Interesting, ok I’ll buy that Ce-137 in the voids in the center of the pellet doesn’t escape but how do you design a pellet to make sure that surface Ce-137 is not formed on the “skin” of the pellet? Any Ce-137 on the skin would vaporise at 640 degrees well within reach of a normal fire, and with as you admit 100 million fuel pellets that could still be a significant effect.
There’s also been Ce-137 released from “somewhere”, new scientist is a pretty credible source right?
So where did that Ce-137 come from if the bubbles in the fuel pellets should trap it even at 2600 degrees?
My interest is not merely academic, I live in Japan and plan to hope to make it my home for many years, not anywhere near Fukushima, but a disaster that merely makes the northern suburbs of Tokyo uninhabitable for 10 years is going to economically devastate Japan and have serious knock-on effects for the rest of the world.
That is why I wrote that I thought there would be some Caesium in the rod’s plenum space. Not a lot, but some. The Caesium is a product of Xenon, and since Xenon is in the plenum, we assume some will turn into Caesium. This is why the rods are sealed, and are themselves designed as a barrier. How much is in the plenum? No idea, and no easy (ie free) way of finding out I suspect.
There has been a partial meltdown of the cores in reactors 1,2, and 3, that much is understood, and that will have minimally breached some rods, if not worse. I would assume that that is the source of the Caesium. Not good, but not progressing further. The loony conspiracy threat is that the spent fuel rods are at some deep risk. The site linked to in the OP moan that many are stored in the open air - as if this was something bad. On the contrary, it indicates that they will stay cool enough with nothing more than passive air circulation around them. The recently decommissioned rods are the bigger risk, as they need to be kept underwater to keep cool. It might be possible that if the containment pool was drained they could overheat to the point that the rod itself failed, and then released the gas (including vaporised Caesium) in the plenum. There is some suggestion that one of the pools at Fukushima did boil dry, but whether any rods were breached is another matter. This could also be the source of the Caesium seen.
This is probably the bottom line. If you walk away and ignore things, bad stuff will happen. But with even a minimum of oversight, and simple maintenance there is no reason to think anything further will happen. There is little doubt that a serious level of complacency pervaded the Fukushima management, with a certain lack of imagination about how bad things could get. One also suspects that they are a bit more focussed now. A devastating earthquake could disrupt society enough that no-one was capable of making sure the pools didn’t empty, but at that point you have a lot of other things to worry about. Even worst case, Chernobyl is leagues ahead. You don’t have a full core meltdown, massive steam explosion, or a huge graphite fire, all contributing to spraying the reactor contents about the countryside.
coremelt, aside from that quite alarmist site, do you have any other concerns/worries about this?
The power failure/coolant system/core meltdown at Fukishima was pretty solidly in the “extreme Murphy’s Law” category of needing a lot to go wrong. Do consider that the plant survived a 9.0 quake just fine - it shut down automatically as it was supposed to, the place stayed intact, etc. What caused the catastrophe was getting hit by a 50 foot wave. THAT’s what caused the cascade of problems leading to the meltdown and release of things like cesium. And it wasn’t just the 50 foot wave, it was the complete loss of power to the cooling system/inadequate battery backup that lead to the meltdown. That’s a highly unusual combination of events even for Japan.
So… let’s take a look at this, shall we?
**An earthquake by itself will not lead to meltdown/catastrophe at a Japanese nuclear plant. **That’s pretty clear. Despite the complacency, safety issues, age of the power plants, and all the rest every single one automatically shut down and physically survived a 9.0 quake intact. View this as reassuring. Just an earthquake is not going to cause more disaster.
Tsunamis are bad for power plants.*** The good news is that tsunamis of that magnitude are very rare anywhere, even in Japan’s “Tsunami Alley”. However, out of all the Japanese power plants in the quake zone this is the only one that melted down and the reasons why are pretty obvious and center around design flaws that have either been eliminated in more recent designs or can be/have been mitigated in other older plants. That doesn’t undo the damage already done, but it goes a long way towards avoiding and/or minimizing future damage.
The longer the plant is shut down the cooler/less melty everything is. The longer these fuel rods are stored the cooler they become. That means they’re farther away from meltdown. Eventually, they get to a point they can’t meltdown, even if entirely uncovered and exposed to open air. Yes, hypothetically a massive, massive earthquake could knock a bunch of stuff over/collapse a storage unit and pile a bunch of rods together but the odds of them just accidentally piling into a mass that will then spontaneously start heating up quickly is so small as to be disregarded. If absolutely they must be cooled down sea water - close at hand - can be poured on them. Granted, this isn’t a great solution (as we’ve seen) but it won’t render Japan uninhabitable and the new contamination won’t go past the areas already evacuated on land, and will just be diluted by the ocean on the water side. Again, not a great solution and don’t eat the fish caught just off shore but it won’t be the end of the world.
The point is, every day that passes means all of the radioactive stuff at Fukishima is slightly less radioactive, and cooler, and further away from any sort of overheating or meltdown. Every day that place gets just a fraction safer. Time is our friend here.
That’s not to minimize the seriousness of this accident. It was a bad thing, no question, but the most dangerous part of all this is over. The place will need to be watched and guarded for decades but it is NOT going to spontaneously blow up or kill millions of people or render the northern suburbs of Toykyo uninhabitable. The worst is over.
Japan has just recently shut down all their Nuclear power stations. I am actually not sure this is a good idea, I’d rather keep the current ones running with higher safety standards and have new Nuclear power stations built to new safer designs, but politically it seems thats not on the cards.
That leaves 64 power stations with spent fuel pools containing 40 years worth of fuel pellets scattered all over an island nation with a average population density of 336 people per square km. Some of the fuel has been reprocessed but only a fairly small percentage of it, most is still sitting in the spent fuel pools at the reactor sites.
According to the nuclear industry those fuel pools are perfectly safe even in a 9.0 earthquake / fire / tsunami combo. According to the wacko’s they could make Northern America uninhabitable. The truth is likely to be somewhere in the middle, and as I’ve said in a country as densely populated as Japan even a minor incident could be very very expensive.
My concern is a drained spent fuel pool getting caught in a conventional fire thats a result of an earthquake, where fire fighters cannot get close due to the radiation risks it could burn out of control for several days. The new scientist article that I linked above seems to imply that a standard 670 degree conventional fire can cause the Iodine and Cesium to leach off into the atmosphere and water.
Is there any direct research on putting spent fuel pellets into standard fuel fires anywhere and testing for Cesium and Iodine release levels?
I think you could be quite sure there has been considerable research into such things. The industry has worried a great deal about the safe transport of materials, and the ability of things like fuel rods to survive (what is a far more likely accident) being caught in a vehicle fire.
The problem with the fire scenarios is that even an empty pool doesn’t have anything in it to burn. It isn’t as if the pool is made of wood. Where things can get really badly out of hand is when there is fire in the reactor itself, here the nuclear reaction ignites the fuel rods themselves, and it is burning zirconium you have to deal with. This would be the proverbial very bad day. Interestingly, probably this already happened.
Maybe you can construct a scenario where the pool boils dry, and them sometime later the building catches fire, and parts of burning building fall into the now dry pool and burn with enough ferocity that they ignite the zirconium.
The New Scientist article skates over a few things (rather typically for the magazine sadly.) Whilst they mention the spent fuel, and also mention that the leaking Caesium is consistent with the accident, they leave an unwarranted, unstated, but easy to read into the article, connection between the two. Remember, three of the reactors have had partial meltdowns. The fuel rods in these reactors will have been breached, and temperatures well past the melting point of the pellets produced. The leaking Caesium is consistent with a meltdown, and does not imply a conventional fire around the spent fuel rods. There is a problem of titanic proportions in cleaning up the melted reactor cores. It will take decades. And the results have been pretty bad. But thus far we have not seen any indication that the spent rods were involved. I do worry a bit about the reports that a pool boiled dry, but there is a significant gap between this and the rods being breached.
Notice that the first three reactors must have boiled dry to have a meltdown in the first place. The difference between them and the spent fuel is twofold - the rods in the reactors will produce 7% of full power for the first few hours even after the nuclear reaction is shut down. This is where the heat for the meltown came from. Any rods in the spent fuel pools are emmiting a small fraction of this after even only a week out of the reactor, and it continues to decay. The rods in the spent fuel pool are kept much further apart - they must be to avoid criticality, whilst criticality is what is desired in the reactor. The lack of cooling flow after shut down (due to one of the more stunning bits of lack of foresight or imagination on the part of the managers) is what caused the meltdown. The same lack of power cut off circulation to the spent fuel pools, and allowed one to boil dry. But the spent fuel pools have a lower density of rods producing a few orders of magnitude less power than the reactor rods. We don’t know, but I really doubt that the rods in the spent fuel pool got hot enough to fail. Note that the other reason the rods are kept under water is to allow easy handling by workers. With a few metres of water above them the rods can be moved about by workers without needing any protective gear. It is likely that most rods are kept under water for this reason, and not for reasons of cooling to preserve their integrity. At least once the rods are past few months out of the reactor. It is this exponential decay of the heat generation by the spent rods that rapidly makes things much safer than the situation where you have an active reactor.
I can’t help but think Japan is going to have some trouble supplying power to their grid with all the nuke plants shut down. I wonder how folks will take brownouts and/or rolling blackouts?
I understand - I’m downwind of a half dozen nuke plants myself, in a densely populated urban area.
Well… as I said, you did have that situation and all of the plants did, in fact, get through the quake just fine. It’s the multiple-disaster scenario that’s most worrisome. However, the mere fact the whacko’s are concentrating so much on a continent entirely separate from Japan should indicate they’re not really thinking clearly on this subject because they seem to ignore Japan and its nearest Asian neighbors.
OK… the fuel pools are basically a LOT of water in a cement pool that contains metal assemblies… um, what exactly is there to burn here? Melt, yes, that’s possible, IF you have a source of fire, but it’s not like there’s a pile of firewood in with the fuel rods. What is supposed to be supplying this hypothetical fire?
The water isn’t just to keep the spent fuel cool, it’s also there to act as a radiation shield. Again, most of that fuel isn’t hot enough (in any sense of the term) to instantly melt if uncovered. Eventually, it’s transferred to dry storage.
Probably, but someone will probably have to do a little hunting to find it.
They had rolling blackouts in Tokyo immediately after the earthquake but now its back to normal.
In Osaka so far there has been none of that. What they’ve done has been reduce lighting on tourist attractions and buildings at night, put up the price of electricity and post lots of patriotic posters about how we should all save electricity because of the earthquake.
In Japan, that works, people switch off aircons and go out of their way to save power, the sense of civic duty is very high here.
That site is hilarious.
e.g.
“How to prepare for the collapse even on a tight budget: Preparing for the inevitable collapse of society as we know it can be a daunting task, particularly when it means forking over wads of cash to purchase expensive preparedness supplies…”
Thats pretty much the scenario I am painting and it’s when, not if. The last quake had it’s epicentre off shore, look at this:
It’s only a matter of time until an 8.0 earthquake has it’s epicentre somewhere on the mainland. Everyone in Japan knows this, every building in Japan is meant to be built to take that. The reality is corners are cut.
Sooner or later a major earthquake will be closer to a nuclear reactor than the 2011 earthquake. The pool will get cracked and drain dry and spent fuel will get scattered over a wide area into burning debris.
Then what happens? I mean how bad will that be for Japan, for the local 50 km radius area.
I realize at Fukashima the storage pool is elevated, but it was my impression that most such pools are set into the ground. Even if the pool drains dry there’s no mechanism to fling the fuel rods out of the pit and scatter them. Even if a burning building fell on them most of the Bad Stuff is going to stay in the pit. And that’s assuming there’s a building in close enough proximity to fall into such a thing while burning.
Granted, if a storage pool is elevated that’s a safety risk, but it should be possible to construct a pool in a pit. My recollection on this point is vague, but I thought most plants designed along the lines of the Fukashima one had already had this done elsewhere.
After about a decade the fuel does not need to be kept in a pool. Nice wide open space with no buildings or anything much else around, and stand in the air. Put a big fence around it.
In the interim, don’t make the building out of stuff that burns easily. Concrete is a good start. Very difficult to set fire to that. In fact steel is fine too, so long as you don’t store stuff inside that can burn hot enough to involve the steel. My impression of the buildings that were destroyed is that the outer building was metal, and that it melted/burned due to burning material inside the building. Probably a good idea to avoid aluminium.
I’d like to see an up-to-date cite for that. While there were claims during the weeks after the accident that the spent fuel pool in unit #4 had gone dry, investigations since then show that the water never dropped low enough to expose the fuel. I haven’t seen anything to indicate that any of the other spent fuel pools went dry either.
Thats a nice sentiment but it all comes down to cost. Dry wall is cheap and is used for internal non-load bearing walls everywhere. Concrete frame buildings are still chock full of stuff that does burn.
It would be interesting. I’m just going on what is probably well out of date info. My intuition is that it is unlikely to have boiled dry, but since we are talking worst case stuff here, I kept with it. The pools certainly get hot, they seem to be kept at about 50C, so there is little doubt that they would eventually boil, but the heat injection can’t be all that great. I would suspect it would take some weeks to boil even a very active pool dry. Getting to 100 C and thence to boiling dry is a very big jump in energy needed.
I have a feeling I might be able to work it out. But it’s late here, so maybe not today.
I’m not sure if these links have already been included in this thread. Some are probably duplicative from other threads at the Dope on Fukushima, but nevertheless may be of interest in answering coremelt’s questions.
The International Atomic Energy Agency issues periodic status reports on the Fukushima Daiichi Nuclear Power Plant. Each of these reports also contains links to additional information and press releases from TEPCO concerning the plant. The most recent release I could find is for April 27, 2012, and is here. (PDF) Within it are the IAEA and TEPCO’s preliminary findings concerning the Unit 3 Spent Fuel Pool (at pages 4-5 of the lined pdf):
I haven’t found in my cursory searches, any statements that say they had a fuel cladding fire, but I think the above quoted language means they aren’t certain that fuel rod cladding integrity was fully maintained. Whether that was enough to leak gaseous radioactivity to atmosphere, I don’t know.
I’ve previously linked the paper, Reducing the Hazards from Stored Spent Power-Reactor Fuel in the United States, Science and Global Security, 11:1–51, 2003, and it can be found here. (PDF) It lists analyses of worst-case scenarios for spent fuel accidents. Among those analyses are helpful tidbits like:
(Page 12 of the linked pdf.) and:
(Page 17)
I believe the authors are speaking of a “densely-packed” spent fuel pool, which I don’t know was the case at Daiichi Reactor Pool 3 or 4. The authors go into more detail with some simple models of heat generation in the next few pages.
The NRC’s NUREG-1738 paper, Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear Power Plants, (February 2001) goes into much more detail on this subject. IIRC, I wasn’t able to find an online copy, but it might have more technical data and models that could help answer some of the questions posed in this thread.
it tried to watch this, it’s painful and doesn’t do the nuclear cause any favours. He spends the entire time attacking their creditionals and almost none addressing the science. In my mind this is the crucial question:
if spent fuel pellets are caught in a 670 degree conventional fire, do they release radioactive Ce-137 and Iodine isotopes or not? can anyone give me a link to a non-paywalled scientific paper that addresses that specific issue.
The pellets do not. The fuel rods however may. The article Gray Ghost linked to above is a very good read. They note that fuel rods that reach 600 C will likely rupture due to the pressure of gas in their plenum. This will release any Caesium in the plenum. But as discussed earlier, the pellets themselves will not release any additional material.
The site that the OP article is from is even more bonkers than I gave it credit for.
Some stuff off their current front page:
Another victim of conventional cancer treatments: Beastie Boys co-founder Adam Yauch
“So in the end, Yauch’s body appears to have been unable to fight the recurrence of parotid cancer that inevitably returned because of the treatments he had previously undergone. And even after later attempting an alternative regimen in India to boost his health, it was too late – surgery and radiation had taken their toll on Yauch’s body, and he simply was unable to recover from the damage that had been inflicted on him in the name of science-based medicine.”
Help STOP Out-of-control Science from destroying us all
“The entire history of polio vaccines is one of blatant scientific fraud and misrepresentation: The vaccines were originally contaminated with “stealth” cancer viruses such as SV40, and today’s polio vaccines actually cause paralysis in children”
“Farmers around the world are committing suicides in record numbers after suffering crop failures from planting GMOs”
“Throughout the Nazi-led mass extermination of the Jewish people in World War II, IBM’s top computer scientists provided key technologies that allowed Hitler’s minions to more “efficiently” exterminate prisoners and organize work camps”
Found the link to NUREG-1738. It is a very lengthy PDF (20+ MB, ~450 pages), that nonetheless should be of interest, as it covers analyses of potential technical risks of spent fuel fires and criticality accidents.
From last year’s threads on Fukushima Daiichi, the poster mattmentioned a more recent study than NUREG-1738, suggesting that zirconium cladding was a lot harder to ignite than previously thought.