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This is some very welcome news in developments at Fukushima as the foundations of Unit 3 are damaged. Workers at Fukushima have already removed 1000 fuel rods IIRC from that reactor building due to concerns about what would happen if the building collapsed.

To get a better understanding of why its an urgent issue, a report called Nuclear Power Plant Security and Vulnerabilities explored vulnerabilities at nuclear power plants.

From that report the issue of spent fuel pool vulnerabilities warranted further study in the now declassified report Safety and Security of Commercial Spent Nuclear Fuel Storage: Public Report by the Committee on the Safety and Security of Commercial Spent Nuclear Fuel Storage within the National Research Council. It details variations of scenarios created from vulnerabilities to terrorist attacks, however the potential outcomes are similar if they are initiated by a natural disaster.

The most sobering scenarios came from analyzing what happens from loosing the cooling water from a spent fuel pool. Spent fuel rods are kept in a pool with a constant supply of water because the water not only cools them, it moderates the neutrons so that they don't become critical. One scenario examined from loosing the cooling water was a plutonium fire that creates plutonium oxide in the smoke with reactors that are MOX fueled, such as Unit 3 was. With several hundred tons of fuel it would be the largest plutonium fire we have ever faced, it would also be in open air.

You can find information about plutonium oxidization Evaluation of source-term data for plutonium aerosolization which starts at around 500 centigrade. I think that because of the proximity to the sea, plutonium chloride would also be created.

Actions to reduce the possibility of these kinds of scenarios are simple and cost effective. Mainly by dry cask storing fuel that has cooled for 5 years and separating and dispersing spent fuel recently removed from the reactor throughout the pools of reactors that are still operating. All very practical, affordable actions for reducing this risk of reactors that are still operating.

Information about the fuel removal process and the damage to the Unit 3 spent fuel pool in Tepco's Fukushima spent fuel removal plan.

There is very little point arguing about Nuclear power from an idealistic viewpoint. To idealize that nuclear power is perfect and requires no improvements means that the nuclear industry cannot evolve legal requirements for new processes. This, according to the official report into the Fukushima accident, is the main reason the disaster occurred.

So this is a great time to commend the workers and engineers at the Fukushima plant and express gratitude for their efforts to get this disaster under control. Thank you!!!!

A report called Nuclear Power Plant Security and Vulnerabilities explored vulnerabilities at nuclear power plants.

From that the issue of spent fuel pool vulnerabilities warranted further study in the now declassified report Safety and Security of Commercial Spent Nuclear Fuel Storage: Public Report by the Committee on the Safety and Security of Commercial Spent Nuclear Fuel Storage within the National Research Council which details variation of the above scenario from a terrorist attack, as opposed to a disaster.

You can find information about plutonium oxidization Evaluation of source-term data for plutonium aerosolization which starts at around 500 centigrade.

Actions to reduce the possibility of these kinds of scenarios are simple and cost effective. Mainly by dry cask storing fuel that has cooled for 5 years and separating and dispersing spent fuel recently removed from the reactor throughout the pool. All very practical, affordable actions for reducing this risk.

Information about the fuel removal process and the damage to the Unit 3 spent fuel pool in Tepco's Fukushima spent fuel removal plan.

There is very little point arguing with people who look at Nuclear power from an idealistic viewpoint. For them Nuclear power is perfect and requires no improvements. This, according to the official report into the Fukushima accident is how it occurred.

Again I would like to express my gratitude to the workers and engineers attempting to get the Fukushima disaster under control.

If you're suggesting they can induce criticality by poking debris with a claw, you're dumber than I give you credit for.

Of course you can induce criticality that way. You can hit a small chunk of uranium with a hammer and reach criticality, at least for a moment. U-235 can reach criticality with a mass as small as 780 g under the right circumstances. And the presence of water, potentially with some amount of uranium in solution, greatly raises the risk. Of course, it would only remain critical while compressed, and so such a small criticality event would likely be a risk only to the robots, because it would be small and self-contained.

Perhaps you meant that it cannot cause a nuclear explosion (which requires not just enough material and moderation to sustain a reaction, but also for it to increase exponentially and not burn itself out in a fraction of a second).

But since it was a 60's style LWR, there wouldn't be pure U-235 in the reactor. It would be LEU which is probably 4% U-235 and 96% U-238 or so as new fuel. Exactly what the isotopic distribution of this material is, I'm not exactly sure, but I'm 100% certain it doesn't contain more than a few percent of U-235. Since U-238 is a neutron poison, I seriously doubt that criticality could be induced accidentally. You probably couldn't induce criticality in this material without explosives (or lots of a moderator material) but I can't be sure of that. The hazard with this material is the fission products and all but the medium lived ones like Cs-137 and Sr-90 will have already burned out by now to stable elements. The long lived stuff like U-235 isn't very radioactive (but it is poisonous). The short lived stuff is now stable isotopes, mostly heavy metals. Its still a hazard to human life, but not in the dramatic fashion you imagine. Its more dangerous because of the amount of heavy metals which are poisonous to humans in high amounts and less dangerous because of nuclear issues at this point.

If you're suggesting they can induce criticality by poking debris with a claw, you're dumber than I give you credit for.

Of course you can induce criticality that way. You can hit a small chunk of uranium with a hammer and reach criticality, at least for a moment. U-235 can reach criticality with a mass as small as 780 g under the right circumstances. And the presence of water, potentially with some amount of uranium in solution, greatly raises the risk. Of course, it would only remain critical while compressed, and so such a small criticality event would likely be a risk only to the robots, because it would be small and self-contained.

Perhaps you meant that it cannot cause a nuclear explosion (which requires not just enough material and moderation to sustain a reaction, but also for it to increase exponentially and not burn itself out in a fraction of a second).

Where, at the end of the day, is your free oxygen?

It's an intermediate product not an end product, and it diffuses into the zirconium

https://www.osti.gov/servlets/...

You can back out ICE efficiency from the EVs on the road. Let's use the Nissan Leaf (you'll see why later). EPA rating of 30 kWh per 100 miles. 112 MPGe combined, 101 MPGe.highway. Top speed of 93 MPH.

30 kWh per 100 miles = 108 Megajoules per 100 miles. Since we're trying to do a comparison and ICE cars don't have regenerative braking, we need to compare the highway mileage. Since the Leaf gets 101 MPGe on the highway vs 112 MPGe combined, this works out to (112/101)*(108 MJ) = 119.8 MJ per 100 miles on the highway. Note that this is energy stored in the battery. To do the comparison, we need energy at wheels to the ground.

Electric motor + inverter efficiency is typically about 85%-93% (page 35). That's for a Prius' motor (the only one I could find detailed stats for), but they're all pretty similar at these levels of power output. Since there's no gearing, if you align the Leaf's top speed of 93 MPH with 6000 RPM, then the highway speed of 55 MPH corresponds to (55/93)*(6000 RPM) = 3550 RPM. Which puts us right around 90% efficiency.

I couldn't find any numbers for battery discharge efficiency. Battery charging efficiency for a Tesla with the home charger is about 85%. Battery discharge efficiency is typically a bit worse (even more so at higher loads, which is why jackrabbit or ludicrous mode starts kill your rnage). so go with 80%. (For those of you complaining this is too unfavorable to EVs, a lower discharge efficiency here corresponds to lower ICE efficiency later on.)

So 119.8 MJ from the battery becomes (119.8 MJ)*(90%)*(80%) = 86.3 MJ per 100 miles wheels-to-ground. The extra energy is lost as heat to the battery, wiring, inverter, and motor.

Gasoline has an energy density of 34.2 MJ/L = 129.5 MJ/gallon. To figure out how many gallons were used in 100 miles, we need the MPG of a gas-powered Leaf. Fortunately we have one - the Leaf's aerodynamic and rolling resistance is almost identical to the Versa since it shares the same body and frame (I had to go back to 2014 to get the hatchback version with a regular transmission). Highway mileage is 35 MPG. Meaning (129.5 MJ/gal)*(100 miles)/(35 miles/gal) = 370 MJ worth of gasoline consumed per 100 miles.

Overall highway efficiency of the ICE and drivetrain is then energy wheels-to-ground vs energy in the gasoline. (86.3 MJ)/(370 MJ) = 23.3%. It's rated at 26 MPG city, so overall efficiency in city driving is (26/35)*(23.3%) = 17.3%. A far cry from the 12% you came up with.

We can also calculate overall efficiency for the EV, from energy source to wheels-to-ground, just like we calculated it for the ICE vehicle from energy source (gasoline) to wheels-to-ground. The average efficiency of a coal plant is about 33%. The average efficiency of a natural gas plant is about 43%. Power line transmission losses are about 5%. As mentioned before, charging efficiency (for a home charger) is around 85%, discharge efficiency around 80%, motor efficiency around 90%. To get an overall efficiency of (33% or 43%)*(95%)*(85%)*(80%)*(90%) = 19.2% or 25%. If you use a fast charger like a Supercharger station, it's even worse, since the charging efficiency is even lower (more of the electricity is lost as heat) the more quickly you charge the battery.

So an EV powered by electricity generated from fossil fuels isn't any more energy efficient than an ICE vehicle. The reason it's cheaper to charge an EV is almost entirely because gasoline is damn expensive for an energy source. Coal costs about $50/ton and contains ab

If your lazy mind cannot extrapolate what happens when you take ten times the amount of fuel that is in a nuclear reactor, pack it close together then remove the moderator from between the fuel rods then we're back to you having inadequate knowledge of the things we are discussing.

A mechanism for plutonium pyrophoricity and THE EXTINGUISHING OF PLUTONIUM FIRES.

At 8 - 10 times the size of the reactor core good luck getting close enough to it to put it out.

It would nice if there were some primary sources in this post.....

Apologies, I've had food poisoning all week and not enough energy to filter out what I thought were the best primary sources, many of which are pdfs that I'm still getting through myself. Here are the ones that cover the salient details:

• (~2002) Status and discussion of SIP
• Issues on Safe Radioactive Waste Management at ChNPP Site in International Shelter Implementation Plan
• Bioassay program for the shelter implementation plan in Chernobyl
• Shelter implementation plan: a way forward for Chernobyl 4
• Chernobyl shelter implementation plan -- project development and planning: Setting the stage for progress
• Regulating nuclear and radiation safety in the frame of the Chernobyl shelter Implementation Plan
• Development of a Fuel Containing Material Removal and Waste Management Strategy for the Chernobyl Unit 4 Shelter

I would link to the Ukraine body of law that governs all this this however I don't speak the language.

Basically, the x-rays will ignite the surface of the asteroid instead. If the material in the asteroid is sub-optimal for this purpose, there have been designs of turning a nuclear bomb into a kinetic weapon that should work in this regard. Basically the bomb sits in an x-ray reflective shell, and when the bomb explodes, the x-rays bounce around the shell before the exploded bits of the bomb destroy it and exit an aperture. At the end of the aperture is a large, dense block of x-ray absorbing material. This material is vaporized by the x-rays and is all traveling in a similar direction as the x-rays were all going in that general direction. This plasma moving at relativistic speeds then slams into the target like a nuclear shot gun blast. IIRC, this design was built for using nuclear bombs against space ships and it was estimated that it could direct 95% of the energy of the bomb at the intended target.

I second that. Masterful tech writing.

This description of Orion propulsion also describes the 'Casaba-Howitzer', a one-shot Orion optimized for a narrow, fast plasma jet. Here objective is more similar to Orion than punching through armor: the most complete, reliable and (as much as possible) directed transfer of energy. The Casaba-Howitzer concept is not even in the declassified SDI flava stuff that DOE is permitted to talk about.

We all love Delta-V-expensive solutions that involve maneuvering 'beside' or 'landing on' a threat (which by definition is heading straight towards us at 10-30kps. There are no cloverleafs in space, people! :) Landing Bruce Willis is out. Doing anything gentle or slow is out. I propose these be shelved for the 'Emergency' context. Parameters are strict. The best we might achieve is some 45 or less approach angle. By this I mean the vehicle's course, the explosion can be directed broadside, as timing allows. The final sequence of events requires precise micro/nanosecond timing. We know our computers are up to it.

Are the warheads? We know how to make warheads that detonate on timing, pressure and 'contact'. But speed is relative and conditions in atmosphere is a cushy affair, a device falling at terminal velocity or missile propelled. Can we assuredly produce a weapon that can range itself accurately or trigger in vacuum, on or just before contact at ~40kps?

And there should be at least three complete missions of them en route, each lagging far enough to escape detonation effects, have enough time to analyze a failure, upload firmware, or adjust course in case we have partial success. And it would br really nice if each mission embodied more than one general approach, or the ability to reconfigure for an alternate strategy... just in case there it becomes clear after the first that the primary will not work. And even an idea that shapes force of a nuclear explosion is a massive fail if a technical snafu has it pointing the wrong direction.

The price of failure is death. And embarrassment.

Your memory serves you well, the aluminium cans did not take off until the late 70's early 80's when the technology needed to recycle them was invented.

Disclosure: one of the inventors on that patent is my father, his other research was in solar panels, ocean thermal engery (otec), the aluminum air battery , the use of adhesively bonded aluminum structures such as the Jaguar XJ and hybrid diesel electric vehicles.

The cornerstone of it is the dusty fission fragment rocket, so I'd start there. Another key aspect is the use of a accelerator-driven subcritical fast reactor rather than a critical slow reactor. Lastly it's a variant of a nuclear lightbulb, albeit (as mentioned) without the primary drawbacks of them (containment and radiation blackening of the chamber blocking the light). This latter aspect is due to the spectrum changes of fused silica (I can't find a paper on short notice that shows the IR spectrum, but you can see that for most types of fused silica / fused quartz, there's little loss of transmission on the red side of the spectrum; this holds true but is even more pronounced in the IR range).

Because of this thickness and the drop from the original pressure to it's present this sand will slowly subside under the pressure of the overbearing layers.
As predicted this subsidence will be in the order of 50 cm (18 in.) at the centre, the scaremongers predict half-meter clefts down the landscape.
Reality is this subsidence takes place over an about 50 km (30 mi) radius and thus the amount measured over say the with of your yard can hardly be expressed.
Reality is also this subsidence takes sometimes place in spurts, it's not everywhere a gradual process over time and those are the very local quakes that cause so much unrest and sometimes damage.
Because of the soft sedimentary nature of the soil and the historical building methods these small quakes can do significant damage.
Sometimes it's suggested to stop production but this would do nothing in preventing future quakes, 90% of the pressure is already gone and the subsidence will continue for many years to come.

Such is unthinkable in the typical shale field, porosity is very low and the thickness is way insufficient to allow for significant subsidence, please don't mix up the two!

This was, like, the plot of a major blockbuster movie well before most people were even aware of the idea, and the idea certainly predates that (as another poster pointed out with this)

Let's see, here's an academic paper mentioning cooler winters as an artifact of global warming, dated from before I was born. And I'm more than old enough to be having this debate with you. What exactly wasn't predicted?

Analyses conducted in the late 1970s concluded that the Mark I would almost certainly result in disaster in the event of sustained power loss - and it did.

Yeah... unfortunately, the containment failures at Fukushima matched the models pretty well. I've posted it before, but the following document is illuminating... see the section titled "BWR 3/4 Perspectives", including the parts regarding station blackout (SBO), transients with loss of coolant injection, and transients with loss of decay heat removal (DHR).

http://www.osti.gov/bridge/purl.cover.jsp?purl=%2F205567-BJIEKT%2Fwebviewable%2F

I still don't understand why TEPCO didn't install hardened containment vents back in the '90s. If they had, things would have gone very differently. They must have known about NRC Generic Letter 89-16.

https://forms.nrc.gov/reading-rm/doc-collections/gen-comm/gen-letters/1989/gl89016.html

The other thing I don't understand is why Unit 1 didn't handle the situation better than the others. It should have because it has an Isolation Condenser instead of Reactor Core Isolation Cooling... I'm not sure that anyone has yet explained what happened with this.

We're entering an era where more countries have nuclear weapons. They've become too easy to make. Isotope separation used to take huge gaseous-diffusion plants. Entire cities were built just to enrich uranium. Centrifuge plants are now medium sized industrial park installations. That's URENCO's plant in New Mexico. It produces enough enriched uranium to power a sizable fraction of US reactors, and it's being expanded. A much smaller plant could enrich enough uranium for a few bombs.

Once you have enriched uranium, making a nuclear bomb isn't a huge job. As a build, it's roughly comparable to making an auto engine from scratch, a job that some auto racing shops can do. Machining uranium isn't that hazardous. Here's a how-to guide from Union Carbide from the 1980s. (Plutonium is a totally different story; there you need glove boxes, remote manipulators, and huge precautions against dust escaping.) There aren't many secrets left about how ordinary atomic bombs work. It's been almost 70 years, after all. (Some of the tricks of fusion weapons still haven't leaked out.)

We've been very lucky that this was a hard thing to do. But it's not that hard any more, and it keeps getting easier.

It's been over 60 years since the first A-bomb. Why doesn't everyone have one? Even third-rate powers have jet fighters.

Building a bomb isn't that hard a job if you have enriched uranium. It's comparable to building an automobile engine - not easy, but a good racing shop could do it. Machining uranium can be done in a standard machine shop with some extra precautions. (Plutonium is much worse.) Machining beryllium is probably more dangerous. Casting and X-raying the explosive lenses is tough, but it doesn't take a big shop. Generating the 1ns rise time power pulse to fire the explosives is a lot easier than it was in the tube era. Between what the US and the USSR have published, there are few secrets left about low-end bomb design.

Gaseous diffusion plants are huge. Oak Ridge Novouralsk. Drome, France. Those things are the size of big steel mills. Entire "nuclear cities" were built around them. Only major countries could afford them.

Then came centrifuge plants. Here's one in the US. URENCO USA. It looks like a big data center, just some big commercial buildings and a parking lot. It's on the outskirts of a town in New Mexico, along with some other unrelated industries. Any reasonably successful country, or even a big company, can afford a centrifuge plant. URENCO is on their third generation of centrifuges, and price/performance improves with each generation. Now countries like India and Pakistan were able to get into the game.

Laser enrichment will reduce the scale even further. Lawerence Livermore had laser enrichment working in the 1990s, but it wasn't cost-effective. Now it is. A laser enrichment plant is a modest operation, perhaps a quarter of the size of a centrifuge plant of the same capacity.

All these processes are multi-stage, with each stage doing some separation and feeding a slightly more concentrated product into the next state. The minimum plant size before you get anything is still reasonably big.

There's work going on towards single-stage laser separation systems. That's a worry, because a very small plant, over time, could enrich enough uranium for a bomb. So far, if anyone knows how to make that work, they're not saying much. But eventually it will be figured out.

I think this is a non-aqueous system. I don't have access to this paper, but in an earlier paper from the same group (using a silicon nitride cell) mentions that a "stock solution for synthesis was prepared by dissolving Pt(acetylacetonate)2 (10 mg/mL) in a mixture of o-dichlorobenzene and oleylamine (9:1 in volume ratio). About 100 nanoliters of the growth solution was loaded into the reservoir of a liquid cell and the solution was drawn into the cell by capillary force."

No, I'm worried about what happens AFTER the fuel dumps into the emergency storage tanks. It just keeps heating, unless something cools it.

OK, I've just done some research: http://www.osti.gov/bridge/servlets/purl/469120-avNXWz/webviewable/469120.pdf
It seems that they're constantly removing the fission products from the fuel, so there simply isn't enough 'after heat' to cause a problem for the cooling of the dump tanks.

I am worried that in normal operation there is a lot of very radioactive stuff being pumped around, controlled by valves, and chemically processed. I'm therefore expecting quite a lot of complex equipment in regions far too radioactive for human maintenance.

Try and read about the real science, it wasn't just a couple of uranium miners, not even close (and those 2000 pages are just a dense selection of research done until 1980). Also, ten times the average background radiation can be naturally found in several places (e.g. in Cornwall or Denver, Colorado) with relatively high thorium/uranium concentrations in the soil, without detectable effects.

Finally, the approach of diluting toxins has not been followed for decades. These days the general approach is concentration and indefinite storage - as most of those toxins know no such thing as a half-life. (Germany is storing more than 2 mio tons at just one site in salt caverns. But nobody cares, because it's not radioactive.)

In general, if you want to know specific data, it's best to look for it yourself. Most people feel disinclined to do this for other people most of the time. However, you may try:
Radioactivity and health: A history (1988)
http://www.osti.gov/energycitations/servlets/purl/6608787-H6blQd/6608787.pdf

Warning, almost 2000 pages and 115MB worth of data to download. No, I didn't read it yet, I was merely trying to find a comprehensive source on the topic. Yes, it is not up to date, but it shows the historic development of the field until two years after Chernobyl.

I could have pointed to you to any number of studies of the soil contents of radionuclides, but most of those were pay-walled (a common problem not just in this area) and I hate referring to summaries and abstracts. Search google scholar if you want to see them. But there were several that had an excess which was equivalent to more than 2500Bq of Cs-137 compared to average concentrations when you add up Thorium, Uranium and their decay chain products.

Back in 1987 when Nevada's Yucca Mountain was selected, it also removed
Gable Mountain at Hanford Washington as a burial site. A lot of money
had been spent on Gable Mountain already; but for the government that means little.

When I took a tour of Gable Mt. a milestone had just been met:
boring a 1000 foot (cite?) horizontal shaft that didn't droop.
That was a few months before Yucca Mountain got the green light and
Gable Mt., it's progress, and employees were dropped overnight.

It was a known fact at that time Yucca Mt. was a bad choice, as the rock
was porous, and radioactive material could get into the ground water. Gable Mt
is a slow cooled basalt, non-porous.

This was a bad time for Hanford. The Chernobyl disaster was a year earlier,
100-N a plutonium production reactor located at the Hanford site shared a
common trait with the Chernobyl reactor. It was also graphite moderated,
because of this it was in the public/political cross hairs.

DOE, President Regan, and the people of the area wanted 100-N to continue
operating. The people west of the Cascade Mountains which splits
Washington State and where the political power is located were against it.

Politics were generally accepted as the decision to abandon Gable Mt. in
no small part because of 100-N. Those who could wanted the Hanford site to go away.

The 100-N reactor was enhanced at a phenomenal cost, started up a few more times
amid a political storm plaster all over the front page, so no secret. Finally 100-N
was shut-down due to the pressure, mothballed and now buried.

The Fast Flux Test Facility (FFTF) took a hit over this as well, and was shut down
even though it could of supplied isotopes for medical use - which are now in demand.
http://en.wikipedia.org/wiki/Fast_Flux_Test_Facility

Now those who can are asking once again for Washington state to be considered
for a burial site. Something they wanted no part of earlier.

High level nuclear waste disposal is a necessity that needs to be dealt with and soon.
Even if Yucca Mountain could leak, it was a disposal site and a leak is nothing
more money can't fix.

Gable Mt. isn't without it's faults :}
Geology of Gable Mountain-Gable Butte Area:
http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6423229

You are worried about MOX instead of "plain uranium" so you must be concerned about the plutonium in MOX. For many people plutonium is an unspeakably deadly substance and while I disagree with that, it is more important to point out that running "plain uranium" in a nuclear reactor continuously creates plutonium and after a period of time, there is substantial plutonium content in both types of fuel rods. https://www.osti.gov/opennet/document/purecov/nfsrepo.html

There doesn't appear to be an issue with fires in spent fuel ponds according to this article I found (below), and the discussions I've been having here: http://bravenewclimate.com/2011/03/18/fukushima-radiation-tsunamis/

Spent fuel heatup following loss of water during storage. [PWR; BWR]
Benjamin, A.S. ; McCloskey, D.J. ; Powers, D.A. ; Dupree, S.A.

Abstract: An analysis of spent fuel heatup following a hypothetical accident involving drainage of the storage pool is presented. Computations based upon a new computer code called SFUEL have been performed to assess the effect of decay time, fuel element design, storage rack design, packing density, room ventilation, drainage level, and other variables on the heatup characteristics of the spent fuel and to predict the conditions under which clad failure will occur. Possible storage pool design modifications and/or onsite emergency action have also been considered.

http://www.osti.gov/bridge/product.biblio.jsp?osti_id=6272964

A commenter posted:
>>Importantly, reading the documents introduction
>>& conclusion section seems to indicate that
>>there is a “decay time” of 5 to 150 days after the
>>BWR fuel assemblies are put in the spent fuel
>>pond, after which the fuel assemblies do not
>>reach the critical 850-950C following a complete
>>water drain.

The article seems to suggest it isn't a burning issue, although the radiation would be quite locally intense (within the pool itself) until it is recovered by water. Nothing would be leaking about into the air though. If anyone has a different take on the article share them.

The following document is a good source of info regarding the situation at the Fukushima reactors. See the section titled "BWR 3/4 Perspectives", including the parts regarding station blackout (SBO), transients with loss of coolant injection, and transients with loss of decay heat removal (DHR). (The remaining parts of the BWR 3/4 section don't appear to apply.)

Core damage frequency perspectives for BWR 3/4...

From my understanding the criteria for shutting down a Nuclear Power plant is assessed on mainly two parameters.

A "Licencee Event Report" (LER) is submitted for issues above a safety significance threshold. For example at Davis-Besse, the frequency of the replacement water filters was out of spec. It should have signaled that something is going wrong in the reactor. This is the type of event that should be signaled as a LER even if it seems insignificant.

The second stage is an "Accident Sequence Precursor" (ASP) which defines events that characterise the lead up to an accident at a Nuclear Plant. Sticking with the Davis Besse example which (from memory) was caused by a fine jet of borated water spraying onto the the *inside* of the reactor head. Water rusts steel, reactor head is steel, rust goes in water, water goes through filter, filter catches rust, management says it's ok, reactor head gets hole [if allowed to continue - reactor core breach and potential for explosion] - 'Accident Sequence Precursor'.

By examining the trends for LER's and ASP statistically for all nuclear plants the NRC can get an overview of the operational state of all the plants *if* the operators of the plant co-operate and share their operational data (which I also believe to be a legal obligation of the Licensee) with the NRC. At issue is the characterisation of what sort of events should lead to a LER.

At the Davis Besse plant I believe that it led to criminal charges as management allowed the plant to operate outside of it's "Basis Design" which is a known operational characteristic of the plant. Filter replacement intervals had been defined and were known about and thus should have characterised the plant as "not operating safely". I'm not sure if the criminal charges were placed because management should have reported several LERs instead of inspectors finding a hole in the reactor head when it was shutdown.

"Basis Design Issues" (BDI) are also revealed whilst the reactors are operating - they are not all known when the reactor becomes operational due to the complexity of the machine. Industry wide knowledge of LERs contribute to knowing what BDIs lead to ASPs (and a sentence full of acronyms). Further information can be found in the NRC document NUREG 1275 - Volume 14 "Causes and Significance of Design Basis Issues at U.S Nuclear Power Plants"

As often observed in plane crashes it's a combination of insignificant issues that lead to a problem. The question at hand is whether the leak is indicative of a larger problem for example; lets say our leak has led to filling a concrete void under the reactor core with water. Together the two events are insignificant, however when combined with a third event like a SCRAM of the reactor that suddenly heats that water in the concrete void you have the potential for a serious explosion.

I'm not saying thats whats happening, just that the water leak my be an indicator (a LER) of a larger issue which is used as part of the determination if the plant should be shut down. A leak of triated water into the environment is a serious concern. What is yet to be revealed is if the leak reveals a Basis Design Issue that is serious enough to be a part of an Accident Sequence Precursor.

No matter what the outcome the continued operation of the reactor will probably be determined on *if* they can find the leak. Anything that affects the cooling capacity of a Nuclear Reactor is not a situation that can be allowed to persist.

It won't work, from that patent image, they are simply rehashing the old laser TV system idea. That polygon motor has to spin at an incredible speed and has to be extremely stable. Synchronization of the laser and the mechanical components is also difficult. Definitely not going to be a mobile display.

There are engineering details to building a nuclear weapon that aren't well known. But they're not all that deeply hidden, either. A few minutes with Google gets you the basics.

A big, dumb Hiroshima-type implosion bomb made of uranium isn't that hard. Plutonium bombs are tougher to build; more compression is necessary. The later designs have reflectors, tampers, and quite a few layers. Considerable simulation is required to get the design right. Of course, the US and the USSR designed their nuclear arsenals with computers in the 1 MIPS range; today, any laptop has enough CPU power for bomb design. Some older hydrodynamic software for this is available, in FORTRAN. Note the test cases provided, "Detonation example" and "SSTAFF warhead".

A more modern version of that software is available from LLNL. The code was released in 1996 and was upgraded through 2005. There's a torrent available.

Making the components is a pain because many of the materials involved are radioactive, poisonous, flammable metals, or high explosives. Machining uranium is difficult. However, there's a convenient how-to guide, "Machining of Uranium and Uranium Alloys", written by a head machinist at the Oak Ridge Y-12 plant and distributed by the U.S. Government. That guide concludes "With proper techniques and safety precautions, uranium and uranium alloys can be safely machined by most shops." Exotic techniques like robotic handling and machining in a liquid bath weren't required. They didn't even use a glove box back then.

Machining plutonium is more difficult. US plants have had troubles with that for decades, and didn't even have a facility that could do it between 1989, when Rocky Flats shut down, and 2002, when Los Alamos started up. But Iran is taking the uranium route, so they don't have to worry about that.

The explosive components have to be made very uniform, to get the uniform compression required. This was a big problem for Los Alamos in the early days, but now that everyone has plastic explosives, it's easier. There's also a problem with the explosion blowing out at the gaps between explosive blocks, but there's a simple trick to fix that. (It's classified in the US, but has leaked out from the USSR side.)

The necessity for krytron detonator switches is overrated. A krytron is a gas-filled tube device from the era of the thyatron. Basically, you need a switch for about 1000 amps at 1KV that turns on in a few nanoseconds. Conveniently, the U.S. Government distributes a design using standard IGBT semiconductors. That's 15 years old; you could probably downsize that design (10" of rack space) today.

Most of the complexity in bomb design appears as bombs are made physically smaller. Truck-bomb sized units are 1940s technology. Smaller warheads require late 1950s technology, and the US did about a hundred full-scale nuclear tests in the 1950s to get that right. Some of that can be replaced with simulation. Eventually, you have to set one off to be confident it will work.

As Ted Taylor (who designed many US bombs) once said, "Everyone (who built an atomic bomb) has succeeded on the first try."

There are engineering details to building a nuclear weapon that aren't well known. But they're not all that deeply hidden, either. A few minutes with Google gets you the basics.

A big, dumb Hiroshima-type implosion bomb made of uranium isn't that hard. Plutonium bombs are tougher to build; more compression is necessary. The later designs have reflectors, tampers, and quite a few layers. Considerable simulation is required to get the design right. Of course, the US and the USSR designed their nuclear arsenals with computers in the 1 MIPS range; today, any laptop has enough CPU power for bomb design. Some older hydrodynamic software for this is available, in FORTRAN. Note the test cases provided, "Detonation example" and "SSTAFF warhead".

A more modern version of that software is available from LLNL. The code was released in 1996 and was upgraded through 2005. There's a torrent available.

Making the components is a pain because many of the materials involved are radioactive, poisonous, flammable metals, or high explosives. Machining uranium is difficult. However, there's a convenient how-to guide, "Machining of Uranium and Uranium Alloys", written by a head machinist at the Oak Ridge Y-12 plant and distributed by the U.S. Government. That guide concludes "With proper techniques and safety precautions, uranium and uranium alloys can be safely machined by most shops." Exotic techniques like robotic handling and machining in a liquid bath weren't required. They didn't even use a glove box back then.

Machining plutonium is more difficult. US plants have had troubles with that for decades, and didn't even have a facility that could do it between 1989, when Rocky Flats shut down, and 2002, when Los Alamos started up. But Iran is taking the uranium route, so they don't have to worry about that.

The explosive components have to be made very uniform, to get the uniform compression required. This was a big problem for Los Alamos in the early days, but now that everyone has plastic explosives, it's easier. There's also a problem with the explosion blowing out at the gaps between explosive blocks, but there's a simple trick to fix that. (It's classified in the US, but has leaked out from the USSR side.)

The necessity for krytron detonator switches is overrated. A krytron is a gas-filled tube device from the era of the thyatron. Basically, you need a switch for about 1000 amps at 1KV that turns on in a few nanoseconds. Conveniently, the U.S. Government distributes a design using standard IGBT semiconductors. That's 15 years old; you could probably downsize that design (10" of rack space) today.

Most of the complexity in bomb design appears as bombs are made physically smaller. Truck-bomb sized units are 1940s technology. Smaller warheads require late 1950s technology, and the US did about a hundred full-scale nuclear tests in the 1950s to get that right. Some of that can be replaced with simulation. Eventually, you have to set one off to be confident it will work.

As Ted Taylor (who designed many US bombs) once said, "Everyone (who built an atomic bomb) has succeeded on the first try."

The part where it is chemically equivalent to hydrogen and hence rapidly dissolves and disperses in water, quickly being diluted to lower than background levels.

Right, so your saying that, magically, Tritium (3H) changes it's physical characteristics, stops being a beta emitter and just isn't radioactive anymore. What about when it's in air?

In addition the very low energy of the beta radiation it emits,

3H is biologically mutagenic *because* it's a low energy emitter. This characteristic makes readily absorbed by surrounding cells.

it's tendency to be ejected with urine or sweat if ingested ( as opposed to staying in the body ) the short half-life, the minuscule amount produced, and the lack of any major pathway into the food-chain that would not first dilute any release by many orders of magnitude.

The available evidence from studies conducted contradicts you, so I'll just quote from those works;

Tritium can be inhaled, ingested, or absorbed through skin. Eating food containing 3H can be even more damaging than drinking 3H bound in water. Consequently, an estimated radiation dose based only on ingestion of tritiated water may underestimate the health effects if the person has also consumed food contaminated with tritium. (Komatsu)

Studies indicate that lower doses of tritium can cause more cell death (Dobson, 1976), mutations (Ito) and chromosome damage (Hori) per dose than higher tritium doses. Tritium can impart damage which is two or more times greater per dose than either x-rays or gamma rays.

(Straume) (Dobson, 1976) There is no evidence of a threshold for damage from 3H exposure; even the smallest amount of tritium can have negative health impacts. (Dobson, 1974) Organically bound tritium (tritium bound in animal or plant tissue) can stay in the body for 10 years or more.

Honestly of all the elements in nuclear waste tritium is one of the more harmless ones.

Tritium can cause mutations, tumors and cell death. (Rytomaa) Tritiated water is associated with significantly decreased weight of brain and genital tract organs in mice (Torok) and can cause irreversible loss of female germ cells in both mice and monkeys even at low concentrations. (Dobson, 1979) (Laskey) Tritium from tritiated water can become incorporated into DNA, the molecular basis of heredity for living organisms. DNA is especially sensitive to radiation. (Hori) A cell's exposure to tritium bound in DNA can be even more toxic than its exposure to tritium in water. (Straume)(Carr)

Good thing then that the secondary circuit is also a closed circuit that is heavily monitored for radioactivity. Seriously can you quote even a single incident where a dangerous amount of radioactive material was released through the secondary circuit ?

Where do you think the numbers come from. Thats authorised effluents - from every reactor. And since the danger is a scale dependent on exposure I'll again just quote the scientists;

First, as an isotope of hydrogen (the cell's most ubiquitous element), tritium can be incorporated into essentially all portions of the living machinery; and it is not innocuous -- deaths have occurred in industry from occupational overexposure. R. Lowry Dobson, MD, PhD. (1979)

Your body fluids are radioactive, as is air, milk, ponies and everything else on the planet.

Well considering that I am talking about radioactive isotope effluents as opposed to radioactivity you have either missed the point or just don't/won't get it. I'd suggest you spend some time educating yourself and re-engage the discussion with some actual facts as opposed to rhetoric.

I don't know if you are unaware of the serious flaws in your sc

There's not enough lithium carbonate that can be produced at *$5/kg* with *today's non-experiental technology*. Which is, of course, irrelevant to the big picture. With lab tech today, lithium can be produced from seawater (in essentially unlimited quantities) for $22-$32/kg. And way cheaper than that for other terrestrial sources (such as Western Lithium Corporation's Kings Valley mine in Nevada) -- just not as cheaply as the Argentinian and Bolivian salars.

So? Well, for example, the Nissan Leaf only contains 4kg of lithium. That's about 20kg worth of lithium carbonate. I.e., about $100 worth. Honestly, who gives a rat's arse if that doubles, triples, quadruples, even quintuples? That's not the impediment to li-ion EV costs. The non-automotive li-ions are limited largely by cobalt costs, while the automotive li-ions are limited by capital costs and labor due to their current low-volume production methods. And contrary to popular belief, the battery packs aren't the only thing that's overpriced right now. The motor, inverter, and charger are, too. They're still largely handmade, very small volumes. The Tesla Roadster's drivetrain is descended from AC Propulsion's AC-150, which will run you about $25k today. However, AC Propulsion expects that if they were made in volumes of hundreds of thousands per year, it'd be more like $3500.

However, the big catch is that we can't really produce enough Lithium to make all those batteries.

God, that myth just won't die, will it?

But there's probably no practical way to extract it.

Of course there is. There are dozens of ways. Here's one -- $22-$32/kg. Given that 1kWh of automotive li-ion batteries takes 1-2kg of lithium carbonate and costs about $500, that's a pretty minor cost. More expensive than the surface-mined stuff, mind you (which runs $5-8/kg), but eminently affordable.

It concluded that if the flow rate of sea water were equivilient to the amount of world wide oil production

Why on Earth would you make that ridiculous assumption? The flow rate of oil is to the flow rate of the world's oceans as a bacteria is to a blue whale.

They're setting up a straw man. Nobody is proposing to process lithium via oil refineries. Here's a random example for you: a first generation seawater lithium extraction process that costs $22-$32/kg of lithium (versus $5-8/kg lithium carbonate from conventional sources). A li-ion battery pack generally uses 1-2kg of lithium carbonate per kWh, and currently costs about $500 per kWh. Do the math.

This is just one of many approaches (evaporation ponds). Others include a technique used for uranium seawater extraction, where you make thin strands of plastics which preferentially bond with the ion of choice, dangle them in ocean currents, then collect them months later, extract the ion, and return them to the sea, in a continuous rotating process. And I'm sure there are more that I haven't read about.

As an example, computer simulations for Los Angeles, CA show that resurfacing about two-third of the pavements and rooftops with reflective surfaces and planting three trees per house can cool down LA by an average of 2-3K. This reduction in air temperature will reduce urban smog exposure in the LA basin by roughly the same amount as removing the basin entire onroad vehicle exhaust. Heat island mitigation is an effective air pollution control strategy, more than paying for itself in cooling energy cost savings. We estimate that the cooling energy savings in U.S. from cool surfaces and shade trees, when fully implemented, is about $5 billion per year (about $100 per air-conditioned house).

Amazing, isn't it? Two to three degrees in temperature reduction in a major city just by resurfacing, repainting, and planting trees. Yeah, sure, it's not sexy. But the cost savings ... staggering. Add in the health benefits of reducing smog, plus the reduction of human misery from over-heated citys, and you wonder why we haven't done this years ago.

I know this is going to sound like a self-serving political statement from a hardcore Democrat -- but well done, President Obama. You picked a scientist to run an agency. You gave him a mission to better humanity through reducing carbon emissions and energy consumption. You gave him a platform where he would be heard. Well done indeed.

In the mean time, try only to realize that hybrid cars are total boondoggles which consume vastly more energy in production to give you less mileage for more money than just buying a car with a small turbo diesel engine

Source, please? "Everyone knows" that hybrids are bad for the environment.

The data says otherwise.

And, might I ask, where are these mythical mid-size cars with small turbo diesel engines? The Prius is not a small car; it's considerably bigger than a "minicar" (like the Yaris or Fit). And those are considerably bigger than a "microcar" (like the Smart).

Diesel also has higher NOx/SOx emissions (even with today's cleaner diesel engines) and higher CO2 emissions (per gallon).

Here are the typical mistakes you see when someone trashes hybrids:

• Unrealistic lifetime estimates. Modern vehicles last much longer than 100k miles.
• Comparing fuel economy of diesel and gasoline, when diesel has more energy and higher CO2 emissions per gallon.
• Comparing a mid-sized hybrid (usually the Prius) with a considerably smaller diesel-powered vehicle (e.g. the Golf).
• Comparing fuel economy using different standards. US fuel economy numbers are considerably more conservative than the UK or Japanese numbers (Prius NHW20 gets 54 mpg-US combined according to the UK, 46 mpg-US combined according to the US).
• Comparing fuel economy numbers in US and UK gallons. The UK gallon is considerably larger.
• Comparing lower-performance vehicles to higher-performance hybrids.

http://www.osti.gov/bridge/servlets/purl/771018-ZIEK33/native/771018.pdf

any idea where you got it?

Here.

Regardless of which Georgia you mean, that's not entirely accurate. In the U.S., there's oil shale in NW Georgia. I don't think that it is being actively exploited right now, AFAIK, but still, the reservoirs are there, and I found a few hints that there may have been some low yield wells at one time in some parts of GA. Consider that last part "citation needed", though. :-)

Um, Fossil carbon contains virtually no C-14 since it decays radioactively Really? Seems like they found it in coal. Guess that blows all the assumptions that are based on this "fact" out of the water...

No, it doesn't. I looked it up once before in an argument with an electric universe guy and I'm too lazy to do it again, but you can find the velocity of the solar wind as measured by SOHO and also by Voyager with a quick Google. I found an average value for Earth's neighborhood as well. Guess what? Fastest at SOHO, slower at Earth, slowest as measured by the Voyagers. That is, the solar wind slows down as it "passes the planets." The solar wind DOES accelerate within a few radii of the sun's surface but it certainly does not accelerate farther out.

You're comparing apples with oranges. Measurements in the immediate neiborhood of any planet will show a very different behavior than at the same distance from the Sun with no planet in the way. Admittedly, the statement you have responded to should have been phrased less ambiguously, in terms of orbital distance.

While it is true that the solar wind does not accelerate, it doesn't slow down either, until very very far out, probably due to the proximity of the heliopause. That slowdown is qualitatively consistent both with the hypothesis of a slowdown due to ionization of interstellar neutrals with the subsequent ion pickup, and with the Plasma Universe hypothesis of the heliopause having the structure of an electrostatic double layer. Note that neither camp has been ready to give a quantitative prediction--we don't even know where the heliopause begins.

The relative constancy of the solar wind in between is consistent with the Plasma Universe hypothesis of the area between the solar corona and the heliopause representing a positive column of a plasma discharge. Since most of the voltage differential occurs inside the double layers--one at the solar photosphere and another at the heliopause--the electric field inside the positive column is very weak. It likely keeps the solar wind from decelerating (the poster you have responded to has been rash to claim absolute acceleration).

For more rigorous comparative data on the solar wind velocity, see:

H.R. Collard, et. al. Radial variation of the solar wind speed between 1 and 15 AU. J. Geophys. Res. 87:A4 (1982)

J. D. Richardson. Solar wind processes. Physics of Space Plasma (1995)

Notably, there is a 1.3 year periodicity to the solar wind averages. The velocity distribution at 1 AU is still very volatile, with the standard deviation of approximately 100 km/s, whereas the standard deviation decreases to 25 km/s at 15 AU. This means that the solar wind becomes closer to constant further on. At 40 AU, decrease of merely 30 km/s has been observed.

Leo

Reaction yes. Explosive no.

It's not like nobody ever considered the risks before. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=7208928

In this study they poured molten sodium into regular old limestone based concrete crucibles. It took about an hour and a half for the reaction to culminate and it left behind black slag in the crucible and a sodium oxide aresol, probably the "sodium snow" described in the film. Where I come from, explosions take seconds or less and not over an hour.

To minimize the damage to structural integrity, the line at risk areas. Metal, or special sodium resistant concretes.

Bad yes. Near miss for Nuclear Meltdown? No. Since this isn't supposed to happen, you have to re-examine all of your other places that may have the same or similar means of failing, and the re-certify the design. Very expensive and time consuming

The RTG references for this are, I think, mostly traceable back to

http://www.space.com/news/nasa_plutonium_020724.html

which indicates that 'for reasons of national security' one RTG-worth of plutonium-238 had been reclaimed from NASA about five years ago.

There are various national-security applications for plutonium-238 - it's perfect stuff for powering, for example, bits of equipment to sit in a cave in Afghanistan or next to an undersea cable off Taiwan quietly recording all that passes to be collected later; it lets you build satellites without shiny solar panels. Lincoln Experimental Satellites 8 and 9 used RTGs; http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5562667 is an abstract claiming there are ten American satellites in Earth orbit with RTGs on board, though I rather doubt it will list names and purposes.

Nope, you're not even close. The first hit on a google search shows a computer game written in 1958.
http://www.osti.gov/accomplishments/videogame.html

Well, it goes like this.

That you just posted is a piece of pseudo-scientific dreck from all I can tell. I had a course on MHD in grad school, the theory of magnetic reconnection most certainly can account for the speed of energy release in solar events. It's also an important problem in plasma instability in tokamaks. Searching on google scholar didn't find any peer-reviewed papers by plasma physicists refuting magnetic reconnection.

Perhaps they were confused by Biskamp's 1986 paper on the Sweet-Parker model failing to achieve fast reconnection that was cleared up in a 1992 paper by Priest and they missed that Biskamp himself seems to accept fast reconnection as possible in his 1994 paper?

I was pro-GE until I learned about jumping genes, now I think it's a terrible idea. We just don't know enough.

It sounds good, but now we are realizing that we don't understand genetics as much as we thought. There are not enough sequences to explain all the proteins that a genome can make - jumping genes make the rest.

Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease by Sharon Moalem
Page 177: " ... Today, the genetic nomads McClintock discovered are called "jumping genes," and they have reshaped our understanding of mutation and evolution. ...

http://www.osti.gov/accomplishments/mcclintock.htm l

and google

The idea is to get aluminum from the service station and return the sludge to the service station for re-processing. The net result is something like a secondary battery.

http://www.osti.gov/energycitations/product.biblio .jsp?osti_id=5272202

I can get 60MPG in city driving if I drive at a fixed 35-40MPH with no stops and use cruise control. The magic number in the Prius is 42MPH. Above this speed, the gasoline engine must run or one of the motors will spin too fast. At or below this speed, it can run pure electric. The other part is everything must be warmed up which usually takes 5 minutes or so according to the graph. Not only the engine has to warm up, but so does the transmission and electric motors (which have oil in them). A couple of very useful documents I found are http://www.osti.gov/bridge/servlets/purl/890029-WI fqPO/890029.PDF and http://www.ornl.gov/~webworks/cppr/y2001/rpt/12258 6.pdf. These documents are great for geeks like me since they show detailed pictures and graphs of what's inside the hybrid system.

I think if Toyota put in more powerful motors, bigger batteries, and a more powerful engine they could actually improve milage further since the electric only system could run better at higher speeds and help more during acceleration. This is what Toyota is doing for the 2009 model, changing to Lithium Ion batteries, more powerful motors, and making it so you can plug it in as well.

I find it impressive how efficient the electric hybrid system is, with the inverter getting 95%+ efficiency and the motor also getting over 90% efficiency. Their simple CVT design also is fairly efficient as well.

I agree that the old EPA tests were severely flawed, though. Car manufacturers could by law not give any other numbers other than the EPA ones.

Please note that those papers are not by the original group responsible for the concept. Klaus Lackner, as credited in the slashdot summary and the GRT information, and all news stories discussing the Branson Prize, wrote such articles about air-capture of carbon dioxide as this and this, and others beforehand.

Yes.

The drivetrain in the Prius is quite simple. See http://www.osti.gov/bridge/servlets/purl/890029-WI fqPO/890029.PDF. The "transmission" has only 6 gears in it (not speeds, gears), no mechanical torque converter. A diagram of it is on page 18 of the PDF file. The other gears are for connecting to the differential. Electronically it is complex, but not mechanically. The engine is a conventional 1.5L 4 cylinder engine, but run with the Atkinson cycle instead of the usual Otto cycle.

Yes, it is being done in northern L.A. county.

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

http://www.osti.gov/energycitations/product.biblio .jsp?osti_id=7092283