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Chain Reactions Reignited At Fukushima
mdsolar writes "Radioactive byproducts indicate that nuclear chain reactions must have been burning at the damaged nuclear reactors long after the disaster unfolded. Tetsuo Matsui at the University of Tokyo, says the limited data from Fukushima indicates that nuclear chain reactions must have reignited at Fuksuhima up to 12 days after the accident. Matsui says the evidence comes from measurements of the ratio of cesium-137 and iodine-131 at several points around the facility and in the seawater nearby."
That is all.
Sensational!
If you melt the fuel, you can get localized criticalities.
Comment removed based on user account deletion
http://www.energyfromthorium.com
We have no one to blame but ourselves for any accident that happens when a safer, cleaner, more efficient, and cheaper nuclear fuel is readily available and already has most of the hard problems with its implementation worked out through several running prototypes.
Has the Gas Effect contributed to the disaster? Its one of the least understood parts of nuclear reactions, fussion/fission and radiation, we need more funding for Gas Effect research.
More and more I see the attempt to design and operate Nuke plant as a very dangerous game of Whack-a-mole. Operator error, Wham, Design error, Wham, Maintenance failure, Wham. Earthquakes. Wham. Tsunamis, Wham. Terrorism, Wham,
and, what do we do with the waste for the next 20,000 years? Wham, Wham, Wham, Wham........
Miss one time, game over.
Kurt
If the reactors had been successfully scram'd completely, heat from decay of by-products would have burned out in a very few days. As became obvious, that didn't happen.
I saw that movie. Not only does it end well but its got Neo in it. Don't worry. There is no spoon.
Seriously though... that's scary. It might not be Chernobyl but this has got to be the worst nuclear disaster of its type. Although since they're in Japan wouldn't it be called the South America Syndrome? (polar opposite of Fukushima is Chile)
Nobodies Prefect
Tidbits for Techs Technology Blog
How, without a moderator?
My understanding is that LEU (low-enriched uranium) cannot achieve criticality without a moderator to slow down the neutrons?
Can anyone with a nuclear physics/engineering background give any explanation of how you can get a chain reaction without moderator?
Ok, they were cooling the reactor with water, and water is a moderator, but the water was also boronated, which should cancel the moderation property of water, shouldn't it?
I've looked through the paper this report is based on http://arxiv.org/PS_cache/arxiv/pdf/1105/1105.0242v1.pdf and I don't see much discussion of the amount of power generated by the proposed post-shutdown criticality. It seems to me that standard operating power is assumed but I don't see how that could work without other signs such as a glowing reactor building.
Join the World Community Grid/Harvard Clean Energy Project.
And don't say you don't have a computer.
Orwell: "In a Time of Universal Deceit, telling the Truth is a Revolutionary Act"
The fictional reactor they developed in the movie "Chain Reaction" as an cavitational sonofusion device. If you can't tell the difference between fission and fusion, please refrain from muddying the waters. And no matter what, never, under any circumstances remove the sands.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
I've been watching the nuclear industry for a long long time, since they publicly announced come watch the test in Nevada next Monday, come to the viewing area at........ back in the 1950's in fact. They always have had newer better safer technology to replace the old dangerous crud.
Child of innocence wake up!
As well as that there has been some speculation that the explosion in unit 3 was more than just a hydrogen explosion. If you compare the unit 1 and unit 3 explosions, you see the unit 3 was far larger in magintude, plus there is a flash right where the spent fuel pool is located. Also pieces of nuclear fuel rods were found 2 km from the site. Arnie Gundersen speculates that this was caused by a "prompt criticality" in the fuel pool, triggered by the hydrogen explosion. http://fairewinds.com/updates
One big issue I see is that the assumption is 7 to 9 months of fuel usage. In block 4, the fuel in the pond was probably significantly older.
This seems like a stronger argument than the current paper.
"The decay heat, which is 7% of 1000 MW"
IIRC, the reactors were 1000MW *electrical* output. Because of thermal efficiencies of steam generators of around 35%, I believe that means the thermal output of each reactor would have been about 1000/.35 ~= 2800 MW thermal energy.
So, instead of 7% of 1000MW = 70MW, I think you're looking at 7% of 2800 = 196MW.
That's a LOT of heat to get rid of, even if it is a small percentage of the 2800MW full output.
There are reactor designs that currently exist that are more resilient to meltdowns.
i have to say that the article is interesting, but as far as i understand the fuel in the different reactors is different and has undergone a quite different history.
The data and evaluation seems a little weak to me in that respect.
I see that you were modded down, but please know if I had 5 I'd give them to you.
If that's true, then there should be some evidence for this assertion other than merely that the unit 3 explosion was bigger than the unit 1 explosion.
So what you're saying is:
It was the worst natural disaster in Japan's history, one that was the perfect storm of conditions, all affecting an ancient design of plant which was NOT designed to handle such disasters, and yet despite this- still to this very day- has not had a substantial meltdown (some radiation leakage is not crowd on the beach in Melbourne)... and you're *complaining*?
Inevitable car analogy is as follows. If I own a regular Toyota Prius, there's a reasonable expectation that if I get into a fender bender I won't die. It's engineered to tolerate that. The car may be a write off, but I'm fairly safe.
But if a TANK shoots my Prius? Well, then I'm fucked. I'll die and it's *not Toyota's fault*, much less the fault of the automotive industry at a whole. You accept that, right? You accept that anything built by anyone, ever, is built to a limited amount of tolerance, and beyond that failure is not the fault of the manufacturer, let alone the whole industry?
In this metaphore, a tank shot my Prius in the engine block... and to the astonishment of most the Prius fucking TOOK IT. That armour-piercing tank shell bounced off like a motherfucker, leaving a huge dent, and shaking the car so I wacked my head, but hey. I'm alive and whole. I walked away after the worst imaginable thing happened, far beyond the design specifications of the vehicle. Yeah, there was a little blood-slash-radiation leakage from my head, but it's not that bad. I could have a concussion. I should probably get checked out, but it could have been MUCH worse. Furthermore, I am astounded on how this Prius is eating tank shells. That's some serious engineering work right there. Damn, dog... ... and yet, people are still like, "Oh, but I'm bruised a little bit, it didn't protect me completely. Priuses are so unreliable!"
Seriously.
Tank.
Prius.
Tepco might be incompetent lying morons, but the reason why the old plant was still around was in no small part because of anti-nuclear fear-mongering ("Not in MY backyard!"). That's the reason that newer, far more safter, reactors are not everywhere. Because constructing new nuke reactors is verboten, like we're still in the 70's or some shit.
If we treated nuclear power with the respect it deserves, keeping the technology up to date and learning from our mistakes... then we can progress.
Check out my sci-fi book "Lacuna" at http://goo.gl/MVxX8
He says they should be able to tell for sure by analysing the smoke from the explosion. However, that data has never been made public.
Err, the water is a moderator, not a reactor. Mental hiccup.
I feel bad for it, but I can't help but wish—just a little bit—that we'll get Godzilla out of this.
You didn't know? The whole earthquake and nuclear reactor incident is just a cover story for Gojira's fight with Destroyah and his subsequent meltdown...
Bow-ties are cool.
Prompt criticality would be suspiciously like an atomic bomb, because that's how they work. But it seems like there was only very minor fallout, of short-term fission products (iodine, etc), which indicates that it just released existing product.
Perhaps the explosion was larger because there was more hydrogen? Also, don't underestimate the power of explosions like that - Chernobyl's steam explosion threw (much heavier) graphite moderator blocks a tremendous distance.
I have developed a truly marvelous proof of this comment, which this signature is too narrow to contain.
Low-Enriched-Uranium doesn't go boom. Period.
"I do not agree with what you say, but I will defend to the death your right to say it"
When did the word "alarmist" start carrying a negative connotation? I'm no etymologist but I'm pretty sure "alarmist" meant "the guy that rings the alarm" at first.
Imagine that you were hired as the Chief Alarmist in a nuclear plant back in the 60's. Back then everyone would thank you for manning the alarm and keep them safe. But 50 years later, everyone thinks you're total nut-case and it's become the worst job in the world.
"However, that data has never been made public."
Does that "data" even exist? Did anyone sample the smoke, or take some sort of optical spectrometry measurements or some other methods of data collection?
Perhaps it was, but I wouldn't necessarily assume that in the midst of a crisis, that when an unexpected explosion happens, that anyone has the equipment on hand or the time/opportunity to take such measurements?
I very much doubt this, since the both the steel and concrete containment of block 3 are still intact. I think the difference may have been due to the difference of the outer shell, which was not made out of reinforced concrete in the case of block 1. Also, the power of block 3 was around double the one of block 1, so it is possible that more hydrogen was produced. On top of that, the hydrogen accumulated for two days longer in block 3 than in block 1.
Ah, just saw that a criticality in the spent fuel pool is claimed. This is also most unlikely. First, if this would have happened anywhere, it would have been in the spent fuel pond of block 4, which had much more fuel stored. Secondly, this was far too big an explosion for a criticality - the energy generated by a chain reaction would immediately boil the moderator and stop very quickly again. Thirdly, a massive amount of neutron radiation would have been measured in that moment - but it wasn't. I think very minor criticality events may have happened from time to time, which might explain the results of the article. It would also explain the dozen or so detections of neutron radiation at very low intensity.
In the grand scheme of the accident, I don't think it played a role.
The explosion wasn't unexpected, it happened after the unit 1 explosion. It's quite ridiculous to suggest they wouldn't be monitoring a serious event like Fukushima.
...is why the fuck don't they have several large, sturdy-built, earthquake-resistant water towers at these nuclear plants so that even if they can't get their backup generators running to pump in cooling water after an emergency shutdown, that they could simply open some valves and allow some gravity-fed water from the towers flow down into the reactor to finish cooling it off after the scram shutdown?
I guess thinking of a water tower is just too damn complicated and incomprehensible of a solution for those sophisticated nuclear plant engineers to think of, eh?
Time to consider LFTR Molten Salt Reactors
http://energyfromthorium.com/
http://en.wikipedia.org/wiki/Molten_salt_reactor
Also pieces of nuclear fuel rods were found 2 km from the site
No credible sources have corroborated that claim. The NYT wrote a story that claims a 'confidential assessment' by the NRC 'suggests' that 'fuel fragments or particals' 'may' have been blown up to one mile from the site.
No fuel fragments have been found at two miles, two kilometers or any other large distances from the site. This is NRC speculation, as selectively interpreted by the NYT and exaggerated by various pundits, including Arnie Gundersen, who has since become the most cited source of this 'fuel rods found at 2 km' claim, and the 'prompt criticality explosion' theory, which has no support elsewhere either.
Arnie is a useful source of insight into Fukushima. Not everything Arnie says is gospel. When there is any room for doubt Arnie always adopts the worst case in his speculation. That is his job; he is a professional advocate for anti-nuclear interests.
The inevitable retort is that fuel was shot out for miles and TEPCO, the Japanese government, Bush and everyone else is covering it up. At that point you're a conspiracy theorist that has abandoned credible information.
I read somewhere that the reactors were equipped with steam injectors which use the pressure of the steam in the reactor to inject cooling water into them, do we know why they were not used?
He is trying to determine the reactor stop time to within 12 days, when the uncertainty on the fuel lifetime (which is necessary to determine the expected I/Cs ratio) was 5 months?? Crazy. How about doing some basic error analysis and putting some error bars on those wretched data points?
Also, any explanations of why there are so many outliers in the data? Something with the analysis method -- or the basic underlying assumptions therein -- is inaccurate.
Interesting that he is measuring the isotopes at reactor 2 and spent fuel pool 4 and suggesting that this didn't happen elsewhere.
NB. Reactor 2's containment system has been breached - Reactor 1 and 3's haven't been.
And Spent fuel pool 4 is the heavily loaded one - the most likely one to have boiled dry, had fuel damage, and thus had small pockets of criticality.
Reactor 1's level of fuel damage is considered to be highest:
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
In all likelihood, there have been pockets of criticality throughout all four problem reactors (the 3 operating reactors + the spent fuel pool at #4). As pointed out elsewhere, this is not very surprising.
The main risk, e.g. that there would be sufficient fuel damage and water loss that the fuel would melt and form a puddle in the bottom of the reactor or fuel pool, and then have a critical explosion, did not occur, hence while this is still a serious nuclear event, it is nowhere near as severe as Chernobyl.
Good analysis. The real problem is that a lot of the rampant speculation around what has happened/is happening revolves around how closely Tepco has held information about what is going on at Fukushima. These days, a vacuum tends to create conspiracy theories.
I'm sure the people of Japan will be pleased to know that you believe this is not significant.
It's certainly a relief to me!
TVA coal ash disaster covered an estimated 1.2 square kilometeres...
The Martin County coal sludge spill polluted 500km of the Tug Fork River...
okay it wasn't 1200 square kilometers, but it wasn't nothing and it doesn't include any buffer regions...
Or at least Raymond Burr in a Speedo.
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
The scientific method in general terms consists of observation, then hypothesis, then designing an experiment to prove the hypothesis. You are arguing "shouldn't it" and closing your mind to the understanding of the observed results - it doesn't matter what it "should" and "shouldn't" do under current models - what is important is what it actually did. Which means that either a) there were conditions that we don't know about that enabled the reaction or b) there are additional underlying scientific principles that we don't fully understand yet.
You know, in actual practice, scientists don't abandon their theories just because a single experiment contradicts them. Galileo didn't give up heliocentrism when confronted with the stellar parallax problem; in fact, he took up heliocentrism in spite of it. Einstein didn't give up on the theory of relativity because of Kaufman's 1905 experiments; he held on to it despite the experimental contradiction.
Are you adequate?
Glad to be of service and put your mind at ease.
actually, LEU can still go boom, it just requires a far larger critical mass than is practical for making bombs. A reactor however has plenty of mass for such an event. Even more so since as the reactor operates, it enriches the fuel... Granted the yield / yield % effective will be really low, but one doesn't need a very high efficiency with 100 tons of fuel to make a pretty big boom. Even the equivalent of couple of tons of TNT is a pretty nasty explosion, never mind 10 kilotons... Anyone who wants to know what 1 ton of TNT does, watch the myth-buster episode where they take on a cement truck.
-=Geoskd
I wish I had a good sig, but all the good ones are copyrighted
Prompt criticality would be suspiciously like an atomic bomb, because that's how they work. But it seems like there was only very minor fallout, of short-term fission products (iodine, etc), which indicates that it just released existing product.
Perhaps the explosion was larger because there was more hydrogen? Also, don't underestimate the power of explosions like that - Chernobyl's steam explosion threw (much heavier) graphite moderator blocks a tremendous distance.
The size of the explosion was only part of the issue. Two other issues also contradict a hydrogen-only hypothesis. The first is the bright orange flash at reactor building 3. Hydrogen burns/explodes translucent. This can be seen with the explosion at building 1: No fireball, but massive and highly visible shock-wave. That had all the hallmarks of a hydrogen explosion. Issue two was the shaped nature of the second explosion. Both the primary (probably hydrogen) blast, and the anomalous orange flash had a distinct upward vector, indicating that some factor was tamping these explosions upward. These two observations together suggest the spent fuel pool, or the primary containment. As there are lots of reasons to believe the primary containment is still intact, this leaves the spent fuel pool as the next most likely candidate.
-=geoskd
I wish I had a good sig, but all the good ones are copyrighted
Actually, when you 'see' a propagating shock wave from an explosion, you are seeing the change in index of refraction of the air as it is compressed and rarefied. It is similar to the mirage over a hot road. At that point, there is no fuel involved.
Mostly, with massive explosions, the debris and smoke is scattered closely enough behind the shock wave that you cant see the optical effects of the wave. With a translucent explosion, however...
-=Geoskd
I wish I had a good sig, but all the good ones are copyrighted
Here is a video that may help. Perhaps the shock is igniting fugitive hydrogen. http://www.youtube.com/watch?v=IlS6535HBNk
It's worth noting that other parts of the world were sampling as soon as it became evident that there was a problem with Japanese reactors. If a "prompt criticality" event happened, it would be seen by a number of parties, including some NGOs and academics, even if Japanese weren't monitoring or revealing the results of their monitoring.