"There is a possibility, we see the possibility of a meltdown," said Toshihiro Bannai, director of the international affairs office of Japan's Nuclear and Industrial Safety, in a telephone interview with CNN from the agency's Tokyo headquarters. "At this point, we have still not confirmed that there is an actual meltdown, but there is a possibility."We do know that both reactors got hot enough to damage the cores. This means hot enough for the zirconium cladding to oxidize and create hydrogen. It has to get much hotter to melt.
You may not believe this, but some of the survivalist and anti-nuclear web sites are already going nuts about the "threat."Older fuel will be dirtier because it will have more fission products. New fuel will be relatively pure. Spent fuel is much much dirtier than new fuel. That's why fuel isn't very hazardous to move around, but waste is.
An earthquake with such loss of life is bad enough, but Japan has also just lost 20 percent of its electric generating capacity. And I’ll go out on a limb here and predict that none of those 11 reactors will re-enter service again, they’ve been so compromised.posted by loquacious at 10:13 PM on March 12, 2011 [8 favorites]
I think there may be translation issues going on involving the term "meltdown," or just an imprecision in terminology.
Is it possible to build a smaller plant with less of a critical mass of Uranium and Plutonium?
Platonic ideals of fail-safe technology are rhetorical games that ignore the messy realities of nuclear power.
Saying they "don't match our lifestyle" is a cop out. Our lifestyle is a bit on the bogus side, and we will need to change it to progress.
Japanese authorities have reported some casualties to nuclear plant workers. At Fukushima Daichi, four workers were injured by the explosion at the Unit 1 reactor, and there are three other reported injuries in other incidents. In addition, one worker was exposed to higher-than-normal radiation levels that fall below the IAEA guidance for emergency situations. At Fukushima Daini, one worker has died in a crane operation accident and four others have been injured.posted by ob1quixote at 4:12 AM on March 13, 2011 [3 favorites]
This post is by Dr Josef Oehmen, a research scientist at MIT, in Boston.posted by purephase at 5:21 AM on March 13, 2011 [21 favorites]
He is a PhD Scientist, whose father has extensive experience in Germany’s nuclear industry. I asked him to write this information to my family in Australia, who were being made sick with worry by the media reports coming from Japan.
The entire “hardware” of the nuclear reactor – the pressure vessel and all pipes, pumps, coolant (water) reserves, are then encased in the third containment. The third containment is a hermetically (air tight) sealed, very thick bubble of the strongest steel. The third containment is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown. For that purpose, a large and thick concrete basin is cast under the pressure vessel (the second containment), which is filled with graphite, all inside the third containment. This is the so-called “core catcher”. If the core melts and the pressure vessel bursts (and eventually melts), it will catch the molten fuel and everything else. It is built in such a way that the nuclear fuel will be spread out, so it can cool down.posted by scalefree at 10:33 AM on March 13, 2011
If you want to know what scares me about Japan right now? It's the broken transport, which means more will die because they can't get supplies, and it's the statement from the JMA stating that there's a 70% of a Magnitude 7 aftershock in the next three days.
Are you sure about that?
A day after an explosion at one reactor [at Fukishima Daiichi], Japanese nuclear officials said Sunday that operators at the plant had suffered a setback trying to bring the second reactor thought to be in partial meltdown there under control. The operators need to inject water to help cool the reactor and keep it from proceeding to a full meltdown, but a valve malfunctioned on Sunday, hampering their efforts for much of the day...posted by BungaDunga at 2:11 PM on March 13, 2011 [1 favorite]
At a late-night press conference, officials at Tokyo Electric Power Co., which runs the plant, said the valve had been fixed, but said water levels had not yet begun rising...
For some time, the plant was able to operate in a battery-controlled cooling mode. Tokyo Electric Power said that by Saturday morning it had also installed a mobile generator to ensure that the cooling system would continue operating even after reserve battery power was depleted. Even so, the company said it needed to conduct “controlled containment venting” in order to avoid an “uncontrolled rupture and damage” to the containment unit.
Why the controlled release of pressure did not succeed in addressing the problem was not immediately explained. Tokyo Electric Power and government nuclear safety officials also did not explain the precise sequence of failures at the plant." (emphasis mine)
Japanese reactor operators now have little choice but to periodically release radioactive steam until the radioactive elements in the fuel of the stricken reactors stop generating intense heat, a process that can continue for a year or more even after the fission process has stopped. To control that heat, the plant’s operator must constantly try to flood the reactors with seawater, then release the resulting radioactive steam into the atmosphere, several experts familiar with the design of the Daiichi facility said. That suggests that the 200,000 people who have been evacuated may not be able to return to their homes for a considerable period and that shifts in the wind could blow radioactive materials toward Japanese cities rather than out to sea.posted by scalefree at 7:10 PM on March 13, 2011
Instead the operators are dumping seawater into the vessel, and letting it cool the fuel by boiling. But as it boils, pressure rises too high to pump in more water, so they have to vent the vessel to the atmosphere, and feed in more water, a procedure known as “feed and bleed.”so this is the explanation I've been waiting for. Maybe the answer is upthread, but I've been in and out all day....
"Reactor analysts like to categorize potential reactor accidents into groups," said Bergeron, who did research on nuclear reactor accident simulation at Sandia National Laboratory in New Mexico. "And the type of accident that is occurring in Japan is known as a station blackout. It means loss of offsite AC power—power lines are down—and then a subsequent failure of emergency power on site—the diesel generators. It is considered to be extremely unlikely, but the station blackout has been one of the great concerns for decades.The rest of that article, which is fairly short and accessible, does a nice job of explaining what's going on in general terms.
"The probability of this occurring is hard to calculate primarily because of the possibility of what are called common-cause accidents, where the loss of offsite power and of onsite power are caused by the same thing. In this case, it was the earthquake and tsunami. So we're in uncharted territory, we're in a land where probability says we shouldn't be. And we're hoping that all of the barriers to release of radioactivity will not fail."
"Seawater was being injected into the reactor vessel and levels had initially risen as expected. However, a gauge indicated that the rise had tailed off, despite ongoing seawater injection.posted by Popular Ethics at 9:01 PM on March 13, 2011
The gauge in question indicated that water levels are around two metres below the top of the nuclear fuel assemblies, which would represent a very serious situation with the risk of fuel damage. However, the Nuclear and Indsutrial Safety Agency was satisfied that pressure within containment was at comfortable levels, while radiation had been decreasing."
"Based on what we understand, the reactor has been shut down, in the sense that all of the control rods have been inserted. Which means there's no longer a nuclear reaction. But what you have to worry about is the decay heat that's still in the core, that will last for many days.posted by LobsterMitten at 9:29 PM on March 13, 2011
"And to keep that decay heat of the uranium from melting the core, you have to keep water on it. And the conventional sources of water, the electricity that provides the power for pumps, have failed. So they are using some very unusual methods of getting water into the core, they're using steam-driven turbines—they're operating off of the steam generated by the reactor itself.
"But even that system requires electricity in the form of batteries. And the batteries aren't designed to last this long, so they have failed by now. So we don't know exactly how they're getting water to the core, or if they're getting enough water to the core. We believe, because of the release of cesium, that the core has been exposed above the water level, at least for a portion of time, and has overheated. What we really need to know is how long can they keep that water flowing. And it needs to be days to keep the core from melting.
"The containment, I believe, is still intact. But if the core does melt, that insult will probably not be sustained, and the containment vessel will fail. All this, if it were to occur, would take a matter of days. What's crucial is restoring AC power. They've got to get AC power back to the plant to be able to control it. And I'm sure they're working on it."
And to keep that decay heat of the uranium from melting the core, you have to keep water on it.Why do they care about whether the core melts or not?
Company documents show that Tokyo Electric tested the Fukushima plant to withstand a maximum seismic jolt lower than Friday's 8.9 earthquake. Tepco's last safety test of nuclear power plant Number 1—one that is currently in danger of meltdown—was done at a seismic magnitude the company considered the highest possible, but in fact turned out to be lower than Friday's quake. The information comes from the company's "Fukushima No. 1 and No. 2 Updated Safety Measures" documents written in Japanese in 2010 and 2009.If this is correct, then it is very surprising. First, megathrust earthquakes on a section of fault can occur with a rough periodicity, but may be separated by centuries. Going back to the 1930s is not enough of a temporal unit of analysis to determine what constitutes a maximum size earthquake. And, if they were working on some kind of seismic model that suggested that there was a maximum size earthquake, well, they were wrong in both principle and in retrospect. It is fair to say that geologists are better at describing seismicity than predicting it.
The documents were reviewed by Dow Jones. The company said in the documents that 7.9 was the highest magnitude for which they tested the safety for their No. 1 and No. 2 nuclear power plants in Fukushima. Simultaneous seismic activity along the three tectonic plates in the sea east of the plants—the epicenter of Friday's quake—wouldn't surpass 7.9, according to the company's presentation. The company based its models partly on previous seismic activity in the area, including a 7.0 earthquake in May 1938 and two simultaneous earthquakes of 7.3 and 7.5 on November 5 of the same year.
"When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.He doesn't say where he got that info about the plugs not fitting, but that's a hell of a thing if true.
Within the 8 hours, another power source had to be found and connected to the power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in.
This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more."
Sunday Update on Fukushima Reactorscontains the alarming statement that
The Mark I is unusually vulnerable to containment failure in the event of a core-melt accident. A recent study by Sandia National Laboratories shows that the likelihood of containment failure in this case is nearly 42% (see Table 4-7 on page 97).
Risk-Informed Assessment of Degraded Containment Vessels[PDF]. There on p. 96 I read,
A very important feature of these results is that there is a very high probability of a melt-through failure. The probability of an early melt-through failure given core damage is roughly 36% for all cases.
Case | Mean | 5% | 50% | 95% | ------------------------------------------------------------------- Un-damaged (Reference) | 0.4169 | 2.393E-06 | 0.3861 | 0.8851 | Un-damaged (Current Study) | 0.4177 | 2.393E-06 | 0.3861 | 0.9754 |The top two lines of
Table 4.7: Probability of Large Early Containment Failure Conditional on Core Damagefrom p. 97 of the referenced study.
In Japan, the western part of the country (Kyoto and west) uses 60 Hz and the eastern part (Tokyo and east) uses 50 Hz. This originates in the first purchases of generators from AEG in 1895, installed for Tokyo, and General Electric in 1896, installed in Osaka. The boundary between the two regions contains four back-to-back HVDC substations which convert the frequency; these are Shin Shinano, Sakuma Dam, Minami-Fukumitsu, and the Higashi-Shimizu Frequency Converter.Presumably, those substations have limited capacity to share power between the two halves of the grid, but IANAEE.
Has anyone heard anything more about this, specifically what its replacement was supposed to be?
Probabilistic Risk Assessment: What Is It And Why Is It Worth Performing It?), but my initial impression is that the statement
the likelihood of containment failure in this case is nearly 42%implies a naive interpretation of the numbers in Table 4-7.
"In reactor No. 2, which is now the most damaged of the three at the Daiichi plant, at least parts of the fuel roads have been exposed for several hours, which also suggests that some of the fuel has begun to melt. If more of the fuel melts before water can be injected in the vessel, the fuel pellets could burn through the bottom of the containment vessel and radioactive material could pour out that way — often referred to as a full meltdown."They're calling the "melt through"/"China Syndrome" scenario a "full meltdown". I thought it could fully melt into a puddle, still be contained, and be a "meltdown"? As I understand it, the hope right now is that it will be contained, even if it melts entirely. NYT seems to not mention that it's quite possible that containment won't fail.
“They’re basically in a full-scale panic” among Japanese power industry managers, said a senior nuclear industry executive late Monday night. The executive is not involved in managing the response to the reactors’ difficulties but has many contacts in Japan. “They’re in total disarray, they don’t know what to do.”posted by BungaDunga at 11:18 AM on March 14, 2011
The reason new nuclear plants probably won't ever be built in the United States is because they are too expensive. That's partly because all of the redundant engineering that needs to go into them just to make them safe and partly because of the enormous up front fixed costs.When President Palin takes office, safety measures won't add any overhead anymore.
At the 40-year-old Fukushima Daiichi Unit 1, where the explosion Saturday destroyed a building housing the reactor, the spent fuel pool, in accordance with General Electric’s design, is placed above the reactor. Tokyo Electric said it was trying to figure out how to maintain water levels in the pools, indicating that the normal safety systems there had failed, too. Failure to keep adequate water levels in a pool would lead to a catastrophic fire, said nuclear experts, some of whom think that Unit 1’s pool might now be outside.posted by dialetheia at 12:49 PM on March 14, 2011 [2 favorites]
“That would be like Chernobyl on steroids,” said Arnie Gundersen, a nuclear engineer at Fairewinds Associates and a member of the public oversight panel for the Vermont Yankee nuclear plant, which is identical to the Fukushima Daiichi Unit 1.
People familiar with the plant said there are seven spent fuel pools at Fukushima Daiichi, many of them densely packed.
Gundersen said the Unit 1 pool could have as much as 20 years of spent fuel rods, which are still radioactive.
午後9時25分 正門 6.8μSv/h 午後9時30分 正門 29.7μSv/h 午後9時35分 正門 760.0μSv/h 午後9時37分 正門 3130.0μSv/h
午前10時15分 正門 431.7μSv/hThe unusual 9:37 timestamp on the high mark suggest that they are reporting the peak from a continuous recording, rather than the normal 10 minute interval, but the lack of measurements after suggests that we may not see a potential later peak of this event.
yes, I mean
yes, as in PG&E signed a deal in 2009 topurchase 200 megawatts of electricity from a startup company that plans to beam the power down to Earth from outer space, beginning in 2016.
午前10時35分 正門 326.2μSv/h 0.001μSv/h未満
Tokyo Electric said it was trying to figure out how to maintain water levels in the pools, indicating that the normal safety systems there had failed, too. Failure to keep adequate water levels in a pool would lead to a catastrophic fire, said nuclear experts, some of whom think that Unit 1’s pool might now be outside.Why is this nuclear engineer not remotely credible? Or what am I missing here that makes what you are saying true.
“That would be like Chernobyl on steroids,” said Arnie Gundersen, a nuclear engineer at Fairewinds Associates and a member of the public oversight panel for the Vermont Yankee nuclear plant, which is identical to the Fukushima Daiichi Unit 1.
Could this be another Chernobylwith a direct answer (paraphrasing)
Not in my judgement.
Could It Happen Here?!?headline with the Reactor 3 explosion footage behind it I'm going to pop a blood vessel.
There is a "possibility" that damage was done to the suppression pool at the bottom of the containment vessel inside Fukushima's number two reactorposted by BungaDunga at 4:54 PM on March 14, 2011
The torus or suppression pool is used to remove heat released if an event occurs in which large quantities of steam are released from the reactor or the Reactor Recirculation System, used to circulate water through the reactor.So are they using the torus right now for cooling? Or, I guess were they.
You have: curie * m^2 / s You want: sievert * 3.7e+10 / 2.7027027e-11So one curie over 1 square meter of area per second exposure = 3.7 * 10^10 sieverts.
now I want to know what 8217 microsieverts an hour meansA chest X-ray every 45 minutes.
I don't think Sieverts and Curies are measuring quite the same thing?Posted earlier upthread by Jeanne
The figures that I've been reading are:
A chest Xray is about 6000 microSieverts
100 milliSieverts (100,000 microSieverts) increases your risk of cancer
500 milliSieverts (500,000 microSieverts) causes the first symptoms of radiation poisoning (lethargy, anemia)
2000 milliSieverts (2 million microSieverts) starts to cause death in a smallish percentage of people
6000 milliSieverts kills everybody.
@Jeanne: if the fuel rods are not burning, they are creating hydrogen by reaction with the atmosphere which is burning.The hydrogen is created by reacting with water once the rods reach a certain temperature.
Regarding robots, when they used them in Chernobyl they were of extremely limited use due to the debris and terrain involved.Yeah our robots are a lot better at this point. The problem, though is that there aren't a lot of ready to go high-tech robots designed for situations like this. Robots are typically designed specifically for various tasks or for research labs. The problem is the research bots are probably not radiation hardened.
Off topic, but the incongruity of furiosxgeiorge's "Don't panic" at the top of this page, with "Ferris Bueller's Day Off" at the bottom, strikes me every time I return to this thread.I feel that way watching a realtime twitter reader, which intersperses every twitter account I'm following:
Oh crud, I looked at the geiger counter graph link flapjax posted, and since 10 o'clock on the graph it's gone from under 20 to around 70 cpm.It looks like 12.01 to me.
They're right next to an ocean. On purpose, for just this reason. Flying fresh water in instead of using seawater would be like...I dunno...if you were freezing to death, deciding that instead of warming yourself by a campfire 10 feet away, you would walk 10 miles to a nice centrally heated house.Yeah, but as seawater evaporates, it will leave salt behind. If the seawater boils off the reactor core would get clogged with salt.
Radiation leak feared at nuke plant, people urged to stay indoorsat Kyodo
In Ibaraki Prefecture, just south of Fukushima, an amount of radiation up to about 100 times the usual level was measured Tuesday morning. In Kanagawa Prefecture, southwest of Tokyo, radiation of up to nine times the normal level was also briefly detected.posted by ob1quixote at 10:32 PM on March 14, 2011
The Tokyo metropolitan government also said it has detected a small amount of radioactive materials such as iodine and cesium in the air of the metropolis.
The wind was blowing from north to south when the incidents occurred at the Fukushima plant.
Japanese authorities informed the IAEA that there has been an explosion at the Unit 2 reactor at the Fukushima Daiichi plant. The explosion occurred at around 06:20 on 15 March local Japan time.posted by ob1quixote at 10:45 PM on March 14, 2011 [3 favorites]
Japanese authorities also today informed the IAEA at 04:50 CET that the spent fuel storage pond at the Unit 4 reactor of the Fukushima Daiichi nuclear power plant is on fire and radioactivity is being released directly into the atmosphere.
Dose rates of up to 400 millisievert per hour have been reported at the site. Japanese authorities are saying that there is a possibility that the fire was caused by a hydrogen explosion.
The IAEA is seeking further information on these developments.
Japanese authorities also today informed the IAEA at 04:50 CET that the spent fuel storage pond at the Unit 4 reactor of the Fukushima Daiichi nuclear power plant is on fire and radioactivity is being released directly into the atmosphere.IAEA Alert Log
Dose rates of up to 400 millisievert per hour have been reported at the site.
In a reactor pool, the time it takes uncooled fuel to begin boiling the surrounding water depends on how much fuel is present and how old it is. Fresh fuel is hotter in terms of radiation than old fuel is.posted by warbaby at 6:15 AM on March 15, 2011 [1 favorite]
Mr. Lochbaum, who formerly taught reactor operation for the Nuclear Regulatory Commission, said the pools measured about 40 feet long, 40 feet wide and 45 feet deep. The spent fuel, he added, rested at the pool’s bottom and rose no higher than 15 feet from the bottom.
That means that in normal operations, the spent fuel is covered by about 30 feet of cooling water.
Potassium Iodide Runs Low as Americans Seek It Out.
One leading supplier, Anbex Inc., quickly sold out of its supply of more than 10,000 14-tablet packages on Saturday, said Alan Morris, president of the Williamsburg, Va., company.posted by ob1quixote at 7:34 AM on March 15, 2011
He said the closely held firm was getting about three orders a minute for $10 packages of its Iosat pills, up from as few as three a week normally.
"Those who don't get it are crying. They're terrified," said Mr. Morris. The company tells callers that the likelihood of dangerous levels of radiation reaching the U.S. is low, but some callers, particularly on the West Coast, remain afraid, Mr. Morris said.
Interest is also high at Fleming Pharmaceuticals, a St. Louis County company that makes potassium iodide in liquid form. "It actually has been insanity here," said Deborah Fleming Wurdack, a co-owner.
The company hasn't accounted for all the recent orders, but Ms. Wurdack estimates the firm is getting dozens of calls an hour, along with emails, requesting the 45-milliliter ThyroShield bottles, which sell for $13.25 each.
“It is crazy, people have been reading about the situation in Japan and they are demanding iodine tablets, but most pharmacies don’t stock the tablets,” said Kuala Lumpur pharmacist Paul Ho.posted by ob1quixote at 7:45 AM on March 15, 2011 [1 favorite]
“There have also been text messages and emails going round that you can use the iodine antiseptic solution, which you place around your neck, to help cut down on radiation absorption,” he added.
Such a treatment would be utterly ineffective, but Mr. Ho said “we have run out of all our iodine antiseptic solution at the moment”.
One SMS text message, also circulating in China, Hong Kong and the Philippines, is billed as a BBC “newsflash” and urges Asians to “take precautions” including sheltering indoors and swabbing the thyroid region of the neck with iodine.
“The BBC has issued no such flash but it has caused particular panic in the Philippines,” a BBC News website story said.
One packet of 14 pills had attracted bids of up to $540 at online auction house eBay and talk about radiation poisoning was so feverish on Twitter and other forums that the World Health Organisation issued a statement urging calm.That's US$3.37/mg.
At 00:00 UTC on 15 March a dose rate of 11.9 millisieverts (mSv) per hour was observed. Six hours later, at 06:00 UTC on 15 March a dose rate of 0.6 millisieverts (mSv) per hour was observed.posted by ob1quixote at 8:58 AM on March 15, 2011
These observations indicate that the level of radioactivity has been decreasing at the site.
FWIW - this article from The New Yorker - if you stick with it - has implications for much being discussed & dealt with here: The Truth Wears Off - Is There Something Wrong With the Scientific Method?Well, there's a big difference between experiments to find, say, the combustion point of hydrogen, and something like the effectiveness of anti-psychotics (which is what the article was about). Early science was mostly about things most people would have no trouble verifying in their homes today. As science progressed you got more and more expensive equipment (up to stuff like the large hadron collider) but the results are pretty unambiguous.
Natural Gas might be the most likely alternative in the US as the regulatory environment surrounding new nuclear power plants is going to get very fighty but it's hardly a "great" alternative.Ugh, fuck natural gas. We don't actually have that much and you need to frack to get it anyway. And on top of that, natural gas (methane) is itself a greenhouse gas far more powerful then CO2. So if there are any leaks you lose out on the reduced CO2 emissions.
then it may be time for local/federal officials to announce that any fears are unfounded.Huh? Are you talking about the actual risks to people on the west coast, or what people would think about the government's statements? I agree that people won't take them very seriously. But I don't think the risks are very great.
Would be just like them to lie like that.
The idea that the core could burn through the base of its containment is about as credible as the idea that it would remain together in the planet's molten interior and then – having somehow done so and thus reached the centre of the Earth – then ascend back to the surface again at the antipodes.The concern is that the molten uranium/plutonium will melt through the floor, then hit water and cause a steam explosion, blasting uranium/plutonium into the atmosphere.
An interesting fact about antipodes--I may have learned it here--is that the antipode of any land mass is almost always water, with very few exceptions.That's not really a fact about antipodes. To the limited extent that it is true, it's mostly just a consequence of the fact that the Pacific Ocean is absurdly humongous.
points like the ending one is what made me think from a thinking standpoint - it was appropriate to link here in regards to the overall debates regarding much related to all that encompasses a debate regarding the safety of nuclear energy:Well, there has never been away to know what's 'true', just what's verifiable. I just skimmed the article, so I can't really comment. But just because someone claims something is scientific and it turns out not to be doesn't mean there is anything wrong with science, just with that person. Science is self-correcting, it's not supposed to be 100% correct all the time, and it doesn't try to be. Obviously the profit motive with things like big pharma, or nuclear plants or whatever can distort that even more, unfortunately.
...
"The decline effect is troubling because it reminds us how difficult it is to prove anything. We like to pretend that our experiments define the truth for us. But that’s often not the case. Just because an idea is true doesn’t mean it can be proved. And just because an idea can be proved doesn’t mean it’s true. When the experiments are done, we still have to choose what to believe."
4.40pm: An update on the plan to drop water on the pour water on reactor No. 4 at the Fukushima Daiichi power station from Kyodo News:I hope the police/firefighters survive that whole ordeal...
The ministry began preparing to dispatch a ground self-defence force helicopter unit in Chiba prefecture, seeing that it would be possible for the helicopters to apply the same technique used for putting out a forest fire - namely, dropping water from the air.
But for now, the spent fuel pool is being cooled by police and firefighters on ground, after the government judged that an aerial approach ran the risk of damaging the spent nuclear fuel underwater and exposing SDF personnel to radiation, according to Kitazawa.
''We will perform our duty when we reach the stage where (the temperature rise in spent fuel) begins to settle down and we decide to drop large amounts of water from the sky,'' he said.
"Greed in the nuclear industry and corporate influence over the U.N. watchdog for atomic energy may doom Japan to a spreading nuclear disaster, one of the men brought in to clean up Chernobyl said on Tuesday."posted by ericb at 11:12 AM on March 15, 2011 [3 favorites]
"Rain is very efficient at removing radioactive particles from the air, and there is the threat of surface and ground water contamination where significant concentrations of radioactive material get rained out. By Wednesday, most of the rain will be gone, and predominately northwesterly winds will build in behind the departing low pressure system. This flow regime will stay in place for the remainder of the week, keeping radioactive emissions from the nuclear plant away from Tokyo, and headed out to sea at low altitudes near the surface.posted by LobsterMitten at 11:34 AM on March 15, 2011
Ground level releases of radioactivity are typically not able to be transported long distances in significant quantities, since much of the material settles to the ground a few kilometers from the source. If there is a major explosion with hot gases that shoots radioactivity several kilometers high, that would increase the chances for long range transport, since now the ground is farther away, and the particles that start settling out will stay in the air longer before encountering the ground. Additionally, winds are stronger away from ground, due to reduced friction and presence of the jet stream aloft. These stronger winds will transport radioactivity greater distances.
[...]One case where a ground level release might get lofted to high altitudes is when the source region is located near an approaching low pressure system (extratropical cyclone), as is the case today. [...] However, there is often considerable precipitation in both of these [systems approaching the power plants today], which will tend to remove large quantities of radiation before it can be transported long distances. There will be some radiation from Japan lofted to high altitudes today by the low pressure system affecting the region, and if the radiation manages to escape being rained out, it could potentially be transported thousands of miles over the next week. A run of the HYSPLIT model following the path of a radioactive cloud emitted at 12 UTC (8am EDT) this morning shows the radioactivity being lofted 4 - 5 km in altitude and being transported over Alaska over the coming week. After a week of transport, this cloud will be considerably diluted, and I strongly doubt the radioactivity would be harmful to human health if rain or snow were to carry it to the ground over Alaska or Canada, assuming that the radiation levels currently being advertised at ground level in Japan are correct."
The risk in Japan is primarily meltdown, not a Chernobyl-style run-away nuclear reaction.From this article and other things posted above, I gather that the design of the reactor at Chernobyl was different in at least two important ways:
The Fukushima reactors don't have this flammable graphite component, so a fire of that type is not possible. (But maybe other types of fire are possible?)There has already been fire.
It is important to note that the distribution and level of radioactive contamination from the Fukushima disaster is likely to be very much less than at Chernobyl, as boiling water reactors (BWRs) like those at Fukushima do not have the potential for the same failure mode as occurred at the Chernobyl RBMK plant. Chernobyl suffered a nuclear explosion on an abrupt power surge aggravated by a moderator fire.The article also describes the types of radiation that could be released, including the time span over which each is a risk (days vs longer) and which body systems they affect.
The Fukushima reactors, where the nuclear reaction had been immediately halted by the lowering of control rods, are instead at risk of meltdown from excess decay heat in the absence of the ability to dissipate that heat. In a full meltdown scenario, the molten core would melt through the pressure vessel and concrete containment, particularly if these have already been compromised by explosive force. The core could melt down into the groundwater, causing steam explosions. Relatively local contamination could eventually be considerable, depending on the final scope of this rapidly developing situation, but I would not expect major international contamination as happened following Chernobyl.
Even within Japan I would not expect widespread gross levels of contamination even under a worst case scenario.
The threat is considered so severe that at the start of the crisis Friday, immediately after the shattering earthquake, Fukushima plant officials focused their attention on a damaged storage pool for spent nuclear fuel at the No. 2 reactor at Daiichi, said a nuclear executive who requested anonymity because his company is not involved in the emergency response at the reactors and is wary of antagonizing other companies in the industry.posted by dialetheia at 12:59 PM on March 15, 2011 [4 favorites]
The damage prompted the plant’s management to divert much of the attention and pumping capacity to that pool, the executive added. The shutdown of the other reactors then proceeded badly, and problems began to cascade.
at some point it will be over, then we can assess the overall severity without just pretending to know what we're doingNo, not true. At some point we will draw a line and say "now it is time to spend resources consolidating our knowledge." The thing will still be going on though. Chernobyl is still a problem today. We are still threatened by hair trigger nuclear missiles.posted by Chuckles at 1:36 PM on March 15, 2011 [1 favorite]
"Thirty-five years ago, Dale G. Bridenbaugh and two of his colleagues at General Electric resigned from their jobs after becoming increasingly convinced that the nuclear reactor design they were reviewing -- the Mark 1 -- was so flawed it could lead to a devastating accident.posted by ericb at 2:48 PM on March 15, 2011 [5 favorites]
Questions persisted for decades about the ability of the Mark 1 to handle the immense pressures that would result if the reactor lost cooling power, and today that design is being put to the ultimate test in Japan. Five of the six reactors at the Fukushima Daiichi plant, which has been wracked since Friday's earthquake with explosions and radiation leaks, are Mark 1s.
'The problems we identified in 1975 were that, in doing the design of the containment, they did not take into account the dynamic loads that could be experienced with a loss of coolant,' Bridenbaugh told ABC News in an interview. 'The impact loads the containment would receive by this very rapid release of energy could tear the containment apart and create an uncontrolled release.'" | more ...
In the early 1970s, just as a number of reactors were about to be licensed, Stephen Hanauer, a senior member of the Atomic Energy Commission staff, suggested banning "pressure suppression" methods to contain radiation in the event of a meltdown -- methods built into General Electric's Mark I and Mark II containment designs as well as Westinghouse's ice condenser design. The advice was considered and disregarded.posted by ericb at 2:53 PM on March 15, 2011 [1 favorite]
"Steve's idea to ban pressure suppression containment schemes is an attractive one in some ways," Joseph Hendrie, then a deputy director with the AEC, wrote in a Sept. 25, 1972, memo [PDF]. Hendrie acknowledged that alternative, "dry" containments -- featuring the towers or domes commonly associated with nuclear plants -- had the "notable advantage of brute simplicity in dealing with a primary blowdown, and are thereby free of the perils of bypass leakage."
But regulators ultimately decided that the technology developed by General Electric and Westinghouse was "firmly embedded in the conventional wisdom." Banning it, Hendrie wrote, "would generally create more turmoil than I can stand." His memo was obtained by the Union of Concerned Scientists through a Freedom of Information Act request. | more ...
Well, they must feel like idiots now, because we lost coolant to multiple units days ago and this hasn't happened.What? The loss of coolant has been the major cause of the problems, and if their advice had been followed we wouldn't be having this discussion, as far as I can tell. I so I don't really understand how that makes them 'idiots'. The problems they identified were real and we still don't know what is going to happen.
If he's a fraud, somebody will take him down hard. If not, then economists (which is what this guy is, not an engineer), can start building nukes and engineers will run the economy.Given the way things have been going lately, I think I'd rather have engineers running the economy instead of economists.
Which, you know, is better credentials than we have here for the most part. It also sounds like they revised Oehmen's letter, changing some things (eg he originally said the reactor has a core catcher, but I believe that was removed in the revised version)The idea of an 'open letter' that's being updated and revised is kind of weird. In fact, the title of the article doesn't even say "why I'm not worried about Japan's nuclear reactors anymore. It's only the URL.
The details about what happened at the Unit 2 reactor are still being determined. The post on what is happening at the Unit 2 reactor contains more up-to-date information. Radiation levels have increased, but to what level remains unknown.So regardless of this guys qualifications, the initial predictions were wrong. Why take it seriously at this point?
FYI, I work as a contractor for MIT and could, very easily, set up multiple Wordpress installations (or whatever) under multiple mit.edu subdomainsit's not even an MIT.edu subdomain. It's mitnse.com, and it was registered like two days ago.
This crisis certainly has revealed what a snow job te nuclear industry pulled on many of us the last few years. It's like the whole oil industry situation in Deep Water Horizon. All this talk of failsafes and protective systems which it turns out were routinely non-functioning garbage. The only thing holding the world together is duct tape and bullshit. Once you factor in the trillion dollar cleanup tab, solar is looking pretty fucking cheap right now.Solar energy stocks have been way up lately.
Spent Fuel Pool Safety FactsWhich I guess doesn't do anything to help in the case the pool boils off because people put live fuel in it while examining the core, then got hit by a combination earthquake + tsunami causing a station blackout and radiation leak that makes it impossible to work in the plant...
To reiterate before closing, the safety and security of spent fuel pools is ensured by a series of physical structures, operational measures and security barriers that are unprecedented in U.S. civilian infrastructure.
Nuclear power reactor spent fuel pools are robust structures constructed of very thick steel-reinforced concrete walls with stainless steel liners located inside protected areas.
Many of spent fuel pools are designed with the pool and fuel located below grade, many are shielded by other structures, and many have intervening walls that would obstruct an aircraft’s or other object’s impact.
Spent fuel pools contain enormous quantities of water and the spent fuel in the spent fuel pool produces significantly less heat than in an operating reactor. As a result, for most events (i.e., loss of cooling or small leaks) plant operators would have significant amounts of time to correct the problem, or implement fixes needed to restore cooling.
In addition to the water in the spent fuel pool, nuclear power plants possess many other sources of water that are readily available that could be made available as a backup supply to the spent fuel pool."
Taken from the NRC paper: http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/reducing-hazards-spent-fuel.html
Gives one great confidence to see...
NHK World just said that the Unit 4 reactor spent fuel pool is not carrying spent fuel. It's carrying the fuel that they took out for the maintenance.Yeah it was also posted in this thread a while ago. :P
I sure as hell hope they're using that kind of stuff right now. This is fucking Japan, they've got robots that will turn old people over in their beds for cryin' out loud. I can only imagine they're not bothering to tell us about all the cool stuff they're doing. I hope.Most electronics are not radiation hardened. They can probably take more radiation then a human can without risking cancer, but how much I'm not sure.
Presumably its not all the live fuel from reactor 4 thats been transferred to the pool. I'm guessing you wouldn't take _all_ the rods out. I mean, would they?If you wanted to maintain it I assume you would, right? You would want to drain all the water, send people down there, whatever. It would be kind of a problem if you left the rods in there.
A Hiroshima-style bomb won't just assemble itself. A lot of engineering is required to make a weapons-grade nuclear explosion. We can safely rule that outcome out.No one is suggesting that. The problem is that the rods heat up, and get hot enough for the zirconium fuel rods to react with water producing hydrogen, which burns, and causes an explosion. It's the same kind of reaction that causes sodium or rubidium to explode when placed in water.
2. If all the Zircaloy fuel cladding oxidises (and as has been shown from the explosions it has been oxidising), as much as 2722 kg of hydrogen would be produced (depending on the plant, but at least it's an order of magnitude). According to WolframAlpha that amount of hydrogen would have an energy content of 393GJThat's obviously an unlikely scenario, but it sounds like there is plenty of zirconium to cause a lot of energy to be released. Plus the potential for steam pressure to build up just from the rods themselves.
On August 29, 2002, the government of Japan revealed that TEPCO was guilty of false reporting in routine governmental inspection of its nuclear plants and systematic concealment of plant safety incidents. All seventeen of its boiling-water reactors were shut down for inspection as a result. TEPCO's chairman Hiroshi Araki, President Nobuya Minami, Vice-President Toshiaki Enomoto, as well as the advisers Shō Nasu and Gaishi Hiraiwa stepped-down by September 30, 2002.[6] The utility "eventually admitted to two hundred occasions over more than two decades between 1977 and 2002, involving the submission of false technical data to authorities"posted by delmoi at 10:51 PM on March 15, 2011
A computer system that forecasts the spread of radioactivity has not been working due to malfunctioning monitoring posts around a troubled nuclear power plant in quake-hit Fukushima Prefecture.[emphasis mine]
The Nuclear and Industrial Safety Agency says it does not know when the system will be back in operation.
The system, called SPEEDI, predicts how radioactive substances will spread in case of radiation leakage from nuclear power plants, based on measurements taken at various locations, prevailing winds and other weather conditions.
SPEEDI data are intended to be used to draw up evacuation plans for residents around power plants in case of accidents.
Kyodo says that workers the facility have been unable to pour water into the pool containing the spent fuel rods because of high radiation levels. Tepco, the plant's operators, are considering spraying the reactor with boric acid from overhead, warning: ''The possibility of recriticality is not zero".That's a hell of a phraseology: "the possibility of recriticality is not zero."
Kyodo has just flashed up a statement that winds are preventing Self Defence Force helicopters from dousing it with water, citing an unnamed minister.
"I've been told to cease & desist pending results of this morning's meeting with chain of command. Thank all of you for support & attention."Over the past few days, we've all been "handled" more than enough by professional communicators. The Fukushima incident has certainly made me more fearful of nuclear power, but it has been these PR flacks and their surrogate spinners that have caused me to severely lose any trust in the companies that design and operate nuclear facilities. I can get over that fear a lot more easily than the industry can possibly repair that loss of trust. The anti-nuke groups have certainly been taking advantage of this incident too, but muzzling a scientist who was providing incredibly helpful information in a crisis is far worse.
"Job is secure. Sometimes faith in management is not misplaced. However, communication will be handled by professionals from now on."
Q+A: What do latest events at Japan nuclear power plant mean?posted Wed Mar 16, 2011 4:26am EDT.
In an unprecidented situation never seen before in its history, Japanese Prime Minister Naoto Kan, facing an obviously difficult and frustrating situation, streched out his leg today and hit the reset button with his big toe.
The Prime Minister was on the defensive after his controversial move, citing the extreme difficulty of the current situation.
"I was facing a whole series of unprecidented difficulties. Problems that you would expect to gradually improve after the earthquake and tsunami kept getting progressively worse. I made my decision, based on what I thought would be best for the Japanese people. We are making all possible efforts to restore from an earlier save point, just as soon as possible."
I had turned my back for awhile to talk with (LDP Spokesperson) Yuriko Koike, only to have this happen. It was like she was trying to distract me, frankly," Kan announced.
Ms. Koike vigorously denied the Prime Minister's claims at a press conference today, but NHK has obtained video which appears to show LDP Leader Sadakazu Tanigaki adjusting settings on the difficulty control screen, while the Prime Minister's back was turned.
Mr. Tanigaki's office had no immediate comment.They are the faceless 50, the unnamed operators who stayed behind. They have volunteered, or been assigned, to pump seawater on dangerously exposed nuclear fuel, already thought to be partly melting and spewing radioactive material, to prevent full meltdowns that could throw thousands of tons of radioactive dust high into the air and imperil millions of their compatriots.posted by yeoz at 5:46 AM on March 16, 2011 [2 favorites]
...
Nuclear reactor operators say that their profession is typified by the same kind of esprit de corps found among firefighters and elite military units. Lunchroom conversations at reactors frequently turn to what operators would do in a severe emergency.
The consensus is always that they would warn their families to flee before staying at their posts to the end, said Michael Friedlander, a former senior operator at three American power plants for a total of 13 years.
"You’re certainly worried about the health and safety of your family, but you have an obligation to stay at the facility," he said. "There is a sense of loyalty and camaraderie when you’ve trained with guys, you’ve done shifts with them for years."
March 16, 2011 - MIAMI - With Japanese authorities warning that the population immediately surrounding the nuclear plant in Northern Japan faces serious health risks from radiation leaks, Ronald DeMeo, M.D., president with Radiation Shield Technologies (RST), is issuing a global call-to-action to provide critical nuclear protection gear and counter-measures to protect first responders and the public.
"The radiation has surged to more than six times the legal limit, reaching levels that will clearly impact the human body, and I'm shocked to see the medical professionals and other first responders wearing cotton scrubs that provide little or no protection from the harmful gamma rays and other threats," said Dr. DeMeo . . . "The Japanese government and other authorities should learn about and use these new technologies to protect first responders and the public." . . .
Dr. DeMeo, the noted surgeon and entrepreneur who invented Demron, is offering to donate several of his company's patented Demron Full Body Suits - currently the only gear on the market that provides total chemical, biological, radiological and nuclear (CBRN) protection from all types of threats as well as heat stress. However, a massive deployment of Demron is needed, he said. "In addition, all manufacturers of any other gear that provides gamma protection should step up and donate whatever they can. During this crisis, every bit of help is needed."
The Demron armor is currently deployed throughout the Middle East, Asia, Europe, and the United States. The technologies are used globally by members of the military, first responders, HAZMAT teams, police and fire-rescue personnel and health care professionals, among others. The New York City Fire Department (FDNY) recently selected it to help improve firefighter safety. However, the suits are not yet being used by emergency teams in Japan.
The cool, lightweight, flexible full-body suits are made of the only impermeable CBRN fabric that permits heat exchange and enables the wearer to be cooled externally, enhancing athletic performance and survivability. In addition to the suit, RST's personal-protection line includes high-energy anti-nuclear ballistic blankets and ballistic vests. . .
RST, with headquarters and manufacturing facilities in Miami, is a global leader in the research, development and production of multi-hazard personal-protection performance enhancement systems. Visit www.radshield.com or call (866) 7DEMRON or (866) 733-6766.
13.56: The spent fuel pool at Fukushima's No 3 reactor has heated up and is emitting steam amid reports the fuel rods had become exposed, the Kyodo news agency has reported.posted by yeoz at 7:16 AM on March 16, 2011 [1 favorite]
Emperor Akihito of Japan, in an unprecedented television address to the nation, said on Wednesday that he was “deeply worried” about the ongoing nuclear crisis at several stricken reactors and asked for people to act with compassion “to overcome these difficult times.”Christian Science Monitor says that the speech will remind older listeners of the speech his father gave when Japan surrendered at the end of WWII.
An official with the Imperial Household Agency said that Akihito had never before delivered a nationally televised address of any kind, not even in the aftermath of the Kobe earthquake in 1995 that killed more than 6,000 people. The address was videotaped.
Wow. Why did they think putting the cooling pools for spent fuel on the roof was a good idea? And not just on the roof, but right next to the working reactor. Seems like that would be the most vulnerable place to locate it.Probably because the rods are so hot, you don't really have a lot of time to move them. I don't know. You probably have to keep them in the core for a long time cooling as well.
Anyone know if there was an actual safety reason for that design, or was it driven by cost or something?
unit RODS CAPACITY est fuel weight 1 292 900 1813.64 kg 2 587 1240 3645.92 kg 3 514 1220 3192.51 kg 4 783 1590 4863.3 kg 5 946 1590 5875.71 kg 6 876 1770 5440.93 kgIt's not clear if the paper is referring to metric tonnnes of 1000kg or english ton of 901.x kg.
FACILITY in tons 1 2 2 4.02 3 3.52 4 5.36 5 6.48 6 6 total 27.38 total at 1-4 14.9OK, so a worst case four-unit fuel-pool recriticality incident is likely to involve about 15 tons of fuel, FAR less than the scenarios explored in the Alvarez paper.
But can we exclude core criticality? Hasn't there been some concern about the possibility of so-called 'recriticality' of the fuel rods in the pool and criticality in the other reactors?From earlier:
Kyodo says that workers the facility have been unable to pour water into the pool containing the spent fuel rods because of high radiation levels. Tepco, the plant's operators, are considering spraying the reactor with boric acid from overhead, warning: ''The possibility of recriticality is not zero".So it's possible, there is some probability other then zero of it happening.
calculated at 391kg UNIT in tons 1 125.95 2 253.19 3 221.71 4 337.73 5 408.04 6 377.85 total 1724.47 total at 1-4 938.58 EST MCI, 1-4 143.71
calculated at 200kg UNIT in tons 1 64.37 2 129.41 3 113.32 4 172.62 5 208.56 6 193.12 total 881.4 total at 1-4 479.72 EST MCI, 1-4 73.45The Alvarez paper considers releases ranging from 3.5 to 35 MCi. These ranges are double the largest in the paper to four times the size.
calculated at 200kg UNIT in tons 1 64.37 2 129.41 3 113.32 4 172.62 5 208.56 6 193.12 total 881.4 total at 1-4 479.72 EST MCI, 1-4 73.45
18.40 The operator of Japan's tsunami-crippled nuclear plant says it has almost completed a new power line that could restore electricity to the complex and solve the crisis that has threatened a meltdown.posted by yeoz at 12:03 PM on March 16, 2011 [6 favorites]
Tokyo Electric Power Co. spokesman Naoki Tsunoda said the power line to Fukushima Dai-ichi is almost complete. Officials plan to try it "as soon as possible" but he could not say when.
The new line would revive electric-powered pumps, allowing the company to maintain a steady water supply to troubled reactors and spent fuel storage ponds, keeping them cool.
calculated at 200kg UNIT in t est MCI 5% 50% 1 58.4 4.87 0.24 2.44 2 117.4 9.78 0.49 4.89 3 102.8 8.57 0.43 4.29 4 156.6 13.05 0.65 6.53 5 189.2 15.77 0.79 7.89 6 175.2 14.6 0.73 7.3 total 799.6 total at 1-4 435.2 EST MCI, 1-4 66.63 5% Mci 3.33 50% Mci 33.32I guess the next thing is to see how to get conversions for MCi to Seiverts, if that even makes sense
18.28 US warns that there is no water at reactor 4 of Japan's Fukushima nuclear plant, saying that radiation is "extremely high". The chairman of the US Nuclear Regulatory Commission Gregory Jaczko says:posted by delmoi at 1:01 PM on March 16, 2011 [1 favorite]
Quote In addition to the three reactors that were operating at the time of the incident, a fourth reactor is also right now under concern. This reactor was shut down at the time of the earthquake..
"What we believe at this time is there has been a hydrogen explosion in this unit due to an uncovering of the fuel in the spent fuel pool," he said, noting the explosion happened several days ago but its effects were cause for concern.
"We believe that secondary containment has been destroyed and there is no water in the spent fuel pool and we believe that radiation levels are extremely high which could possibly impact the ability to take corrective measures."
7.49pm: Jaczko's worrying comments below (see 7.30pm) are at odds with reports from the Japanese media saying that coolant continues to be added into the Fukushima reactors.It's being suggested here, apparently, that the US may believe the Japanese government is not being an honest information broker. Apparently, there's a history of that sort of thing in Japan.
According to the last report from the Jiji Press agency, posted nearly three hours ago, states:
[Tepco] kept working to pump seawater into the pressure vessels of the No 1, 2 and 3 reactors of the Fukushima No 1 nuclear plant. But the water levels have not reached the top of the nuclear fuel rods, and portions of the fuel rods thus remained exposed.
On the other hand, the discrepancy between the US and official Japanese position might explain why the US has told its citizens to maintain a 50 mile (80km) exclusion zone around Fukushima, compared with the 20 mile (30km) zone imposed by the Japanese government
But I also believe that a series of people will make a series of decisions that will inevitably lead to nuclear power plants going totally and tragically FUBAR. As they have. Like for real. Now and in the past. We don't have to wonder if some seriously bad decisions at a nuclear plant will lead to them spewing radiation all over the landscape. We know with 100% certainty that they will. We have video.I think you're over reacting. There are hundreds of nuclear power plants all over the world. There isn't a 100% guarantee that they will all blow up, and we don't know if the area is going to be scorched for hundreds of years after this either.
There's a lot of information, misinformation, and downright unfounded hype being thrown around about the nuclear accident at the Fukushima Daiichi plant, and I'm hoping to clear up a good deal of that, using simple analogies....That was... really uninformative.
7.49pm: Jaczko's worrying comments below (see 7.30pm) are at odds with reports from the Japanese media saying that coolant continues to be added into the Fukushima reactors.The U.S. guy was talking about the pools, not the reactor. So those statements are not actually contradictory.
...
[Tepco] kept working to pump seawater into the pressure vessels of the No 1, 2 and 3 reactors of the Fukushima No 1 nuclear plant. But the water levels have not reached the top of the nuclear fuel rods, and portions of the fuel rods thus remained exposed.
Rainy: I'm not sure that's the case. How can something get hotter than the temperature of the fire? What extra energy is going into the system?Um, did you miss that it's a nuclear fuel rod? The energy comes from decay of fission byproducts, so it's internally heated. The water needs to be there to keep it cool.
The operator of Japan's tsunami-crippled nuclear plant says it has almost completed a new power line that could restore electricity to the complex and solve the crisis that has threatened a meltdown.Not heard anything about that before, but it sounds promising. Is the problem really just down to no power for the coolant pumps?
Tokyo Electric Power Co spokesman Naoki Tsunoda said early Thursday the power line to Fukushima Dai-ichi is almost complete. Officials plan to try it "as soon as possible" but he could not say when.
The new line would revive electric-powered pumps, allowing the company to maintain a steady water supply to troubled reactors and spent fuel storage ponds, keeping them cool.
Certainties of Modern Life Upended in Japan.posted by ericb at 2:20 PM on March 16, 2011 [2 favorites]
First, their report offers the hyperbole:No, all probability measures are the same. That's the whole point. The odds of a plant's core being damaged is 10 times more likely then an individual ticket purchaser winning the power ball. It is true that there are a lot of power ball winners each year, but that's because there are a lot of tickets sold.
It turns out that the U.S. Nuclear Regulatory Commission has calculated the odds of an earthquake causing catastrophic failure to a nuclear plant here. Each year, at the typical nuclear reactor in the U.S., there's a 1 in 74,176 chance that the core could be damaged by an earthquake, exposing the public to radiation. No tsunami required. That's 10 times more likely than you winning $10,000 by buying a ticket in the Powerball multistate lottery, where the chance is 1 in 723,145.
First, all statistic chances are not created equally. There are 104 commercial nuclear power plants in the U.S. (69 pressurized water reactors and 35 boiling water reactors). That means there's roughly 1 in 742 chance per year of core damage -- or roughly 1 in 7.4 chance per century of such an incident at a single plant.
By contrast there are dozens of $10,000 "Powerball multi-state lottery" winners every year and will likely be thousands of winners per century. Thus the comparison itself is a bit puzzling.
Japanese authorities have denied the claim by Greg Jaczko, chairman of the US Nuclear Regulatory Commission, that the No 4 reactor at Fukushima may have lost all its coolant.good news, unless this is cover up.
AP reports Hajime Motojuku, spokesman for plant operator Tepco, as saying the "condition is stable" at the No 4 reactor.
Several water pumps and hoses were being sent from U.S. bases around Japan to help at Fukushima, where technicians were dousing the overheating nuclear reactors with seawater in a frantic effort to cool them. The U.S. had already sent two fire trucks to the area to be operated by Japanese firefighters, said Cmdr. Leslie Hull-Ryde, a Pentagon spokeswoman.source
Japan's Chief Cabinet Secretary Yukio Edano says his government expects to ask the U.S. military for additional help. But Lapan said Wednesday that no request had been received yet. If a request were received that required troops to go within the 50-mile no-go zone around the power plant, that would be reviewed, he said.
The reason why radiation was disseminated so widely from Chernobyl with such devastating effects was a carbon fire. Some 1,200 tonnes of carbon were in the reactor at Chernobyl and this caused the fire which projected radioactive material up into the upper atmosphere causing it to be carried across most of Europe.It's not clear to me why "there is not the same flammable material present" implies "there cannot possibly be a fire which would spread radioactive material beyond a local area".
There is no carbon in the reactors at Fukushima, and this means that even if a large amount of radioactive material were to leak from the plant, it would only affect the local area.
So, um, yes it's a fucking mess. No, it's not the end of the world (just may 20 square kms of it).A circle of radius 20 km has an area of about 1260 square km, not 20 square km.
Spent fuel pools are "overmoderated." When water becomes less dense (up to a point) it can actually promote criticality. Now, all of my spent fuel pools (we're in "what I specifically do for a living" territory) are specifically designed to avoid criticality even under "optimum moderation" scenarios, like perfectly dense steam instead of 1.0 g/cc water. I'd assume their pools are designed the same way, but if they're not, or they're just acting overconservatively, use of borated water would certainly help to preclude a criticality event. That being said, criticality in the pool would be a localized effect and should be very brief, or at worse in cyclical pulses, that wouldn't be able to create any sustained energy or heat. However, it would make things much much worse for the fellows in the immediate area. They really need to get water in there ASAP....posted by ob1quixote at 4:22 PM on March 16, 2011 [9 favorites]
10.39pm: Greg Jaczko of the US Nuclear Regulatory Commission was buttonholed by journalists in Congress and pressed on his claims of no water remaining in a No 4 reactor's spent fuel pool, subsequently denied by Japanese officials. Jaczko says:ob1quixote, thanks for the info re: criticality in Storage Pools. So the pools are designed to prevent criticality - do you mean even if all the water has boiled/drained away, and the zirconium around the rods is igniting, etc?
The information I have is coming from staff people in Tokyo who are interfacing with their Japanese counterparts. I've confirmed that their information is reliable.
The NRC has 11 staff currently in Japan. Jaczko did also say: "It is my great hope that the information is not accurate."
---[ARTICLE BEGINS]--- Fukushima Fifty on whose bravery all hope rests By Andrew Gilligan, The Daily Telegraph
---[ARTICLE ENDS]---
The criticality [at Tokaimura] continued intermittently for about 20 hours. As the solution boiled vigorously, steam bubbles (see Void coefficient ) attenuated the water's action as a neutron moderator and the solution lost criticality. However, the reaction resumed as the solution cooled and the voids disappeared.Does that seem credible, other nuke geeks? Mine's trying to get himself to focus on something other than modeling fuel ponds so he can have a real life for a bit.
Unit 4 14 March, 10:08 UTC: 84 ˚C 15 March, 10:00 UTC: 84 ˚C 16 March, 05:00 UTC: no data Unit 5 14 March, 10:08 UTC: 59.7 ˚C 15 March, 10:00 UTC: 60.4 ˚C 16 March, 05:00 UTC: 62.7 ˚C Unit 6 14 March, 10:08 UTC: 58.0 ˚C 15 March, 10:00 UTC: 58.5 ˚C 16 March, 05:00 UTC: 60.0 ˚CThe IAEA is continuing to seek further information about the water levels, temperature and condition of all spent fuel pool facilities at the Fukushima Daiichi nuclear power plant.
I patiently and honestly answered the media's questions. I would like them to return the favor.posted by fairytale of los angeles at 7:01 PM on March 16, 2011 [8 favorites]
The problem with an empty tube is it probably wont stay in, the weight of the tube from the outside of the structure would be more than the weight inside and could drag it out. Or you could get a siphon action accidentially and start pulling water out of the pool.Tie a big lead weight to it.
Health and nuclear experts emphasize that radiation in the plume will be diluted as it travels and, at worst, would have extremely minor health consequences in the United States, even if hints of it are ultimately detectable. In a similar way, radiation from the Chernobyl disaster in 1986 spread around the globe and reached the West Coast of the United States in ten days, its levels measurable but minuscule.Anyway, back to the thread --
A couple days ago, I had someone who generally knows better, who is quite bright, ask me where the heck they got hydrogen at a nuke plant. Another coworker spent his weekend explaining that earthquakes do not happen because we've pumped out all the oil that lubricates the tectonic plates.Analogies can be enlightening, I suppose, but the problem is that his analogy for Fukushima #1 makes little sense even if his Chernobyl one does. How is this like leaving the car on the tracks? If anything, it's like having the break lines cut while driving a hundred miles an hour down hill, but it's totally cool because you're not stepping on the gas anymore. And all the backup safety systems are dependant on the break lines. And you're towing a U-haul filled with nuclear waste.
I think there might well be some people who require the explanations we give bright three-year-olds.
(Corium) Relocation to the lower plenum. "In scenarios of small-break LOCAs, there is generally. a pool of water in the lower plenum of the vessel at the time of core relocation. Release of molten core materials into water always generates large amounts of steam. If the molten stream of core materials breaks up rapidly in water, there is also a possibility of a steam explosion. During relocation, any unoxidized zirconium in the molten material may also be oxidized by steam, and in the process hydrogen is produced. Recriticality also may be a concern if the control materials are left behind in the core and the relocated material breaks up in unborated water in the lower plenum."I took this to mean that it was all the fuel melting together that allows recriticality, but re-reading it, she does basically say "if there's water", which I didn't see the importance of when I read it initially.
3) Can we get a criticality accident? Harder, but not impossible, and actually more likely than an explosion, but you need severe core damage for it to happen. With the control rods in and coolant limited, you have a bunch of neutron absorbers in place, and with the coolant very hot, fewer prompt neutrons are being moderated into thermal neutrons, which are the ones more likely to cause a further fissioning.posted by LobsterMitten at 9:18 PM on March 16, 2011 [3 favorites]
But if the heat becomes extremely high, the core can melt. Liquids flow, and they'll flow down into the bottom. Intermixed with that will be bits of control rod, but it'll basically be random. Get enough fuel material together, and not enough control material, and you can reach criticality. This is often hard on people nearby. It's not an automatic thing, though -- Chernobyl #4 melted down after the explosion, but the "corium" that flowed out of the reactor and into the basement didn't go critical. This release of core material was very limited, easily contained, and while it made that building suck, it didn't do the massive damage.
The core material blown out of the top of the reactor by the steam explosion, followed by the core material carried up in the ashes of the burning graphite moderator, that's what caused the massive release of radioactive materials. If Chernobyl had just melted down and flowed into the basement, we'd have been a lot better off.
Note that the graphite fire that put this stuff up into a fly ash plume that could carry for miles won't happen here, because there's no graphite to burn.
Fukushima Drinking Game Pressure rising 1 shot Edano press conference 1 shot NISA press conference 1 shot >100 mSv/hr measurement 1 shot Something dropped from sky 1 shot Temperatures rising at someplace we never heard of 1 shot Some pumping fails 1 shot Loud sound, white smoke 2 shots Evacuation 3 shots
Fukushima Drinking Game Pressure rising 1 shot Edano press conference 1 shot NISA press conference 1 shot >100 mSv/hr measurement 1 shot Something dropped from sky 1 shot Temperatures rising at someplace we never heard of 1 shot Some pumping fails 1 shot Loud sound, white smoke 2 shots Evacuation 3 shots"
0352: The temperature of Reactor 5 is now a growing cause for concern, a Japanese official reports. "The level of water in the reactor is lowering and the pressure is rising," he says.Although the bit about Reactor 4 might actually be good news if it means they can get to the spent fuel pool now.
0355: Pressure is rising again at Reactor 3, the power station operator says - Reuters. That reactor includes plutonium and uranium in its fuel mix.
0358: The US is chartering aircraft to Tokyo help Americans leave Japan - Reuters, quoting state department.
0401: Ceiling of Reactor 4 reduced to frame, power station station operator Tepco says
Although one would expect that the failure probability associated with bringing in a hose (over a period of four or more days) would be very low, it must also be remembered that working next to 385,000 gallons of potentially contaminated boiling water on top of a 10-story building is not a trivial problem.posted by LobsterMitten at 11:53 PM on March 16, 2011 [3 favorites]
7:45 CET [Comment from user charles]posted by neal at 12:21 AM on March 17, 2011 [2 favorites]
Maybe this is a little naive, but I don't understand why they're not using human-controlled robotic devices. Especially in Japan, a country that I believe leads in this technology.
7:45 CET
@Charles: Indeed, although Japan is the homeland of robotics, only France and Germany have robots specially prepared to operate in nuclear plants. The IAEA has sent a request to the countries that have robots and unmanned vehicles capable of functioning in a highly radioactive environment.
The CEO of Éléctricité de France has offered to send the French robots to the Japanese operator Tepco.
07:45 CET
This paradox is explained in this excellent article from Atlantico: "The Japanese have expended a lot of effort on personal robotics for comfort and pleasure, because that's where there's an economically attractive mass market. On the other hand, they've worked very little, maybe even not at all, on intervention robots, which still remains a niche market."
In some reactor designs [such as the ones at Fukushima] the spent fuel pools are contained within the reactor building, which is typically constructed of about 2 feet of reinforced concrete.[...]That document also says (two pages earlier):
The typical spent fuel pool is 40 feet (12 meters) deep and can be 40 or more feet in each horizontal dimension. The pool walls are constructed of reinforced concrete typically having a thickness between 4 and 8 feet (1.2 to 2.4 meters). The pools contain a 1/4 to 1/2 inch (6 to 13 mm) thick stainless steel liner, which is attached to the walls with studs embedded in the concrete. The pools also contain vertical storage racks for holding spent and fresh fuel assemblies, and some pools have a gated compartment to hold a spent fuel storage cask while it is being loaded and sealed.
The storage racks are about 13 feet (4 meters) in height and are installed near the bottom of the spent fuel pool. The racks have feet to provide space between their bottoms and the pool floor. There is also space between the sides of the racks and the steel pool liners to allow for circulation of water. There are about 26 feet (8meters) of water above the top of the spent fuel racks. [...]
[...]nearly all pools contain high-density spent fuel racks. These racks allow approximately five times as many assemblies to be stored in the pool as would have been possible with the original racks, which had open lateral channels between the fuel assemblies to enhance water circulation.
[Normal] Pool heat loads can be quite high, as exemplified by a "typical" boiling water reactor (BWR)... [An imagined case study by the NRC, a storage pool which has 3000 assemblies stored in a pool that's 35'x40'x39' with a water capacity of almost 400,000 gallons] the total decay heat in the spent fuel pool is 3.9 megawatts ten days after a one-third core offload. The vast majority of this heat is from decay in the newly discharged spent fuel. Heat loads would be substantially higher in spent fuel pools that contained a full-core offload.posted by LobsterMitten at 12:30 AM on March 17, 2011 [4 favorites]
> I'll risk pissing off the "no policy discussions" crowdBoth Jessaymn and coretex have stated this is the right place to have this discussion.
12.14pm: A Tepco official has told a press conference in Japan that radiation levels at the site soon after 9.30 am were at 3,750 millisieverts per hour, Ian Sample has just told me. "These are absolutely dangerous levels," Ian said.posted by yeoz at 5:58 AM on March 17, 2011 [1 favorite]
Power cable to the #Fukushima Daiichi No.1 Nuclear power plant is connected.posted by yeoz at 6:02 AM on March 17, 2011
12.37pm: Speaking of which, Kyodo is also reporting that Tokyo Electric Power Company has said the water shots we saw being administered earlier have been effective "in cooling fuel pool as steam rose", so perhaps the process is more efficient than it looked.posted by yeoz at 6:14 AM on March 17, 2011
nuclear fission releasing lots of particles which leads to direct exposure to radiation, including electro-magnetic radiation.The English language NISA website is useless.
'I am writing my name down, knowing I will be abused and hurt because of this. There are people working to protect all of you, even in exchange for their own lives.'She describes the work that she and fellow employees performed at the plant following the earthquake:'
'Watching my co-workers putting their lives on the line without a second thought in this situation, I'm proud to be a member of Tepco, and a member of the team behind Fukushima No. 2 reactor.
'In the midst of the tsunami alarm (last Friday), at 3am in the night when we couldn't even see where we going, we carried on working to restore the reactors from where we were, right by the sea, with the realisation that this could be certain death,' she said.'Otsuki adds, "I hope to return to the plant and work on the restoration of the reactor."'
'The machine that cools the reactor is just by the ocean, and it was wrecked by the tsunami. Everyone worked desperately to try and restore it. Fighting fatigue and empty stomachs, we dragged ourselves back to work.
'There are many who haven't gotten in touch with their family members, but are facing the present situation and working hard.'
13:22 Kazuko Yamashita was five when the atom bomb was dropped on Nagasaki. She now lives in Tokyo and she's sanguine about the risk from the Fukushima nuclear reactors.posted by sokkupapetto at 7:19 AM on March 17, 2011
I may be a bit too callous about this due to the fact that I was really heavily exposed to radiation, but I don't think this is anything to turn pale over.
People seem to be much too sensitive, though of course it's not really for me to say, and heavy radiation exposure is a serious thing. But I was 3.6km (2.2 miles) from the bomb, and they've evacuated for 20km. I really don't understand this kind of feeling.
Then Columbia crashed on re-entry. The risk assessment was wrong, minority views were discounted and ignored.Actually the people who were worried were not that worried. It was more of a "hypothetically, theoretically something bad could happen. And if something bad did happen, there is nothing we could do about it anyway"
AFP reported a Twitter message by a woman who said her father, just six months from retirement, had decided to offer his help.posted by ericb at 7:52 AM on March 17, 2011 [6 favorites]
"I fought back tears when I heard father, who is to retire in half a year, volunteered to go," the message read.
"He said 'The future of nuclear power generation depends on how we'll cope with this. I'll go with a sense of mission'... I've never been more proud of him," she added.
A core team of 180 emergency workers has been at the forefront of the struggle at the plant, rotating in and out of the complex to try to reduce their radiation exposure."*
In the first place, Japan's plants are better constructed with significantly more attention to safety and levels of accident defence. Although Fukushima is ranked by the International Atomic Energy Agency as an accident at level 6 (Chornobyl was 7), its consequences have been greatly reduced by the containment levels over the reactor.The consequences so far have been less. We don't know yet what the final consequences will be, especially if the pools, with no containment, can't be brought under control.
[11:35 a.m. ET Thursday, 12:35 a.m. Friday in Tokyo] The Pentagon says it is offering voluntary evacuation flights to all U.S. military family members on Japan's main island of Honshu. Pentagon spokesman Col. Dave Lapan said the potential number of evacuees could be in the thousands. Military family members will be flown to the United States on commercial aircraft, commercial charters or military aircraft as necessary, Lapan said.posted by ericb at 8:54 AM on March 17, 2011
[11:24 a.m. ET Thursday, 12:24 a.m. Friday in Tokyo] The U.S. Embassy is making 600 seats available on buses to evacuate Americans from quake-stricken Sendai, Japan, to Tokyo. Buses will depart Sendai City Hall at 9 a.m. Friday and again at 9 a.m. Saturday if seats remain, the embassy said in a statement on its website.
[11:14 a.m. ET Thursday, 12:14 a.m. Friday in Tokyo] Stars and Stripes reports that the U.S. military on Thursday began voluntary evacuations for families and dependents on four bases in Japan: Atsugi Naval Air Facility, Yokosuka Naval Base and the Army's Camp Zama, all near Tokyo, the Misawa Air Base in northern Japan. Non-essential workers will also be allowed to leave.
Fukushima Will Be a Wastelandposted by saulgoodman at 9:40 AM on March 17, 2011
Scientific American's David Biello judges Fukushima to have reached Chernobyl proportions. Steve Mirsky reports
Danger of Spent Fuel Outweighs Reactor ThreatThere's been some discussion throughout this thread about what the counts of spent fuel rod assemblies versus spent fuel rods, active fuel rods, etc., at the site are. This seems like a pretty clear statement of the facts.
Some countries have tried to limit the number of spent fuel rods that accumulate at nuclear power plants — Germany stores them in costly casks, for example, while Chinese nuclear reactors send them to a desert storage compound in western China’s Gansu province. But Japan, like the United States, has kept ever larger numbers of spent fuel rods in temporary storage pools at the power plants, where they can be guarded with the same security provided for the power plant.
Figures provided by Tokyo Electric Power on Thursday show that most of the dangerous uranium at the power plant is actually in the spent fuel rods, not the reactor cores themselves. The electric utility said that a total of 11,195 spent fuel rod assemblies were stored at the site. That is in addition to 400 to 600 fuel rod assemblies that had been in active service in each of the three troubled reactors.
It depends on the power history of the specific core or batch of fuel. I can only describe the process of getting that #... Fission products build up based on length of time at a power level and decay away based on physical properties. Reactor engineers at plants carefully monitor core power with time. They need this info for fuel reloading & reporting. When I did fuel pool safety analysis (fuel drop accidents) we'd make conservative assumptions so we'd bound reality.The original querent then asked "How close was your model to reality? Enough to predict with a degree of certainty?:, to which Arclight replied:
I didn't do reactor engineering work but yes, we were accurate enough that operations could use our numbers. There's an interplay between the operations staff (guys who touch the equipment) and engineers who analyze & design things; Ops takes a lot of data & compares it to predictions, that data is used to make better predictions, etc. This is why these sorts of accidents are very difficult to deal with - we lost a lot of monitoring to tell us plant state."Querent then asked how you produce response strategies in the absence of real data; the response was "You make a lot of models & a lot of assumptions, develop a plan & run field exercises & fix what you find broken."
In the event that normal circulation of the cooling water is disrupted, e.g., due to station blackout, pump failure, pipe rupture, etc., the water temperature of the pool would steadily increase until bulk boiling occurred.... Even in the most pessimistic case ... the water level in the pool would drop only about 6 inches per hour. Thus, there is considerable time available to restore normal cooling or to implement one of several alternative backup options for cooling.Severe Accidents in Spent Fuel Pools, in support of generic safety, V.L. Sailor, et al, Brookhaven National Laboratory. Issue 82. July, 1987.
On August 21, 1984, the Haddam Neck plant experienced a failure of the refueling cavity water seal with the refueling cavity flooded in preparation for refueling. The refueling cavity water level (23 feet) decreased to the level of the reactor vessel flange in about 20 minutes, which flooded the containment with approximately 200,000 gallons of water. The leak developed when the pneumatic seal assembly was forced out of the normal position as a result of static water pressure. The pneumatic seal assembly remained intact but was extruded through the gap for about 25 percent of its circumference.They weren't actively moving fuel at the time, fortunately.
US support was based on dismantling the troubled reactors run by Tokyo Electric Power (TEPCO) some 250 km (155 miles) northeast of Tokyo. However, the government and TEPCO thought the cooling system could be restored by themselves, the report said.The most dire interpretation still makes sense...
« Older I was doing some research on Dryads when I stumble... | Ferris Bueller's Day Off: re-c... Newer »
This thread has been archived and is closed to new comments
posted by furiousxgeorge at 9:10 PM on March 12, 2011