In Nuclear Power, Size Matters

PerlJedi writes "Most nations with nuclear power capabilities have been re-assessing the risk/benefit of nuclear power reactors following the Fukushima plant melt down, a newly released study suggests the U.S. should expand its nuclear power production using 'Small Modular Reactors'. 'The reports assessed the economic feasibility [PDF] of classical, gigawatt-scale reactors and the possible new generation of modular reactors. The latter would have a generating capacity of 600 megawatts or less, would be factory-built as modular components, and then shipped to their desired location for assembly.'"

Comments

Re:Lots of little Carrington events?

[Anonymous Coward]

Lots of little diesel generators are going to come online?

right idea - Wrong fuel

[denis-The-menace]

Should be using Thorium instead.

Re:right idea - Wrong fuel

[denis-The-menace]

/. ate my link
http://thoriumremix.com/2011/

Re:right idea - Wrong fuel

[vlm]

Theres a whopping big wiki article that tries a little too hard to be "balanced" when in all fairness Th is a PITA fuel, that kinda sucks.

Its only good for non-proliferation from a distance. Up close its worse. You need to boot up with a slug of Pu because there are no fissile Th isotopes. So no one ever builds "a Th reactor" they build a "bomb grade Pu reactor" surrounded with a Th shell that eventually can breed itself into reacting, hopefully your breeding plan curve matches your electrical demand curve.

Its only good for non-proliferation if you define proliferation as current designs. Historically plenty of U233 bombs were blown and research done. No you cannot make a current model US B61 out of stuff from a Th reactor. Yes, you can make something almost as good as a B61 that is U233 based using what comes out of a Th reactor. It in no way prevents proliferation merely makes it a slightly more involved research project (slightly!)

In a way, not being useful for proliferation dooms Th. The US and Russia and China and god only knows who else (Iran?) are still going to need U based reactors so now you've gotta run both technologies... Why not just run one? And that one's gotta be U, at this time. So trying to push Th means your sales will be pitiful because you can only sell to 3rd world and not much else.

Plus it gives the non-proliferating Th owners experience in plant operation which they can transition to new/secret U plants of their own anyway, its like bootstrapping proliferation not preventing it.

Anyone who says Th = nonproliferation is either misinformed or being paid or trolling.

Its an unholy PITA to recycle due to hard gammas, or you can have agony when disposing. Its waste stream is just "worse" than a traditional reactor.

Its harder to run, more neutron poisons like Pa build up.

To be economical, you just have to burnup into the ground, which is kind of like saying a F-350 has a lower lifetime environmental cost IF you can get it to survive 600K miles. Its... ambitious. You don't achieve high burnup by just wishing, its difficult, dangerous if you have cladding failures, and expensive. Otherwise the prius wins again for overall lifetime costs.

Its interesting to learn about, good to learn about, but it shows good engineering judgment to avoid a Th design.

Re:right idea - Wrong fuel

[vlm]

Whoops also forgot another reason why Th sucks, its harder to make fuel rods. Hotter manufacturing temps. So they end up being more expensive and/or less reliable than U, which is supposedly the opposite of what the system is supposed to produce. So the theoretical 3rd world operator finds it easier and safer and cheaper to use U rods.

Th is a second class fuel. The best thing to burn in your steam locomotive is anthracite, if you can still get it. Next worse is bituminous. If you're really scraping the bottom of the barrel and gotta do what ya gotta do, you harvest irish peat and burn that in your steamie. But trying to convince people peat is just as good as anthracite, or peat is cheaper, or peat should really be your first choice, or I read an article about peat and figure it might be fun to try, thats just not gonna work. Stick to the U and Pu designs until the world runs out of U in 20000 years or so. After that, you gotta do what you gotta do, and whip out the Th designs.

Re:right idea - Wrong fuel

[denis-The-menace]

Watch the video first. (at least first 10 seconds of it)

1. With LFTR you have next to no waste.
From what I remember, there are 2 radioactive leftovers and both are valuable.
-molybdenum-99 (Medical usage)
-Plutonium-238 (Space probes)(VERY valuable)

2. Uranium has an [Expensive] established fuel chain. You can only get fuel pellets from ONE supplier: the one who built the reactor. And no, they don't have sales.

3. Advantage of thorium vs uranium:
-No enrichment
-No 10000 year radio-active waste
-No high-pressure water cooling schemes that need power to work and backups up the wazoo.
-Others mentioned in the video

Re:right idea - Wrong fuel

[BlueParrot]

1. With LFTR you have next to no waste.

Other than all the fission products, including radioactive iodine, strontium and caesium (and others). Heck, just avoiding excessive tritium production involves isotope separation of lithium to enrich it in Li-7.

Essentially somebody has not told you teh full truth, or outright lied.

2. Uranium has an [Expensive] established fuel chain. You can only get fuel pellets from ONE supplier: the one who built the reactor. And no, they don't have sales.

Fuel costs are less than 10% of the cost of nuclear power. Construction and operation is the majority of it. Most estimates conclude that reprocessing ( even in the LFTR ) would be more expensive than uranium enrichment. You may save some money by not needing fuel manufacture , but in return you have a larger inventory of fissile material since it is not all in the core.

3. Advantage of thorium vs uranium:
-No enrichment
-No 10000 year radio-active waste

Nonsense. Thorium is not fissile, so it needs to be started on a large seed of fissile material. This could be either reprocessed plutonium or enriched uranium, just as with other reactors. Also, since plutonium cannot be effectively destroyed in a thermal spectrum, there will be a buildup of plutonium and curium, both of which have half-lives in the range of thousands of years, while still be very toxic.

-No high-pressure water cooling schemes that need power to work and backups up the wazoo.

Most modern designs, whether they use water or some other coolant, are built to not need power for emergency cooling.
The ESBWR doesn't even use pumps during normal operation. This is not a feature of thorium, but a general property of
decent engineering. Hot liquid flows up, cold comes down. This has been demonstrated successfully in virtually all types
of coolant, including water, lead, sodium, salt and carbon dioxide and even nitrogen.

You may have a point about pressure, but there are other issues with salt systems. The need to keep the salt above it's several
hundred centigrade melting point is one of them.

-Others mentioned in the video

There's loads of videos. Most of them are half-truths at best, and I'm not just talking about reactors. Seriously, you seem to never have come across a marketing campaign before.

I Thought NIMBY Prevented Even the Big Sites ...

[eldavojohn]

So you're going to increase the number of sites? I thought Not-In-My-Backyard was the reason we didn't just build more big nuclear reactors. You can make the designs as safe as you want -- hell, look at molten salt thorium reactors and the CANDU design. The problem is that the people living anywhere near it are going to be dead set against it. And Fukushima didn't help that image.

Also I didn't see anything about this increasing the number of attack sites for anyone who wants to hit one of these things or steal it. That would be an increased risk factor, as well, right?

From an engineering and economic perspective these things are probably great ideas. But what state or township is going to approve a nuclear power plant -- even a small modular one -- given unfortunate recent events?

interacts badly with neighbor opinion

[Trepidity]

One thing favoring the big plants is that neighbors' opinion about nuclear power, at least in the U.S., often follows a pattern where initially putting one in is very unpopular, but once one is put in, as it brings jobs, seems to be safe, and unlike traditional industry doesn't pollute or produce bad odors, local popularity goes up. In fact when you poll people living near a major nuclear plant about the possibility of putting in a new unit, results are usually quite positive. So from a political perspective at least, that favors putting in a bunch of power generation in the same place: it's not worth going through the trouble of convincing the local population in each place only to generate 600 megawatts there.

For these to work, I think we'd need a more widespread change where the default attitude towards being near a nuclear generating facility is positive or at least neutral. Then you could just scatter then around without much worry.

Re:interacts badly with neighbor opinion

[jheath314]

That's a horrible idea. America is already in trouble because we've become a nation of consumers instead of manufacturers... just about the only advantage we have left is a slight lead in innovation.

Becoming a leader in alternative energy technologies could have enormous benefits for America, such as reversing the dynamic of wealth flowing out of the country in exchange for foreign energy. I'd much rather put American scientists and engineers to work on the problem rather than getting foreign experts to build it for us (and racking up debt by paying them with money we don't have).

Re:Olds

[ColdWetDog]

A friend of mine was interning for a company that did a lot of work with these about 10-11 years ago. He was saying they were the big thing, back then. Lower risk, easy to setup/install, cheap due to mass production. Of course, he was stating they they wouldn't go above 100MW., which is a bit of a difference.

Anyway, I'm surprised it's taken this long for them to see the feasibility in the idea. It really does make a lot of sense.

And Toshiba has been trying to get it's small, modular 4S reactors sited in nowhere Alaska for decades and hasn't been able to do it. Not gonna happen.

The only way for this to work is, as mentioned in TFA, have the US government buy a bunch and test them out. Seems actually a fairly reasonable idea - the military has need of off grid power in odd places, has built in technical and security forces that should allow for safe evaluation of the reactors, has the money to do this. So, if this has been true for at least a decade, what's the problem? Whatcouldpossiblygowrong?

Toshiba 4S

[scorp1us]

The Toshiba 4S seems like it would make an ideal neighborhood reactor. Plus, I love the design. Rather than using control rods to stop the reaction, the reflector enables the reaction. By controlling the radioactivity of the core you ensure it can never get too critical. And the reflecting band even if it gets jammed only enables a small part of the core to overheat.

And it's small enough to be self-contained.

Re:Toshiba 4S

[DerekLyons]

You forgot "and it's pretty much vaporware", never having been tested or proven in hardware.

Cheap energy saves lives.

[Anonymous Coward]

It took one of the worst Earth Quakes immediately followed by one of the worst Tsunamis in modern history to take down a 40 year old nuclear plant via a flaw found and reported 35 years ago (but never corrected). Like it or not, nuclear energy has come a long way and is pretty damn safe.

Don't like that the flaw wasn't fixed or how the accident unfolded ... but I admire how tough that facility was engineered.

Re:Cheap energy saves lives.

[Jappus]

As far as I understand it, the main problem most people have with Nuclear Reactors -- at least over here in Europe -- is not that they can go kablooie when something deemed "unlikely" hits them. This is just a problem as long as they are actually running, and a few years after for cooling down.

The problem is rather: Where do you put all that irradiated waste, ranging from water over metals, concrete, oils, various sealants and so on? After all, most of this stuff happily glows for a few decades at minimum and hundreds of thousands of years at the upper echelon. I mean, if I look at the Egyptian tombs for example, I find it hard to believe that anybody could guarantee that a sign of "Keep out or else you'll die horribly" would actually stop future people from digging up that stuff.

And that already excludes the observation that nothing humankind has ever built or excavated managed to stay permanently, physically sealed for more than a few hundred in most cases and a few thousand years in all cases. That's at least two orders of decimal magnitudes too few time to guarantee anything.

Of course things like coal, gas, etc. are not better -- especially regarding the climate. But at least they don't cause such extremely permanent issues that we can't even imagine a kind of physical or chemical process to get rid of it. They are still bad, but in a less ... distant way.

And if you finally arrive at hydroelectric, geothermal, solar and wind generation, the scope of the problems you cause by running them can be measured in "less than a decade" for cleaning up a broken dam and "what problems?" for solar and wind. That fundamental difference between nuclear, coal/gas and finally regenerative power is what is important to most environmentalists and general critics of the first and to a lesser extend next two kinds of power generation. The fact that they can go kablooie is just icing on the cake compared to that.

I always wonder if people who fully and blindly support nuclear power have ever heard what the term "neglectful precursors" means. After all, economy is mostly a private affair and expires with the generation who had to live in it, but ecology gets inherited fully and permanently.

Re:Cheap energy saves lives.

[Solandri]

The problem is rather: Where do you put all that irradiated waste, ranging from water over metals, concrete, oils, various sealants and so on? After all, most of this stuff happily glows for a few decades at minimum and hundreds of thousands of years at the upper echelon.

The problem is, we ask these questions only of nuclear.

Of course things like coal, gas, etc. are not better -- especially regarding the climate. But at least they don't cause such extremely permanent issues that we can't even imagine a kind of physical or chemical process to get rid of it.

The elemental mercury released by burning coal sticks around not for years, or decades, or hundreds of thousands of years. It sticks around practically forever. At least as long as it'll take for current organisms to absorb it, die, and turn into coal themselves. Yet we're happily pumping it into the atmosphere because we're too afraid of nuclear.

Each year, the U.S. generates about 2000 tons of spent nuclear fuel (high level radioactive waste) in exchange for ~20% of its electricity. By volume that's about two tractor trailers. This is the stuff which can potentially be dangerous for thousands of years. (The 10,000 to 100,000 year stuff lasts so long precisely because it has low radioactivity. By the time it got that old, it would no longer be high-level waste, contrary to what anti-nuclear activists like to imagine.) This "waste" could actually be used as fuel in breeder reactors, reducing the total amount of "high level radioactive waste" to just 1/10th or 1/20th what we currently generate.

But because we're scared to death of what to do with such a small quantity of nuclear waste, we continue to pump into the environment billions of tons of coal ash, including mercury, CO2, radioactive uranium and thorium, and a host of other nasty materials which together kill an estimated 250x as many people as Chernobyl every year. That is what saddens me so much about the energy situation. Yes long-term we should be working towards renewables like wind, geothermal, solar. But while we are working towards scaling those up and making them cost effective, it is absolutely criminal not to be switching out our fossil fuel plants for nuclear. Environmentalists have fabricated a false dichotomy between nuclear and renewables, where we must choose either nuclear or rewnewables. There is no such choice. We can switch to nuclear while we continue to work on renewables.

And if you finally arrive at hydroelectric, geothermal, solar and wind generation, the scope of the problems you cause by running them can be measured in "less than a decade" for cleaning up a broken dam and "what problems?" for solar and wind

Just how do you define "problem"? People see the evacuation zone around Fukushima as a problem. A hydroelectric dam creates a permanent evacuation zone behind it larger than Fukushima's. It's called a reservoir. Why is vacating people for one bad, while the other acceptable? Because one has the N word and the other is just water? Water kills nearly 100x more people each year than nuclear power has in its entire history. So which is truly more dangerous?

Measured in lives lost per unit of energy generated, nuclear is by far the safest power source. So your "less than a decade" and "what problem" assessments are only accurate if you assign zero value to people's lives.

Love the post title

[Anonymous Coward]

It's not the size of your fuel rod, it's what you do with it.

Now baby, give me a tour of your breeder reactor.

Citation?

[Anonymous Coward]

I work as a consultant for electricity planning, and I have *never* seen a single survey which shows that folks who live near a nuclear plant are in favor of new units being built at the site. Not a single survey. Not even for Vogtle units 3 and 4, being built right now next to units 1 and 2, located on the Georgia-South Carolina line... a place where I'd expect a more favorable response than most.

If you've got one, I'd love to see it.

Cause and effect all backwards

[vlm]

Cause and effect all backwards. Its not that small reactors are inherently more economical than large reactors, they most certainly are not. Its that new designs including some pretty radical fuels and coolants are being proposed, and you don't scale those bad boys in one jump from lab simulations to GW+. So these new designs are going to start small, then you build midrange 100s of MW, then you build the big ole GW+ roasters, thats just how its always been and going to be.

The next issue is there is a magic shopping list of rewards, but they're all interrelated to people that know about nukes. Can use natural convection cooling. Well, OK. Look at cube-square law and tell me how a smaller reactor at a given specific thermal output could not possibly be harder to cool? Or given an infinite budget to make a really low specific volume thermal output giant, you can convection cool them too, assuming you can manufacture something that huge. Also you get safety tradeoffs, the dough you spent on a 5 times larger vessel could have gone to quintuple redundant diesel drive coolant pumps on top of 100 meter tsunami wave proof seawalls... Big pieces of reactor grade steel are staggeringly expensive. So you are getting better burnup and better Pu non-proliferation? OK well tell me how to get better burn up without eating its own bomb isotope Pu? Answer, you can't, has nothing directly to do with size, the longer a rod sits in a core the less bomb grade Pu you can refine out of it.

Don't get me wrong, these are cool, very cool. But don't confuse having to release version 1.0 at a small scale as a permanent long term trend. "In the long run" the only thing better than an itty bitty cute little modernized PBMR or a cute little RS-MHR is a cool freaking huge PBMR or RS-MHR, but the big momma version is most certainly not going to be release 1.0. Maybe 10, 20 years after the new high tech ones are rolled out, then, out comes the plans for big ones.

I think this is the mistake the fine article makes, confusing this small beta release, with a long term roadmap. Its very much like thinking that internet sites that roll out slowly via invitations means they intent to stay small forever... not so, its just the scale up process.

Re:I Thought NIMBY Prevented Even the Big Sites ..

[Eternauta3k]

NIMBY might be less of a problem outside the US. For example, I suspect China doesn't give a shit about who wants what on his backyard.

It's University of Chicago economics

[Animats]

The point of the actual paper has nothing to do with reactor design. It's that the financing of a 1GW plant creates too much economic risk for utilities. They point out that 70% of utilities with large nuclear plants at some point faced a bond rating downgrade.

A production line with steady production improves costs more than "modularity". That's how France did nuclear power - a lot of plants, built in the 1980s, all the same, with common components. There's a scale issue with how big an object you can move to the site - if the thing will fit on a road or rail car, it can be built and tested in a factory. There's a big discontinuity in delivered price when something gets too big to move and essentially gets built on site. The paper doesn't address that issue when talking about "modularity".

(This is even an issue with wind turbines. The upper limit on size comes from how big an object you can truck to the site. Ocean units can be bigger because they're brought in on barges.)

You obviously didn't watch the video...

[andersen]

They are NOT at suggesting using solid thorium and making fuel rods. That would indeed be truly stupid.

The LFTR uses thorium dissolved in molten floride salt. It is proven tech, since the US government
built one back in the late 60s and ran it for 5 years -- with 1.5 years at full power...

Watch the video http://thoriumremix.com/2011/
then and only then can you properly comment on thorium....

Re:You obviously didn't watch the video...

[BlueParrot]

The LFTR uses thorium dissolved in molten floride salt. It is proven tech, since the US government
built one back in the late 60s and ran it for 5 years -- with 1.5 years at full power...

The devil is in the details.

While it is indeed possible to build an LFTR, that old bugger called economics tends to come and mess things up.

First of all you need a larger amount of fissile materials since the molten salt transports it out of the core. and around the entire primary loop. Secondly, as with sodium, you need to have a secondary loop to make things safe. Then there's the hydrolysis that can occur at low temperatures, which means you have to keep the salt molten. If the reactor has problems, that may involve drawing power from the grid. The reprocessing technologies kinda work, but are unproven at large scale, and nobody has an idea what the cost will be for a large reactor. They also imply building reprocessing tech for every single plant, which increases capital costs.

Then there is the startup material. Natural uranium is not good enough, so you either need to breed U-233 in a different reactor ( proliferation concern ) , use highly enriched U-235 ( proliferation concern, expensive ) , or startup on plutonium. Now plutonium in a thermal spectrum leads to accumulation of Curium, which is a troublesome waste product that cannot be efficiently destroyed in a thermal reactor.

Add in that while Thorium and Uranium dissolves easily in fluoride salts, plutonium and the other actinides do not. In fact, even at high temperatures with a completely pure salt, the solubility of Pu fluorides is just a few percent. The molten salt reactor experiments got around these issues by using a very exotic salt. Beryllium and Lithium fluorides, with the lithium enriched in Li-7. Now, beryllium is highly toxic, expensive and difficult to work with. It's such a pain that the US and UK considered developing new nuclear warheads that did not use it, even though it is the best lightweight neutron reflector there is. Enriched lithium-7 is a different problem in itself, and even if 99% pure, you will get quite a bit of tritium when it is exposed to neutrons. Perhaps not more than in a CANDU reactor, but all tritium control systems ever designed are made for water coolant.

Then is the issue of in-core materials. The molten salt reactor developed by the US dealt with damage to in-core materials by replacing the graphite core materials frequently. Not only is this expensive, but it's not very fun to handle radioactively contaminated graphite. It is hard to reprocess since it forms organic compounds and is difficult to dissolve in nitric acid. Pyro-processing by electro-refining and similar is also poorly suited for graphite. This is one of the reasons why the pebble bed reactors are usually seen as "once through". Nobody has come up with a practical way to deal with the graphite. Since the material will be in direct contact with the fuel salt, it will likely adsorb quite a bit of contaminants.

Plateout on heat exchangers is another issue. The noble metals have poor solubility in fluoride salts, so unless a very potent ( i.e expensive ) reprocessing system is able to get rid of them quickly, they will plate out on the cold parts of the reactor, which is usually the heat exchangers. A suggested solution is to use graphite-based heat exchangers, which has its own spectrum of development issues and research needs.

I'm not saying molten salt reactors can never become a good idea. I'm just saying that in comparison to the number of issues that need to be resolved to make them practical for a power plant, they are extremely hyped.

The navy doesn't have any answers

[fyngyrz]

Naval reactors -- be they powering submarines, aircraft carriers, etc. -- don't have to show a profit. When they need money to run them, they just take it from you and me. Rinse, wash and repeat.

Compare that to one of the very few nuclear powered cargo ships, the NS Savannah. Truly beautiful ship; fast, clean, etc. Couldn't be run cost-effectively, some of which was due to a bit of overzealous streamlining and so forth, but in terms of propulsion costs, oil fueled cargo ships are simply less expensive.

That's why you're not going to see naval reactor designs in your back yard. Ever. Commercial reactors have to be practical.

The right answer is solar and/or wind and/or hydro plus storage. We just don't have cost-effective / space-effective storage. Yet.

Re:The navy doesn't have any answers

[frosty_tsm]

Compare that to one of the very few nuclear powered cargo ships, the NS Savannah. Truly beautiful ship; fast, clean, etc. Couldn't be run cost-effectively, some of which was due to a bit of overzealous streamlining and so forth, but in terms of propulsion costs, oil fueled cargo ships are simply less expensive.

From the link, that ship was built more than 40 years ago, had an overly-small cargo-hold and was done more as a proof of concept (which seems silly). Doing the same today (and doing it economically) would yield different results.

Re:Lots of little Carrington events?

[Anonymous Coward]

He reads fine. Chernobyl (and reactors with that design) as well as Fukushima (and other GE Mark Is) have design flaws that make it easier than it should be to have a meltdown or similar critical failure. By even the late 1970s, newer designs avoided some of the specific problems the older ractors had, and by even the early or mid 1980s, inherently safe reactor designs were designed. (They were designed so even with a complete failure of the rods, they would not runaway and melt down -- and newer ones don't rely on rods at all.) I don't think I'd like a Mark I in my back yard (there is one about 30 miles away from me though..) but the modern designs? I wouldn't mind at all.

Re:Lots of little Carrington events?

[Anonymous Coward]

That's an engineer looking for a complicated solution. The right answer is dig a hole beneath the local water table or below sea/lake/river level, and install a one way valve. Local water table is 500 feet below? Don't build the plant there, build it somewhere within 50 feet of the water table, or lake/sea/river level..

Nope, digging a hole to the water table to store anything hazardous is about the worst idea I have ever heard. I think I'll stick with solutions designed by engineers, thanks. A reservoir of water on higher ground, with gravity feed, to a pool that is designed with eventual cleanup and - very importantly - de-comissioning considered from the outset.

If you want to know how bad it is to dig a pit below the water table and chuck radioisotopes into it, do some reading on Dounreay in Scotland. Still, not to worry, they should have it sorted it out in another 300 years.

The truth is that pools often are bad news, because stuff gets chucked into them as an alternate to proper safe long term storage. This happened at Fukushima and is basically a problem all over the world. The most hazardous building in Western Europe? B30 at Sellafield in the UK, which contains a huge fuel pool full of all kinds of crap (they aren't sure exactly what is in there -- but it is thought there is a about 1500kgs of plutonium sludge amongst the rods in various states of decay). The second worst building is right next door. These pools are open-air, and you can see both of these pools if you go to google maps and have a mooch around the Sellafield site.