Comments on: Don’t lose your cool

By: Cómo funciona una central nuclear y por qué tiene que importarme. « Círculo Escéptico Argentino

Tue, 29 Mar 2011 14:45:04 +0000

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By: dave chamberlin

dave chamberlin — Sun, 27 Mar 2011 16:05:02 +0000

Congratulations to Daniel for accurately predicting what would happen. I was really really worried that the radiation would get so deadly at one plant that human control would not be possible at the others. The still isn’t talking about the eventual course of action that Daniel predicted way back on March 16th. They are going to entomb some if not all of these plants. This is why we trust the good folks at science blogs.

By: John

John — Thu, 24 Mar 2011 20:29:22 +0000

http://english.kyodonews.jp/news/2011/03/80539.html

Words fail me, so I’ll only say this: NEUTRONS OVER A KILOMETER FROM THE PLANT??

By: Cody Wilson

Cody Wilson — Wed, 23 Mar 2011 16:30:22 +0000

I’m sure they must be putting a great deal of containment rod material around the radioactive fuel rods to soak up the neutrons and prevent the water from evaporating, right?

If a nuclear plant produces energy for such a long time after being turned off why isn’t that power used to cool the system as the first line backup?

By: dave chamberlin

dave chamberlin — Tue, 22 Mar 2011 15:44:51 +0000

The poor Japanese people are not being given the truth and it is scaring them worse than if they were. The news sounds a lot like war propaganda when your side is losing. A radiation leak from reactor three that forced the work force to retreat from on 3/21 is now being called “puffs of grey smoke”. On the one hand the news is the reactors are “verging on stability” (US report) or have been stabilized (Japan report) and on the other hand Kyodo News (the Japanese equivalent of the Associated Press) says reactor 4′s spent fuel pool is “feared to have renewed nuclear chain reaction.”

If the crane and concrete pumping truck now in front of reactor 4 are doing what I think they are doing, continuously pumping water mixed with boron into this spent fuel pool, things should be OK. This is just my construction management speculation, I don’t know what they are doing. But no one knows because the news is scant and not to be trusted. The only reliable news is levels of radioactivity measured outside of the 18 mile concentric circle surrounding the plant. They have to give that information and even that you have to dig for.
Just my opinion but if I were living in Tokyo I would be scared to death not from the facts but from way they have been presented.

Kyodo News reports that Fufushima Nuclear Power plant was designed to withstand a tsunami of 5.7 meters but got hit by one of 14 meters. That is a 46 and a half foot high wall of water that hit that plant! Incredible.

By: John

John — Mon, 21 Mar 2011 21:58:11 +0000

The "US Army" is helping out at reactor 4, according to TEPCO. They read 0.1 Sv/h n the inland side of reactor 4, and four times that at reactor 3.

By: dave chamberlin

dave chamberlin — Mon, 21 Mar 2011 16:26:55 +0000

Well things are getting blowed up better in other parts of the world so the reactors have become second page news. That is from an old SCTV skit, “I like how dat blowed up, it blowed up real good. ”
Two quotes to leave you with, the first from Leo Szilard who first patented the idea of a nuclear reactor and wrote the letter which he had his more famous friend Albert Einstein co sign which directly led to the Manhatten Project.

The three Stages of truth for scientists
1) It’s not true
2)If it’s not true, it’s not very important
3) We knew it all along

The second from Peewee Herman

There are some things you wouldn’t understand, there are some things you couldn’t understand, and there are some things you shouldn’t understand. HEHEHEHEHEHE

By: John

John — Sun, 20 Mar 2011 20:22:58 +0000

I should probably shut up at this point, you are right, dave chamberlin. I am sure those in charge know full well what is happened or will happen, and the good news is that it does not seem that explosive release of radiation from #4 has occurred. In that sense maybe it really is stable…

This also made me feel a little better: http://atomicinsights.blogspot.com/2011/03/stop-worrying-about-spent-fuel-pool.html

Maybe the zirconium cladding is intact?

By: dave chmberlin

dave chmberlin — Sun, 20 Mar 2011 17:29:32 +0000

I appreciate your analysis John. One point I would like to add is these kinds of conversations are probably best kept on a science blog, the poor folks in Tokyo are almost in full panic mode already. Japan is giving a mixed messege to their people. On the one hand the power company is painting a rosy picture but the impact of the Emporer addressing the public for the first time telling them to be deeply worried really shook the people up. I guess what I am saying is maybe it is best that the public recieve all the details later. As long as the people in charge are not deluding themselves and give the general population enough warning of what is coming, that may be best. I have another concern. If one reactor has fuel that has reached critical how in the hell are they going to manually control the other reactors? Robots can’t do it. Hopefully a better management team is now in charge.

By: John

John — Sun, 20 Mar 2011 01:57:17 +0000

I’ve done a bit more calcualation based on what is out there on the intertubes:

Reactor 4 SFP: 2 MW decay heat load (Wikipedia). Assume 10^6 kg uranium. Specific heat of uranium: 120 J/kg/K.

If all the heat goes into the uranium, then

2 MW/10^6 kg ==> 2 W/kg = 2 J/kg/s ==> 1 K/minute

If the fuel rods are intact, but not in contact with water, then maybe the heat does not all go into the uranium. But suppose even a tenth of the heat goes into the uranium, that’s still 140 K increase per day! If there was no flow to the SFP in reactor 4, it is hardly surprising that it went dry (according to the NRC on Thursday).

The heat of vaporization of water is 2.2 kJ/kg, and there are 10^6 kg of water, approximately. So we need 2.2 GJ of energy, and we have a heat load of 2 MW, meaning that once the pool reaches boiling, it takes on the order of a thousand seconds to boil off. Not long. You need water to keep flowing. I see no indication anywhere, in any report, that they have gotten a kiloton of water into the pool.

If the pool is dry, the temperature in SFP #4 is going up by on the order of a hundred to a thousand degrees Kelvin a day, depending on how, if at all, heat gets out of the pool. It’s been a few days – let’s assume that the temperature was 100 C when the water boiled off, and that was on Wednesday. The temperature is now several hundred degrees C, and when it hits 1100 C the uranium will melt, not long before the steel does (1400 C). This means the uranium will melt, pool, and possibly go critical as early as a week from now, maybe sooner, maybe later unless they get cooling water – a kiloton of it – to the pool.

It is really hard to believe that this has not already occurred. The good news is that there was no explosive release of radiation yet. But has the pool gone critical? Is there a uranium/iron/fission byproduct soup at the bottom of it?

Would someone please tell us what is going on? The radiation at the plant gate continues to increase exponentially.

By: John

John — Sun, 20 Mar 2011 01:13:39 +0000

dave davis: If I were Daniel I would delete your comment. There are millions of innocent people – including children – who would be in the path of that cloud. You can’t wish this on anyone. Your statement reflects a diseased mind. The worst case scenario is that this event leads to great numbers of deaths, no matter whose.

By: dave davis

dave davis — Sat, 19 Mar 2011 23:51:03 +0000

A worse worst-case scenario is that the radioactive cloud gets pushed by prevailing winds towards North Korea. Consider that..

By: dave chamberlin

dave chamberlin — Sat, 19 Mar 2011 20:42:23 +0000

It blows my mind there are two completely different stories being handed to the public regarding how things are going regarding something as important as a nuclear meltdown near a metropolitan area of 35 million people and nobody is talking about it. The Japanese have one version and the United States and the New York Times have another. The Japanese are highly motivated to downplay the seriousness to keep their population from freaking out further and the US and New York Times have nothing to gain by spinning the story in a negative direction.
The situation is now being called stabilized, which is just about the last word I would use to describe a huge quantity of uranium that (if you believe the US State Department) is not being cooled in any way. The zirconium cladding has probably not burnt off yet because when it does it is projected to give off a far larger radioactive burst than we have seen so far. Regarding the IAEA, they have not visited the site yet but they plan to in the very near future, unbelievable.
What the US is now recommending is to bury the mess in boron, sand, and concrete, just like they did in Chernobyl. The russians didn’t have robots but they might have got their money’s worth out of their considerable fleet of bombers as they bombed the hell out of Chernobyl for ten days with the products listed above.

meanwhile, time’s a wasting.

By: Stella Elliott

Stella Elliott — Sat, 19 Mar 2011 09:24:15 +0000

The International Atomic Energy Agency (IAEA) website has all the facts if you want publicly available information.

By: dave chamberlin

dave chamberlin — Fri, 18 Mar 2011 23:19:01 +0000

response to John # 69

What you deduce makes sense. It wouldn’t have been a fire, just a quick violent explosion if it was hydrogen. What else in the building would be flammable? Whatever is happening is not going to be put in the papers, nor should it be. The poor people of Japan are freaked out enough. You can assume that thermal imaging cameras flown by the drone planes know the exact temperature and experts in Washington and Japan can predict not only what has happened but may even be able to project what will happen in regards to reactor #4. They may not know the exact timing but they know that Uranium mass cannot come in contact with the water table underneath the thick concrete foundation. Roman in #65 makes a point that there will come a time very soon when water just creates more radioactive steam.

We will only read later about the crack team of experts that are working right now on what the best course of action is.

By: John

John — Fri, 18 Mar 2011 22:23:00 +0000

I read today that the fuel in the spent fuel pool at reactor 4 is not all “spent”: they had removed the active fuel from #4 for inspection and rearranging, storing it in the spent fuel pool. There are 1479 fuel assemblies in the pool, many of them quite fissile.

To my mind it seems highly probable that when the fire broke out on Weds. that it must have been the zirconium cladding burning off on at least some if not all of the rods. I have yet to hear a better explanation. This also explains why they put the fire out then it popped back up again.

The assemblies are each put in square pigeonholes which I assume are made of steel. I presume that the steel got hot enough to at least slump. They cannot seem to put water into the SFP and have it stay and in any case, they only squirted 50 tons today; that pool is huge: from the diagrams it appears to be 10 m x 10 m x 15 m deep. That would hold 1500 tons of water alone. You can see yourself that the helicopter drops are pretty useless. So we can safely assume there is little if any water in there. There are reports that the steel liner is cracked, also. I think we can forget getting water in there by any means other than someone carrying a fire hose up there.

But why have they not tried using a fire truck with an extension arm, and shooting in water through the side of the building (which burned away)? I realize that the radiation levels are very high, so they are trying to stay a distance away, but still…

Anyway we have a very hot, if not molten, mass of steel, uranium/spent fuel (which basically has “every atomic isotope there is”), and all held up by concrete. What happens next?

I actually think that if the entire mass becomes molten, eventually it will be a big uranium/steel “lava lamp” and the higher density uranium will, inevitably, sink. Eventually the whole bottom layer of the SFP will be molten uranium and heavy metals, about half a meter thick. (Do the math.) It will be getting hotter, and hotter, and hotter. Maybe leaking out through cracks in the concrete. A million kilograms of partially depleted uranium. Maybe it will already have begun to go critical, well before this, giving us a mass of molten steel sitting on top of it.

What is wrong with this analysis? Something, I hope.

By: réalta fuar

réalta fuar — Fri, 18 Mar 2011 17:51:57 +0000

I’m not willing to let TEPCO off the hook for not planning for a disaster of this magnitude, great as it was. Given the location of the reactors, a disaster of this magnitude was pretty much a certainly, on a timescale of a century or so. Build enough dangerous things in enough dangerous places and you’re going to get dam collapses, slurry spills, reactor meltdowns: things you haven’t planned for because you thought they were too unlikely and thus too expensive to plan for. As has been pointed out, nature really doesn’t care what you think. There comes a point where the worst-case-scenario is truly unthinkable and one should instead think about other solutions. The fact that sufficient coolant water couldn’t be supplied on loss of power after 12 hours or so seems like a major failure in design. Coolant water is the one thing you obviously have to have in any failure scenario. I’m not particularly impressed by the reactors “surviving” the initial quake since for a quake of that magnitude, in or near that location, a huge tsunami is essentially guaranteed. Would 10 km further inland really been that much more expensive? You’d never design a bridge with a safety margin of only a factor of two. Everyone should remember that these reactors are about 40 years old and that the Japanese nuclear industry’s safety record isn’t really any better than that of the U.S. or France.
Andrew @52 has made the most important commentary on this disaster: it’s all about cost. nuclear power is hugely expensive and only cost competitive in countries that don’t really have a choice (or at least THOUGHT they didn’t have a choice), like Japan. Pick any fancy, new, presumably safer design you want, and the price only goes up once you’ve put in the decade of research needed to commercialize your design of choice. Nuclear power seems to only be a viable solution at a) the South Pole or b) aboard a submarine.
Best idea I’ve ever heard for nuclear power: Ireland should build a nuclear power reactor, but build it in France!

By: dave chamberlin

dave chamberlin — Fri, 18 Mar 2011 16:57:43 +0000

The New York Times is the best source of in depth news coverage and the following information is a summary of what I read there and found to be of the most importance. The excellent news is power has been restored to reactors 5 and 6. The good news is yesterday, 3-17 is there was not a further decline in the situation. When the US says that there is no water in the spent fuel storage tank #4 they should simply be taken at their word as they have the intelligence gathering means to look directly into the building. This is terrible. There are 1479 spent fuel rods in the overhead storage tank at reactor 4, 548 of which are not spent but placed there while maintenance was going on in the reactor itself. These rods are covered in a zirconium cladding that will burn at a very high temperature when they get hot enough. The tank cannot be refilled because it is leaking. Helicopters have tried to drop water on this but they can’t get close enough and if they could what is the point, it will leak out anyway.

By: Mel

Mel — Fri, 18 Mar 2011 16:49:11 +0000

Thanks for the recap that is neither alarmist nor dismissive of possible outcomes. There’s far too little of that going around right now! I think our fear of the word ‘radiation’ is in part a hold over from Cold War fears. We’re no longer afraid that the Russians are out to get us, but any kind of nuclear threat remains disproportionately terrifying.

One question for you concerning the hydrogen explosions: you said that the hydrogen gas was produced when the zirconium cladding on the fuel rods began to melt. If that were the case, wouldn’t the hydrogen collect inside the containment vessel , and any explosion would have to happen there?

Other explanations I’ve read said that the hydrogen was a result of superheated steam splitting into its component atoms. When the workers vented steam to reduce pressure in the core, they released it into the building (outside the containment vessel, inside the building walls) so it would have a few minutes for the majority of its radioactive components to break down before releasing it into the atmosphere. These sources said that the hydrogen collected inside the building, and ignited there, thus blowing the roof off without damaging the containment itself. It sounded like the goal was to help calm the public by reducing the (already minor) amount of released radiation even further, unfortunately the explosions were far more frightening and damaging than the radiation would have been.

Can you speculate on which chain of events is accurate, or if there’s a more complicated explanation that I’m not understanding?

By: Roman

Roman — Fri, 18 Mar 2011 14:36:36 +0000

I’ve re-read the story of Chernobyl recently and it is a chilling read. Even though I was in the fallout zone at the time (Poland) and my then 4 yo daughter was given iodine (in liquid form as I can remember) I didn’t know much about the mechanisms of the disaster for a long time.
Two things that struck me were that in the Chernobyl case, it was of highest priority at some point to REMOVE the water from the reactor to prevent catastrophic steam explosion and that genuine safety concerns initiated the fateful chain of events.