to worry about than a little bit of radioactive material. Like the trifling matter of the global nuclear winter, for example.

Re:Same as it ever was

[TheTurtlesMoves]

1000 tons is not that much.

Re:Same as it ever was

[MachineShedFred]

Fiscal conservatism has absolutely nothing to do with why the current production fleet of reactors are mostly 30+ years old. Hint: if the utility companies *could* build new plants, they *would*.

Re:Same as it ever was

[Anonymous Coward]

Perhaps not, but 1000 tons at 10000 km/h is quite a bit of KE.

Re:Same as it ever was

[MoriaOrc]

One would think that with a 9.0 earthquake and devastating tsunami, Japan would have more to worry about than a little bit of radioactivity. Like the thousands dead and millions displaced, enormous amounts of property damage, and land already rendered useless for farming for several years due to the tsunami. But yet here we are talking about the nuclear plant.

Re:Same as it ever was

[LordLucless]

In the US, maybe. In Japan, their most recent reactor was opened in Dec, 2009 (Tomari-3). It's a PWR.

My point about fiscal conservativeness isn't limited to the nuclear industry, though. It's endemic.

Re:Same as it ever was

[Anonymous Coward]

Political tie-in FAIL.

Re:Same as it ever was

[LordLucless]

Comprehension fail. "Conservative" doesn't always reference politics.

Pebble Bed

[schmidt349]

Supposedly the pebble-bed reactor type is also resistant to the type of damage suffered at the Fukushima plants, and it has the added bonus of not being encumbered by ex-Microsoft patent trolls. I remember reading that the Germans had been experimenting with the design but dropped it for political reasons.

Re:Pebble Bed

[Anonymous Coward]

Actually, the pebble reactor in Julich, Germany (I'll assume that's what you are referring to) had severe problems leading to long half-life fission products contaminating the soil and water around the reactor.

The flaws are not based on the particular design of the AVR facility, but seem to be flaws in the whole pebble-bed idea. You can read the Julich Research Facilities own post-mortem here: http://www.eskom.co.za/content/AVR-Report-Press.PDF

Re:Pebble Bed

[Anonymous Coward]

Um, no. While http://en.wikipedia.org/wiki/Pebble_bed_reactor mentions political reasons as well as economical ones, you should keep in mind that the pebbles are graphite-based, so if the brown stuff really hits the fan, you get a Chernobyl-like fire and thus a larger area of contamination. Also, the Chinese test reactor is said to have suffered from pebble deformation - which makes unloading depleted pebbles rather difficult (and the Germans suffered an accident that released radiation due to just the same problem).

Re:Pebble Bed

[nedlohs]

With those political reasons being the radiation leaks, contaminations, the plant operator covering up and lieing about the the problems, and so on.

Re:Pebble Bed

[Anonymous Coward]

I remember reading that the Germans had been experimenting with the design but dropped it for political reasons.

PBRs make beautiful paper reactors. The real world, however, is adverse to giant piles of super heated uranium laden graphite that erupts into a vicious fire in the presence of oxygen and must therefore be somehow permanently isolated from air, water or any other substance that might provide oxygen. The primary ingredient of a tsunami is sea water, btw.

Also, uneven cooling causes damage to the fuel leading to contamination. Cooling a PBR is a fluid dynamics problem that will probably never be solved. When decommissioned, the AVR reactor was found to have a large crack that captured fuel pellets. Cracks are really bad when you have to isolate all that hot, fire prone graphite.

As for the traveling wave reactor, I see two big problems. First, it's sodium cooled. Molten sodium isn't compatible with power generation; a leak of molten radioactive sodium is a heinous problem with extreme consequences for a power generation industry that has proven it can't be expected manage mere water, much less anything as unforgiving has molten sodium. Second, you can't shut off a traveling wave reactor. There is no SCRAM. It will burn until the fuel is exhausted. Earthquake? Tsunami? War? LOCA? Doesn't matter; the reactor keeps making heat.

Light and heavy water reactors are very forgiving. Small, common coolant leaks don't make the news because it's just water. SCRAM is always just one push of the big red button away.

Could we perhaps not site reactors in the path of tsunamis? Yes. Would it be a good idea to develop a strong response for reactor blackouts like Fukushima? Yes. Could we let grownups address the spent fuel issue and not leave vast quantities of barely protected spent fuel at reactor sites? Yes. Would it be wise to decommission old reactor designs that are clearly less safe than anything the first world has allowed to be built in 20+ years? Yes.

See? Not a single unstoppable molten metal or graphite hell-mouth reactor in sight. A subset of those 'ideas' would have precluded Fukushima, a name you would then never have known.

With the exception of the spent fuel pools, the problems encountered at Fukushima could have been handled without drama by AP1000 light water reactors, a design that will passively cool itself when circulation is lost due to a blackout. You don't need to take my word for that; China is going to build multiple plants of these reactors on their own coast, right in the path of inevitable tsunamis.

Thorium??

[Kickboy12]

Once again, Thorium is ignored as a solution. Thorium is cheaper and easier than TerraPower's concept, yet it is continually ignored.

Re:Thorium??

[Anonymous Coward]

It's not ignored. Thorium energy is under development in India for example. This is just ANOTHER solution.

Why do you have a problem with that?

Re:Thorium??

[drsmack1]

I must confess, you have an astonishingly good idea there, Doctor.

Cobalt Thorium G is even better - if it is a shroud you're wanting.

Re:Thorium??

[kevinmenzel]

It's not ignored. CANDU reactors can use Thorium. That means, for example, all of Ontario, Canada's reactors (which provide more than 50% of Ontario's power mix) could switch to Thorium without problems.

Re:Thorium??

[Anonymous Coward]

AFAIK, it doesn't produce viable weapons grade materials unlike other present reactor designs and implementations

Overall benefit for mankind, but unfortunately M.A.D. still haunts the psyche.

Re:Thorium??

[sh3p]

That sounds like an awesome idea, and it appears we Canucks have plenty of Thorium. Why isn't this being done??

Re:Thorium??

[Anonymous Coward]

I agree. I cannot believe Thorium is not recognized as the obvious answer. In the near term, thorium can be used to consume our uranium and plutonium waste and in the long term new nuclear plants can be sub-critical reactors that are melt proof since they require constant excitement from particle accelerators. Additionally we have one of the largest reserves with enough to produce our power needs for a thousand or more years. The only barrier is overcoming the existing industry and overcoming the ignorance of both our politicians and the public.

Re:Thorium??

[Anonymous Coward]

Actually read this:

http://www.telegraph.co.uk/finance/comment/ambroseevans_pritchard/8393984/Safe-nuclear-does-exist-and-China-is-leading-the-way-with-thorium.html

China is about to produce and use Thorium reactors.

Re:Thorium??

[Nimey]

Anthrax Leprosy Mu best of all.

Re:Thorium??

[Anonymous Coward]

Excellent, I knew my salt mine futures would pay off.

Re:Thorium??

[rbrander]

"Whenever the question is, 'why don't they...', the answer is, money" - Heinlein (roughly)

Wikipedia "Candu". The article runs down all the special features. It's the multi-fuel stove of reactors, able to burn other reactor's waste, old nuclear weapons. The last comment, after enthusing about that, is that it can "breed fuel from thorium". So it's an extra step, and thorium isn't cheap enough (or uranium is) to make it worthwhile.

Still, it's bonus that they're proof against the year of Peak Uranium.

Re:Thorium??

[TheTurtlesMoves]

This is not true. Th232 is not a fuel, it is fertile. You smack a neutron into it to get P233. You *need* to separate out the Pa233 as its created, otherwise you end up absorbing too many neutrons. Pa233 decays into U233. Now that you can use as a fuel... or in a bomb. In fact they did use it in a bomb. Since you can separate out the Pa233 as its created, you can have rather pure Pa233 with almost no Pa234 --the problem with Pa234 is that it decays into U234, which is not a fuel and is a horrible gamma ray emitter. You don't want it around even in a nuclear plant, so your going to be getting that Pa233 out as soon as you can.

If i have a bunch of Pa233, i just wait a few 100 days, and now i have almost 100% pure U233.... nice of making bombs.

Proliferation resistance of a Th cycle is wishful thinking at best.

Safe nuclear does exist -- it is spelled LFTR

[Anonymous Coward]

http://www.telegraph.co.uk/finance/comment/ambroseevans_pritchard/8393984/Safe-nuclear-does-exist-and-China-is-leading-the-way-with-thorium.html

http://www.wired.com/magazine/2009/12/ff_new_nukes/

Re:Safe nuclear does exist -- it is spelled LFTR

[drwho]

Yes, you are correct. I am starting to believe that not is LFTR viable, it is ESSENTIAL. Without LFTR, we will gradually become poorer in many ways, while countries which embrace LFTR will become richer (China, perhaps India). Failure to adopt LFTR could be one of those points where future historians will mark as the final straw that broke the camels back, the camel being American-European society (yeah, those white guys that everyone seems to love to demonize). As it goes, so it will take with it the fundamental philosophies and perspectives on human rights and dignity that we have fought so hard to preserve and extend.

We need cheap electricity. In a global economy, the availability and price of electricity are very important.

What about Thorium, Molten Salt Reactors

[Anonymous Coward]

From: http://en.wikipedia.org/wiki/Thorium

Some of the benefits of thorium when compared with uranium as fuel:
  * Weapons-grade fissionable material (U-233) is harder to retrieve safely and clandestinely from a thorium reactor;
  * Thorium produces 10 to 10,000 times less long-lived radioactive waste;
  * Thorium comes out of the ground as a 100% pure, usable isotope, which does not require enrichment, whereas natural uranium contains only 0.7% fissionable U-235;
    * Thorium can not sustain a nuclear chain reaction without priming, so fission stops by default.

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

One of the reactors at Fukushima actually uses Thorium.

Re:What about Thorium, Molten Salt Reactors

[Goragoth]

Where are you getting this information? 5 of the 6 reactors at Fukushima Daiichi use low-enriched uranium fuel and one uses MOX, none of them use thorium.

Re:What about Thorium, Molten Salt Reactors

[Cramer]

You make it sound like it'll shutdown quickly like a coal fired plant. A coal power plant will shutdown within minutes of killing the coal feed -- stop blowing coal dust into the tower, and the fire goes out. A thorium breeder reactor will continue to run for quite some time before it's sufficently depleted. It's similar to a log in camp fire.

Re:What about Thorium, Molten Salt Reactors

[ColdWetDog]

Rebuttal from Physicians for Social Responsibility

Weapons-grade fissionable material (U-233) is harder to retrieve safely and clandestinely from a thorium reactor

Thorium is not actually a “fuel” because it is not fissile and therefore cannot be used to start or sustain a nuclear chain reaction. A fissile material, such as uranium235 (U235) or plutonium239 (which is made in reactors from uranium238), is required to kickstart the reaction. The enriched uranium fuel or plutonium fuel also maintains the chain reaction until enough of the thorium target material has been converted into fissile uranium233 (U 233) to take over much or most of the job. An advantage of thorium is that it absorbs slow neutrons relatively efficiently (compared to uranium238) to produce fissile uranium233. The use of enriched uranium or plutonium in thorium fuel has proliferation implications. Although U235 is found in nature, it is only 0.7 percent of natural uranium, so the proportion of U235 must be industrially increased to make “enriched uranium” for use in reactors. Highly enriched uranium and separated plutonium are nuclear weapons materials.
In addition, U233 is as effective as plutonium239 for making nuclear bombs. In most proposed thorium fuel cycles, reprocessing is required to separate out the U233 for use in fresh fuel. This means that, like uranium fuel with reprocessing, bombmaking material is separated out, making it vulnerable to theft or diversion. Some proposed thorium fuel cycles even require 20% enriched uranium in order to get the chain reaction started in existing reactors using thorium fuel. It takes 90% enrichment to make weaponsusable uranium, but very little additional work is needed to move from 20% enrichment to 90% enrichment. Most of the separative work is needed to go from natural uranium, which ahs 0.7% uranium235 to 20% U235.

Thorium produces 10 to 10,000 times less long-lived radioactive waste;

Proponents claim that thorium fuel significantly reduces the volume, weight and longterm radiotoxicity of spent fuel. Using thorium in a nuclear reactor creates radioactive waste that proponents claim would only have to be isolated from the environment for 500 years, as opposed to the irradiated uraniumonly fuel that remains dangerous for hundreds of thousands of years. This claim is wrong. The fission of thorium creates longlived fission products like technetium99 (halflife over 200,000 years). While the mix of fission products is somewhat different than with uranium fuel, the same range of fission products is created. With or without reprocessing, these fission products have to be disposed of in a geologic repository.

Thorium comes out of the ground as a 100% pure, usable isotope, which does not require enrichment, whereas natural uranium contains only 0.7% fissionable U-235

Compared to uranium, thorium fuel cycle is likely to be even more costly. In a oncethrough mode, it will need both uranium enrichment (or plutonium separation) and thorium target rod production. In a breeder configuration, it will need reprocessing, which is costly. In addition, as noted, inhalation of thorium232 produces a higher dose than the same amount of uranium238 (either by radioactivity or by weight). Reprocessed thorium creates even more risks due to the highly radioactive U232 created in the reactor. This makes worker protection more difficult and expensive for a given level of annual dose.

(The article goes into a bit more detail. One does have to keep in mind that PSR is generally quite anti nuclear - but I think these are fairly reasonable counterarguments)

Lastly, no one has actually made a commercial level thorium cycle reactor despite decades of trying. It MIGHT have some advantages and engineering and research efforts should continue, but it's hardly a viable solution as of yet.

Re:What about Thorium, Molten Salt Reactors

[slashqwerty]

Rebuttal from Physicians for Social Responsibility

I was going to mod this up but decided to respond instead*. The Physicians for Social Responsibility has a tagline of "United States Affiliate of International Physicians for the Prevention of Nuclear War". Which raises serious questions about their credibility.

*It should probably be modded up anyway just for its alternative perspective.

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Here is an article from cosmos that counter what you have read. Most notably the thorium nuclear cycle is dynamic in that it produces uranium 233 as a part of its nuclear cycle. This article aligns with other sources that the waste products have a half-life of 500 years and it does not produce weapons grade material.

Re:What about Thorium, Molten Salt Reactors

[ColdWetDog]

I warned you. I warned you, didn't I? .....

No harmless bunnies here and you're correct, PSR does have an agenda (like everyone else) but the little blurb was nearly a point by point refutation of the ACs post. There were a whole bunch of posts touting Thorium, very few rebuttals to that point of view. IMHO, the biggest issue with Thorium cycle reactors is that there aren't any. They've been studied for decades but no one has yet to build a successful commercial sized unit. Perhaps the Indians will be able to get everything together and move forward, but one obviously should not plan much of a buildout on a technology that has yet to really work.

If you're going to do that, hell, just put up some big Tokamaks.

Re:What about Thorium, Molten Salt Reactors

[KonoWatakushi]

Nice "fact sheet" by people who are clearly not experts in the field and obviously have an anti-nuclear agenda. Most importantly though, it is anything but objective; it is highly selective of the "facts", full of half truths and strawmen, and has a clear intent to deceive the reader. While I have little desire to sift through their drivel, I fully expect that they have similar "fact sheets" for many other competing energy sources. What we could use is a real fact sheet for fossil fuels, and especially coal...

Just to start with, anything with a half life of 200,000 years is so stable, that it is only technically "radioactive", and poses no health risk whatsoever, beyond possible issues of toxicity. Any residual radiation remaining after a few hundred years is below the background level; the only reason to point out things like this is to incite fear and induce hysteria.

Otherwise, while some hypothetical straw man reactor in once-through mode might suffer from some imaginary reprocessing problems, real designs such as the Molten Salt Reactor are conveniently ignored. There is no solid fuel to start with, no separation necessary, and the "reprocessing" is basically just removing the reaction products, and can be done online.

The amount of real waste from such reactors is so small, and the timeframes so short, that it is ludicrous to even begin talking about geologic storage. For a comparison of the waste and mining requirements, see this presentation. In terms of raw environmental devastation and heath effects, it would also be nice to see a comparison with coal.

Re:What about Thorium, Molten Salt Reactors

[mdmkolbe]

longlived fission products like technetium99 (halflife over 200,000 years).

Don't long lived isotopes decay slowly? That is to say only a small fraction of the atoms actually decay and thus there are a small number of decays to produce radiation? With the half-life of T99 only 3.5e-7 of the system decays each year. Maybe that's enough to be worried. But how many Sv does a single T99 decay amount to? How pure and how much T99 are we typically talking about?

Re:What about Thorium, Molten Salt Reactors

[dbIII]

Benefit 1 has been the deal breaker everywhere apart from India after they decided they already had enough stockpiled material for nuclear bombs - so they are building a Thorium reactor now.. The USA could have gone that way for the same reason but the influence from those that had already sunk a lot of money into Uranium reactors killed the government run projects that used Thorium.
Just about everywhere else civilian nuclear has been the minor side benefit of a weapons program so tied to potential weapons materials. Japan in an exception but they imported their technology from the USA so were tied to Uranium and Plutonium.

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Lastly, no one has actually made a commercial level thorium cycle reactor despite decades of trying.

Who has tried?

Except for one test reactor back in the 50s, who has done any research into Thorium reactor technology?

Are the rest of your facts as accurate?

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

* Thorium comes out of the ground as a 100% pure, usable isotope, which does not require enrichment, whereas natural uranium contains only 0.7% fissionable U-235;

Heavy water reactors (and other designs?) can use natural Uranium without enrichment...

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Lastly, no one has actually made a commercial level thorium cycle reactor despite decades of trying.

I'm still waiting to find out who it is who has been "trying" for decades.

Re:What about Thorium, Molten Salt Reactors

[NeutronCowboy]

I was going to mod this up but decided to respond instead*. The Physicians for Social Responsibility has a tagline of "United States Affiliate of International Physicians for the Prevention of Nuclear War". Which raises serious questions about their credibility.

Sooo..... being against nuclear war means that you suddenly cannot possibly put together a cogent and reasonable analysis of the risks in a nuclear reactor? Why do you think that?

See, the problem with this sort of bullshit commentary is that you can dismiss everything and everyone as being "tainted", and therefore unreliable. Not only does everyone have by definition a certain amount of bias, but anyone can be accused of harboring some secret agenda, without them having any chance at disproving it. This makes it trivial for anyone to stop discussion by invoking the mantra of "they're not credible because they have an agenda" and directly leads to the current political situation in the US, where every asshole is entitled to creating their own facts - because, hey, everyone's biased anyway, and we're just making sure that the alternative is being put out into the open.

So unless you have an actual rebuttal for the analysis done by PSR, please, kindly, STFU. You're actively destroying the discussion.

Re:What about Thorium, Molten Salt Reactors

[haruchai]

Check out the Energy from Thorium site. It's not true that "no one has actually made a commercial level thorium cycle reactor despite decades of trying" . The fact is that a molten-salt reactor was in operation for over 5 years ( research, not commercial) but the entire thorium project was sunk because it does NOT produce (significant amounts?) of plutonium which was regarded as necessary for the US weapons program.
So it might be more accurate to say that a commercial grade thorium reactor has not really been tried. Some experts think that India is off on the wrong foot because they've been attempting a solid-fuel thorium reactor. The thorium proponents staunchly believe that MSR / LFTR is the way to go.

The site has recently put up a PDF of a 1962 report to President Kennedy regarding civilian nuclear reactors.

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Just what part of that nonsense is "cogent and reasonable"?

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Indeed, there has been very little trying. Most "new" ideas in nuclear engineering date back to the 1950s, and they have never received sufficient attention.

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

In addition, U233 is as effective as plutonium239 for making nuclear bombs. In most proposed thorium fuel cycles, reprocessing is required to separate out the U233 for use in fresh fuel. This means that, like uranium fuel with reprocessing, bombmaking material is separated out, making it vulnerable to theft or diversion.

This is true, but there is a clever workaround proposed in the literature. Addition of small amounts of U-232 (a high-energy gamma emitter) makes the separated uranium quite unsuitable for weapons-use. The gamma radiation interferes with the electronics you'd need to control the triggering mechanism -- an unreliable nuclear weapon is no deterrent at all. Furthermore, the gammas make the fuel "self protecting." Bottom line: we can't make diversion impossible, but we can make it all but impossible to do clandestinely.

Some proposed thorium fuel cycles even require 20% enriched uranium in order to get the chain reaction started in existing reactors using thorium fuel. It takes 90% enrichment to make weaponsusable uranium, but very little additional work is needed to move from 20% enrichment to 90% enrichment.

This is technically true, but highly misleading. As the enrichment level increases, the details of how you arrange the centrifuge cascade changes in order to prevent a criticality accident. In an IAEA-monitored site, this cannot be concealed. 20% enrichment is the upper end of civilian or reactor-grade uranium, as defined by the IAEA -- largely because this is a nice, safe level above which it's easy to detect non-proliferation cheaters. Again: diversion is always going to be possible, given sufficient political will and resources (e.g. Iran's ongoing revelations about concealed nuclear facilities). But we can make it awfully hard to do it undetectably (again, e.g. Iran. It's a bit of an open secret that US satellites were very much aware of what Iran was doing at Kum, etc. They "announced" it before the Americans could.)

This claim is wrong. The fission of thorium creates longlived fission products like technetium99 (halflife over 200,000 years). While the mix of fission products is somewhat different than with uranium fuel, the same range of fission products is created.

This claim is not wrong. Indeed, U-233 fission creates a wide variety of fission products with a wide range of half-lives. Useful ones, Tc-99m, for instance, can be extracted and purified for medical applications (in the full-inline-reprocessing MSR concept). Graphite moderation leads to an "epithermal" neutrons spectrum. Those more energetic neutrons tend to interact with long-lived fission products more readily than the fully thermalized neutrons of a water-cooled reactor. Those collisions break down the bad actors in the core during the fuel's normal life-cycle.

Reprocessed thorium creates even more risks due to the highly radioactive U232 created in the reactor. This makes worker protection more difficult and expensive for a given level of annual dose.

See above. This is a design feature. The additional shielding requirements are a small price to pay for the non-proliferation benefits.

Lastly, no one has actually made a commercial level thorium cycle reactor despite decades of trying. It MIGHT have some advantages and engineering and research efforts should continue, but it's hardly a viable solution as of yet.

Actually, the US built and operated one graphite-moderated, gas-cooled reactor that made use of thorium TRISO fuel kernels. It was an ambitious design (it used concrete as the containment vessel, no stainless heavy forging required). Unfortunately, it was a little too advanced for its time -- problems with the water-bearings in the turbopumps caused all sorts of difficulties. General Atomics, the designer, has vastly improved an simplified the concept and is close to seeking NRC licensing. Sadly, the Fort St. Vrain reactor was

Re:What about Thorium, Molten Salt Reactors

[kazurai]

Rebuttal from Physicians for Social Responsibility

Weapons-grade fissionable material (U-233) is harder to retrieve safely and clandestinely from a thorium reactor

Thorium is not actually a “fuel” because it is not fissile and therefore cannot be used to start or sustain a nuclear chain reaction. A fissile material, such as uranium235 (U235) or plutonium239 (which is made in reactors from uranium238), is required to kickstart the reaction. The enriched uranium fuel or plutonium fuel also maintains the chain reaction until enough of the thorium target material has been converted into fissile uranium233 (U 233) to take over much or most of the job. An advantage of thorium is that it absorbs slow neutrons relatively efficiently (compared to uranium238) to produce fissile uranium233. The use of enriched uranium or plutonium in thorium fuel has proliferation implications. Although U235 is found in nature, it is only 0.7 percent of natural uranium, so the proportion of U235 must be industrially increased to make “enriched uranium” for use in reactors. Highly enriched uranium and separated plutonium are nuclear weapons materials.

Use of U-235 or Pu-239 is only required as "start up" charge if U-233 is unavailable (regarding the proliferation risk of Thorium-derived U-233, see below). Also, this is only true for molten salt reactors, Accelerator-driven systems aka "subcritical reactors" may even work without any fissile material present from the get-go (though they have their own problems)

In addition, U233 is as effective as plutonium239 for making nuclear bombs. In most proposed thorium fuel cycles, reprocessing is required to separate out the U233 for use in fresh fuel. This means that, like uranium fuel with reprocessing, bombmaking material is separated out, making it vulnerable to theft or diversion. Some proposed thorium fuel cycles even require 20% enriched uranium in order to get the chain reaction started in existing reactors using thorium fuel. It takes 90% enrichment to make weaponsusable uranium, but very little additional work is needed to move from 20% enrichment to 90% enrichment. Most of the separative work is needed to go from natural uranium, which ahs 0.7% uranium235 to 20% U235.

Reactors don't have to be 100% proliferation resistant, it just has to be harder to use them to make a bomb than the old graphite/uranium pile + plutonium extraction process. In other words, if someone can do the former, they could do the latter much more easily. U-233, like any fissile material, can be used to make bombs. However, if U-233 is bread from Thorium, it is invariably contaminated with U-232 which has a massive gamma emitter in its decay chain. This makes handling this material hard, requiring shielding both when making the bomb. Even worse, it would make an inferior bomb since you would have to shield the bomb itself to make it safe for the operator as well as shield the electronics of the bomb. Finally, the gamma emission would make the presence and location of such a device easy to detect. If you are a bad actor with the appropriate resources, it's much easier to just build one of those World War 2 piles and extract the plutonium from it.

Furthermore, note that commercial power reactors tend to be poor sources for bomb material in general unless they are specifically designed to make it easy, you require regular fuel changes in matter of months to avoid spoiling the material with elements which will ruin your bomb-making effort. This will interrupt operation and raise red flags if the reactor is shut down on every three months, which ruins your effort to be secretive which is likely your reason to use a commercial plant in the first place. This is why all the bomb making efforts in countries either use straight enrichment (rare - South Africa is the only example I'm aware of) or special-purpose bomb-making

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Is Technetium99 really a worry though? A half-life of 200,000 years means it isn't very radioactive, and (leaving aside Technetium99m) it decay produces only weak beta radiation that could be stopped by a test-tube. Also, it has low chemical toxicity. So what's the worry?

Re:What about Thorium, Molten Salt Reactors

[BlueParrot]

This claim is wrong. The fission of thorium creates longlived fission products like technetium99 (halflife over 200,000 years). While the mix of fission products is somewhat different than with uranium fuel, the same range of fission products is created. With or without reprocessing, these fission products have to be disposed of in a geologic repository.

Technetium can be destroyed through neutron capture. Same with Iodine. Since a thorium breeder would necessarily make use of reprocessing technology there is no reason not to do this. The remaining fission products decay to uranium-ore levels within a few hundred years.

Also, while you would still need a repository, the capacity of a repository is limited by heat generation, not the volume of the waste. Since thorium generate orders of magnitude fewer actinides the long-term heat generation ( past a few hundred years ) is much lower than for a once through uranium cycle. It is also much easier to design a repository for a few hundred years than for a hundred thousand years.

Compared to uranium, thorium fuel cycle is likely to be even more costly.

This is correct, but your reasons are wrong. The main reason is that a thorium thermal breeder would have to reprocess the fuel much more often than a plutonium based fast breeder, and this greatly increases costs. The attractiveness of thorium is mostly due to the possibility of creating a thermal breeder reactor, but with advances in fast breeder technology, in particular the possibility of using safer coolants than liquid sodium ( lead, supercritical water, molten salts or helium ) this advantage is not as great anymore.

Lastly, no one has actually made a commercial level thorium cycle reactor despite decades of trying. It MIGHT have some advantages and engineering and research efforts should continue, but it's hardly a viable solution as of yet.

This is not due to technical limitations, but is mostly because it is cheaper to just dig up more uranium. In the long term our once through use of uranium is of course not sustainable, but as long as it remains cheap it is likely to dominate in commercial nuclear power. Also India is developing thorium reactors aggressively and have a few prototypes running.

Re:What about Thorium, Molten Salt Reactors

[squizzar]

Surely amounts per watt-hour are important here. It may produce waste with the same components, but if it produces less waste, or less of the particularly nasty components then it's a big improvement surely?

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

The use of enriched uranium or plutonium in thorium fuel has proliferation implications.

Why don't we use thorium in subcritical reactors instead? At least they really stop working when switch is flipped, we can choke them just like we can choke chemical reaction (combustion) power plants, unlike current ones which are just quenched by control rods, and that only as long as their structural stability is intact. If core structure of common design nuclear power plant is compromised, e.g. by overheating, the fission fuel is piled up at the bottom of the containment vessel and it keeps heating up until it melts down and leaks out!

You can't domesticate an animal specie which can merrily survive on its own without you. Likewise, don't construct something that can accidentally keep on working when it shouldn't, while it is broken at that, no less, because it can keep on doing it without you. That goes for nuclear energy, as much as for GM living organisms, self-assembling mechanisms, certain software entities, autonomous weapon systems, or anything else similar that our minds might produce in the future but we can't imagine today.

Re:What about Thorium, Molten Salt Reactors

[TheTurtlesMoves]

Th has very real issues. It is just another fuel cycle and you *must* breed U233 to make it work. It produces similar wastes and the whole 10-1000 times lest waste is only if your compare once through with reprocessing and you get the same results regardless of the fuel (U235 compared to U233). In fact a huge chuck of the "Benefits of Th" is from using a molten salt reactor. You get the same benefits if you use U in a molten salt configuration as well.

Also these plant designs can fail just as badly as the Japanese plant did. Additionally if using fluoride salts, which is the norm, you get hydrogen production with any contact with water...

About the only really good about a Th fuel cycle is that there are so many people out that don't have a clue, and are telling everyone else without a clue that its awesome, safe and secure. And PR matters.

Also straw man does not mean what you think it means.

Re:What about Thorium, Molten Salt Reactors

[TheTurtlesMoves]

WTF are you talking about. The molten salt reactor never used any Th. It used U to save money since the Th was going to be in a separate breeding blanket. They made enough U233 from Th in experiments (probably breeding blankets) to make and test a bomb from it.

Note that many of the "advantages" of Th are just from using a MSR/LFTR reactor, and you can use U235/Pu239 fuels with similar advantages. In fact you have to start with U235/Pu239 since you need to breed your U233 from the Th232.

Re:What about Thorium, Molten Salt Reactors

[TheTurtlesMoves]

If you are using a MSR or any homogeneous reactor, you can safely burn actinides even with U235/Pu239 fuel cycles. So many of the advantages can be realized for all fuel cycles. This is a good thing since a Th based MSR will need to be bootstrapped with U235/239

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Ummm the subject of the post was for MOLTEN salt reactors and the response was for thorium in a typical solid-state nuclear reactor.

For a molten salt reactor one does not have to worry about a core melt down because the core is ... a fluid. A big plus is its negative void coefficient meaning that when the salt gets too hot it expands decreasing the neutron density. So a negative feedback is built in.

U233 makes for a terrible bomb! The highly radioactive daughter products end up frying the electronics (and people) and the only known experiment (teapot) had to use a lot of U235 to make it.... fizzle.

Proponents actually claim 300 years and about 1/2000th the amount of waste will be generated as compare to a typical Light Water Reactor. Technetium is VERY important in medicine and saves thousands of lives every year. Unfortunately it is also in short supply. Also note a long half life means it isn't that radioactive perhaps you were looking for its biological effect and that is measured in Sieverts or rem (Röntgen Equivalent in Man).

True nobody has made a commercial Liquid Fluoride Thorium Reactor and there are several reasons for it. One reason is that all the development was at Oak Ridge National Laboratories and the goodness didn't get spread around.

for ORNL original documentation: http://www.energyfromthorium.com/pdf/

Re:What about Thorium, Molten Salt Reactors

[Anonymous Coward]

Your points are almost all wrong or subjective. For example, CANDU reactors can use the pure, usable natural uranium without any enrichment.

Secondly, Uranium fuel cycle is well understood and much less expensive. It is possible to build reactors that produce no long term waste, and still be cheaper than Thorium. Current "waste" is actually quite a bit of fuel so permanent disposal is ill advised - the fuel may end up being very useful in 50-200+ years.

Re:What about Thorium, Molten Salt Reactors

[Ihlosi]

Your points are almost all wrong or subjective. For example, CANDU reactors can use the pure, usable natural uranium without any enrichment.

Yes, but they can still only burn the 0.7% U-235 in natural uranium ... and they create plutonium from the U-238.

On the other hand, natural thorium is pretty much 100% Th-232.

Re:What about Thorium, Molten Salt Reactors

[Lorens]

Rebuttal from Physicians for Social Responsibility

What are PHYSICIANS doing talking about nuclear science and nuclear war? My first thought was that there was some subtle UK/US difference, but no, both sides of the pond are in total agreement: physicians practice medicine, physicists practice physics.

I'd take with a grain of salt things said by people who don't know what their profession is called . . .

Re:What about Thorium, Molten Salt Reactors

[KonoWatakushi]

A more thorough rebuttal of the so-called "fact sheet"...

Re:What about Thorium, Molten Salt Reactors

[haruchai]

The project used several fuels in its life, of which one was U233, bred from Th232, which is not fissile. While you do need something fissile to kickstart a Th-based reactor, the Thorium fuel cycle is inherently safer and more proliferation-resistant than that of Uranium. An MSR running solely on Uranium/Plutonium would generate considerably more was and troublesome actinides.

Re:What about Thorium, Molten Salt Reactors

[TheTurtlesMoves]

It seems they did burn as well U233. However every reference i have checked explicitly states that there was no breading blanket for the MSRE. The U233 source is not clearly disclosed, but was most likely from solid breading blankets used at other facilities.

You can burn actinides in a molten salt reactor. The reason you can't in solid fuel reactors, or fast reactors is that you end up with very difficult to control dynamics (ie hotter means more fission events). There are other designs that permit burning of actinides as well. You still end up with fission products after that, but its a lot less material per kWh and generally shorter decay times (100s of years IIRC).

I have nothing against a Th fuel cycle, but a lot of the proponents at least here on /. make a lot of claims that are simply false, or totally untested. It is not a magic bullet of nuclear energy. It is not proliferation resistant.

Re:What about Thorium, Molten Salt Reactors

[haruchai]

I've heard plenty to the contrary, but I'm still learning about it so I won't make any claims without reference. What gets me is that no matter which way you lean on nuclear technology, it seems that any option apart from the tech that is currently in place is 15-20 years from likely deployment. By then, we just might finally have a workable fusion reactor. ; )

Re:What about Thorium, Molten Salt Reactors

[TheTurtlesMoves]

Yes it will take some time to get new fission reactor designs validated. Yes we may have fusion working at a place like ITER, but it will be another 20 years to get something commercially viable from that.

It's so safe...

[MrEricSir]

...that we never bothered testing it!

Thorium makes more sense

[Anonymous Coward]

There's a lot of good things about a thorium reactor (substantially less waste, can burn the waste we already have, and can be easily shut down with the flip of a switch). What a shame Bill isn't working on one.

CANDU

[andymadigan]

Since a CANDU (Heavy Water) reactor's fuel isn't naturally capable of going critical, couldn't that existing, tried and true design be used instead? We can fuel it with nuclear waste from American reactors, or use raw uranium ore, with no need for centrifuges or other tech that can be used to create nuclear weapons. If the cooling system fails, then you should have the backup of draining the heavy water from the reactor core, thus killing the reaction.

I'm not saying that's the only solution, I'm just saying that a known good solution that's been working for decades is probably better than a new one.

Re:CANDU

[h4rr4r]

But then Microsoft patent trolls can't benefit. How are they supposed to become even more wealthy without rent seeking?

Re:CANDU

[Anonymous Coward]

Not only that but is is enclosed in a massive light water heat sink to soak up the residual decay energy once the initial moderator controlled reaction has stopped. It would take about a week to overheat the passive heat sink which can easily be cycled using a standard 4" fire hose and pump should its standard cooling system be compromised.

Re:CANDU

[Fierlo]

The calandria is in a vault, which is generally filled with light water (shield tank). The purpose of the light water is shielding and keeping the temperature of the concrete low. It's not really meant to be a heat sink.
The calandria is filled with heavy water, which *is* meant to be the ultimate heat sink for certain types of accidents (large loss of coolant accidents, for example).

Re:CANDU

[sjames]

You can't just drain the coolant from a reactor, even when its already been shut down. The reactors in japan shut down the instant the ground started shaking.

The problem is all the decay products starting with the iodine. It takes a while for those to break down enough to not melt the fuel rods.

That's not to say that CANDU's heavy water design isn't a good idea, it is. It just isn't a solution to this particular problem.

Re:CANDU

[Anonymous Coward]

CANDU is banned in the US because it has a small positive void coefficient when initially fueled. Over the life of the fuel it moves into small negative void coefficient - basically the reactor is neutral. Chernobyl had a HUGE positive void coefficient so that was probably a reason why CANDU is banned - another is it would compete with US corps.

But TBH, CANDU reactor was the first reactor designed for safe power generation. The BWR and similar designs are scaled up version of what drives US aircraft carriers - they are not designed to be safe. CANDU on the other hand, has dual independent cooling loops. The moderator is liquid (heavy water). It has dual emergency shutdown (control rods and neutron poison into the moderator). CANDU breeds and burns plutonium - so it can be a proliferation risk though normally plutonium content in fuel is very small.

I think CANDU is vastly safer than BWR. You can also refuel it without turning it off. Runtime can be up to 3 years before you have to power down for maintenance. I'm not certain what is better, the EABWR or CANDU-6, but I think I would stick with CANDU for now. They are more expensive to build than equivalent power EABWR.

Funny thing is, people built cheaper rather then safer and then they complain that the plant is not as safe as they wanted.

Re:CANDU

[Anonymous Coward]

As a Nuclear operator working at a 4 unit candu station in ontario, I can give you some information on our technology. There are two separate heavy water systems in CANDU reactor cores, the moderator system, and the heat transport system. The heat transport system is an array of pressure tubes containing the fuel bundles. Surrounding those tubes is the moderator system, which uses heavy water to thermalize (slow) the neutrons. As the moderator is completely separate from the HT system, You CAN drain the moderator system which surrounds the fuel channels which is one of the shutdown systems available at the Pickering station, and an optional configuration in other plants. Newer designs such as the Bruce or Darlington stations have a system which injects gadolinuim nitrate into the moderator, which absorbs all the neutrons and kills the reaction in a split second. There are also other redundant means to shutdown the reactor.

In an emergency, light water can also be injected into the reactor core, having the effect of not only stopping the reaction, but also cooling the fuel as new inventory comes into the system. Light water absorbs rather than slows neutrons down like heavy water does. Also, because Candu reactors use unenriched fuel, there is much less stored energy in the core than BWR and PWR designs.

Re:CANDU

[ehud42]

You can't just drain the coolant from a reactor, even when its already been shut down

I remember getting a tour of a research CANDU in the Pinawa, MB area years ago ("powered" by large electric heaters - not uranium, hence the research status). I thought one of the major self-limiting safety features was the heavy water / primary coolant. If anything went wrong / ran away / threatened melt down - there was a large trap door at the bottom that opened and dumped the heavy water effectively stopping the reaction.

I'm sure this is Canadian propaganda I'm spewing from my youth, but these things seemed to be the magical answer the world needed. They ran on lower quality uranium and were fail safe. Perfect for selling to less stable countries or for places like Japan that were prone to natural disasters.

I guess the lack of sales shows I missed some of the less than perfect details to the design.

Re:CANDU

[Anonymous Coward]

There are two types of water in the reactor vessel in the CANDU design -- circulating heavy water in the fuel channels serving mainly as the coolant, and heavy water in a large vessel surrounding the fuel channels acting mainly as the moderator. The latter acts somewhat as a thermal buffer, but it isn't in the main coolant cycle and isn't involved much in removing the heat. In some designs it can be dumped, in which case you've removed the moderator and the reaction will slow (the coolant keeps flowing). Furthermore, the moderation from the heavy water gets less efficient as temperature rises, and thus the reaction will slow if that happens. All designs also have the option of injecting gadolinium in solution into the heavy water to "poison" the reaction, not to mention the usual control rod systems. If you started pumping regular water through there in an emergency the same sort of thing would occur. Essentially you can either remove or poison the moderator, which is a pretty useful safety feature.

They aren't flawless designs, but they are pretty nice. The main downside is extra cost.

Re:CANDU

[sjames]

Actually, another reply to my post explained it. Apparently the coolant and moderator are kept separated so the moderator could be dumped while keeping the coolant.

Re:CANDU

[Anonymous Coward]

"Since a CANDU (Heavy Water) reactor's fuel isn't naturally capable of going critical"

Neither could the fuel in a RBMK (ie Chernobyl), it could also use unenriched uranium (Though the minimum is now higher due to safety improvements)

Re:CANDU

[sjames]

That explains it! I had been envisioning a combined coolant/moderator rather than isolated.

That doesn't really address the cooloff after shutdown, but since the moderator is unpressurized, I'm guessing it would be easier to take emergency measures such as having the fire department (for example) refill it with light water if all else failed. Of course it also seems that it wouldn't take nearly as much power to keep it filled since the pumps don't have to work against pressurization. Am I somewhat on track?

Re:CANDU

[Ihlosi]

Since a CANDU (Heavy Water) reactor's fuel isn't naturally capable of going critical, couldn't that existing, tried and true design be used instead? CANDU reactors will produce just the same problems as the light water reactors in Japan if you turn off all power to them.
Also, CANDU reactors can produce weapons-grade plutonium much more easily than the designed used in Japan.

Re:CANDU

[Anonymous Coward]

Please note that the US Navy uses Pressurized Water reactors with a Primary (reactor coolant water) and Secondary (steam plant water) fluid sides separated by a fancy heat exchanger called a "Steam Generator" - Nothing like a boiling water plant.

They use 2 cooling loops as well on the reactor side and if the power cuts they out fall back to natural circulation (http://en.wikipedia.org/wiki/Natural_circulation) to cool the plant.

Re:CANDU

[Anonymous Coward]

The reactors in japan shut down the instant the ground started shaking.

Never EVER again shut down a working nuclear reactor in distress! Apparently that's how all major reactor disasters started. It obviously has to be operational to be safe. It can only be put to rest if everything is fine and external power for cooling system can be supplied reliably and abundantly.

Re:CANDU

[TheTurtlesMoves]

CANDU is banned in the US because it has a small positive void coefficient when initially fueled.

Citation required. When you use water as a moderator and you are ruining with such an extreme neutron economy, my numbers say that its always a negative void coefficient. That is excluding doppler broadening as well.

Re:CANDU

[TheTurtlesMoves]

Also, CANDU reactors can produce weapons-grade plutonium much more easily than the designed used in Japan.

No they can't. In fact because CANDU designs are so tight with neutron economy, they can't afford to lose neutrons to U238 capture. That is why they use a thermal spectrum than will generate far less Pu that a reactor that can be a little more lax with neutron economy.

In general thermal designs produce less fuel than they burn (so less than 0.7% Pu after all the U235 is burnt--but then some of that is burnt too), you need a fast neutron spectrum to breed.

Re:CANDU

[dunkelfalke]

CANDU is a heavy water reactor, not a light water reactor.

Re:CANDU

[TheTurtlesMoves]

Which part of moderated by water is changed by that? Heavy water is used because is absorbs less neutrons, normal water would not work because of the extreme neutron economy requirements. This also does not affect the void coefficient.

Re:CANDU

[DarthVain]

The main problem with the CANDU design from what I hear is that it is A) Pretty complex and thus expensive to maintain, and B) Expensive to initially build and long construction time.

It is the most flexible though at what kind of fuel you wish to consume which is pretty nice however. (not including some exotic designs that have never been built)

The downside is that India proved you could alter it to produce weapons grade stuff. Of course that was the old design, not sure if anything changed to make it harder since then. Then again the reactors in question in Japan were specifically designed to run off of weapons grade stuff so kind of moot in that example.

Re:CANDU

[Anonymous Coward]

Well, as a resident canadian I hate to say this, the only place that can manufacturer the Clandaria of the CANDU recator was in Japan. :/

Re:CANDU

[Anonymous Coward]

You can't just drain the coolant from a reactor, even when its already been shut down.

No, but you can dump the heavy water moderator. That might be what the parent was referring to. That will stop the reaction, and you will still have cooling water flowing through the reactor.

Re:CANDU

[johnkennethhunter]

This is true, and was a credited shutdown system at the Pickering A reactors, but was not that reliable as a shutdown technology because it takes too long to drain the moderator. Shut off rods and poison injection are much faster in making a reactor good deep in the negative criticality zone. In the event of a loss of coolant accident following an earthquake, overheated fuel could deform the fuel channels to the point where they would start to touch the calandria tubes, allowing for heat transfer to the large volume of room temperature heavy water by conduction, which has it's own cooling loop. So it's actually a good thing to keep the moderator in place when you loose coolant (as mentioned, are in separate systems).

What happened to thorium power?

[NoAffiliation]

I read a wired article about how using thorium instead of uranium will give you a much safer reactor, and would cause much less damage in the case of a meltdown. Also, thorium nuclear power can't be used to fuel WMD's. In the article, it was saying that its inability to be used as WMD's is why it wasn't developed back in the 50's. Our country wanted to make nukes. Anyone know anything about this, or am I just crazy?

Re:What happened to thorium power?

[TheTurtlesMoves]

Well if it is in wired it must be true then.

Thorium

[stazeii]

Or there's thorium. http://en.wikipedia.org/wiki/Thorium#Thorium_as_a_nuclear_fuel Just because Gates is behind something doesn't mean it's a good idea. Pretty sure Gates started out liking "Clippy" too.

What is the advantage of this over thorium?

[Anonymous Coward]

Why not use Thorium reactors instead?

http://www.telegraph.co.uk/finance/comment/ambroseevans_pritchard/8393984/Safe-nuclear-does-exist-and-China-is-leading-the-way-with-thorium.html

Re:What is the advantage of this over thorium?

[Goragoth]

Thorium is another great solution, especially because it is so abundant. However, the huge advantage of the TerraPower design is that it burns existing nuclear waste, making it very cheap (nobody wants the waste) and solves one of the biggest problems with all those existing reactors (what to do with the waste).

Is there nuclear technology?

[ShakaUVM]

"Is there nuclear technology that could withstand such a catastrophe? Possibly."

Yeah, as in all other modern designs.

Passive cooling has been the hot new thing since, you know, the 80s.

Re:Is there nuclear technology?

[Chris Burke]

Yeah, as in all other modern designs.

Passive cooling has been the hot new thing since, you know, the 80s.

It's funny, because I've seen a couple U.S. nuclear industry representatives/experts on TV being asked about the disaster, could it happen to our reactors, is nuclear power safe? And they'd hem and haw and talk about designing structures around local conditions. Nothing about technology itself. I'm guessing because they don't want to have to talk about how outdated reactor designs in the U.S. are, and how we didn't keep up in research so they're going to be outdated for quite some time. Especially since when your unfortunate take-away message is "Um, yeah, it totally could happen here if there was an unprecedented earthquake", you don't really make people feel much better by saying "But technology developed in the 1980s and which we could have built by the 2030s won't have that problem!"

Re:Is there nuclear technology?

[Locutus]

and from what I've read, putting the backup generators in water proof rooms would have solved the problem too. I guess they need to keep a big ass extension cord around next time to bring in outside power when their generators flood. If those generators really did get flooded and taken out the tsunami, the operator should be blamed for the event, not mother nature. IMO

LoB

Re:Is there nuclear technology?

[Anonymous Coward]

Could you provide a few examples of commercial reactors that can be passively cooled (following an emergency shutdown)?

Re:Is there nuclear technology?

[mcguiver]

The technology developed in the 80's could have been deployed much sooner and there are designs of plants that are approved (some of which have even been built). There is even new technology that could have been retrofitted on the old reactors to make them safer. The major problem is that it is so hard to build a new plant that we are continuing to milk these old plants for all that they are worth. Lets forget about renewing licenses on old plants and build some new ones. The reactor design in Fukushima is the old GE Mark I. This is the original BWR design from GE. Reactor 1 went online in 1971 and was scheduled to be decommissioned at the end of the month. GE later developed the Mark II, Mark III, Mark IV, Mark V, and Mark VI reactors. In these designs even the entire containment system underwent a couple of complete redesigns. Subsequently GE has developed the ABWR and SBWR reactors. Japan is even running some of the ABWR designs. Saying that the 1980s technology wouldn't have been build until 2030 does not reflect the reality of the situation. BWRs have undergone radical redesign since the Fukushima reactors have been built.

Re:Is there nuclear technology?

[Cramer]

Have we even built a new reactor in the US since 1974? Duke Power tried to build one in Cherokee, SC, but there was so much bitching and other bullshit, they abandoned the project. (sold to E.O. Studios who filmed The Abyss there.)

So, yes, this *could* happen to us, but huge earthquake + tsunami is so unlikely, I'm not worried about it. The thing that *does* worry me is the fact that our plants are ~40 years old. (and they were only designed to run 30 years.)

Re:Is there nuclear technology?

[TopSpin]

The thing that *does* worry me is the fact that our plants are ~40 years old.

I'll give you something to worry about: Power uprates. This is where a utility gets the NRC to approve operation of a plant above its design power level. 105%. 115%. One day a 40 year old uprated reactor is going to fracture a main steam line and blow-down into containment. Zero pressure. The LPCI better kick in as designed because nothing else will save it.

but there was so much bitching and other bullshit

That, ultimately, is the real problem in the US. The little enthusiasm a utility might have to replace an old facility is utterly overwhelmed by the legal tar-pit that must be forded to accomplish anything. The somewhat greater desire to expand existing plants or even create a new plant is also legally infeasible. Tying up billions in capital for years on an uncertain outcome is financially infeasible; much easier and more profitable to take that money to Asia. The US can rot in its legal morass; money doesn't care.

This is a matter of political will; stimulus projects have exemptions from "environmental review." Border fence construction enjoyed that as well. When either the left or the right wants to stop muddling around and accomplish something they can make it so. They know exactly what the problem is and they know exactly how to fix it.

They just don't want to.

Re:Is there nuclear technology?

[Jane Q. Public]

This is all old news.

First, the Fukushima Daichi reactor is Generation II, using powered pumps. Long ago now, Generation III plants were designed that use natural convection to circulate the coolant, making this whole entry in Slashdot pretty damned irrelevant.

Second, the U.S. is not behind in research. Quite the contrary. What the U.S. has been behind in, has been public support for nuclear power, and thus financing and funding for nuclear power.

The whole "global warming" scare has caused many people to re-think that, and it is possible that the U.S. will start building new reactors again soon. But if they do, they should use the newest, most efficient technology available, not designs that are already outdated, as some have proposed.

Re:Is there nuclear technology?

[Anonymous Coward]

Shame this reactor is from the early 70s, then. It's even older than Chernobyl.

Re:Is there nuclear technology?

[TheTurtlesMoves]

Well when someone says water proof. And then you get hit my a 10m (>30 feet) wall of water, you tend to have things like the door is blown in from the pressure. Or the walls and roof collapse.

Water proof is *not* tsunami proof. What they really need is enough passive cooling within the main containment vessel.

Re:Is there nuclear technology?

[QuantumPion]

Natural circulation will continue to cool PWR's in an emergency situation, unless/until a steam bubble forms. This still depends on power to the feedwater pumps though, once the steam generators run dry, you've got TMI.

The GE ESBWR is designed to operate at full power on natural circulation, and if shut down will continue to cool itself normally. Even if it loses feedwater circulation, it has huge accumulator tanks which are able to provide cooling water for several days without any operator intervention required.

Re:Is there nuclear technology?

[Chris Burke]

The technology developed in the 80's could have been deployed much sooner and there are designs of plants that are approved (some of which have even been built). There is even new technology that could have been retrofitted on the old reactors to make them safer. The major problem is that it is so hard to build a new plant that we are continuing to milk these old plants for all that they are worth.

That's what I meant by "could have built", as in "we could have new reactors using the 1980s technology built by 2030 if we started today", because the reality is regardless of whether 1980s-tech reactors would have been operational by now is irrelevant because we didn't build them. So we'd have to start from the reality of today, which is no construction and minimal research into these designs in the U.S. It was worded poorly, I know.

Alternative reactor designs

[SkOink]

Another promising reactor design is the pebble-bed reactor. Its reaction has a negative temperature coefficient, meaning that the reaction self-moderates if it gets too hot, rather than requiring an external control system to prevent meltdown. This means that if the cooling system were to fail, the reactor would just sit in a mostly-dormant state until cooling was re-established.

http://en.wikipedia.org/wiki/Pebble_bed_reactor/

Re:Alternative reactor designs

[Ihlosi]

Its reaction has a negative temperature coefficient, meaning that the reaction self-moderates if it gets too hot, rather than requiring an external control system to prevent meltdown.

News flash: Most light water reactors have a negative temperature coefficient, too. However, negative temperature coefficient don't do anything at all about decay heat after the reactor is shut down, because there's no more chain reaction after shutdown.

Decay heat alone is enough to cause a meltdown, and the only way to deal with decay heat is to cool the thing until heat generation has decayed below the level where it will melt the fuel rods, fuel pebbles, reactor walls, etc.

Molten salt

[Anonymous Coward]

Wiki it.

Dumb question...

[sideslash]

If nuclear power plants are used to power cities, why can't they power their own cooling? Seems like keeping the darn thing running would be safer than watching it sit there unpowered and on the verge of blowing up. (Don't get me wrong; I'm sure there's a good reason. I'm just curious.)

Re:Dumb question...

[h4rr4r]

That works quite well, until a say an earthquake rated at 9 on the Richter scale hits and then the tsunami from it does even more damage.

Re:Dumb question...

[TD-Linux]

You are exactly right. The Fukushima plant actually had steam-powered water pumps that could have kept the core cool during operation. But the reactor was automatically (or procedurally?) SCRAM'd at the first sign of the earthquake, which means that the reactor wasn't putting out close to enough steam to power the pumps.

Re:Dumb question...

[Anonymous Coward]

It's not a dumb question, I'm curious myself.

I'm guessing you don't want it to run during an earthquake because if mechanical damage happens inside, you won't be able to power it off or control it (e.g. if control rods can't be lowered). Once it was stopped, it's probably a very bad idea to power it back on without adequate water circulation.

A related question is - why can't the decay heat be used to actually produce power? Why can't the steam turbines continue to operate after shutting down the reactor, since it's still producing a lot of heat?

Re:Dumb question...

[Anonymous Coward]

I guess that could work. But safety regulations say that in case of a disaster, the reactors should automatically stop, as they did in Japan. Come up with a design for your suggestion and try convince some safety commission that, in case of a major disaster that destroys even the emergency power generators, you still need to keep one reactor critical in order to prevent the others from exploding. Although your solution technically works, you will probably get as an answer, to just design better emergency power generators.

Re:Dumb question...

[neiras]

It seems like it should be possible to design a closed storage pool that would use depleted fuel rods' decay heat to create circulation through a passive radiator of some sort, delaying or eliminating the need for powered cooling.

Has this been done?

Re:Dumb question...

[CrimsonAvenger]

If nuclear power plants are used to power cities, why can't they power their own cooling?

They do power their own cooling.

Alas, when you shut the plant down, it stops providing power for its own cooling. Which they did here.

Note that the kneejerk response (earthquake, therefore shutdown the reactor!!!!), was, in this case, absolutely the worst thing that could be done. If they'd left the reactor running but begun a slow shutdown (as opposed to a SCRAM), they'd likely have had enough power to keep things under control.

And if it turned out an emergency shutdown was needed, well, that option would still be on the table.

It is probably worth noting also that there's a pretty good chance of lot of reactor plant operations manuals are going to be revised as a result of this little adventure. With an eye toward keeping the reactor operational at lower power output until it absolutely, positively needs to be shutdown right the fuck now!

Re:Dumb question...

[frosty_tsm]

If nuclear power plants are used to power cities, why can't they power their own cooling? Seems like keeping the darn thing running would be safer than watching it sit there unpowered and on the verge of blowing up. (Don't get me wrong; I'm sure there's a good reason. I'm just curious.)

The reactors were configured to shutdown when a major earthquake hit as a precautionary action, which they did. The reactors would then use power from the grid to continue cooling. Just in case the grid had issues, there were on-site generators (which I've heard were not sitting above ground, but I'm not 100% sure on that one). The tsunami knocked out the power lines to/from the grid and either the generators or the electronics between the generators and the reactor.

Their planning wasn't horrible as they 1) went into a safe mode and 2) had on-site backups. They failed to anticipate the scenario where a tsunami swept over the sea wall (where you want to build things to be waterproof, protected, and able to just ride things out).

Re:Dumb question...

[Charliemopps]

Because, in order for the reactor to produce power it needs at least some of its control rods to be removed. Having the control rods removed during an emergency is FAR FAR more dangerous than a loss of cooling. The point of the cooling pumps is to prevent the core from getting so hot that it melts the control rods and the slags down to the bottom of the containment chamber. All modern reactor designs do not need active cooling like these reactors do. They are some of the oldest reactor designs in existence and upgrading such reactors have by put off due to cost and unending legal challenges by environmental groups. It's sad that we could replace our horrendous coal and hydroelectric power grid that does untold damage to the environment, with modern safe reactors within a few decades but can't because "Environmental" groups hold on to this windmill pipe dream... oh wait, they file legal challenges on the windmills to...

Re:Dumb question...

[thetartanavenger]

When something goes wrong you have to stop the reaction shutting down the generation. Or the something that goes wrong damages something else along the line similarly stopping the generation. Hey presto, no more power for cooling. You probably could for a lot of situations, but for that one time every goes very wrong, kinda like fukushima, you don't want to have to rely upon it.

Re:Dumb question...

[Anonymous Coward]

The reactor shuts down automatically when the earthquake is detected and switches to aux (diesel) generators. This is what happened at Fukishima. However, the generators only had an hour of fuel due to the Tsunami wiping out the fuel lines.

Location, Location, Location.

Re:Dumb question...

[v(*_*)vvvv]

It's like asking why my car won't start when the engine is blown. Or why my wounds aren't healing when I'm already dead. The power plants just broke. It's not really an issue of how they're suppose to work at that point but rather the extent of how fault tolerant they are. Like airbags if it were a car etc.

Re:Dumb question...

[c6gunner]

A related question is - why can't the decay heat be used to actually produce power? Why can't the steam turbines continue to operate after shutting down the reactor, since it's still producing a lot of heat?

Yeah, that's been bugging me for quite a while now. They have steam-turbines and generators, and a fuckload of steam. What's the problem?

Re:Dumb question...

[Anonymous Coward]

Clearly we need a reactor within the reactor to provide power while it's unpowered.

Re:Dumb question...

[Leuf]

I understand there isn't enough power to run the turbines, but couldn't they have a secondary smaller turbine designed to run on the power level available in the shutdown state that would just generate enough power to run the cooling systems?

Re:Dumb question...

[Creepy Crawler]

Seems simple to me: Put some stirling engines with big heatsinks in and out of the reactor vessel to provide continual energy for cooling. With the reactors running at 7% load, you can still siphon lots of power.

Re:Dumb question...

[Anonymous Coward]

If nuclear power plants are used to power cities, why can't they power their own cooling?

Normally it does, but when you're trying to turn it off, you still need power to do that safely. The heat from the nuclear reaction continues to require cooling even after the reaction has been damped down enough that you don't have any more electricity from the process.

Re:Dumb question...

[Locutus]

but it put out enough steam and pressure to require venting and then subsequent explosions? Just maybe they could implement a system whereby the residual energy after shutdown can power the cooling system long enough( 48hrs? ) to bring the reactor down to safe temp levels. That would have at least given them 48hours plus to work on the minor cooling system required to keep the spent rod pools cool enough.

LoB

Re:Dumb question...

[maxume]

GE apparently did the design work:

http://en.wikipedia.org/wiki/Boiling_water_reactor#The_simplified_boiling_water_reactor_.28SBWR.29

Re:Dumb question...

[sjames]

As much trouble as the reactors have been, they're a lot less hot now than they were before due to being shut down.

They pretty much had to shut down once the quake started, and actually cannot be restarted without a cooldown period.

Once a reactor is shut down, the neutron flux drops and various poisons (neutron absorbers) build up fast. Until they break down you can't restart the reaction. When operators at Chernobyl tried to overcome the poisons by fully withdrawing all of the control rods, they rendered the reactor dangerously unstable with well known consequences.

I suppose a new design could include 'low temperature' auxiliary turbines for that purpose, but newer designs render the point moot with passive cooling.

They do have emergency diesel generators on site for this, but the tsunami damaged everything.

Re:Dumb question...

[XiaoMing]

I'm sorry, but that is one of the most misleading and misinformed sequence of words to get marked up regarding this whole issue.

First off, it should be noted that this reactor was in the middle of what can be considered by the general public as three chronological regimes of reactors:

1. Very unsafe reactors that have little or no passive safeguards (i.e. reactors reminiscent of Chernobyl or Simcity2k's 50 year kaboom)
2. Relatively safe reactors that have many passive safeguards (multiple layers of containment, and spill region with unfavorable fission geometry etc.) but that still rely on external containment measures (active cooling in the situation we're discussing now)
And finally
3. Very safe reactors that have many passive safeguards built in for every foreseeable (keyword, so no need to go thinking up magical exceptions to this category) circumstance (such as the capability to snuff themselves out via high concentrations of neutron absorbing daughters etc). As these reactors were being constructed and developed during a period of nonproliferation and disarmament, you see mixed results as many in operation were also once-off prototypes, but there are many places (Japan, France, Canada, etc.) where standarization and continued development/production means that most of the public fear is about as accurate as the tea party's propaganda regarding Kenyan birth records.

As an aside, it's also a good time to note that nuclear power plants are still nothing more than a fancy way to boil water. I.e. after a few heat exchange processes, the steamy water from these reactions is still used to do what water flowing downhill is used for, to drive a turbine.

Now the important part: Shutting down the reactors was by far the correct thing to do here because cooling was necessary for the daughter isotopes.
That is, the stuff we've been cooling all this time is the result of decay from before the plant was shut down.

What does this mean? Now here comes the simple part: It means that if you took the exact same situation, but kept the reactors running critically (i.e. no full insertion of control rods), you'd not only continue to generate heat from the primary fission reaction itself, but ALSO continue to generate more heat from the fission of the daughter products.

So sure, you might have had a few hours, hell maybe a day to generate additional energy before the subsequent tsunami--that managed to wipe out: the national electrical grid, thirteen backup diesel generators; and backup batteries that last for eight hours--is now expected to leave your steam turbine energy generation system completely untouched and functional. (http://www.voximate.com/blog/article/1058/failover-backup-systems-redundant/)
And in the very very likely case that it doesn't? Well now you have all that additional heat as well as even more daughter products to take care of.

No manuals will be rewritten, if this shit happens again they'll shut down the plants just like they did this time, only get plugs that fit rather than risking a full blown meltdown while hoping that a damaged powerplant can supply its own cooling somehow.

And of-course, if these defunct cores are replaces with newer designs after this is all over, we'll be in much better shape regardless.

Re:Dumb question...

[dave420]

FISSION.

Re:Dumb question...

[shermo]

Minimum load limits. Nuclear power plants (and many others) can't generate below a certain level. A massive earthquake probably just destroyed all your transmission lines, and you can't generate power without somewhere to send it to.

Yeah you could design a smaller nuclear power plant that was only meant to power the coolant facilities in the case of an emergency. But if that's all it's used for, why not use a diesel generator instead?

Re:Dumb question...

[Martin Blank]

Just to follow up your post, they designed the plant to withstand a 5.7m tsunami. But the tsunami that actually hit was 10m. I don't know how difficult it is to engineer against a 10m wall of water, but I imagine that it's very difficult.

Re:Dumb question...

[skyraker]

The quake cause the reactor to shutdown, which is the primary source of power. Since the quake took out power from the grid, there went the backup. The emergency power systems cut in, but the tsunami took those out.

Re:Dumb question...

[Orgasmatron]

I had the same thoughts. But, no regulatory body will EVER allow a reactor to operate through a severe earthquake.

Too unpredictable. Too much unknown.

A desirable outcome, and one that might actually happen (not counting politics), is to replace all the old reactors with new designs that are safe under "SCRAM and walk away" conditions. And by new, yeah, I mean only 20 or 30 years old instead of 40 or 50.

Re:Dumb question...

[Mspangler]

The emergency pumps would not have to be full sized, say only 10% full size to hand the decay heat, which is about 6% of full power. Assuming the main steam stops shut on scram, which I'm sure they do, they should have been able to open one of them to get all the steam they needed to the emergency feed pump. Or even just open the bypass valves you have to open to warm the header. You are not talking about that much steam.

If cooling is working, steam pressure will drop off, or at least it will once cooling exceeds decay heat, but as the steam pressure drops, so does the pressure your pump has to overcome. So you should be able to run it down to 50 psi or so, so long as you have water to push feed the reactor.

 

Re:Dumb question...

[mcguiver]

The problem with the reactors was not the SCRAM. The idea is if you have to SCRAM the reactor you use grid power to maintain cooling. In the even of losing grid cooling you have back up diesel generators. In the event of losing the back up diesel generators the plant has steam driven pumps that can keep the reactor cool. The steam for the pumps comes from the water boiling off the reactor. There is plenty of heat left there to boil water and steam will be produced. After the earthquake and tsunami the plant operated as it should have. There was no power so they had an event called a station black-out, meaning the control room was without power. But there were battery packs that was able to provide power to key systems. The problems started when the batteries died. One of the biggest problems is that running the steam pumps requires the valves between the reactor and the Wetwell to be opened (Google for pictures of the the GE Mark I design. The Wetwell is the torus that goes around the reactor). The valves that go between the reactor and the Wetwell were designed to fail closed. When power was lost the valves failed closed and the steam pump could no longer provide cooling.

Having the reactor SCRAM in an earthquake event is the prudent thing to do. Depending on the damaged caused by the earthquake you may not want to delay that decision. If all is well you can bring the reactor back to a low power state, if not full power. More modern designs are a lot more forgiving and are able to 72 hours before any kind of intervention is needed. The reactors at Fukushima only had about 12 hours in them, max.

Re:Dumb question...

[Anonymous Coward]

Sorry, but you don't have a clue what you are talking about. Reactors are rated for a given energy band - you can't run them at 5% power - they are unstable. Secondly, the generator is not designed to provide that little power!!

Nuclear plants are ALWAYS shutdown during an earthquake because you don't want to have a 4000MW cooker going when your reactor is shaking at 1-2G. Imagine if something sprung a leak, or cooling failed because of shaking. It would be a complete fuck up. Yes, MUCH MUCH MUCH worse than current mess. Turbines also cannot function when they are shaking - it can cause fires and explosions in the generator room.

Even when shutdown, reactors do produce significant heat that is then cooled by emergency cooling. All that worked, until the tsunami flooded the backup power. So basically, the problem was in design of backup generators - you know, out in the open facing the ocean. Who would have thought?? (sarcasm here considering tsunami is Japanese word!!) Second problem was inability to cool the reactor externally - that will have to be addressed for extreme-failure cases. At least for newer designs - and I think that problem has already been addressed.

So the basic lesson will be to protect your backup power. Put them in strong boxes that can run underwater and have air supply via snorkel going up the vent chimney. 2nd problem was inability to cope with the emergency during the 8 hours that they run on batteries. They should have emergency backup generators available to be air lifted in case of failure of the primary/backup. And they should check that backup plugs would fit!

Re:Dumb question...

[Dan667]

the brief version is a 40 year old plant was hit by a once in a 1000 year tsunami.

Re:Dumb question...

[murpup]

They have such systems. One is called RHR or residual heat removal system, and one is called RCIC, or reactor core isolation cooling. The RCIC pumps are steam driven, and they take water first from a condensate water storage tank and then the suppression pool and send it to the reactor to remove the decay heat. As the water in the pressure vessel boils away, the steam gets vented to the suppression pool, as well as the steam used to power the RCIC pumps. The steam condenses in the suppression pool, slowly heating it up. This pressurizes the containment which must be vented to the outside in a controlled way to prevent over-pressurization. The RHR system operates at lower pressure and its pumps are not steam driven. It operates more like a traditional Carnot cycle, using secondary pumps to circulate water through a condenser to remove the decay heat. Of course, without offsite power, these secondary pumps don't work.

Re:Dumb question...

[CrimsonAvenger]

Now the important part: Shutting down the reactors was by far the correct thing to do here because cooling was necessary for the daughter isotopes.
That is, the stuff we've been cooling all this time is the result of decay from before the plant was shut down.

It should perhaps be noted that I'm a former reactor plan operator. I have a clue.

Yes, cooling the daughter isotopes is exactly the issue. You generate fewer of them when you reduce output from commercial levels to self-sustaining levels.

And when you reduce power (but not shutdown completely), the decay products begin to decay down toward the new steady-state level. Which is a LOT less than steady state when you're operating at 90%+.

Every minute that goes by with the reactor operating at a reduced output is another minute you don't have to find an external power source to cool things down. And another minute farther from a core meltdown.

As was, by doing a hard shutdown immediately, the reactor was placed into a position such that the only possible way for a "good" outcome would be for the national electrical grid to stay completely intact during the next few days. There's no way that the battery back-up they had could keep cooling that plant for the next couple days by itself.

Which leaves as your only real option to try to use the reactor's output to maintain cooling while you burn through the decay products for as long as possible. After all, you can always scram the reactor later, if things don't work out.

Re:Dumb question...

[Anonymous Coward]

OK, SCRAM was the right thing to do. Here's another dumb question:
The decay heat generates >5MW for weeks following the SCRAM. Can we reroute the steam to a smaller turbine that would power the pumps to cool the reactor?

Re:Dumb question...

[Anonymous Coward]

> 1. Very unsafe reactors that have little or no passive safeguards (i.e. reactors reminiscent of Chernobyl or Simcity2k's 50 year kaboom)

I'd say "Chernobyl after The Experiment started", because around ten layers of passive defense eager to drop the rods and leave them that way had to be disabled. The main thing that changed right after 1986 is that some layers of defense lost the ability to ever be switched off.

Re:Dumb question...

[Anonymous Coward]

Perhaps they felt with a 9.0 earthquake going on that they could not risk the control rods getting stuck outside the core due to damage of some kind - especially if the earthquake managed to damage the cooling system as well.

What I don't understand is why the spent fuel ponds are on top of the reactor. I think they didn't do too well after the reactor releases hydrogen in that area and it blew up.

Re:Dumb question...

[hcdejong]

In additions to the reasons already mentioned, keeping a big, heavy turbine running at 50/60 Hz in an earthquake is likely to (violently) destroy the turbine.
So you need to stop the turbine, which means you've got to stop producing steam. In case of a BWR, the steam is radioactive so you can't vent it so you have to scram the reactor.

Re:Dumb question...

[Anonymous Coward]

> As was, by doing a hard shutdown immediately, the reactor was placed into a position such that the only possible way for a "good" outcome would be for the national electrical grid to stay completely intact during the next few days. There's no way that the battery back-up they had could keep cooling that plant for the next couple days by itself.

Well, actually the diesel generators should have done that. But they failed for some reason, most likely the tsunami.

Re:Dumb question...

[Ihlosi]

What I don't understand is why the spent fuel ponds are on top of the reactor.

Spent fuel rods are intensely radioactive - enough that merely being a few seconds in their vicinity will give people doses in the range of a few Sieverts (i.e. deadly within a few days). Hence you want to take them out of the reactor remotely and immediately cover them with water again, without having to move them all over the place.

Also, the rods still produce quite a bit of heat, which is another reason why they need to be submerged as soon as possible after removing them from the reactor.

Re:Dumb question...

[PeterBrett]

Yeah, that's been bugging me for quite a while now. They have steam-turbines and generators, and a fuckload of steam. What's the problem?

Suppose you have a 100-tonne steam turbine running at 20000 RPM, and you fail to stop it before an earthquake grabs it and gives it a good hard shake. Your turbine hall is likely to literally explode, and foot-long aluminium turbine blades travelling at hundreds of metres per second will trash the entire place, including your high-pressure steam pipes. These turbines are huge

As I understand it, in the first fraction of a second of the earthquake, and at the same time as the reactor was SCRAMed, the turbines at Fukushima were crash-stopped and pressure release valves dumped the steam pressure in the turbine feed (probably to the torus). This was to protect the equipment from the earthquake.

So, they have steam turbines and generators (which have been emergency stopped and require a fairly tedious recommissioning to ensure that the bearings and drive shaft alignment haven't been damaged by that or the earthquake), and considerably less steam being generated than would be being generated while the reactor is running normally, and possibly an already-lowered coolant level due to emergency steam quenching.

That's the problem.

Re:Dumb question...

[Anonymous Coward]

If nuclear power plants are used to power cities, why can't they power their own cooling? Seems like keeping the darn thing running would be safer than watching it sit there unpowered and on the verge of blowing up. (Don't get me wrong; I'm sure there's a good reason. I'm just curious.)

For a perfect example of why this is a very, very bad idea, look up a site called "Cherynoble".

Turned out that the technicians were running a test- specifically they were testing a new idea; the idea of using the nuclear reactor to power its own cooling system. And that's where things really went to hell. You see, if the reactor starts heating up, you need more power for cooling. To get more power, you have to... heat up the reactor. Now you have a catch-22 situation where the only way to get more power to solve the problem, is to make the problem even worse thus preventing a solution. When you do an emergency shutdown, you also shut down all your cooling power... but you need to continue cooling the fuel rods for quite a while afterwards or they'll melt down and then you've got a really big mess.

So ya, it's already been done and resulted in disaster, literally.

Re:Dumb question...

[Anonymous Coward]

As was, by doing a hard shutdown immediately, the reactor was placed into a position such that the only possible way for a "good" outcome would be for the national electrical grid to stay completely intact during the next few days.

You're assuming the primary cooling system can only be powered by the main reactor. That's not true.
The reactors SCRAM'd when the earthquake hit, and they were running on the primary cooling system until the tsunami knocked out their grid connections and backup power generation. At which point they activated the backup "cooling system" namely flooding with sea water.
So if they'd have left them running on minimal output, they would have had more daughter products to deal with. Not that it was enough time to make much of a difference either way.

What I see as the critical failure of the plant was not the automatic shutdowns, but the failure to secure the backup power sources. Hell, at one point they ran out of diesel to power the backup water pumps. Those batteries are supposed to work like a UPS; they aren't supposed to run the entire site for 8 hours they're just supposed to keep things going during a power cutover, or if you need to refuel a backup generator, etc.... they're just there to add a little bit of "wiggle room".

Re:Dumb question...

[Neil Boekend]

An important question is: could current systems be upgraded to an extra cooling system based on sterling engines that can produce energy from the waste heat. Building new nuclear plants is way to expensive to do overnight.

Re:Dumb question...

[Rufty]

The backup generators wern't out in the open, facing the ocean. They were behind a tsunami-protection wall 1m higher than the highest on record in the region. Shame this tsunami was 3m higher than that...

Re:Dumb question...

[Anonymous Coward]

"high concentrations of neutron absorbing daughters etc."

I understand the whole "this is in the middle of a nuclear reactor" thing, but where, exactly, would I find one of these plants with high concentrations of daughters?

Re:Dumb question...

[raynet]

And that will fail when you are hit with 12m tsunami so...

Re:Dumb question...

[c6gunner]

But you don't need to run the turbines at max capacity to get some power output from them. Run it at a few hundred RPM and use a rectifier to recharge your backup batteries, or use transformers to get some useful current out of 'em. I realize it wouldn't be easy since they clearly didn't plan for it ahead of time, but it's also far from impossible to quickly rig up a temporary solution. Unless the turbines really are damaged to the point where they can't even get them started.

Re:Dumb question...

[QuantumPion]

If nuclear power plants are used to power cities, why can't they power their own cooling? Seems like keeping the darn thing running would be safer than watching it sit there unpowered and on the verge of blowing up. (Don't get me wrong; I'm sure there's a good reason. I'm just curious.)

Because the tsunami washed away the switchyard and transformers, and flooded the entire electrical switchgear system.

The reactors do have a steam-driven pump to continue to cool itself with their own decay heat, but they ran out of battery power to operate its valves after 8 hours. What they needed was a second steam-driven pump to power a generator in the reactor building.

Re:Dumb question...

[Anonymous Coward]

I do understand a plant shutdown would not provide their own power. But the info seems to be incomplete. Why?
Remember when the US grid failed years ago and the failure cascaded across much of the US. The press reported the domino effect happened because a nuke plant shutdown when it lost power from the grid. So, I continue to be confused by statements that nukes provide their own power when others say they do not.

Re:Dumb question...

[QuantumPion]

You are exactly right. The Fukushima plant actually had steam-powered water pumps that could have kept the core cool during operation. But the reactor was automatically (or procedurally?) SCRAM'd at the first sign of the earthquake, which means that the reactor wasn't putting out close to enough steam to power the pumps.

That's not exactly correct, the problem was they ran out of battery power to operate the valves for the steam pumps after ~8 hours. And they had no way of recharging the batteries due to tsunami/flooding damage to all of their electrical systems.

Re:Dumb question...

[QuantumPion]

It should perhaps be noted that I'm a former reactor plan operator. I have a clue.

Really? Then tell me how you would power the station's loads with no switchyard, station service transformers, or switchgear room, which were all washed away/flooded by the tsunami?

Re:Dumb question...

[rubycodez]

uh hah, and the once in 10,000 year meltdown has happened six times in 50 years. oh well, maybe it's just a statistical blip and we'll go the next 60,000 years meltdown free.

I'm actually pro nuclear, but these stupid Gen I and II reactors should be decommissioned.

Re:Dumb question...

[Anonymous Coward]

Now the important part: Shutting down the reactors was by far the correct thing to do here because cooling was necessary for the daughter isotopes.

That is, the stuff we've been cooling all this time is the result of decay from before the plant was shut down.

It should perhaps be noted that I'm a former reactor plan operator. I have a clue. ...

And when you reduce power (but not shutdown completely), the decay products begin to decay down toward the new steady-state level. Which is a LOT less than steady state when you're operating at 90%+.

Every minute that goes by with the reactor operating at a reduced output is another minute you don't have to find an external power source to cool things down. And another minute farther from a core meltdown. ...

Which leaves as your only real option to try to use the reactor's output to maintain cooling while you burn through the decay products for as long as possible. After all, you can always scram the reactor later, if things don't work out.

You've just illustrated a perfect example why operators must follow procedures all the times.

1. Your configuration is unstable
2. In an earthquake strong enough, the turbines shut down to protect themselves
3. changing power like you indicate would result in possible power surge within minutes (max power -> very low power -> surge)
4. did I say that SCRAM was needed because electric turbines shut themselves down so they don't explode??
5. what happens when reactor has a problem, or something happens because the earthquake was more than expected?? there is a reason for emergency shutdown and it is because there is an emergency
6. instead of going to unstable configurations and risk Bad Things, why not simply protect backup power properly? Japanese invented the word tsunami - they should have planned for complete swamping.

Re:Dumb question...

[sjames]

The diesel backup seemed reasonable enough, the problem was not making sure the connections would match up and (apparently) not being equipped to fix that quickly.

Re:Dumb question...

[Martin Blank]

And the odds of a 12m tsunami hitting are...?

"The plant's operator tried to bring in mobile...

[Rick Richardson]

"The plant's operator tried to bring in mobile generators to restore power, but the connections reportedly didn't match up."

Ref: http://cosmiclog.msnbc.msn.com/_news/2011/03/14/6268351-clearing-up-nuclear-questions

Pebble bed reactor

[ickleberry]

I'd love one of these in the back of my field connected to the grid. A cool 10MW or so is all I need.

These are only the size of a shipping container and are a self contained unit. They would be a great way to bypass the NIMBYism associated with nuclear power plants. They are also much safer. If these can be bought by people with a bit of cash in the attic and installed in the countryside unknown to the neighbours we can all enjoy cheap nucular energy while everyone is blisfully oblivious to the fact that the neighbours little 'storage' container is actually a nucular power plant

Re:Pebble bed reactor

[Anonymous Coward]

These are only the size of a shipping container and are a self contained unit. They would be a great way to bypass the NIMBYism associated with nuclear power plants. They are also much safer. If these can be bought by people with a bit of cash in the attic and installed in the countryside unknown to the neighbours we can all enjoy cheap nucular energy while everyone is blisfully oblivious to the fact that the neighbours little 'storage' container is actually a nucular power plant

It turns out that pebble beds aren't quite so maintenance free. Although the helium used as a coolant doesn't become radioactive, the graphite in the pebbles absorb radioactive metals and spread it around in graphite dust particles. Both the the AVR and HTR reactors in germany had big problems with contamination of the reactors due to this and due to the inability of the pebbles to contain radioactive isotopes.

Also, the pebble bed itself can't be instrumented so it becomes a black box resulting in unexpected hot currents of gas that can be significantly (200+K) warmer than expected. This resulted in maintenance issues in the two reactors in Germany (I don't think there is information on other experimental or production reactors using a pebble bed design). These problems might be surmountable but right now they're pretty big issues.

no one will need more then 640W

[Joe The Dragon]

no one will need more then 640W

Re:no one will need more then 640W

[BronsCon]

I believe the quote was actually 640kW

Re:no one will need more then 640W

[RockDoctor]

Ha, ha.

But seriously, how much power do you actually use? Averaged over a day.

Yes, the shower may run at 8kW, but you probably only run it for 10 minutes a day. You may have a 700W power supply in your desktop, but what's it's duty cycle? (I run on a laptop with a 90W power supply, and a NAS that has a 100W PSU with a 10W standby load)

I can't remember when I had to put a fuse into any piece of electronics bigger than 3A ; 3A is the smallest fuse that you can get for a UK mains socket. (And of course, the fuse is there to protect the lead, not the device. And yes, I check fused devices to see if they have the nearly inevitable 13A fuse attached to a 3A cable. It's surprisingly hard to find packets of 3A fuses.)

One of my friends is of the opinion that you can run a house off a 13A fuse, and most of that is capability for handling start-up currents. That would be 3+kW, and doesn't sound incredible. For the UK, that would imply around 4m of solar panels per household. Which doesn't sound particularly insane. Maybe a little low for winter in colder parts of the world, but not incredible at first glance.

GSoD

[geekgirlandrea]

With Bill Gates involved, we're sure to discover the joys of the Gamma Screen of Death soon.

... or maybe: "Your Microsoft Nuclear Reactor is experiencing a prompt criticality incident. Please remove all the fuel rods, reinstall them, and restart the reactor."

Re:GSoD

[Outtascope]

Hell, I'd pay good money to watch Gates' demonstration of this one. From a (very) remote terminal of course.

Re:GSoD

[Anonymous Coward]

Shouldn't that be the beta screen of death (bsod)?

Re:GSoD

[Anonymous Coward]

I sent an email to Steve Jobs about Apple's reactors failing in an earthquake, and he said "just don't shake it that way"

or just used a modern...

[Anonymous Coward]

...design.

The problem with the reactors in japan is their age. The designs are over fifty years old and were constructed over forty years ago. You need only use a design which is slightly older than 30 to have been extremely resistant to these types of failures. In fact, passive, convective cooling is an integrel component of newer generation reactors and have been so for several generations now.

Really, the biggest problem is anti-nuke dorks have made it so difficult to migrate to newer technology, older, less safe designs are being extended rather than replaced. If you must shake a finger of blame, it largely lies with the the anti-nuke dorks rather than any other place.

Nuclear is extremely safe, clean, and can be made even moreso if only we can get anti-nuke idiots to stop forcing higher risks on the wold just because they are ignorant and/or stupid.

The only problem with TerraPower

[Anonymous Coward]

They've never actually built a reactor...so when they do then I'll consider them more than perpetual motion salesmen

Doesn't Matter

[sycodon]

It doesn't matter how safe they are, the forces of extreme environmentalists and Luddites will say No! No! No!

Already idiots in Congress, without knowing anything more than the hyperbolic news reports, are calling for shut downs and "slow downs" and endless Congressional Investigations where people who know about Nuclear Power try to convince people that don't that you can't burn a hole in the earth straight through to China

Re:Doesn't Matter

[kwerle]

It doesn't matter how safe they are, the forces of extreme environmentalists and Luddites will say No! No! No!

Already idiots in Congress, without knowing anything more than the hyperbolic news reports, are calling for shut downs and "slow downs" and endless Congressional Investigations where people who know about Nuclear Power try to convince people that don't that you can't burn a hole in the earth straight through to China

I'm eternally optimistic that our fine congressfolk know better. Most of 'em, anyway. And that they are calling for shutdowns and slow downs as a response to their constituents - because they are spineless and because nobody [at the top] has stood up and said "we can and should make better, safer reactors."

Re:Doesn't Matter

[Cramer]

burn a hole in the earth straight through to China

I've always loved that... for starters what's most likely to happen is the molten goo hits the water table resulting in a flash boil the blows toxic, radioactive crap everywhere. The less likely possiblity (and this is WAY remote) is that it burns burns all the way through the mantle and becomes lava. (then you have lava and toxic, radioactive crap everywhere. :-))

Re:Doesn't Matter

[Anonymous Coward]

Telling them that Nuclear powers is safe enough might not convince them.
How about giving them the numbers of killed because of hydro power?

Here are a few. You can spend a few days and try to track down more incidents if you want to. You can probably fill a book with reports of dam breaks.

Bilberry reservoir - causing the deaths of 81 people.
Gleno Dam - killing at least 356 people.
Fujinuma Dam - Eight people were missing and four bodies were discovered after searches began at dawn.
Edersee Dam - About 70 people died
Coedty Reservoir - The resultant flood caused the loss of 17 lives in Dolgarrog.
Dale Dyke Dam - destroyed 800 houses, and killed 270 people
Kurenivka mudslide - The estimated number of casualties varies from 1,500 to 2,000, but only 146 people were officially recognized as such.
Banqiao Dam - 26,000 people died from flooding and another 145,000 died during subsequent epidemics and famine.
Gusau Dam - killing 40 people and destroying 500 homes.

We can have afford to have 10 more chernobyls without even being close to the kind of death and destruction that hydro power causes.

Re:Doesn't Matter

[ifiwereasculptor]

It doesn't matter how safe they are, the forces of extreme environmentalists and Luddites will say No! No! No!

What? Why? They must be high, man. We should try to make them go to rehab or something.

Re:Doesn't Matter

[PacMan]

It has already been shown that pebble bed reactors are not inherently safe designs

Do you have a reference for that? I'd really like to have a look at it.

Re:Doesn't Matter

[similar_name]

I'm eternally optimistic that our fine congressfolk know better.

There's only one question they have to consider. Will my constituents pay more for electricity if I shutdown there power plant? Fiss, baby. fiss.

Re:Doesn't Matter

[Anonymous Coward]

The problem is as I see it, the same claims of safety were made about the existing reactors.
So why should people trust the people who claimed they were safe?
Sure they wont have the same safety issues.They will have different ones!

Re:Doesn't Matter

[Dan667]

that is the coal and oil lobby exploiting irrational fears to keep killing people with things like the Iraq war, mountain top removal, smog, and Gulf of Mexico oil spills.

Re:Doesn't Matter

[Anonymous Coward]

If you're trying to convince an environmentalist that hydro is bad, it's probably best not to lead with human death figures. When it comes to saving the environment, the vast majority of human beings are part of the problem, not the solution. Animals deaths are good (evidence), because their numbers are pretty well regulated by hunter-prey dynamics and things like nuclear waste interfere with that natural regulation. But our almost complete lack of predators and our ability to import food from anywhere on the globe make our population dependent on other factors.

Of course, you can always talk about the number of trees and plants that die when you flood a previously-unflooded area. All those dead plants give off a ton of CO2, which makes hydro one of the dirtiest green power sources. For the finishing blow, get some pictures of the area before and after the dam was built. For instance, by most accounts, the Hetch Hetchy Dam destroyed an area that look very similar to Yosemite Valley. Pictures like that are like porn to an environmentalist.

Re:Doesn't Matter

[Anthony Mouse]

The problem is as I see it, the same claims of safety were made about the existing reactors.

I don't think that's accurate. Nobody in the west have claimed that RBMK reactors like the one in Chernobyl were safe -- many Soviet reactors were markedly unsafe. They were designed to be cheap and make plutonium for bombs. In Soviet Union reactor safety is number three priority.

So then you have US reactors -- and by what metric are they not safe? Newer reactors may be safer, but how about some reality -- deaths attributed to the industry by terrawatt-hour produced:
Wind power: 0.15
Nuclear power: 0.0009 (including TMI and Chernobyl)

Re:Doesn't Matter

[Talderas]

How about throwing the numbers around about the water consumption of thermoelectric plants compared to hydroelectric plants?

If I remember the numbers from the USGS it was around half a gallon of water consumed for ever kWh from thermoelectric plants (all types) and around 15 gallons consumed for every kWh from hydroelectric. Consumed water means water lost to evaporation.

Re:Doesn't Matter

[SacredNaCl]

Can a pebble bed reactor survive: The complete & total loss of any supporting structures which keep the fuel pebbles at a distance, the simultaneous loss of its cooling system, and the complete loss of *every single control system in place*? Plus the complete failure of humans not to do *exactly the wrong thing in every single instance in a crisis*? Or to not be able to do anything at all? (Say chemical weapon attack?) Not hours, not days, not weeks, indefinitely -- without being a risk to those living in the surrounding community?

That is the real test. These aren't toys, and its no small danger we live with. I live next to something with the potential to destroy the 1/3 of the agricultural capacity of the United States, and make areas of 3 states unlivable for generations to come.

I'm a big believer in multiple event scenarios, and in the tremendous overconfidence in tables for how strong something really is & narcissistic egos of engineers that have killed numerous people with their pronouncements of "that is simply an impossible scenario" ..only to watch it happen.

I'm a big believer in incredible amounts of human error, and a tremendous decline in the quality of the education system; to the point that a fair number of those with even advanced degrees aren't worth their salt. If it can't be run, and maintained by people with a 70 IQ, it just might be a problem. Never underestimate the effect of those 50 bonus points on the hiring test for minorities, social promotion in schools, and future government mandated quotas for degrees, and management promotion.

If your reactor can be screwed up because the maintenance person Tyrone puts in the wrong size bolt after a hard night of celebrating his/her recent casino win with an all nighter of amphetamine, cocaine, alcohol, and sex with random strangers (possibly for money) ... You know what? It will probably happen. If your reactor can be screwed up because Susie decided she needed to have an excuse not to come home so she is able to cheat on her husband by smashing the levee that feeds the water to your plant ...you know what? It will probably happen. (The few of you who live in or near Machens, Missouri, and West Alton, Missouri know why I reference such an event.)

We are reasonably near the New Madrid fault line. I really do not believe a pressurized water reactor like they have at Callaway would survive a seismic event even remotely close to what Japan experienced. The propaganda minister at Ameren tells us:

Emergency Safety Systems include six emergency power sources:
â 2 Ameren power lines to the site
â 2 Emergency Diesel Generators (onsite)
â 1 power line from local Rural Co-op
â 4 Standby Diesel Generators (offsite)
Additional Emergency Safety Features:
âSteam powered cooling water pump with DC battery powered controls system
âA 30-day cooling water supply stored on-site in a seismically designed retention pond.

All well, and good. Except in my scenario, the upwind rail line has a pair of trains passing at the exact same time of the seismic event. Each of the trains has tanker cars filled with a total of half a million gallons of things that react to cause long lasting fire, and/or creating a poison gas cloud that kills everyone downwind (meaning every single nuclear plant employee, including recent big winner at the casino Tyrone) for miles around. The twin events or the earthquake, and train accident make the area inaccessible due to chemical contamination, numerous bridge collapses, and the rerouting of surrounding rivers (not unprecedented). The water feeds for the plant are now broken, as are any power lines from anywhere else underground or otherwise. Due to problems with the communications system, and widespread power outages -- outside authorities remain unaware of the situation, and are mobilized to other areas before the extent of the crisis is realized.

Re:Doesn't Matter

[fritsd]

Here you go: http://en.wikipedia.org/wiki/Pebble_bed_reactor#Thorium_High_Temperature_Reactor,

In spite of the limited amount of radioactivity released (0.1 GBq Co60, Cs137, Pa233 the THTR management tried to hide the accident, probably because this accident pointed to some specific problems of pebble bed reactors, i.e. pebble flow and radioactive dust. The management probably expected that the emission might not be detected due to the Chernobyl fallout happening just in the same time. However a whistle-blower informed authorities and public. The THTR management continued to charge the Chernobyl fallout for all the contamination in the surrounding, until the presence of Pa-233 in the vicinity of the THTR-300 was detected: Pa233 is not formed in Uranium reactors as Chernobyl, but only in thorium reactors. Thus, step by step, the THTR management reported the whole truth. The activity in the vicinity of the THTR-300 was finally found to result to 25 % from Chernobyl and to 75 % from THTR-300. The handling of this minor accident severely damaged the credibility of the German pebble bed community, and pebble bed reactors lost a lot of support in Germany.[

Protactinium-233 has a half-life of only 27 days, fortunately, unlike Cesium-137 with its 30 year half-life.
and from http://en.wikipedia.org/wiki/THTR-300:

... It started generating electricity on April 9, 1985, however it did not receive permission from the atomic legal authorizing agency to feed electricity to the grid until November 16, 1985.

On September 1, 1989 the THTR-300 was deactivated due to its ever rising cost: in August, 1989, the THTR-company became almost bankrupt after a long shut down time due to broken components in the hot gas duct. It had to be bailed out by the government with an amount of 92 million Deutschmark (...)

And the aftermath (for the taxpayers):

(...) The remaining facility was "safe enclosed" and dismantling will not start before 2027.

Re:Doesn't Matter

[GooberToo]

Coal deaths per terrawatt-hour: 161 (avg); 278 china, 15 US

The simple fact is, nuclear is the safest, cleanest source of energy known to man. We have far safer designs available today than those forty year old designs. And anti-nukers are literally making the world more dangerous by making nuclear competition of evolution of economically and politically inviable.

Far too much is said about nuclear waste. The simple fact is, if it were not for anti-nukers, we would have wide spread reactors feeding on this waste today. We have waste problems BECAUSE of dip shit anti-nukers.

Now that the "need" or nuclear weapons has been reduced, it literally opens the door for far, far safer reactor designs and continued development - if only we can get idiot anti-nukers to shut the fuck up and help all of mankind instead of vomiting ignorance, stupidity, and propaganda. Statistically and factually, everything anti-nukers say is either a half-lie or a whole-life and yet sadly, largely, world opinion has been shaped by these fuck-tards.

Literally, the world would be a better place without anit-nukers.

Re:Doesn't Matter

[GooberToo]

So does this invalidate the pebble bed reactor entirely or does this mean its still a viable design yet still requires additional research and study?

Re:Doesn't Matter

[oh_my_080980980]

Yeah because safety should never be a concern, especially when you raise issues with a design flaw in a reactor design developed in the 60s that the industry continues to use today. Yeah you don't want to review problems like that. Time to insert head into hole in ground.

Re:Doesn't Matter

[dunkelfalke]

Please read about this guy and then tell me again about everybody who is against nuclear power being luddites.

Re:Doesn't Matter

[HungryHobo]

"Can a pebble bed reactor survive: The complete & total loss of any supporting structures which keep the fuel pebbles at a distance, the simultaneous loss of its cooling system, and the complete loss of *every single control system in place*? Plus the complete failure of humans not to do *exactly the wrong thing in every single instance in a crisis*? Or to not be able to do anything at all? (Say chemical weapon attack?) Not hours, not days, not weeks, indefinitely -- without being a risk to those living in the surrounding community?"

that's a fine philosophy as long as you apply the same standard to everything in life.

nuclear isn't special.

Bhopal killed more people than every nuclear power accident ever and maimed tens of thousands more for life.
and that was just a fertaliser plant.

The Banqiao Dam collapse killed more people than every nuclear power accident ever and left countless more homless and that was just a dam.

When lakes of coal sludge break they can leave vast tracts of land unusuable due to heavy metals.
Say what you like about half lives but arsenic is forever.

Drilling for gas in indonesia caused a mud volcano which destroyed the homes of 10000 people and the land will likely be unusuable for decades.

"I don't want to hear "we run our reactor with a 99.997% safety record"."

that's a lovely lovely soundbyte but it's nothing but that. a soundbyte.
Everything in life is a matter of 99.9999.

nothing is ever 100% and no that doesn't automatically win you the argument.
There's a finite chance that every single dam in the US could collapse at once, that every solar pannel could fall from their roofs at once and kill people, that ever wind turbine could fail explosively at once.

nuclear is dangerous like air travel while most of it's competitors are safe like driving to the airport.

you're more likely to die in your car on the way to the airport yet people are more afraid of flying.
why? drama.
when there's a plane crash everyone hears about it.
when there's a near miss everyone hears about it.
It only makes the local news whenever someone dies driving there.

it's the same with nuclear. It's vastly vaslty safer than almost any other option. that nuclear plant near you is orders of magnitude less likely to kill you than almost anything else in it's place yet whenever there's any drama involving nuclear you hear about it.

so you hear stupidity from people like "I'm too afraid that a nuclear plant would kill be, I'd much rather install solar pannels on my roof, that's far safer" when in reality you're vastly more likely to fall off and die while installing or cleaning the pannels than to die in a nuclear accident.

Re:Doesn't Matter

[Urban Garlic]

Nice.

Of course, people die crossing the street, too. Maybe even Tyrone, whose replacement turns out to be worse.

On a good day, you can manage risk, but even on your best day, you can't eliminate it.

One apparent pebble-bed failure mode, just from looking at the Wikipedia page, is a moderator fire. Construct your own scenario, but if you get oxygen in that gas-cooling circuit at high enough temperatures, it's not hard to imagine an end game that features significant quantities of radioactive smoke and ash being vented to the local atmosphere.

Re:Doesn't Matter

[makomk]

That's not exactly surprising. A lot of claims that nuclear reactors are "safe" have turned out to be lies, and the nuclear industry seems to have a long history of cover-ups (including several cover-ups of major safety violations at the Fukushima Daiichi plant). It would appear that pebble bed reactors fall into that category.

Re:Doesn't Matter

[fritsd]

I don't think it invalidates the pebble bed reactor idea per sé entirely, since the accident at THTR-300 was a stuck ball of fuel in a pipe. IANANE but the Helium coolant seems volatile (i.e. disappears during earthquake) and the graphite moderator balls are flammable (à la Chernobyl).
However, my primary complaint is that whichever reactor model is proposed, the waste disposal issue is a much more difficult problem with underwhelmingly few safe long-term solutions.
For example: let's say a low-lying country wants to stuff steel barrels of vitrified waste in a salt mine underground. 1000 years later, that part of the country is under water. Warm salt water is not good for steel. Now what?

Re:Doesn't Matter

[Will.Woodhull]

Congresscritters is congresscritters. Do not expect too much from them.

I do wish that the more vocal advocates of nuclear power would get beyond yelling "we can and should make better, safer reactors" and start talking rationally about what it will take to create a nuclear power industry that will handle its waste properly. I know that could be done, but I also know it won't be done by continuing to shout "four legs good, two legs BETTER!"

Nuclear sheep: the proponents that radioactive wastelands are caused by.

Re:Doesn't Matter

[tehcyder]

It doesn't matter how safe they are, the forces of extreme environmentalists and Luddites will say No! No! No!

There would be a lot fewer people saying No! No! No! if the nuclear industry hadn't lied consistently since it first began: lied about cost, lied about government subsidies needed, lied about long term waste disposal, lied about environmental impact, lied about leaks and accidents...

The nuclear industry is a dog that has given itself a bad name.

Re:Doesn't Matter

[HungryHobo]

A paper on possible failure modes:
http://dspace.mit.edu/handle/1721.1/17748

apparently you're good for about a week even in a worst case *everyone who knows about the plant has suddenly died and all the safety systems have failed at once* scenario.

I also imagine that a direct asteroid strike would be bad for the reactor.

Re:Doesn't Matter

[LandGator]

Mod up, please. Very well said.

Highy Complex

[StefanJ]

I'm sure there's a good reason. I'm just curious.

Long-standing rules require that cooling system pumpbs be turned by thirteen blind eunuchs running on a treadmill, backwards.

Backup systems powered by steam engined fueled by burning kittens and the tears of homeless orphans are becoming popular.

Re:Highy Complex

[h4rr4r]

Damn that blind eunuchs union, if only we could remove the right to collective bargaining from blind eunichs.

Re:Highy Complex

[Anonymous Coward]

They'll never see the change coming.

Location, location, location

[Anonymous Coward]

Placing a plant at sea-level in an earthquake zone was mistake number one. And one that likely won't be repeated.

That then leaves other inherently melt-proof designs like pebble bed and CanDU as existant.

Fast, as in Fast Breeder?

[Bruce Perens]

The problem with Fast Breeder reactors is that they make plutonium. Great for atomic bombs, and if you don't want to develop the technology, it's still an extremely powerful chemical poison.

Re:Fast, as in Fast Breeder?

[Gordonjcp]

It's also a great fuel for nuclear reactors. Keep two fast-breeder plants running in slightly different configurations, and you never have nuclear waste to worry about - you can take "waste" from older reactor designs and burn that up.

Re:Fast, as in Fast Breeder?

[mbkennel]

Non breeder reactors, like every power reactor on the planet, also make plutonium.

For weapons you want only Pu-239 and not much Pu-240 or heavier nuclei which will cause problems in your weapons.

The only thing is that you take the fuel rods out early (uneconomically) if you want to make weapons.

In either case, the critical problem is cracking open the fuel rods and separating the plutonium from the very dangerous (if free) radioactive products. Reprocessing is the critical technology for weapons manufacturing, not 'breeder vs non breeder' reactor.

A high density of fast neutrons also makes the heavier actinides (that's how they get that way) which makes bomb making more difficult.

Re:Fast, as in Fast Breeder?

[Rashdot]

There's an abandoned Fast Breeder in Kalkar Germany: http://en.wikipedia.org/wiki/SNR-300

Re:Fast, as in Fast Breeder?

[rahvin112]

There are several isotopes that are still classified that are usable in atomic weapons. The usefulness and in some cases the existence of these isotopoes in uranium, plutonium and other fissionable nuclei is still a closely guarded secret.

If you doubt, consider the effort and research in the hundreds of test weapons, and the existence of the primary fission/fusion munition in the 500mton range that weighs so little you can put 5 of them on a single ICBM. These kinds of yields aren't possible with the poor mans fission weapon of the gun type uranium or implosion plutonium bomb. The existence of these weapons is highly dependent on classified isotopes and weapon designs that maximize yield per pound and were developed over 30 years of testing and refinement.

Re:Fast, as in Fast Breeder?

[mbkennel]

All that """"progress""""" arises from superior understanding of exotic fluid dynamics and radiative transfer, and not nuclear physics.

The high-burnup and yield of compact weapons come from fast fissioning of plain-old U-238. The trick is the implosion of the fusion/fission secondary and the high quality coupling from primary to secondary. It's much much cheaper and efficient to use fusion once you know the tricks to fission cheap depleted uranium.

Re:Fast, as in Fast Breeder?

[Anonymous Coward]

And you know this because......

Re:Fast, as in Fast Breeder?

[BlueParrot]

Reactor grade plutonium is everything but great for making nuclear weapons. The DOE analysis of the actinide component from sodium cooled fast breeders suggested that simply lumping it together as a sphere ( as you do in plutonium based nukes ) would cause the plutonium to melt under its own decay heat. Now you're going to do that with the thing surrounded by plastic explosives, somehow shield the weapon and workers from the intense neutron radiation generated by isotopes of Californium and Einsteinium, and even then the large number of spontaneous neutrons would make it almost impossible to get a high yield from such a weapon.

Also plutonium is not really that powerful a poison compared to stuff you can make yourself in a test-tube. There are other things in spent nuclear fuel that is however...

Re:Fast, as in Fast Breeder?

[Ihlosi]

Great for atomic bombs, and if you don't want to develop the technology, it's still an extremely powerful chemical poison.

The chemical toxicity of plutonium is pretty much irrelevant compared to its radiotoxicity. If you're looking to poison something with a heavy metal, pretty much any other heavy metal will do the job as well as plutonium while being much, much easier to acquire and handle.

Also, "extremely powerful" chemical poisons are about one thousand times as toxic as plutonium. Truly extremely powerful chemical poisons are about one hundred thousand times as toxic as plutonium. A few ten nanograms of plutonium will make a person develop cancer within a few years, a few ten nanograms of botulinum toxin will make sure that the person doesn't get a chance to develop cancer in ten years.

Re:Fast, as in Fast Breeder?

[Anonymous Coward]

This is the same argument that got fast breeder reactors outlawed in the US in 1977. It's false. Yes, plutonium is generated BUT IT'S USED IMMEDIATELY. That's one point. Second, the only place the plutonium exists is INSIDE THE REACTOR CORE. Yes, it's toxic but the fuel doesn't need to be reprocessed any more frequently than ten to twenty years AND you only have the in situ plutonium to deal with. You're not talking about bomb-level amounts (critical mass), just enough in close enough proximity to fission.

Go join the anti-vaccine people if you want to spread FUD like this.

Re:Fast, as in Fast Breeder?

[DarthVain]

Well considering the Japan reactors burn weapons grade stuff, the US must feel comfortable giving it to them.

Re:Fast, as in Fast Breeder?

[Anonymous Coward]

I think plutonium being a chemical poison is a urban legend. In reality it's not more chemically poisonous than any other heavy metal out there, e.g., lead. It's very dangerous because of its radio-toxicity, especially when inhaled.

Toshiba 4S reactor

[Dog's_Breakfast]

The Toshiba 4S (Super Safe, Small and Simple) reactor solves all these problems: http://en.wikipedia.org/wiki/Toshiba_4S It's a mini-sized fast neutron reactor... http://en.wikipedia.org/wiki/Fast_neutron_reactor It can burn thorium or depleted uranium, and actually help to eliminate the current stockpile of nuclear waste. This was invented several years ago, but has yet to be deployed anywhere. It's mainly the fear of anything with the word "nuclear" that prevents use of this technology. Ironically, the failure to build more nukes means we'll be building more coal-fired power plants, with disastrous effects on climate. Yeah, I know, the anti-nuke people say that "wind and solar is all we need." And they are right - all we've got to do is reduce the world's population by 90% and move everybody to a place that is windy or very sunny. So, if you live in the Aleutian Islands, the never-ceasing howling wind can provide lights for your hut. Or if you live in Death Valley solar will keep your cell phone and laptop recharged. See, we don't need nukes.

Re:Toshiba 4S reactor

[h4rr4r]

Or we could put the panels in the desert and let the people live where ever they like. I know crazy idea.

Sure nukes have a place, but at this point they are more heavily subsidized than any other power generation method. I say that because cleanup costs always come from the tax payer. Solar thermal plants in our deserts and Wind where that fits can be a large part of our power needs. Nukes will still be needed, but unless something can be done about their high costs, coal will sadly stay in use.

Re:Toshiba 4S reactor

[Anonymous Coward]

Whoosh! Power distibution isn't practical so you wind back up at the gp post.

Re:Toshiba 4S reactor

[Anonymous Coward]

Or we could put the panels in the desert and let the people live where ever they like. I know crazy idea.

Right, because having fields of solar panels enormous enough to power cities would have little-to-no effect on desert ecology, and transmitting said power for great distances has no loss of efficiency. Oh, wait.

I'd much rather see per-building solar panels (you've got the roof space anyway, why not use it for something useful?) be more popular, with safer reactor designs being used for base load.

Re:Toshiba 4S reactor

[Martin Blank]

Living near a desert that is often mentioned for solar power (the Mojave Desert in California), it's not always easy to get them built there. The problem of distance from significant population bases means that construction costs soar as the materials have to be sent by truck out to some remote places. Contractors generally require more money for the workers who are driving longer distances (often because of union requirements) to the job sites. And environmentalists worry about the impact to endangered species such as the Joshua tree and the desert tortoise.

The Sahara may be an easier, less-expensive place to build a solar farm than US deserts.

Re:Toshiba 4S reactor

[h4rr4r]

Oh noes teh scorpions! We can lose some desert just fine. Power transmission over great distances is already done today. That is what we call a solved problem.

Re:Toshiba 4S reactor

[hawguy]

It's a bit more than "some" desert.

California uses 257000 million kwh in a year or 257000 gwh

The Moura Photovoltaic Power Station ( an example of a large-scale plant) it generates 93 GWh per year in around 1 square mile of land. So to generate all of California's power would take 2700 square miles of desert, or 10% of the Mojave desert. And of course, this ignores the extra land that would have to be devoted to energy storage mechanisms to provide nighttime power. And ignores the need for excess capacity to account for cloudy/rainy days (even a desert gets rain - the Mojave desert receives around 5 inches of rain/year)

And this is for just one state (albeit a large one)

it seems much less destructive to build 15 modern 2 GW nuclear plants, consuming around one hundredth of the amount of land.

Re:Toshiba 4S reactor

[loshwomp]

Nukes will still be needed, but unless something can be done about their high costs, coal will sadly stay in use.

Nukes only seem expensive because you're comparing them to coal, which has massive external costs not accounted for. Compare nukes to other massively-scalable generating technology that emits low CO2 (e.g. what, again?) and they start to look pretty good.

Re:Toshiba 4S reactor

[h4rr4r]

The closest to that would be wind, and is why in places where that makes sense they are putting them up as fast as they can.

To make such a change we really will have to tax CO2, but that will never happen in the USA.

It isn't a matter of innovation.

[v(*_*)vvvv]

Be it the levees that failed in New Orleans, or the I-35W bridge over the Mississippi, it isn't a lack of innovation that causes any of these disasters. It is in lack of maintenance, and just *caring* in general.

"If it ain't broke, don't fix it."

Well, look where it got us.

I would contest innovation actually. That is how governments waste tax dollars. Stick to time tested simple solutions that multiple contractors can compete for. Innovation is for the private sector.

Re:It isn't a matter of innovation.

[blair1q]

"time tested simple solutions that multiple contractors can compete for" is what they had in Fukushima.

The thing about testing things with time is that time doesn't tell you when it's going to hit the random combination of inputs that will crap-out your system.

Testing them thoroughly by assuming that all inputs will exhibit their full range in all combinations is how you ensure that your systems work.

But hardly anyone does that now, and when they were designing these things there was no engineering discipline devoted to safety, and no sense of what safety and real testing looked like. They imagined a couple of things going wrong, bolted on one layer of backups, collected the check and flew home.

Re:It isn't a matter of innovation.

[benjamindees]

They imagined a couple of things going wrong, bolted on one layer of backups, collected the check and flew home.

I imagine it's worse than that. This thing was designed and built before the digital age. They didn't even imagine a couple of things going totally wrong. They imagined some percentage of probability of something going wrong and then increased the safety factor by some multiple of that probability and called it good. Total analog design mentality.

Re:It isn't a matter of innovation.

[Anonymous Coward]

You mean the same private sector that brought you the Internet, spread-spectrum and frequency-hopping radios, the grand challenge, and onion routing?

Breeder Reactor = weapons grade material

[Anonymous Coward]

Breeder reactors have the potential to create material that is considered "weapons grade."

A google search for "breeder reactor weapons grade" will give you a laundry list of such concerns.

Hands up all those that want a nuclear breeder reactor in, say, Iran, or Afghanistan, or ... get the picture?

Re:Breeder Reactor = weapons grade material

[KillAllNazis]

Worst case scenario it levels the playing field?

Re:Breeder Reactor = weapons grade material

[Patch86]

While you may have a point, that hardly works as an argument against such reactors being built in France, say, or China (both of whom have nuclear bombs, and plenty of nuclear reactors of various designs).

I doubt many people would say that the US can't build a type of reactor for fear of it allowing them to get nuclear bombs...

Re:Breeder Reactor = weapons grade material

[Hartree]

Did you even bother to look at the travelling wave reactor info? Did you just hear the word "fast" or breeder and stop?

It's designed to make proliferation nearly impossible. That's a big reason why Gates is interested.

It only generates the fissile fuel in a narrow strip where the reaction is going on, and then burns it up. In front of the reaction wave, no plutonium. Behind the wave, maybe some traces left. In the wave, it's an active reaction. That's a touch difficult to turn into a bomb.

Re:Breeder Reactor = weapons grade material

[Culture20]

Worst case scenario it levels the playing field?

That's the best case scenario. Medium case scenario: a young punk with a shiny new gun challenges the grizzled gunslinger to a duel. Almost-worst case: Chernobyl boy poops in the classroom, and it's diarrhea, and it gets all over the place! Worst case: a young punk with a shiny new gun assassinates the grizzled gunslinger by shooting him while he sleeps, then goes around shooting anyone he pleases until he's brought down by the schoolmarm with a shotgun.

Re:Breeder Reactor = weapons grade material

[Anthony Mouse]

Hands up all those that want a nuclear breeder reactor in, say, Iran, or Afghanistan, or ... get the picture?

So don't build one there. Or build one of the ones that breeds Pu-240 which will "contaminate" any Pu-239 and prevent it from being used in a weapon.

Re:Breeder Reactor = weapons grade material

[Neil Boekend]

To paraphrase: If you make breeder reactors illegal only the terrorists will have a steady supply of weapons grade plutonium

We need even more advanced reactor technology.

[Anonymous Coward]

... which don't require radioactive materials.

Yes, laugh now... we'll see later.

Environmentalists would LOVE pebble bed and breed

[Anonymous Coward]

It doesn't matter how safe they are, the forces of extreme environmentalists and Luddites will say No! No! No!

The extreme environmentalists only have a problem with the waste disposal - the fact that it takes 10,000 years or more for it become safe. If these new reactors will actually use nuclear fuel until it's about as radioactive as any other natural source, the "extreme" environmentalists will be behind it 100%.

I have never, ever, come across a Luddite who was against nuclear power - ever.

Nuclear power plant lost power?

[Anonymous Coward]

Im confused. A power generating device lost power? Where did the power go to? Has anyone found it yet? They should have used a current bush.

From the same folks that brought you

[Anonymous Coward]

the blue screen of death? doh.

Thats a Thorium reactor then

[Anonymous Coward]

http://www.youtube.com/watch?v=WWUeBSoEnRk

Looks like Congressman Chet Holifield can be blamed for us not having safe reactors

Wikivertisement

[mangu]

The Wikipedia article has been hijacked by their marketing dept, it's the closest things I've seen to an advertisement in Wikipedia.

Re:Wikivertisement

[517714]

Yeah, but check out the talk page. There is a lot more information on the design there than in the main article.

Re:Wikivertisement

[spun]

Good Lord. This looks like a total scam. This is all funded by a known patent troll. It appears to be some sort of viral marketing campaign to drum up customers, i.e. moronic investors willing to part with huge sums of money they will never see again. And now we're all part of it, they'll point at Slashdot and say, "Look! Nerds are talking about it. Smart people. See them talking about it? Now give me some money." I feel dirty now.

What makes it so safe?

[hawguy]

I'm having trouble finding any details on what makes this TWR reactor safe. They mention that it uses passive liquid metal cooling to ensure safety, but even passive cooling has potential failure modes. They state that relying on the laws of physics makes for a reliable reactor, but the laws of physics that govern diesel generators are well studied, yet they still failed at Fukushima.

From reading about other liquid metal designs, it sounds like natural convection alone is enough to keep the coolant flowing, but what happens if the earthquake or some manufacturing flaw causes a leak in the coolant pipes and the liquid coolant ends up on the floor of the reactor?

The PBR is supposed to be self regulating -- higher temperatures reduce the rate of the reaction, so even a total loss of coolant means that the fuel heats up to some steady state temperature and will stay there forever. What happens to a TWR if the coolant flow stops for any reason?

Re:What makes it so safe?

[Anonymous Coward]

The PBR is supposed to be self regulating -- higher temperatures reduce the rate of the reaction, so even a total loss of coolant means that the fuel heats up to some steady state temperature and will stay there forever. What happens to a TWR if the coolant flow stops for any reason?

Didn't you just answer your own question?

From reading about other liquid metal designs, it sounds like natural convection alone is enough to keep the coolant flowing, but what happens if the earthquake or some manufacturing flaw causes a leak in the coolant pipes and the liquid coolant ends up on the floor of the reactor?

How about you build it so it will not crack and leak. Liquid sodium is flammable in air and explosive in water. Yet, it can be quite safely used. Or are you looking for excuses like, what would happen when a meteor hits it?

Well, what do you think happens to a city when an asteroid hits it? What happens to everything downstream when an asteroid breaches a massive hydroelectric dam? What happens at the end of the universe?

There are some things one can plan for. These situations tend to involve cases where people actually survive the event. There are others that you don't really care about, like getting hit by an asteroid, a black hole going through the solar system, or end of the universe.

Anyway, TWR is something in the future, like fusion. Until then we have to deal with today's 1 in a billion reactor years safe designs, or with the yesteryear's "1 in 100,000 reactor years safe" designs until they are decommissioned.

Re:What makes it so safe?

[Magada]

How do you deal with ~ 2000 tons of radioactive molten metal, currently bubbling on top of your spent fuel elements, when it's de-fueling time?

Re:What makes it so safe?

[hawguy]

The PBR is supposed to be self regulating -- higher temperatures reduce the rate of the reaction, so even a total loss of coolant means that the fuel heats up to some steady state temperature and will stay there forever. What happens to a TWR if the coolant flow stops for any reason?

Didn't you just answer your own question?

If my question was "What makes a PBR reactor so safe", then I guess that answers it, but I asked what makes the TWR reactor so intrinsically safe, aside from the fact that they say so.

How about you build it so it will not crack and leak. Liquid sodium is flammable in air and explosive in water. Yet, it can be quite safely used. Or are you looking for excuses like, what would happen when a meteor hits it?

Well, tell me what a liquid metal cooling system looks like - is it 5 feet of pipe that makes a loop outside of the reactor, or is it 1000 feet of cooling pipes that need to run outside of the containment building to radiate the heat?

I guess maybe I should have just asked "What makes this TWR so safe?" Oh wait, I did. And the best answer you can give is "You build the cooling system so it can't crack and leak". Isn't that like saying "If you have active cooling, design the plant such that you can't lose electricity?"

Re:What makes it so safe?

[lisp-hacker]

The PBR is supposed to be self regulating -- higher temperatures reduce the rate of the reaction, so even a total loss of coolant means that the fuel heats up to some steady state temperature and will stay there forever. What happens to a TWR if the coolant flow stops for any reason?

The heat is self-regulating the chain-reaction only,
But the reactor will still heat up to some state above 2000 Degrees and you reactor structure needs to dissipate the generated decay heat at that point. It should not melt, crack (and let any air or water in) for possibly a loong time.

Teller and Dyson - TRIGA Mark I - designed in 1956

[Anonymous Coward]

quoted from http://www.ga-esi.com/triga/about/index.php ... TRIGA is no ordinary light water reactor because much of its "moderation" of neutrons is due to the hydrogen that is mixed in with the fuel itself. Therefore, as the fuel temperature increases when the control rods are suddenly removed, the neutrons inside the hydrogen-containing fuel rod become warmer than the neutrons outside in the cold water. These warmer neutrons inside the fuel cause less fissioning in the fuel and escape into the surrounding water. The end result is that the reactor automatically reduces power within a few thousandths of a second, faster than any engineered device can operate. In other words, the fuel rods themselves act as an automatic power regulator, shutting the reactor down without engineered devices.

Why is this on Slashdot?

[janwedekind]

The last thing we need now is Intellectual Ventures and their toxic patents. Nuclear research already is crippled enough in the interest of national security.

Re:"The plant's operator tried to bring in mobile.

[blair1q]

How nice of GE to provide one-off parts for a safety system.

On the other hand, you'd think the operators of an electric plant could splice a couple of 3-phase lines together.

Kind of off topic, borderline AC even, but..

[drfreak]

If Bill Gates' life was to flash before his eyes, would it be a blue flash?

Re:Kind of off topic, borderline AC even, but..

[Xacid]

I'll be honest - I have no idea what you're referencing. But the 5 mod points for funny make me think it's worth asking.

Re:Kind of off topic, borderline AC even, but..

[drinkypoo]

I just wonder what he looks like under the fake skin. Where's Charlie Sheen when you need him? Oh, wait...

Re:Kind of off topic, borderline AC even, but..

[ElectroPrime]

Depends on how close he was to a nuclear reactor's core.

Re:Kind of off topic, borderline AC even, but..

[Anonymous Coward]

Yes, but with a LOT of green.

THESE reactors should't have had a problem

[unassimilatible]

It can't believe nobody has mentioned this, but the reactor designs were not the problem. All of these cooling problems could have been solved by some sort of waterproof backup power, even if it had to be stored 50 miles away and delivered via an underground cable that comes up under the reactors. Some of these reactors' cooling systems failed because the battery backup power was in the farking basement for crissakes! Below sea level on an Island! Totally flooded. I'm a social science (excuse the contradiction of terms) and I know better than that.

How hard would it be to either 1) keep battery backup at a high point above a nuke plant* (I know, weight, whatever, engineer around it) or 2) the plan I mentioned above, the same redundancy that data centers have, redundant power located elsewhere. Either would have likely saved these reactors.

*Patent pending.

Re:THESE reactors should't have had a problem

[Aqualung812]

All of these cooling problems could have been solved by some sort of waterproof backup power, even if it had to be stored 50 miles away and delivered via an underground cable that comes up under the reactors.

Right, because an underground cable wouldn't be harmed by an earthquake?

Re:THESE reactors should't have had a problem

[sdiz]

> ... 50 miles away and delivered via an underground cable

50 miles away, be it underground or not, are prone to earthquake damage.

Re:THESE reactors should't have had a problem

[Col Bat Guano]

If they cooling ponds were slightly below sea level it wouldn't have been a problem either.

A pipe leading from the sea that could be opened in the case of loss of power, or alternatively that is always kept closed by power (so it automatically opens on power failure) would have been a better design.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

backup power ? run underground? Same ground that moves during an earthquake? Casing/conduit breaks, shorts to ground, no power.
Just like the 7 - 10 mile power cable being run to reactors now since local power failed, Fifty miles away is no better if the electrical fault is 1/2 mile away or 7 miles away from need. same result.

Re:THESE reactors should't have had a problem

[nitehawk214]

All of these cooling problems could have been solved by some sort of waterproof backup power, even if it had to be stored 50 miles away and delivered via an underground cable that comes up under the reactors.

Because there is certainly no way that could have failed.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

The earthquake moved parts of Japan about 8 feet, odds are good that a backup 50 miles away would have had the connection damaged during such a severe quake if it were underground or had the utility towers knocked over by the tsunami. They designed these to withstand a major earthquake, not one that shattered the record books, let alone one accompanied with a tsunami. I can see your argument for battery backup, but keep in mind that there is only so much redundancy that can be put in place - ships are often double or triple hulled, but 1000 hulled would be impractical. Also keep in mind that for all of these backups you are adding interfaces that could create problems - batteries inside containment unit to protect from tsunamis could conceivably leak acid into the reactor/that eats into the containment unit.

Re:THESE reactors should't have had a problem

[Khyber]

Cables tend to flex, so their chance of withstanding an earthquake even shifting them multiple feet should be rather large.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

Cables under ground to supply emergency power is not viable in the case of an earthquake. Ask the people in Christchurch NZ who have had to resort to over head lines to recover power.

But alternative sources of power could have been bought in sooner, such as anchoring a ship in the harbor, or flying in several large portable power generators.

*Patent obvious.

Re:THESE reactors should't have had a problem

[bongey]

It was using active cooling, modern designs have passive cooling. I actually talked to the chair of the nuclear engineering department at University of Missouri Rolla or now Missouri University of Science, about modern designs. Modern passive cooling system build a large pool of water above the main reactor. I don't know all the details but I pretty sure they would just use a nature heat cycle. Hot water goes up to main cooling pool, the cool water is pulled by gravity back through the reactor. No backup power needed, unless gravity someone how fails.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

"even if it had to be stored 50 miles away and delivered via an underground cable that comes up under the reactors"

It didn't have to be. The reactor site is carved out of a hill at the coastline that has a plateau on top at 30 to 40 metres elevation -- plenty high for any tsunami short of one generated from an asteroid impact. The backup generators could have been sited at safe elevation no more than a couple hundred metres away.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

Waterproofing via distance may not save the back up from the earthquake, or the aftermath of the earthquake.

Nuclear power mistakes/design flaws/misc errors/etc. in this country would fall to the taxpayers to cleanup, which is funny to me, given that the technologies biggest proponents are currently whining non-stop about taxpayer bailouts.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

I'm sure it's easy to make such assertions from our armchairs, armed with hindsight. If they had power 50 miles away connected by underground cable, then you have 50 miles of cable that could break, flood, catch fire, etc.

Every now and then, something unexpected, which lies outside what anyone planned for, will happen. This is one of those times. That no one has died is amazing and a testament to the foresight and planning that was in place -- just think about how many coal miners are killed each year.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

Underground cables? Those would be perfect - the power supply would be guaranteed unless the earth itself moved! Oh wait...

Backups in the basement seem like the best option - they won't bear the brunt of any tsunami, and won't be toppled by an earthquake. But obviously other backups away from the sea, connected to the plant by fast-to-repair overhead powerlines would be a good backup backup.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

Good idea on the underground cable. Moving the backup location inland would have helped, and since electrical lines are tested in pools of water anyways, the lines if simply buried would have been fine.

Fail on the high point. The problem isn't that the battery is in the basement or below grade. That's fine. It simply has to be sealed, pumped out, double channel walled, or the wall taller than the flood or wave. For the first, it's essentially building a ship on land--a ship's engine is usually below water grade when it's out on the ocean after all. For the others (pump, double wall, tall wall), it's not unusual in residential construction to have a double basement, where the lower level is gravel and you pump it out (massive sump pump pit essentially) and to line the walls with a channel material (like an out double wall, so the water falls straight down). Run a powergrid electrical main, plus the nuclear electrical output, and a couple diesel generators there, and it could run the pumps for both the pit and the reactor. Third line of defense would be to raise the backups up a bit, so if water somehow made it in to the higher basement level, you have yet another chance to eject the water.

I'm surprised they didn't have mobile, massive backup generators of some sort on boats. Not sure why their peacekeeping force, or the US military, didn't send in a ship, and draw the electricity from the engine or the ship's power. That could have been there in hours. Then again, the Japanese government and nuclear company seem to be covering their asses; I think the Japanese government is too pliable and trusted the nuclear company, with the gov only waking up when the US government pointed out what a huge crisis was unfolding.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

In case you didn't notice, there was a landscape altering earthquake a bit before the water got there... your nice underground cable would probably have snapped like the main intercontinental links did.

Which social science are you, by the way? ;)

Re:THESE reactors should't have had a problem

[Anonymous Coward]

The advantage of having the batteries in the basement is that you don't need a long cable. Surely the longer the cable, the more likely it is to be damaged in an earthquake?

Re:THESE reactors should't have had a problem

[Anonymous Coward]

How about not requiring electricity for the damned safety-critical cooling? Like some of the very frist reactors e.g. in the Netherlands have done successfully?

Re:THESE reactors should't have had a problem

[Anonymous Coward]

I think it would be a simpler and easier idea to just make the fucking cooling pond at the bottom of a shaft that sits 100 foot below sea level. If a tsunami floods the facilty, well then you've got 100 foot of water already covering the spent rods.
They could do the same thing with the reactor core: Suspend it over a deep shaft full of water, if the thing melts down or is in a very bad situation you just pull a big lynchpin and the whole thing goes Splash!

The best part is, if you lose ALL ability to cool the thing, all you need to do is have a ditch or channel of some kind pre-dug, and gravity will keep it filled up no matter how much steam evaporates.
And it's not like it would be that hard to make those wells pre-contained just like we would engineer a long-term nuclear storage "coffin".

Or in other words, instead of focusing our engineering on preventing problems, and then adding a few mitigation plans, we should be designing these things from the ground up with the assumption that they WILL fail, and horrible, no matter what we do to stop it. I would also say we should build these facilities in a ready-to-Entomb condition, so that in the event of a really nasty disaster we can just "flip a switch" and seal the whole thing off.

Re:THESE reactors should't have had a problem

[squizzar]

Because that would complicate the handling of the spent fuel. You need to do the risk assessment to work out if repeatedly moving the fuel over a large distance is more dangerous than the chance of the larger than expected earthquake occurring, followed by the larger than expected tsunami, followed by all the other things that went wrong.

There have been cases of spent fuel bundles catching fire after removal from the reactor, so I'd wager that's why the pools are close to the top of the reactors.

Whether we should need the spent fuel ponds is a different matter, and one that to me stinks of the same cheap politicking that affects the entire nuclear debate. Building a proper waste repository or breeder reactors that can significantly reduce the amount of waste means someone would have to stick their neck out and upset some voters. Building more modern plants that are safer and have passive cooling and intrinsic safety designed in would upset some voters. Shutting down the existing plants and losing 25% of base load power would upset some voters. Doing nothing and pretending like there isn't a problem has worked until something went wrong, so now someone or something needs blaming or some voters would get upset. No-one wants to stick their neck out now and say they should have had the guts to do something about the problem before we narrowly avoided disaster.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

I too wondered why they didn't have backup generators controlling pumps. But as far as backup battery packs are concerned.. I'm pretty sure they would have been damaged even if they were elevated above the ground when a 20 foot wave hit the facility. Some engineering and waterproof diesel generator might have helped things though.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

Some of these reactors' cooling systems failed because the battery backup power was in the farking basement for crissakes! Below sea level on an Island! Totally flooded. I'm a social science (excuse the contradiction of terms) and I know better than that.

Yeah hindsight is 20/20 like that, funny they didn't plan on a 9.0 earthquake (which moved the nation 8') causing a 33' Tsunami and flooding the island. Maybe they had planned more around getting hit by an airplane?

Re:THESE reactors should't have had a problem

[mortonda]

even if it had to be stored 50 miles away and delivered via an underground cable that comes up under the reactors.

Yeah, that's a great idea in earthquake country. O.o

Re:THESE reactors should't have had a problem

[Ol Olsoc]

Accch! as an emergency last resort maybe, but once you flood the reactor with seawater, you ruin it. Much better to have more failsafe freshwater circulation cooling whenever possible.

Re:THESE reactors should't have had a problem

[Col Bat Guano]

I was really imagining the spent fuel rod pool in the same building, just down a long way. That way you could still use the same crane mechanism to move it (presumably a gantry crane), but you would just need a lot more cable.

Issues of accurately aligning the longer pendulum into the pool are left as an exercise to for the designer.

Re:THESE reactors should't have had a problem

[Col Bat Guano]

It's what they are doing right now - pumping sea water onto/into the cooling ponds.

Re:THESE reactors should't have had a problem

[Anonymous Coward]

Actually designing out the need for external power is the only solution.

Any back-up system that you can conceive will have a point of failure. You can design a 600 times redundant system, however there will always be the chance of a 601st level failure. I am quite sure that the current system had an inconceivably low probability of the multi-level failure that they currently have.

The only way to guarantee 100% that external power will not cause a problem is if you don't need external power. A new design could introduce new points of failure, but you could absolutely guarantee that a need for external power will not be one of them.

Re:THESE reactors should't have had a problem

[Ol Olsoc]

Yes they are. And the reactors will be pretty useless after that. But they had to do something. Pity is, if the emergency generators wouldn't have been in a vulnerable location, it would have been a simple scram, the emergency generators would have kicked in, and they'd be restarted by now, and providing power.

And that's the thing that amazes me. A lot of folks are defending this whole disaster, calling anyone who might question the process as dim witted or environmentalist as a pejorative. They know the truth and the right way, and if you dare criticize, ye be a schmuck.

When in fact, this was a chance for the industry to shine, and they missed it. All because of decisions made about the system, not the process.

Re:THESE reactors should't have had a problem

[Jonathan_S]

All of these cooling problems could have been solved by some sort of waterproof backup power, even if it had to be stored 50 miles away and delivered via an underground cable that comes up under the reactors

50 miles of buried power cable; massive earthquake...

I think I see a flaw in this little plan.

Problem with terra power

[mbkennel]

"the two biggest advantages of the fast reactor design is that it requires no spent fuel pools and uses cooling systems that require no power to function"

Let's translate what this means. The core of the reactor will be VERY radioactive as it will have decay products from many more gigawatt hours---yes it will transmute quite a bit of these but do not underestimate just how hot it will be.

The cooling systems use molten sodium. It has the wee problem that it is explosive in contact with water. Say from a flood. Or if the building catches on fire. (and it's probably quite radioactive in itself simply from activation from the neutron flux). Or suppose there's a leak in the roof and it rains.

And it's right next to an extremely radioactive core. And if the explosion results in something cracking open......

One huge problem at Fukushima reactors was the unappreciated dangers of flooding, combined with the hydrogen explosions. These explosions damaged other important machinery and structures---you get a 'blunder chain reaction'.

See some other comments about the TWR

http://theenergycollective.com/barrybrook/43928/terrapower%E2%80%99s-travelling-wave-reactor-%E2%80%93-why-not-use-ifr

Re:Problem with terra power

[Anonymous Coward]

The cooling systems use molten sodium. It has the wee problem that it is explosive in contact with water. Say from a flood. Or if the building catches on fire. (and it's probably quite radioactive in itself simply from activation from the neutron flux). Or suppose there's a leak in the roof and it rains.

That gave me a pretty good chuckle. I don't think any serious attempt at building a sodium-cooled reactor would permit a "leaky roof" to cause a problem of that magnitude. Consider that the rather antiquated primary containments at Fukushima haven't allowed anything in or out (apart from planned steam ventings). The hydrogen explosion in Unit 2's containment may turn out to be an exception, but there are promising signs that even it may be intact, or need only minor repairs.

For a sodium-cooled reactor, the pool is under a dry-inert atmosphere that is maintained above 1 atm. The whole thing is in a robust, modern containment with lots of redundancy. Unlike the water-cooled reactors at Fukushima, residual decay heat is removed passively -- no pumping, no operator intervention required. Natural convection in a liquid metal (excellent heat transfer properties) used with a metallic fuel (as opposed to the ceramic, low thermal-conductivity, UO2 fuel in an LWR) is a beautiful, beautiful thing.

Bottom line: your concerns are very much on the mind of Na-cooled fast reactor designers. Clever engineering and some vastly improved materials science can (and have, look at the history of the IFR, god rest her soul) make this safe and feasible.

Re:Problem with terra power

[MrSteveSD]

The cooling systems use molten sodium. It has the wee problem that it is explosive in contact with water.

There was a serious sodium coolant leak at the Japanese Monju reactor in 1995. It got so hot that steel structures in the room started to melt. You can imagine how such a leak could result in the destruction of other critical safety systems.

The more I learn about nuclear reactors, the more I learn of the potentially catastrophic accidents that have occurred along with a catalogue of lies, safety report falsifications and cover-ups. Nuclear does not seem to be a very safe way forward.

Re:Problem with terra power

[Beliskner]

how about having a huge chlorine bath under the sodium reactor, and if there's a reactor problem the barrier dividing the two is lowered resulting in radioactive NaCl being created?

Re:Problem with terra power

[Ihlosi]

how about having a huge chlorine bath under the sodium reactor,

Great idea. Let's build a huge potential bomb by placing a metal that reacts violently with pretty much anything else next to the substance that it reacts most violently with.

and if there's a reactor problem the barrier dividing the two is lowered resulting in radioactive NaCl being created?

The reaction between chlorine and sodium is hugely exothermic. What you propose basically amounts to blowing the reactor and its contents sky-high.

Also, you don't want chlorine anywhere near neutron radiation, since the Cl-36 created that way has a half-life of a few hundred thousand years. Short enough to make it a radiation hazard, and yet long enough to make disposal quite difficult.

Re:Problem with terra power

[MachineShedFred]

So don't use sodium.

Use a lead bismuth eutectic mixture: http://en.wikipedia.org/wiki/Lead_cooled_fast_reactor

If we had invented the perfect energy generating device, we wouldn't be building anything else. Everything has it's drawbacks - you just have to engineer around them in order to mitigate them.

Re:Problem with terra power

[lisp-hacker]

"the two biggest advantages of the fast reactor design is that it requires no spent fuel pools and uses cooling systems that require no power to function"

A cooling system without power for magnitudes like 10MW does not exist.
You may have a primary sodium circle, but you still need to remove the heat from it by pumping water through a heat exchanger and removing the heat from the water. If you don't do this, the sodium will start to boil at 900 Degrees and then the pressure will break out and be very reactive.

Because taking them offline reduces heat by 95%

[unassimilatible]

And they do have their own cooling, as well as battery backup for cooling. In the case of many of these failed reactors, the battery backup was in the basement, where it was flooded. If only there was some technology that could have saved the day, like not putting batteries in the basement below sea level. Someday...

Re:Because taking them offline reduces heat by 95%

[PeterBrett]

And they do have their own cooling, as well as battery backup for cooling. In the case of many of these failed reactors, the battery backup was in the basement, where it was flooded. If only there was some technology that could have saved the day, like not putting batteries in the basement below sea level. Someday...

To be precise: the backup pumps were powered by electricity from the local grid. If that failed (i.e. if all the reactors were shutdown) it could use power from other power stations along the coast. If that failed (i.e. the lines were cut by an earthquake) it could use local diesel generators. If those failed (i.e. because the tsunami was 10m high rather than the 5.7m that the flood defences were designed for) it could use batteries. The batteries worked fine, and kept the reactors cool for 8 hours until they ran flat. That's when the problems started.

Re:Because taking them offline reduces heat by 95%

[Neil Boekend]

For a moment ignoring the fact that the batteries worked and the diesels failed.
Next step is: Put them as high as possible, so no water can reach them. A storm blows them off the roof into the outer containment shell... People shout: We should put them in the basement where no storm can blow them off. A new tsunami, etc.

Re:Because taking them offline reduces heat by 95%

[Ihlosi]

Next step is: Put them as high as possible, so no water can reach them.

It's like with data backups: If you make three backups and put them all in the same place, they'll all be gone if that place burns down. Instead, make three backups and put them in different places.

Freakonomics looking backward

[PopeRatzo]

Once again, the folks at Freakonomics suggest that the solution to a problems is some new technology.

But they just won't go far enough and say "What about a "new technology" for energy that is not based upon another scarce resource?"

It's surprising to me that this "Freakonomics" movement, which prides itself on "thinking outside the box" is such a prolific purveyor of short-sighted conventional wisdom.

If they were just engaging in thought experiments it might be benign, but you've got people out there who take what these economists say as gospel. Instead of attacking the pseudo-science of Economics as the drivel that it is, they are simply supplanting it with even more banal pronouncements.

I think it's time to say to all of the post WWI economists, including the Freakshop, that you've done enough damage and put them on the shelf next to astrology and phrenology where they belong.

Which reminds me, that the Nosferatu of Economists, Alan Greenspan, showed his ugly face in public again in the past few days, demonstrating again that when you are among the economic or political elite, no matter how badly you fuck up everything that can be fucked up, no matter how much pain you cause to fellow humans, no matter how often you are catastrophically wrong, again and again, once the Media Elite believe you are one of the "Wise Old Men" you never ever have to feel the least bit of shame or remorse and there will always be a seat for you at the tables of the Sunday Morning News Shows. (See McCain, John and Lieberman, Joe for further examples).

As long as I'm at it, did anyone else notice that Colin Powell's son, who was the head of the FCC under George W Bush has now taken a job at the head of the largest and richest lobbying firms representing the Cable Television Industry? What are the chances that he was auditioning for this job when he was making cable TV policy at the FCC? These fuckers will destroy our world, utterly.

Re:Freakonomics looking backward

[maxume]

Is there a large scale energy technology that doesn't require some relatively scarce resource?

Wind and solar both work best with a few somewhat scarce resources (at least, resources that require mining), and stuff like tidal or wave power hasn't really been demonstrated to be practical.

Re:Freakonomics looking backward

[Anonymous Coward]

But they just won't go far enough

Would it be ok with you if we were permitted to converse about legacy energy systems without having the discussion derailed by green pipe dreams?

It would be nice.

Re:Freakonomics looking backward

[benjamindees]

Is there a large scale energy technology that doesn't require some relatively scarce resource?

No, and while I think the GP post is pretty wacky to suggest otherwise, it does have a point. The point is that if such an energy technology were ever developed, it would just have the effect of growing the 'economy' (not really savings but consumption) until it again became dependent upon some limited resource and we would just be back to where we started.

So the solution really is to re-examine the economic assumptions that underlie western society. There is an assumption that we have a "free market". We don't. There is an assumption that work is good. It isn't. There is an assumption that we have an innate right to certain goods and services. We don't. There is an assumption that consumption drives the economy. It doesn't. There is an assumption that growth is good. It isn't. There is an assumption that externalities are accounted for. They aren't.

Re:Freakonomics looking backward

[Anonymous Coward]

But they just won't go far enough and say "What about a "new technology" for energy that is not based upon another scarce resource?"

That freakonomics article is hopelessly short on information. Bill Gate's TEDtalk has more information, specifically:

The idea of Terrapower is that, instead of burning a part of uranium, the one percent, which is the U235, we decided, let's burn the 99 percent, the U238. ....And, because you're burning that 99 percent,...You actually burn up the waste, and you can actually use as fuel all the leftover waste from today's reactors.

Wikipedia: Emphasis mine.

...burning fuel made from depleted uranium, natural uranium, thorium, spent fuel removed from light water reactors, or some combination of these materials...

TL/DR: These type of reactors uses the waste from other type of reactors, which is more readily available.

Re:Freakonomics looking backward

[fredmosby]

Breeder reactors are probably the least short sighted non-renewable method of producing electricity. Their primary fuel is U238, which is more than 100 times as common as the U235 used in conventioal reactors. The real problem is that most breeder reactor designs cost about twice as much to build. If these reactors can be built as cheep as conventional plants they make economic sense, even in the long term.

Re:Freakonomics looking backward

[Anonymous Coward]

Not surprising since the SuperFreakonomics book was basically just a huge plug for Intellectual Ventures. Pity, since the first book was actually interesting.

Re:Freakonomics looking backward

[Anonymous Coward]

Traveling wave reactors burn depleted uranium - i.e. nuclear waste, that nasty, nasty stuff that's really hard to dispose of. According to Intellectual Ventures Labs (who developed said technology): "The U.S. has 700,000 metric tons of this nuclear waste. Using this as fuel for our reactor, it represents a 3000 year national energy reserve." So while non-renewable, it will last plenty long enough to transition to carbon free energy. Solar and wind cannot currently supply baseload power, so we really do need nuclear.

They do

[unassimilatible]

Holy shit, does anyone read anymore? The battery backup systems were flooded, because at last some of them were in the basement.

Re:They do

[Leuf]

The question wasn't why don't they have backups, but why they don't have a self-contained backup in addition to external ones.

Re:They do

[squizzar]

The battery systems worked as designed for 8 hours. They did not flood, they just ran out when they were expected to. The generators that should have come online within that period (diesel generator sets don't just start up immediately) were flooded.

Wrong

[Anonymous Coward]

You mean the private sector that takes an economic downturn to lay off workers and fatten CEO paychecks then brag about how much more "efficient" the employees, scared for their jobs, have become?

I'd rather have government funded research. Innovation is for the public sector not beholden to shareholders.

Thorium ... the future

[jmd]

Thorium reactors anyone?

  http://www.wired.com/magazine/2009/12/ff_new_nukes/

Re:Environmentalists would LOVE pebble bed and bre

[Culture20]

The extreme environmentalists only have a problem with the waste disposal - the fact that it takes 10,000 years or more for it become safe. If these new reactors will actually use nuclear fuel until it's about as radioactive as any other natural source, the "extreme" environmentalists will be behind it 100%.

No they won't. Even if the radioactive materials are rendered into lead, they'll complain that:

• It is poisonous!
• Its elemental symbol is Pb, which is also short for peanutbutter, which causes deathly allergies in children

The *Extreme* environmentalists will also complain that:

• Uranium was mined from mother Gaea, hurting her
• Any energy production helps support an unnatural amount of humans who will continue to rape mother Gaea

Re:"The plant's operator tried to bring in mobile.

[Locutus]

ah, wrong connectors so send the generators back and run in circles try something else? WTF, they can't cut the cables and weld or clamp the wiring together?

LoB

An Autonomous Nuke Plant

[SplicerNYC]

Free standing, self contained, powers it's own cooling system. At the first sign of trouble, it launches itself into space. I think it could work.

Re:"The plant's operator tried to bring in mobile.

[Anonymous Coward]

"connections reportedly didn't match up".... To keep a nuclear plant from meltdown, I'll bet I could stick a crowbar across a couple pieces of wire and MAKE them match up. Now if they are talking phase or frequency, that may be different, but the "connections"?!?

Some might, but some wouldn't:

[Hartree]

That's not entirely true.

For example. Amory Lovins, one of the notables of the anti-nuclear movement was asked in an interview what he thought of a truly cheap clean energy source. He said it would be a disaster. Why? Because he believes that whenever humans are given concentrated sources of power, they use it to destroy nature. Thus humans need to be limited to diffuse and limited sources of energy.

Quite often the waste and radiation questions are arguments used against nuclear power, when some of the motivation would have problems with any concentrated source of energy.

Needless to say, I disagree with that viewpoint, but it is one that can be argued and is not totally without merit.

Re:Some might, but some wouldn't:

[Joce640k]

Yep. If you destroy their "principal" argument (deadly nuclear waste!!) they'll just pull another one out of their asses. These people have too much emotional/peer investment to suddenly go around saying they were wrong and we should start using nuclear power.

Re:Some might, but some wouldn't:

[uradu]

Not necessarily. Take for example Dr. Patrick Moore, one of the founders of Greenpeace. He did a complete 180 on nuclear power, seeing it now as one of the few vital long-term energy sources.

http://www.wired.com/science/planetearth/news/2007/11/moore_qa

Re:Some might, but some wouldn't:

[Will.Woodhull]

I would not go as far as Lovins does, but I do favor a broadly distributed energy source over a highly centralized one. If a significant part of the base load was provided by neighborhood sized micro reactors, that would alter the politics of power management in a very favorable way.

That said, I'd be comfortable with a nuclear power industry that appropriately handled its own waste. That probably means some kind of breeder reactor would be involved.

Re:Some might, but some wouldn't:

[Hartree]

I think highly decentralized power has merits. Certainly it's less vulnerable to a natural disaster, point failure or military strike. There are also some areas that for technical or political reasons big centralized power plants have downsides.

Nuclear is just one energy source. I think that it's a useful one. I'm not sure the public reaction to a neighborhood nuke plant with Joe Average running it would be favorable enough to site them. In time, perhaps.

But, it's only one of many ways to supply our energy needs. All of them have downsides. None of them are appropriate for every situation. It'll be a mix of things regardless of what direction we go.

The travelling wave design is brilliant

[Anonymous Coward]

If it can be effectively scaled, the travelling wave design combines some very compelling features. The advantages of a fast breeder without the downsides. You burn the Plutonium as fast as you make it. What little Plutonium is there at any given moment is too small to be worth harvesting. Sadly, I suspect this is only true when managed appropriately. If held by a hostile power, the net Plutonium output could probably be amplified substantially.

As Seen On Slashdot!

[somepunk]

You guys do read Slashdot, right?
story

Earthquakes?

[slapout]

Wouldn't it be better to not build nuclear plants in earthquake prone areas?

Re:Earthquakes?

[PeterBrett]

Wouldn't it be better to not build nuclear plants in earthquake prone areas?

Good idea. I'll let you go tell the Japanese that they have to dismantle their entire economy and cut their population by 25% because they're not allowed to have electricity any more.

34.5% of Japan's energy comes from nuclear reactors. 21st century Japan would be an entirely different country without nuclear power. Or perhaps you think they should be burning dinosaurs for their power?

a new class of newclear inspectors

[Anonymous Coward]

we'll decide after we inspect the 'other' (magnetic) sources of power (the end of the subscription hostage era) that are available now that we pretend do not exist. thanks. just like we won't send our kids to just any school now, until we see if the father mopery types are still on staff, not sparing the rod etc....

Yep, I've even considered this for PC cooling

[unassimilatible]

Should my investments eventually allow me to live on the water. I've seen guys watercool their PCs with their swimming pool as the heat exchanger, why not the ocean?

But this tsunami thing does have me rethinking the "live right on the water" plan.

Re:Yep, I've even considered this for PC cooling

[Hadlock]

There's a nuclear power plant that is right on the ocean just south of Miami, near Homestead (the location of the only Whataburger in southern FL also). If you zoom in on it in google maps you'll see that they've got some sort of m.c. escher water flowing uphill scheme going on over an area of a couple hundred acres. As I understand it, the original plan was to use seawater directly, but the EPA put the nix on that and they went with the current solution instead. I've personally canoed past water inlets for nuclear power plant heat exchangers on the columbia river, the largest river west of the mississippi, so they're certainly doing it already, and have been for quite a while.

Re:Yep, I've even considered this for PC cooling

[tehcyder]

But this tsunami thing does have me rethinking the "live right on the water" plan.

Just make sure you have an 11m high flagpole to climb up

But that's not what happened is it?

[unassimilatible]

The batteries got flooded, not damaged by the earthquake. The power cable would be yet more redundancy.

Re:But that's not what happened is it?

[thegarbz]

The batteries got flooded, not damaged by the earthquake. The power cable would be yet more redundancy.

[citation needed] Citations are a great thing really. For instance here's one that says the battery backup system worked flawlessly as intended, but was only ever designed to run for 8 hours.

Funny thing about backup backup systems, is that the backup backup is only ever designed to buy you time to allow you to get your backup ... back up and running.

Fission is fission

[Anonymous Coward]

Fission is fission, regardless of the reactor type or fuel source (U, Pu, Th). The fission daughter yield spectrum includes many unstable isotopes that decay over time, creating the problem of decay heat that must be removed. All reactor designs rely on an engineered system to facilitate decay heat removal. There will always be a natural disaster of some magnitude that can disable that system. The solution is not one technology over another, but a constant process of research, analysis, and improvement. In addition, the public needs to be better educated about the probabilistic risk assessments and economic tradeoffs involved in nuclear power.

But the earthquale didn't cause loss of power

[unassimilatible]

The tsunami did. And I didn't say just remote power via cable. I said battery backup power not below sea level that can be flooded.

No solution is perfect - wind power has killed more people than nuke power - but the evidence suggests that had the power of the Japanese reactors been protected from water, NOT earthquake, these nuclear incidents might have been averted.

Re:But the earthquale didn't cause loss of power

[Aqualung812]

Don't mistake my poking holes in your hindsight for thinking that nuke power isn't the safest form of mass power we have. I'm all for using nuke instead of coal/oil/dam-hydro.

It is just easy to sit back after the event and point out all of the things that could have been done to protect it. Maybe they'll do that next time, or maybe someone will decide that it isn't worth the money to keep all of these 4th or 5th level redundant components working.

Re:But the earthquale didn't cause loss of power

[bloodhawk]

I work with a few datacenters, we spend a lot of time and money coming up with Disaster recovery plans for all conceivable problems we can face at each site, everything from flooding/air con failure/fire/power failure/water failure etc etc. I expect a nuclear power plant to exercise 10 times the caution we do as the consequences are obviously a lot more severe. There is nothing in this power plant that required any hindsight to predict these problems, they are by the sea, if flooding wasn't part of the basic investigation for a disaster then many engineers need to be lined up and shot.

Re:But the earthquale didn't cause loss of power

[thegarbz]

So it's a building designed to withstand an earthquake larger than any that has been recorded in history. It's a building with a 6m tsunami wall around the grounds to withstand a larger tsunami than has ever been experienced anywhere on that pacific rim. Oh and it had battery backup that is stored in a sealed room which was completely unaffected by all the above and worked entirely as intended, but ultimately ran out of juice.

Basic planning. You don't rely on your backup backup to run the plant as it's designed. You rely on that first backup in case the main system fails, and you rely on the second backup to buy you enough time to restore one of the primary backups. This is common in all industrial situations. Here's a question for you, can your datacentre run indefinitely on battery power, or does battery power only keep you up for an hour or so to ensure that your diesel generators have a) time to kick in, and b) if they are out you can reasonably expect main power to come on within the intended time anyway?

Here's another question for you. Has your disaster plan taken into account a direct nuclear strike? I mean just because it hasn't happened before doesn't mean it couldn't happen right? What about an alien attack? Both of these were just as likely to occur as an earthquake of this magnitude followed by a tsunami of that size.

Re:But the earthquale didn't cause loss of power

[Ol Olsoc]

But it did happen, didn't it? Standing around saying "Well, no one saw that coming" is useless or worse. Just like Homer Simpson said "As God is my witness Marge, I never thought I would get caught"

There is a certain place for prudence in design. If a place is likely to be hit by a Tsunami, prudence says you don't build a power generation plant there. You build it in a place that it would take a Tsunami of extra-biblical proportions to hit it. The problem with gaming these things is that you will eventually lose. and that is because nature has a tendency to throw more than one problem at a time at you, in unexpected combinations.

Re:But the earthquale didn't cause loss of power

[bloodhawk]

Here's another question for you. Has your disaster plan taken into account a direct nuclear strike? I mean just because it hasn't happened before doesn't mean it couldn't happen right? What about an alien attack? Both of these were just as likely to occur as an earthquake of this magnitude followed by a tsunami of that size.

Actually yes our plan DOES take into account a direct nuclear strike/bomb attack. We have a remote disaster recovery site for just such an occurance. As for the liklihood of a tsunami of that size and a earthquake together, FFS Earthquakes are the major cause of Tsunami's, it only stands to reason that a massive earthquake would also have a high probability or a similarly massive tsunami. If you think the 2 are so unrelated that a alien invasion is more likely then there is no reasoning with you, what I don't understand is how the hell you got marked up as informative.

Re:But the earthquale didn't cause loss of power

[thegarbz]

Notice how nuclear power plants are often littered along the ocean? Let's suppose it wasn't built on the ocean and some other disaster caused a near meltdown, now where would the large portions of seawater come from that in this case can be credited in preventing this from turning into an even bigger disaster?

Everything happens somewhere. Somewhere someone got hit by a meteorite and is probably wondering why he didn't consider building a giant trampoline over his house. Engineering in general is about design compromises and not all problems can be engineered away, sometimes not even because of expense but because it just doesn't work. You can't make anything everything-proof, the same applies to general risk thinking you do every day. You could be killed in a car accident tomorrow yet you still go to work right?

This is the problem with all safety systems is they are designed around quite strict rules of probabilities, the probability of the event occurring and the probability of it having an impact. In this case the probability of a never before seen earthquake, followed by a never before seen tsunami, followed by people not being able to get cooling systems running while the battery backup was doing it's job. The probabilities of those lining up are infinitesimal, but even something with a 0.00000000001% chance of happening, could still happen. Simple economics state when we try to design something to take into account of every possible accident it becomes uneconomical.

Or to think about it this way, in safety systems we talk about probability of failure on demand. What happens if the valve fails to close? Well easy to limit the probability in high consequence scenarios we put two in series. But what if both fail to close? Put a third in. But what if all three fail? Put a forth...... it will never eliminate the risk, and your string of valves is suddenly 100m long. Where do you draw the line?

Re:But the earthquale didn't cause loss of power

[thegarbz]

Read again. I never said the two events are unrelated. I said the two events were bigger than any that could be reasonably predicted for the region. So the earthquake was bigger than what it was designed for, should we make the buildings more structurally sound? Hell yeah... in retrospect. What happens when a 9.6 magnitude quake strikes next time? What happens with a mag 10, 11, 12?

My point which you conveniently missed is that disaster scenarios typically take into account all things that could happen to you based on probabilities and reducing the risks to an acceptable level. Do you only have one remote disaster recovery site? What happens if that is nuked too? Not unreasonable either given that in the event of nuclear war you can imagine nukes flying around all over the place. There's plenty enough evidence that they did take into account the possibility of being hit by a tsunami, they had a tsunami wall. But the tsunami was too big and ultimately the problem with probabilities, is that even if it is approaching zero unless the probabilities of something happening is actually zero it's still a probability and all you can do when it does happen is swear under your breath.

So while the Japs work on nuclear reactor surrounded in solid rubber that's water and shake proof, you go build a disaster recovery site disaster recovery site, and I'll stock up some ammo awaiting the aliens.

Re:But the earthquale didn't cause loss of power

[Ol Olsoc]

This isn't about making everything everything proof. It's about putting things where they should or shouldn't be. We can slippery slope the discussion like you did, with an endless series of valves in case the other doesn't close, which actually reduces reliability, or we can make good safety decisions.

My point is that they played too close to the limits. No one foresaw a 10 meter Tsunami wave? Does that mean that a 10 meter Tsunami wave cannot exist? Hard to argue that one now. But a 10 meter wave is not out of the question in that area.

The likelyhood of a 10 meter Tsunami wave is now 1, on a scale of 0 as "not going to happen", and 1, as "will happen."

A prudent person does not build a house in a flood plain, even though people regularly do, and then are shocked when their house washes away. Related are the probabilities in that case also. There are flood plain maps that show 10, 50, and 100 year underwater boundaries. That doesn't mean that you can't have a 100 year flood tomorrow, and then another a year later. People get probability and certainty mixed up all the time. We talk about an average time between earthquakes of X number of years, then get all nervous when it's been X years since the previous one, or worse, saying we're "overdue".

It is almost certain that if the plant were placed at a higher elevation, the plant would have tripped form the earthquake, then gone back on line after the situation stabilized enough. The biggest problem would have been restoring any lines that were down. The the industry could have used the plant as an example of how even an old plant like this was safe.

And as for economics? Even if the plant cost more to build, how about we do a analysis of the price of the safer plant versus the cost of what has transpired?

And finally, Give some thought to this. The biggest problem I can see people having with this technology isn't the technology. It's the human element. The industry has a credibility issue. And when people come to me as a potential customer and say that "nobody foresaw this", or "It would have cost too much to prepare against that." What is my takeaway?

What I take away is that by building one of these, there *will* be a problem, and the people won't take responsibility for it, they'll just have excuses. No sale. I think we desperately need nuc as a power source, I also see some of our proponents as our own worst enemies.

Re:But the earthquale didn't cause loss of power

[thegarbz]

The likelyhood of a 10 meter Tsunami wave is now 1

Gotta love 20:20 hindsight. What's the probability of an 11 meter tsunami wave then? This is my point. You say we don't need to engineer out everything, but in the same breath you're talking about engineering against a disaster on a scale which no one thought was ever possible on that fault line. Interesting that you say if someone in the industry comes to you to build one of these... There's 440 reactors world wide and there's only 1 serious incident and 2 semi serious incidents. People blame the nuclear industry for a lot, but the reality is not only is it one of the safest industries in the world, but all the credibility issues you cite actually exist in every industry. No one is going to stand up and say "Yes I made that decision and I thought it was acceptable" after a major disaster, especially if it was best practice to build like that.

We engineer to strict standards. We create strict standards by consulting the science. This isn't a case of BP skimping on stabiliser because "she'll be right". This is a case of a well designed, and well built plant being completely overcome. The floodplane issue you cite is also political. I live in Brisbane which got massively damaged by floods and all the houses which went under had something in common. ... we knew they flood and they've flooded before. There's no best practice standards to design a house in a flood plane, there's just government rules saying don't approve developments there, followed by under the table cash transactions to get the paperwork through anyway. I point this out because again it's not a comparison given the amount of paperwork and auditing that goes into the construction of a reactor.

Re:But the earthquale didn't cause loss of power

[Ol Olsoc]

Gotta love denialism too. Care to argue that another big wave will come through? How about an even larger one?

You accuse me of 20/20 hindsight. You are 100 percent wrong. What I would say a lot of people do is willfully put blinders over their eyes. The few times I have been involved in design, I've looked into the worst case scenarios, and then doubled them. There is a lot of opposition to that, from folks who are looking at what they call bottom line, and from folks who believe that the worst case scenario is actually the worst case scenario. It isn't, it's a freaking guess, usually based on the largest event in the past. Tell me, Now that that coast was hit with a larger than predicted wave, does that mean that no wave larger than that will hit? Does that mean that if the plant is rebuilt, that you build it to the old specifications regarding handling a wave of that size? After all, the odds are vanishingly small, are they not?

And there lies the final takeaway form this. I have people arguing with me who are trying to say that wrong was right. Anyone who says or said a wave like that can't or won't happen there was was wrong. No middle ground, no caveats, just 100 percent wrong. It happened. You were wrong. Deny it, if you like, accuse me of 20/20 hindsight if you will, if that helps you sleep at night, then that's great.

As a pro-nuc person, I find the thinking of some other proponents disturbing to say the least. I find that the biggest impediment to nuc power, because some folks will take a location flaw, dismiss it, and then try to make excuses for it after what they said almost certainly couldn't happen, does happen.

It's a pity the plant wasn't built a little higher. I wonder what the cost/benefit would have been?

Re:But the earthquale didn't cause loss of power

[thegarbz]

So you design for worst case and double? And you use history as your best guess? Then you'd too have gone under. After all we have an earthquake here which is 8 times higher than the worst in history for the country. I think it's pointless to continue this conversation further. You don't get the point, but the way you're going one day you'll learn it the hard way. No matter how right you think you are, one day you'll realise somewhere something was wrong, even with your supposedly "conservative" methods, which actually sound more like standard practice in the industries I've worked in.

Re:But the earthquale didn't cause loss of power

[Ol Olsoc]

Nonsense. My point is that the reactor should have been built on higher ground. And if an apparent retard like myself can "get that" then Intelligent people like yourself.

You are making a false dillema. Building the device at a slightly higher altitude does not mean it won't be built. It might affect the price, but there is the issue. This is not about safety, but about finances. So tell me, You'd rebuild in the same location with the same safety margin? After all, the odds of another wave like that have to be vanishingly small.

you weren't one of the actuaries at Ford Motors that did the cost analysis of allowing people to burn to death in the Pinto automobile rather than spend 11 dollars to fix each one were you?

Re:But the earthquale didn't cause loss of power

[Ol Olsoc]

The problem with your "in retrospect" design changes is that in the design of nuc plants, the cost of an "oopsie" is pretty drastic. And this one continues to get worse. They're looking at the possibility of a core breach after some workers burned their legs after wading in some pretty severely radioactive water. By the time this is over, we're looking at contaminated groundwater, and a ban on fishing over a fair sized area. Crops from that area will be affected to some degree. "Oops, my bad, but who knew?" is simply not an acceptable excuse.

This isn't rocket surgery. In Japan, there are two main likely "act of God" failure mechanisms. The first is earthquake damage.This is widespread over the country, so it is something they have to live with. Structures can be designed to withstand almost any earthquake, fortunately, so that isn't insurmountable. Reports so far indicate that the plant survived the earthquake.

The second is Tsunami. This one is hard to defend against. But a map can be made of the inundated area for any given size wave. And since there is a likely hit area, there is an option to locate in an area that has enough altitude. Another option is to build the facility in the dangerous zone, but assume that a tsunami will happen, but no critical areas will be inundated if the worst case scenario happens.

The first option is better, as once you locate above sea level, extra height is not so expensive as building a lot of facility that is unuseable for critical components.

This does not meant that you have to slippery slope the plant to the top of Mount Fuji. It means that you take stock of the situation, and adjust for likely scenarios. A prudent location might have been along a river, at the very least 60 feet above sea level. The location should also be free of landforms that would lead to a funneling height effect.

There is a solution: LFTR

[greg_barton]

Liquid Fluoride Thorium Reactor

energyfromthorium.com

Educate yourself.

Re:There is a solution: LFTR

[mbkennel]

Water + coolant = big ass explosion right next to big radioactive core.

The one advantage of water as a coolant is that if it leaks out --- which as we can see is not a trivial possibility --- you can always find more in an emergency. Which is what has been the case in Japan.

Suppose a plant with liquid flouride or sodium had been, say flooded with *water*?

Re:There is a solution: LFTR

[greg_barton]

Considering they're designed to run completely sealed and most likely buried I'd say that's unlikely. Also, consider that the reactor in Japan is a far less safe design and that did NOT happen, even after a 9.0 quake and tsunami.

Jimmy Carter worked on a Melt Down at Chalk River

[gary_7vn]

Jimmy Carter actually went inside a reactor that was melting down. Jimmy Carter FTW.

As long as we have Jimmy Carter around, I'm not worried bout no meltdowns.

THORIUM is the answer. You just aren't asking the right question.

"On Dec. 12, 1952, the NRX reactor at Atomic Energy of Canada’s Chalk River Laboratories suffered a partial meltdown. There was an explosion and millions of litres of radioactive water ended up in the reactor building’s basement. The crucial reactor’s core was no longer usable. With the Cold War then in full swing, and considering this was one of the first nuclear accidents in the West, the Americans took a great interest in the cleanup. Mr. Carter was a young U.S. Navy officer based in Schenectady, New York, who was working closely with Admiral Hyman Rickover on the nuclear propulsion system for the Sea Wolf submarine. He was quickly ordered to Chalk River, joining other Canadian and American service personnel. “I was in charge of building the second atomic submarine and that is why I went up there,” said Mr. Carter. “There were 23 of us and I was in charge. I took my crew up there on the train.” Once his turn came, Mr. Carter, wearing white protective clothes that probably, by today’s standards, provided little if any protection from the surging radiation levels, was lowered into the reactor core for less than 90 seconds."

http://ottawariverkeeper.ca/news/when_jimmy_carter_faced_radioactivity_head_on/

The AP1000 also has passive cooling

[jordan314]

Other reactors such as the AP1000 which are planned on being built in China and the US have passive cooling. http://en.wikipedia.org/wiki/AP1000#Passive_Core_Cooling_System

Re:The AP1000 also has passive cooling

[arthurpaliden]

Except the water reservoirs are on the roof. Earthquake cracks the pipes then what?

Re:The AP1000 also has passive cooling

[vlm]

Except the water reservoirs are on the roof. Earthquake cracks the pipes then what?

Fire departments have remarkable experience at spraying water unto roofs. They really are quite good at it.

If a 9.1 quake couldn't crack the Japanese pipes I'm guessing it would take a "near miss" from an asteroid to crack the pipes. Now a tsunami did ruin the Japanese plant, so you'd want to put yer goods on the roof to keep them dry... Err thats exactly this design... Interesting.

Best tech ignoring paranoia

[Twinbee]

Ignoring paranoia over weapon potential. And ignoring safety to a large degree, and even semi-ignoring nuclear waste to a degree, what is the most efficient/cheapest/most power giving nuclear reactor there is with current tech?

Re:Best tech ignoring paranoia

[ceoyoyo]

I believe they call them hydrogen bombs.

Re:Best tech ignoring paranoia

[benjamindees]

You're looking at it explode on the evening news. Safer designs are less efficient and produce more waste. Designs that produce less waste cost more and are more dangerous.

Re:Best tech ignoring paranoia

[mbkennel]

You could probably buy some RBMK reactors (Chernobyl style) for really really really cheap, but you'd have trouble finding insurance.

More seriously the modular factory-built reactors proposed by Babcock and Wilcox might be pretty good.

Re:Best tech ignoring paranoia

[Vectormatic]

post-chernobyl all remaining RBMKs were modified to somewhat mitigate the design flaws which contributed to the chernobyl disaster.

while i would highly recommend against anyone ever building any type of RBMK again, a revised RBMK is a slightly different animal to Chernobyl-4

Re:Environmentalists would LOVE pebble bed and bre

[spun]

Do you often fantasize about extreme environmentalists? Could you share more of what happens in those fantasies? I mean, get to the good stuff, this part's boring.

The cold truth

[ShooterNeo]

If I were a nuclear engineer, I would start thinking about an exit strategy from the field. If I were a nuclear engineering student or a wanna-be, I'd switch majors. If I were investing in a nuclear reactor, I'd sell my shares.

Why? The truth is, a minor dose of radiation doesn't increase your risk of dying any worse than a bad sunburn. Ever had your skin burned so bad you had some blisters and/or peeling? Congrats, you just may die from melanoma. The UV radiation is not significantly different than gamma rays in the ultimate effect it has on living tissue.

And perhaps a few hundred people will die at most in the long, long term from this disaster. No more than killed by coal pollution and coal mining accidents.

But none of that matters. The Japanese have a sterling reputation for good engineering and adherence to standards : if they can't keep the nuclear demon under control, who can? Just like 3 mile island put a halt to new generators in the U.S. for 30 years, this disaster will stop new plant worldwide for the next 30 years.

It's time to stop wasting money on nuclear and spend it on something the public will accept - massive amounts of solar and wind, backed up with massive amounts of storage. Truth is, in the long term it'll probably cost more to do it this way - but it's still better than throwing more money down the nuclear rathole when public pressure will stop almost all new plants from ever being built

Re:The cold truth

[Lehk228]

if by sterling reputation you mean a checkered past of coverups of industrial, chemical, and nuclear accidents then yes.

Re:The cold truth

[Quiet_Desperation]

And a culture where the very concept of a whistleblower is utterly alien.

Reading comp fail

[Anonymous Coward]

OK, and the battery power above ground solution?

Does anyone here read?

[unassimilatible]

The BATTERIES failed because they were flooded by the tsunami. Not because of the earthquake.

Re:Does anyone here read?

[Phoshi]

The *generators* failed because they were flooded, the batteries failed because they could power the cooling for 8 hours, and 8 hours passed.

Re:Does anyone here read?

[thegarbz]

I'll just duplicate of my last reply for you here, oh what you didn't like my citation? how about another one?:

[citation needed] Citations are a great thing really. For instance here's one that says the battery backup system worked flawlessly as intended, but was only ever designed to run for 8 hours.

Funny thing about backup backup systems, is that the backup backup is only ever designed to buy you time to allow you to get your backup ... back up and running.

All I am saying

[unassimilatible]

Is put the damn batteries on the roof, instead of in the basement. That's 1 hull, not 1000.

Re:All I am saying

[squizzar]

I'd imagine that the batteries are quite large and heavy. Turning your nuclear reactor building into an inverted pendulum with a lead and sulphuric acid bob may turn out to be a bad idea in an Earthquake.

The roof also needs to be able to explode away (as it did in several of the Fukushima reactors) in case of hydrogen explosions.

In the eventuality of a meltdown you'd have made it much more difficult (if not impossible) to smother the core in borosilicate, which is what stopped Chernobyl from melting down any further.

Nothing was wrong with the batteries, they lasted 8 hours as designed. Should they have been designed to last longer? Looks that way now. Should the backup generators have had a tsunami wall 2-3x as high as it was? Looks that way now. Should older reactors be replaced with better designs that don't require active cooling? Yes, no hindsight required. Should someone have the balls to say either accept nuclear power and build newer safer designs or turn the things off and we can all go without some electricity? Absolutely.

Re:All I am saying

[Ihlosi]

Turning your nuclear reactor building into an inverted pendulum with a lead and sulphuric acid bob may turn out to be a bad idea in an Earthquake.

I believe they use high-temperature sodium-sulfur batteries.

Re:All I am saying

[squizzar]

Fair enough. Bet they'd still be heavy and in the way though...

Re:All I am saying

[raynet]

Why put the batteries on the roof? They worked perfectly where they were for the 8 hours they were designed to work.

Armchair warriors often fail, the've been poisoned

[Anonymous Coward]

Hindsight really is 20/20 isnt it. If only.. If only... If only. T...hey have done a great job using ancient technology, and that technology is both reliable and trustworthy. They had a complete failure, and did not have a mushroom cloud. Nice. No body knows exactly what the shape of the internal containment vessel is, but the outer containment vessel is in good shape. Everyone points to the design, and they try to gloss over the fact that Japan had a 9.0 earthquake and a tsunami.
The plant has been working and working well for 30+ years.

Fast breeder reactors make plutonium, and when they go bad, they contaminate the surrounding area for millions of years. Chernobyl is good for at least another 300~400 years. Perhaps with the development of those nifty micro spy gadgets we might get a peek sooner at the real situation. The translation and the reporting has really sucked all around as well as the American NRC has tried to paint the situation as bleakly as possible, while the JIANA has been misinformed by TPL. who sugar coats everything, except what first hand witness say.

I just love all those pictures of personal radiation detectors. Completely meaning less, like looking at the tire pressures of the tires of a race winner. Were they near a concrete building?

Im waiting to hear from IEEE which published the best report on the TMI accident to publish, then you will find out the expert thinking, till then its armchair city.

Would you like to hear MY opinion?

Re:"The plant's operator tried to bring in mobile.

[Anonymous Coward]

"The plant's operator tried to bring in mobile generators to restore power, but the connections reportedly didn't match up."

Where's MacGyver when you need him?

Mox and extra control rods

[Silverlok]

From what information is available it appears that the Fukushima plant changed to Mox (partial plutonium, "as a way to get rid of "surplus" weapons grade Pu) rods last year( and according to the EE times it was amidst protests from locals including the Mayor.. http://www.eetimes.com/electronics-news/4214120/Plutonium--fuel-rod-reactions-stoke-nuclear-tensions?pageNumber=0 ), I am curious if anyone here knows if the plant was sufficiently upgraded to handle the higher neutron absorption and lower thermal conductivity of using plutonium in a reactor that was designed for uranium. At the least one would figure that it would need more control rods. Given the massive plume of Xe-133 ( a neutron absorber ) released 3-20/21-2011( http://tinyurl.com/4s4z6uz , go the bottom of the page) one has to wonder if part of the problem stemmed from all the cascading disasters and then a dearth of control rods ... It may explain why the boric acid had utility at teh beginning Perhaps simply not putting "surplus" weapons grade plutoniun mox into older reactor cores located on fault lines and then crossing ones fingers is something that could be considered forward thinking technology

credibility

[manaway]

The Physicians for Social Responsibility has a tagline of "United States Affiliate of International Physicians for the Prevention of Nuclear War". Which raises serious questions about their credibility.

Yes indeed. Any person or group opposed to nuclear war has enormous credibility; at least regarding nuclear war. Anyone who favors or is neutral to nuclear war has serious credibility problems.

Re:credibility

[Anonymous Coward]

We would love for the puny humans to eradicate themselves. Do you believe we are not credible? The Intergalactic Council For Eradicating Puny Humans (the contrived acronym is great in Intergalactic Default) does not care.

I'm confused

[wembley fraggle]

Isn't Nathan Myhrvold the guy who wrote the latest food pornstravaganza, Modernist Cuisine?

Re:I'm confused

[isaac]

Yeah, same guy. Made his nut as CTO of Microsoft in the 90's, but has had a pretty solid career in numerous fields over the years.

-Isaac

Re:"The plant's operator tried to bring in mobile.

[Anonymous Coward]

Splicing the conductors is slightly complicated when it is all under water..

US Military Industrial Complex Free Energy

[Anonymous Coward]

The US Military Industrial complex has developed nearly free, zero pollution, and completely renewable energy generators with our tax dollars. We could use that to decommission all the nuclear and coal plants worldwide. It was developed with our tax money. Yet they won't give it to us because they want to control us. It's time for all the free energy scientists to step forward and forget the threats from these people; even using wikileaks or other websites to publish such works.

ESBWR

[Anonymous Coward]

The improved design over the Fukushima reactor is already present which incorporates non-electric cooling system.

http://en.wikipedia.org/wiki/Economic_Simplified_Boiling_Water_Reactor

It's just a case of the Tokyo Electric Co. finding it inconvenient to decommision a previously built in-operation reactor for a better design to avoid financial discomfort.

TEA

[Quiet_Desperation]

Thorium energy amplifiers? Turn off the proton beam and the thing shuts down because it's subcritical.

Re:TEA

[Ihlosi]

Thorium energy amplifiers? Turn off the proton beam and the thing shuts down because it's subcritical.

And then it melts to slag, since decay heat doesn't care about criticality or lack thereof.

Re:TEA

[Quiet_Desperation]

Still better than going boom. Fix the error, slap in a new block, and off you go! :-) Modularity, son, modularity! No worries. We'll get Don Draper to do the initial sales pitch.

falesafe systems

[Jookey]

So far all the comments from the pro nuclear crowd have been something along these lines of: Step1: Build safer reactor Step2: ??? Step3: Profit I used to be in-favor of nuclear power. But seeing how big this screw up is I am not so sure. here are some ideas that may help: 1:all current designs should be phased out in 5 to 10 years 2.All new plants should be lead cooled. 3.There should be no radioactive or toxic materials at high pressure. 4:All heat exchangers should be robust and the less radioactive side should be at higher pressure 5. use thorium 6. The backup scram system should be foolproof by using melt plugs. (If the reactor gets hot enough a structural component fails and inserts emergency control rods or perhaps the core structure melts and fuel components are no longer in a critical configuration.) 7. To dissipate heat from the delayed reaction after scramming, another melt plug is used that allows some of the coolant do drain onto an emergency heat exchanger attached to a pool of water outside. These two safety features are so robust the only way of sabotaging them is to go scuba diving in molten irradiated lead. 8.The entire contraption should be able to be transported on a barge to be encased in concrete and dumped in the middle of the pacific ocean if anything goes wrong.

The problem is Murphy's law

[Casandro]

No matter what kind of failsave systems you design into it, something unexpected will always go wrong.

Just think of it. The type of reactor advertised here is meant to be put into residential areas. Imagine some idiot trying to cut it open or running his oversized SUV into it. Imagine the truck transporting the spent fuel having an accident.

The point is, of course you could potentially find ways to deal with those problems, but doing so is expensive and will probably move the cost beyond solar/wind plus storage. In Germany for example even though nuclear plants really aren't on top notch security, the businesses are already heavily subsidized. For example they don't need to pay for spent fuel disposal.

Let's hope that...

[akayani]

their reactors have less errors than their website. Broken links, video with sound so low you can't hear it... Where is the QA??? Oh that's right they are associated with Microsloth.

Re:"The plant's operator tried to bring in mobile.

[loshwomp]

WTF, they can't cut the cables and weld or clamp the wiring together?

Good point. I'm sure they didn't think of that. Pity Locutus wasn't there to explain it to them.

We're talking about tens of megawatts of thermal cooling required. This isn't exactly off-the-shelf hardware.

Half Way There

[hyades1]

Candu reactors still have the spent fuel problem, but they have two passive systems that shut down the reactor in the event of a power failure.

The first is a bunch of control rods positioned above the reactor and held in place by an electromagnet. If the power fails, the magnet stops working and gravity drops the rods into the core.

The second measure also relies on electromagnets. Nitrogen is kept under pressure behind magnetically controlled valves. If power fails, the valves let go and the nitrogen forces neutron-hungry gadolinium into the core.

Re:Half Way There

[Ihlosi]

The first is a bunch of control rods positioned above the reactor and held in place by an electromagnet. If the power fails, the magnet stops working and gravity drops the rods into the core.

Most current reactors have ways of shutting down the chain reaction if power fails. I'd wager that using liquid nitrogen to push the control rods into the core is even better than using gravity, since that way you can force the control rods into the core even if it has already begun to deform, warp or melt.

However, all of these measures do exactly nothing against decay heat. You cannot turn off decay heat in any way - if you don't cool the part of the reactor that contains the fission products, it will happily heat up to temperatures that will melt or otherwise destroy pretty much any material known to man.

Re:Half Way There

[hyades1]

Excellent point. However, I think the point is that things shut down fast enough that dealing with decay heat wouldn't be a problem...in theory.

Let's be clear: I just mentioned the specific safety measures in the CANDU. I get pissed off at people who fail to appreciate that when things go catastrophically wrong, it's usually because reality finds some new and interesting way to screw with "foolproof" systems. As somebody once said, idiot-proof designs frequently fail to account for the incredible ingenuity of idiots".

Re:Jimmy Carter worked on a Melt Down at Chalk Riv

[giorgist]

Jimmy carter was an Engineer,
Presidents have been lawers ever since

Breeder reactors have a bad history

[light_rock]

See the wikipedia on fast breeder reactors, and note that the sodium exchange concept appears to result that Thorium can indeed result in Plutonium if so desired. The designs they are communicating leave out a lot of details. I hope they don't use Windows. Somebody will write a virus, Blue Screen of Meltdown. How is this design moderated and or shut-down ? ...heh, otherwise...

Re:Environmentalists would LOVE pebble bed and bre

[Slur]

Me: vegan, no car, mid-40's, computer geek, Buddhist, atheist, totally love nuke power, still hoping for better but realistic. Seriously, why assume the lowest common denominator has any bearing on what will actually happen? Or are you trying to demonstrate that straw men make better fuel?

environmentalist aren't the problem

[taharvey]

Unfortunately the "environmentalist holding up the progress" of Nuclear power isn't true.

It is disingenuous to reduce the very sophisticated web of VERY serious issues that nuclear power must deal with to be some type of environmentalist conspiracy. There are very REAL technical, political, social, environmental, proliferation and logistical problems that nuclear power has - no other power source comes close to having these issues.

Fundamentally, nuclear is impossible to make safe. It is a reliability problem. How many 9's can you build into trying to make it fail safe, and at what cost? You can't make it to 100% safe, no system can. Yet the risks of failure are enormous. A wind turbine fails, its not a big problem... No other power facility has 100MW-1GW of heat being generated, that when you turn it off, essentially stays-on for weeks still producing heat. It is a huge fail-safe problem. It is easy to think after the fact, that they shouldn't have had generators in a basement - fact is there are millions of interdependent issues that can cause it fail, and they all can't be planned for.

RIght now the statistics are very bad, 500 plants in the world, 4-5 major disasters in 50 years, and dozens of near misses, 100s of serious mishaps. You can come up with better systems, but the inherent problems are fundamental and aren't going away.

Re:environmentalist aren't the problem

[strack]

aaaaaaand those issues are made worse by keeping old reactor designs running while the newer, safer designs are held up by hand wringing legal challenges. also, i think you fail to appreciate just how little energy wind power generates.

Re:environmentalist aren't the problem

[PeterBrett]

RIght now the statistics are very bad, 500 plants in the world, 4-5 major disasters in 50 years, and dozens of near misses, 100s of serious mishaps. You can come up with better systems, but the inherent problems are fundamental and aren't going away.

Um. Can I just point out right now that both hydro and wind power are much more dangerous? Hydroelectric power disasters have killed two orders of magnitude more people than all of the nuclear "disasters" in history. What power supply solution would you support? Burning dinosaurs?

Re:environmentalist aren't the problem

[Ihlosi]

Hydroelectric power disasters have killed two orders of magnitude more people than all of the nuclear "disasters" in history.

Hydroelectric power disasters stop killing people a few days after the disaster. Nuclear power disasters just keep on killing for centuries or longer.

Re:environmentalist aren't the problem

[taharvey]

Again, the idea that nuclear has been held up by legal issues is just not true. The main issue is their hasn't been an economically viable business case. Recent hurdles cleared in the USA have been about federal loan liability giveaways (i.e. it hasn't been economical to kick start these things on the free market).

I think you are uninformed about the scale of renewables. For the last two decades global wind power installations, on a electricity output basis, have vastly outpaced nulcear capacity installs by something on the order of 30-1. In 2009 alone 12 nuclear plants worth of wind electricity generation installed, while only 1 nuclear reactor came on line. Why? not the environment, its because wind is cheaper and faster to deploy - it has a much better business case.

Re:environmentalist aren't the problem

[PeterBrett]

Hydroelectric power disasters have killed two orders of magnitude more people than all of the nuclear "disasters" in history.

Hydroelectric power disasters stop killing people a few days after the disaster. Nuclear power disasters just keep on killing for centuries or longer.

[Citation needed]. Seeing as it's considerably less than a century since the first "nuclear disaster", I think your assertion requires substantiation. Let's consider the worst three nuclear incidents in history. Firstly, Windscale:

A 2010 study of workers directly involved in the cleanup -- and thus expected to have seen the highest exposure rates -- found no significant long term health effects from their involvement.

Or Three Mile Island:

A variety of studies have been unable to conclude that the accident had substantial health effects.

Or perhaps even Chernobyl:

Apart from [57 direct deaths and about 4,000 cases of thyroid cancer], there is no evidence of a major public health impact attributable to radiation exposure 20 years after the accident.

I find no evidence that these "disasters just keep on killing." Let's compare that to the Banqiao Dam failure: 26,000 immediate deaths and 145,000 from epidemics. By itself, that incident dwarfs all actual deaths and all projected deaths from all nuclear power disasters in history. I guarantee you will not find a power generation source currently in use that has a better safety record in deaths/TWhr than nuclear power.

Re:environmentalist aren't the problem

[Ihlosi]

Let's consider the worst three nuclear incidents in history.

Kyshtym isn't on that list?

http://en.wikipedia.org/wiki/Kyshtym_disaster

I find no evidence that these "disasters just keep on killing."

That's because the studies aren't sensitive enough and don't include sufficient population. Chernobyl basically affected a few hundred million people all over Europe. Are these studies sensitive enough to pick up small increases in cancer rates, e.g. a dozen additional cases per year in a population of half a billion people? I don't think so.

If Chernobyl didn't do much, why are we still checking wild boar meat for contamination decades after the accident, and why do we still find boars that need to be disposed?

Re:environmentalist aren't the problem

[squizzar]

Some of those problems are related to the fact that Nuclear power is more regulated. I'd be interested to see the waste disposal obligations that the Nuclear industry faces applied to other energy sources. Not to mention the reporting levels and monitoring of environmental damage (across the supply chain, so not just at the plants, but from mining/drilling to exhaust gas and fly ash disposal). How many oil spills, coal mine disasters, strip mining operations, floods caused by burst dams have occurred in that 50 years?

Re:environmentalist aren't the problem

[taharvey]

Wind power disasters? Where exactly? Look at how Japan winds farms survived, and stepping up operations to fill the gap [google it]

I don't think I ever talked about hydro. Pretty much all large hydro in the world is build out. So there isn't a real comparison here. Its not a future new market competitor. A small hydro, which still has growth, doesn't have that issue.

Solar, Geothermal, Wind, small hydro, combined cycle - all are cheaper than nuclear and more fail-safe. What is the drive to pursue something so issue laden and problematic? I don't think cause its "neato" cuts it.

Re:environmentalist aren't the problem

[taharvey]

Really? Please.

Radioactive waste and nuclear proliferation on the same level as how much steel a windmill manufacture recycles?

Give me a break.

Re:environmentalist aren't the problem

[PeterBrett]

That's because the studies aren't sensitive enough and don't include sufficient population. Chernobyl basically affected a few hundred million people all over Europe. Are these studies sensitive enough to pick up small increases in cancer rates, e.g. a dozen additional cases per year in a population of half a billion people? I don't think so.

You're right, they're not sensitive enough. They can't be. The problem is that such levels are well below the noise threshold in background radiation, let alone variations in exposure to other carcinogens. For example, naturally-occurring radon emissions cause more than 20,000 lung cancer deaths a year in the USA.

If you are scared of nuclear fission power generation, you should be terrified of getting out of bed in the morning.

Re:environmentalist aren't the problem

[PeterBrett]

Wind power disasters?

I must have missed where I claimed there had been any. I was talking about deaths per energy generated, where nuclear fission beats wind quite comfortably. Deaths per TW/hr: wind 0.15, nuclear 0.0009. I can even provide citations:

D.J. Ball, L.E.J. Roberts, and A.C.D. Simpson "An Analysis of Electricity Generation Health Risks: A United Kingdom Perspective." Centre for Environmental and Risk Management, School of Environmental Sciences, University of East Anglia, Norwich, UK (1994).

Re:environmentalist aren't the problem

[dunkelfalke]

That is because people are not allowed to live in and around Pripyat'. And won't be for centuries to come.
Still can't spot the difference?

Re:environmentalist aren't the problem

[Ol Olsoc]

One of the first things I have to tell you is you won't get a lot of traction by yapping at the environmentalists. You are busy accusing them of hand wringing, and they have evidence.

I'm very pro nuc power, and I have to cringe at the belittling attitude that so many of us take towards the people considered "the enemy". We come off like "this stuff is perfectly safe, I know, and you don't, so STFU and let the smart folks lead you of lesser ability."

Then we go on to make patently ridiculous statements on how all the accidents we've had just "prove how safe our designs are." There is a whole lot more to safe design than some folks semi-irrational fear of the obvious nasty bits.

We need a good business model, which frankly I believe means more and smaller plants, placed in safer locations (no Tsunami prone shoreline) We need to work at operating the things in less highly stressed fashion, we need to be scrupulously honest, and we need desperately to drop the attitude. In short, those people have been told many times how these things are perfectly safe, and just perhaps, we might try a different approach.

Re:environmentalist aren't the problem

[jrvz]

Didn't I read that the entire German windmill farm doesn't generate as much power as Vermont Yankee, all by itself? The "business case" for wind power includes a lot of government mandates.

Re:environmentalist aren't the problem

[boxwood]

don't forget about all the people who die in coal mines, so even burning dinosaurs isn't very safe.

Re:environmentalist aren't the problem

[taharvey]

Every energy source gets government support. And nuclear has received more than most.

When to take away that support, the cost for new electricity for nuclear is $0.11-0.17/kWh depending on the estimate source. Cost for new wind is $0.07/kWh, one of the lowest for any energy source, including coal. And that still includes all the back-end government support nuclear gets for things like waste disposal and a free insurance ride - that without nuclear would be completely unviable.

If you check out the below reference, you can see on the graph on page 13, that one of the key problems beyond the electricity end-cost, is the much higher capitol costs of nuclear. This is a major problem for nuclear, the financing doesn't make sense, you have to leverage big and long.

Nuclear is risky, not just technically, but from a business perspective. The Congressional Budget Office study on the loan guarantees for nuclear concluded that the default rate on the nuclear loans would be "very high—well above 50 percent". This why you've only seen nuclear industries flourish under the skirt of a centralized socialist government program - like France and Japan.

https://old.rmi.org/images/PDFs/Energy/E08-01_AmbioNuclIlusion.pdf

IN re. Terra Power

[Anonymous Coward]

I notice that TerraPower most specifically doesn't seem to mention what the remnants of their process are. They mention what fissile materials the process converts to, but not whats left after the materials themselves split. Nor do they talk volumes of material left over. I like nuclear as a medium term option, but I think this presentation is a might scant on key details

Re:"The plant's operator tried to bring in mobile.

[paul248]

Weld the cables? Are you insane? Those things must cost thousands of dollars.

Re:"The plant's operator tried to bring in mobile.

[fnj]

It's pretty clear they didn't have people with the right skills on scene and nobody was willing to take the initiative and improvise.

Quality :-)

[cheros]

Thank you. That was my feeling as well, but I like the way you voiced it :-)

Murphy vs. Technocracy

[Required Snark]

"Something unexpected will always go wrong" is the key.

Engineering get better through failure. This is why cars, airplanes, household electricity, etc. are safe. Engineers do the best they can with the existing experience base, and then see what happens. Over a long enough period of time, and enough failures, safe and cost effective results can be produced.

How many Level 5 nuclear events will it take to achieve an acceptable level of safety? The only way to answer this question is to keep on building real world nuclear reactors and see what happens. After this event I am not very comfortable with that answer.

Most of the pro-nuclear support here is really a form of Technocracy http://en.wikipedia.org/wiki/Technocracy. The short version is "if you just let the technical types make all the important decisions then we wouldn't have all these problems, and things would run well."

Talking about the Fukushima situation, this takes the form "if they just had a better emergency backup" or "use a pebble bed reactor" or "thorium" or some other technical solution. Those are simplistic answers to complex system problems. If it was that easy then the Fukushima system would not have failed, because a cost effective backup power system able to withstand the actual tsunami could have been build.

Japan is the one place in the world a tsunami should not have had this consequence. They have earthquakes and tsunamis, they have a very sophisticated technical society, and a great fear of the bad effects of nuclear radiation. But they failed.

The failure was not a technical problem, it was a system problem. With all the planning and prevention measures, they did not see the result of a combination of failures at the system level. This is exactly the kind of problem that is easy to see after it happens, but is hard to predict before it occurs. You cannot plan your way out of a problem you cannot see. This is where hard lessons are learned through painful real world experience.

At this point, we might be a lot better off putting resources towards other power sources then nuclear. If we build wind farms, harvest ocean power, or build large solar power plants we will also experience serious failures, but we won't be faced with problems that will last for tens of thousands of years. We will just take our bad experiences and make things better one failure at a time.

Re:Murphy vs. Technocracy

[Ol Olsoc]

Someone needs to mod you up Snark!

The Rabid supporters here are trying to have it both ways. The design fails, and then somehow blame is placed on people who said the design will fail.

Look, no one tries to build an unsafe design. the problem is, there are enough different people in the mix that can make otherwise insane decisions seem reasonable. Look at the Challenger accident. Bad O-ring design. Launch in direct contradiction to protocol, and over strenuous objection by the manufacturer. Sad and predictable results. Someone wanted that launch, and they got their way.

It was a long time ago when this was built, but I would speculate that someone brought up the issue of what would happen if a larger than anticipated Tsunami hit the complex. S/he was probably scoffed at, then the process moved on.

The only part I disagree with is that the possibility of multiple problems could not be foreseen. Earthquakes and Tsunamis are highly related to each other. And building a system on the shoreline of an area where both were simply going to happen was a design error. If no one saw the possibility, they were guilty of poor judgement.

Re:Environmentalists would LOVE pebble bed and bre

[squizzar]

Because you're not the guy that gets to influence politicians and be quoted in the media... that all happens to the other guy...

Stuxnet warworm possibly exploded Fukusima backups

[Anonymous Coward]

The Fukushima series of explosions was possibly caused by the Stuxnet malware, which prevented the proper working of Siemens Simatic-controlled backup systems that were activated in the aftermath of the earthquake and tsunami to continue to cool the emergency-scrammed reactors.

The Stuxnet malware was created by the Mossad and the CIA, to sabotage the iranian military uranium refinery centrifuges and the Bushehr civilian nuclear-electric plant. Regrettably it continued to spread uncontrollably via USB memory sticks throughout the whole of Asia (including loss of the hindi INSAT-4B civilian comms satellite, whose Siemens ground control system was paralyzed by the Stuxnet infection). Symantec says they detected Stuxnet on at least 63 computers in Japan. The IAEA boss warned 5 weeks ago that Stuxnet malware represents a grave danger to all nuclear power companies. Japanese operators complained of false instrument readings when trying to activate the backup systems, typical Stuxnet tactics.

Re:Stuxnet warworm possibly exploded Fukusima back

[Ihlosi]

The Fukushima series of explosions was possibly caused by the Stuxnet malware, which prevented the proper working of Siemens Simatic-controlled backup systems that were activated in the aftermath of the earthquake and tsunami to continue to cool the emergency-scrammed reactors.

Right, because a reactor designed by GE will include control systems from their fiercest competitor, Siemens.

GE management would probably rather have a fuel rod for breakfast and wash it down with coffee brewed with reactor coolant before that happens.

Got any other good jokes?

Re:"The plant's operator tried to bring in mobile.

[Anonymous Coward]

Frequency. East Japan runs of 50Hz, West Japan runs on 60Hz. When you want multi-phase power in the megawatt range, this is a BIG problem, and a jury-rigged solution will not cut it.

You mean its *FAIL SAFE*

[Anonymous Coward]

Ahh failsafe.

Those halcyon days of when nuclear reactors were expensively designed to fail safely instead of cheaply designed to need constant, active, high-power technical interventions. I do believe I'm getting all emotional.

Re:"The plant's operator tried to bring in mobile.

[mbone]

I am sorry, but I don't buy this, and have not bought this since I first heard it, at least as the complete story. Nobody could hot wire this ? Different generators could not be found ? Different plugs could not be found or made, anywhere on the planet ? The only solution is to bring in a 1 km + extension cord from the grid a week later?

There is something here that we are not being told. We'll find it out, and it will probably be pretty embarrassing for someone, in 6 months to a year or so.

Re:"The plant's operator tried to bring in mobile.

[Anonymous Coward]

There is a reason different plugs exist. Some are different due to different current load limits, some are different because it is important to use different plug types on different voltage lines. Then, there are single vs. polyphase connectors, 3-pin delta vs. 4-pin wye connectors, and so on.

Often you cannot simply "splice" lines together, especially if your source is a typical 3-phase wye generator and you only have 3-conductor delta cables and plugs.

Re:"The plant's operator tried to bring in mobile.

[vlm]

ah, wrong connectors so send the generators back and run in circles try something else? WTF, they can't cut the cables and weld or clamp the wiring together?

LoB

That part of the story stinks, no absolutely reeks, of journalistic simplification and talking down to the audience. I'm fairly certain when the whole story comes out, it'll be that they shipped a gen waaaay too small, or a single phase gen to run a three phase motor, or a 60 Hz gen to run a 50 Hz motor, etc.

VFDs are a whole nother exciting topic, if the motor had one, where theoretically you could have a situation where the supply cannot run the VFD safely (voltage too high, whatever) even if the motor could be trivially rewired to handle it. I'm guessing not an issue at a nuke site, but....

Only Small Changes Nessesary

[Anonymous Coward]

Large shifts in fuel and design really aren’t needed to avoid this problem. GE's newest BWR design has large water tanks that it can use to passively cool the reactor for up to three days. At that point all one has to do is refill the tank. This is made simpler by the fact that there will be no radiation released. The sad thing is that these reactors will likely never be built following Fukushima.

great stuff

[hesaigo999ca]

Another reason to move forward in the world and go from old to newer tech., I hate people that do not want to change over from older models....you get stuck with these situations....the US powergrid is in the same boat too.

2008 and 2009

[DarthVain]

http://en.wikipedia.org/wiki/Chalk_River_Laboratories#2008_radioactive_leakage

Happened again more recently. I remember the world was all pissed off because of an isotope shortage for medical scanners.

My first reaction was, "holy crap that nuclear plant is HOW old?"

If these isotopes are so vital and valuable why don't we (or somebody) build another one? The only thing I can think of is its being subsidized below cost, so there is no incentive for any country to make another.

Rossi Cold Fusion reactors available in 2012

[Zdzicho00]

Well, what about Cold Fusion reactors??
http://www.washingtontimes.com/news/2011/mar/17/nuclear-future-beyond-japan/
http://www.nyteknik.se/nyheter/energi_miljo/energi/article3108242.ece

Rossi and Defcalion Technologies are currently constructing 1MW fusion reactor in Greece.
They say it will be ready in October this year and production of 20kW market ready devices should start in 2012.

New factory in Xanthi (100mln euros investment) is expected to manufacture 300.000 such devices per year:
http://translate.google.pl/translate?js=n&prev=_t&hl=pl&ie=UTF-8&layout=2&eotf=1&sl=el&tl=en&u=http%3A%2F%2Fwww.energypress.gr%2Fportal%2Fresource%2FcontentObject%2Fid%2Fe7cf318d-06b8-414a-8183-54af3baf5897

Cost of 1kWh energy production is expected to be within US cent range.

CANDU Reactors Are Safe

[foxalopex]

Canada uses a Heavy Water reactor that seems to be fairly fail safe as the Heavy Water is required to sustain the reaction. If the reactor overheats, the Heavy Water in theory would boil off and that would effectively stop the reaction. Last I recall thou, the biggest problem was that the CANDU reactors are very expensive but they are very safe.

Re:CANDU Reactors Are Safe

[lisp-hacker]

The chain reaction was off in Fukushima, but there was still x*10MW of decay heat that needed to be dissipated. The process is declining in an exponential curve that starts at 5-10% of the reactors nominal thermal power and this is the same for *all fission* reactors (including CANDU)

Oblig.

[MachineShedFred]

Yo dawg, I heard you like reactors, so I put a reactor in your reactor so you can react while you react to your reactor!

HOLY CRAP YOU SLASHTARDS SUCK!

[Thud457]

Eleventy dozen messages on the first page, NOT A ONE talking about the subject at hand, to whit - the proposed traveling wave reactor design. But plenty of kibitzing about situation in Japan, and detailed misnalysis of various other reactor designs and plain non-nuclear power generation solutions. I guess it was my mistake to not read with a +3 threshold and expect meaningful discourse.

AP1000

[lrdplatypus]

Loss of power is a solved problem. The Westinghouse AP1000 reactor is a current design that is passively cooled, no external power necessary. I'm not sure about the spent fuel pools, but the reactor itself is entirely passively cooled and there are several of them already in existence.

A "traveling wave reactor" sounds like a neat idea, but the summary makes it sound like nobody's ever thought about a loss of external power event. We have to remember that the Fukushima plants were built in the 70's, they are old designs. Newer designs take that into account. The only point I'm trying to make here is that current generation designs have already taken loss of external power into account.

so... there wasn't an earthquake?

[Anonymous Coward]

"meaning the loss of power from the tsunami might not have crippled a fast reactor plant so severely." Yeah, because they didn't have an earthquake or anything.

tritium leakers

[rubycodez]

CANDU's leak 1% of their tritium, most of the 7 bq/L contamination in Lake Ontario is from CANDU reactors. In accidents and incidents, they leak even more.

no thanks, CAN"T DU

There are plenty of safe nuclear reactor already.

[macpacheco]

The Japan nuclear accident was a combination of a VERY old reactor with an EXTREME EARTHQUAKE.
All reactors dating back to 1960/70s designs are much less safe than today's reactors.
Modern Advanced Heavy Water reactors are essentially immune from such accidents, since they use sub-critical fission fuel, that depends on heavy water (deuterium) to actually produce fission. In an emergency, just releasing the heavy water and inserting regular water into the reactor stops fission and prevents overheating.
The reason is regular water absorbs neutrons, while heavy water don't, by not absorbing neutrons, heavy water reactors can sustain fission with much less radioactive nuclear fuel.
What should happen is a worldwide ban on old reactors on earthquake prone regions. But even heavy water reactor designs from the last 1990/early 2000s in Fukushima would not have caused the radioactivity release that happened there.

Re:There are plenty of safe nuclear reactor alread

[Ihlosi]

Modern Advanced Heavy Water reactors are essentially immune from such accidents,

No, they're not at all immune to meltdown from decay heat.

Stopping the fission reaction worked just fine in Japan, but doing that alone does nothing about all the MW of decay heat that cannot be shut off by any process known to man - the fuel rods have to be cooled for days or weeks.

Any modern design should be designed with the question of "What happens if you cut the main coolant feed line and turn off all power (including emergency power) to the reactor?" in mind. Even in this scenario, the radioactive mess should be confined to the interior of the reactor building.

Here it is on sale:

[fadethepolice]

Taking orders for delivery in 2013 http://www.hyperionpowergeneration.com/

Re:"The plant's operator tried to bring in mobile.

[mhotchin]

I'm sure there's just a little hyperbole here. The 'connectors didn't match' probably because the voltages / amps / phase didn't match.

If the generator is 480 / 3 phase, but the industrial input is (say) 380 / 3 phase, all bets are off.

*click to see hot nuclei? ;D timescale of failure?

[Anonymous Coward]

one question/thought i've had after reading and watching a couple of google tech videos on liquid thorium reactors is;

there is a design which was featured on a google tech talk video which had a salt plug at the bottom of the liquid reactor vessel which it is claimed would melt and allow the reactor content to drain into a safe tank below if the temperature ever rose too high (via some unforeseen mechanism). BUT over what time scales does each event occur, that is, how long does the salt plug take to melt and then the tank to drain, and over what time scale could a possible (merely improbable?) departure from expected parameters and say a significant or even hypothetically a runaway increase in reaction rate???

essentially, does the salt plug have time to melt and get out of the way and the tank to drain before the presumably very very hot liquid gets even hotter possibly producing HF gas/rupturing or releasing hot nuclei.

(this is for a failure despite the negative coefficient of reactivity, which means the reaction rate drops with an increase in temperature (although i doubt this whole curve is monotonic decreasing and i suspect this coefficient is only negative over some range, hopefully encompassing the entire normal range of parameters and some)))

Re:Environmentalists would LOVE pebble bed and bre

[Anonymous Coward]

So why is it okay for you to do the same?

Re:Environmentalists would LOVE pebble bed and bre

[spun]

Please make more sense. The same what?

How does a power generator loose power?

[Anonymous Coward]

I may be slow. This just hit me. Nuclear reactors generate power. How did it run out?

Re:Jimmy Carter worked on a Melt Down at Chalk Riv

[myth24601]

Jimmy carter was an Engineer,
Presidents have been lawers ever since

I am pretty sure that only Clinton and Obama were Lawyers while Reagan, Bush and George W. were not.

FUJI liquid reactor ??

[Anonymous Coward]

FUJI reactor is the only fullish size liquid fluoride thorium reactor ive read about ... it generates ~300MWe

which isnt that far off the 6 fukushima bwr's which are from around 400MWe to about1GWe

Re:"The plant's operator tried to bring in mobile.

[Locutus]

that would make more sense.

LoB

Re:"The plant's operator tried to bring in mobile.

[Locutus]

but wouldn't they know what was required to connect up external power? I know there's probably no sticker/label but it sounds like there were not people there who know what to do and what was required. Probably just people who knew what knobs to turn when the dial went to position X so it then moved to position Y. They are very old reactors and from what I heard, the company running it even falsified testing and maintenance records so I wouldn't doubt they skimped on keeping properly skilled Sr Engineers around who knew many of the systems. sad and I doubt I would have been much help.

LoB

Re:Jimmy Carter worked on a Melt Down at Chalk Riv

[phaggood]

Reagan wasn't a lawyer.

Re:Environmentalists would LOVE pebble bed and bre

[Culture20]

Do you often fantasize about extreme environmentalists? Could you share more of what happens in those fantasies? I mean, get to the good stuff, this part's boring.

Sure, here's one of my favorites:
Mother Gaea is lounging by the pool, reading a smutty novel. The camera pans over a few mountains and valleys in slow-motion, then focuses on her face. The doorbell rings, and her eyes flash in alarm. She hurriedly dresses herself (oh, yeah, she was naked), and rushes to the door. It's the pizza guy.
"Extra Sausage, right?", the delivery boy said.
"It should be cheese."
"Well, yeah, it's cheese, but.."
"Here's a twenty, keep the change.", Mother Gaea said as she closed the door on a surprised pizza guy.
Cut to outside the door. "What kind of porno fantasy is this?"
Did I mention he was a robot? 'Cuz that's kinda important. Yeah, a robot
...awesome!

Re:Environmentalists would LOVE pebble bed and bre

[spun]

You sound just like my fave web comic, Dinosaur Comics. Sexy times!