Why is Fukushima nuclear crisis so threatening?

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andybwell said:
"Stochastic effects are those that occur by chance. Stochastic effects caused by
ionizing radiation consist primarily of genetic effects and cancer. As the dose to an
individual increases, the probability that cancer or a genetic effect will occur also
increases. However, at no time, even for high doses, is it certain that cancer or
genetic damage will result. Similarly, for stochastic effects, there is no threshold
dose below which it is relatively certain that an adverse effect cannot occur."

Truly terrifying.

http://140.194.76.129/publications/e...5-1-80/c-3.pdf

Someone has likened it to playing Russian roulette. It wouldn't be so scary, except for the fact that if you are exposed and you know it, you spend a good part of your life thereafter wondering if the gun went "click" or "bang".
 
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Physics news on Phys.org
apropos threat:

If the SFP at reactor 4 collapses and fuel/concrete mess covers the area, will it still be possible to approach the reactors with humans?

If any SFP gets leaky and runs out of water, will the contamination of burning fuel make the plant area unapproachable?

If they fill the overflowing trenches with concrete as announced, won't the accumulating highly active water eventually flow over the area and seep its surface with contamination?

Any good articles about such questions available?

(TIA for infos, links etc)
(Hope it's the correct thread to ask this.)
 
Atomfritz said:
apropos threat:

If the SFP at reactor 4 collapses and fuel/concrete mess covers the area, will it still be possible to approach the reactors with humans?

If any SFP gets leaky and runs out of water, will the contamination of burning fuel make the plant area unapproachable?

If they fill the overflowing trenches with concrete as announced, won't the accumulating highly active water eventually flow over the area and seep its surface with contamination?

Any good articles about such questions available?

(TIA for infos, links etc)
(Hope it's the correct thread to ask this.)

To your first two questions: if the fuel overheats and melts in any of the pools, for any reason, it's going prompt critical, almost for sure. If that happens, you'll wish it was just burning.

To question three: yes (unless they pump it out).
 
zapperzero said:
To your first two questions: if the fuel overheats and melts in any of the pools, for any reason, it's going prompt critical, almost for sure.

Why? If it melts there's no water. If there's no water, there's no moderator for a chain reaction.
If it's unused fuel, a criticality is more likely. But why should it melt then? There are no fission products generating heats inside those.
 
zapperzero said:
To your first two questions: if the fuel overheats and melts in any of the pools, for any reason, it's going prompt critical, almost for sure. If that happens, you'll wish it was just burning.

To question three: yes (unless they pump it out).

To me the worst case scenario (not much discussed in medias for obvious reasons, but I think clearly foreseen by some experts) was (and maybe still can be) a level of contamination outside of the containments which would force humans to retreat from the site, then of course we can imagine the worse domino effect with situation degradation on site and radiation worsening, disabling any possibility for operations with humans without complete sacrifice.

Even if the containments are breached, most of the fuel is still right now under water (SFP) and shielded by big amounts of concrete in the reactor buildings. If a fair amount of fuel is exposed outside on the ground (SFP explosion or fall, core explosion, etc.) then no more shielding and the worst case scenario above would probably happen. This would be even worse if some re-criticalities could happen (big discussions on the forum to know if it can happen, and even if it locally happened, by the way).

With the amount of fuel in the plant (reactors + spent fuel), and a situation completely out of human control if no human presence possible, one could imagine that the location could become so dangerous than maybe even the Daini site (12 kms away) could be difficult for humans to stay. Then who knows what could happen...

This is a real worst case scenario, with worst domino effect, to answer your question. We were not so far from this with the Attic SFP, big luck that none complety exploded exposing the fuel on the ground.
 
jlduh said:
To me the worst case scenario (not much discussed in medias for obvious reasons, but I think clearly foreseen by some experts) was (and maybe still can be) a level of contamination outside of the containments which would force humans to retreat from the site, then of course we can imagine the worse domino effect with situation degradation on site and radiation worsening, disabling any possibility for operations with humans without complete sacrifice.

Even if the containments are breached, most of the fuel is still right now under water (SFP) and shielded by big amounts of concrete in the reactor buildings. If a fair amount of fuel is exposed outside on the ground (SFP explosion or fall, core explosion, etc.) then no more shielding and the worst case scenario above would probably happen. This would be even worse if some re-criticalities could happen (big discussions on the forum to know if it can happen, and even if it locally happened, by the way).

With the amount of fuel in the plant (reactors + spent fuel), and a situation completely out of human control if no human presence possible, one could imagine that the location could become so dangerous than maybe even the Daini site (12 kms away) could be difficult for humans to stay. Then who knows what could happen...

This is a real worst case scenario, with worst domino effect, to answer your question. We were not so far from this with the Attic SFP, big luck that none complety exploded exposing the fuel on the ground.

Quoted 100%. I would just be a bit more definitive on conclusion. SFP4 collapsing (or draining out) would have conclusively led to uncontraollable domino effect.
The closest thing I can imagine to apocalypse.

I think G. Jazco was sharing our vision last march the 16th.

I do not want to see such a nightmare at risk of unfolding ever again.
 
"my advice to friends that if there is a severe aftershock and the Unit 4 building collapses, leave (Tokyo)."


"Individuals have sent Fairewinds some car air filters from Tokyo and they turn out to be one of the ideal ways of measuring ways of radiation, because they trap a lot of these hot particles. And had one person with seven filters and they ran a body shop or something and five of the filters were fine. And two were incredibly radioactive. So what that tells me is that the plume was not regular and you’ll have places where there was not much deposition and you’ll have places where there was a lot of deposition. That same thing happened up to the north, but within Tokyo it seems like wherever the official results were being reported didn’t really represent the worst conditions of the plume. And I saw that on Three Mile Island – we shouldn’t be surprised that a plume meanders and a plume may miss a major radiation detector by a quarter of a mile and not be detected. It doesn’t mean it’s not there, it means we just didn’t detect it."



"you can’t put the concrete at the top (of 4) because you will collapse the building and it’s so radioactive, you can’t lift the nuclear fuel out. I used to do this as a living and Unit 4 has me (Arnie Gundersen!) stumped."


[link to us1.campaign-archive1.com]
 
zapperzero said:
Somewhat. The idea of recriticality in spent fuel pools is still up in the air, close to being discarded, in fact.

Arnie Gundersen: "Unit 3 may not have melted through and that means that some of the fuel certainly is lying on the bottom, but it may not have melted through and some of the fuel may still look like fuel, although it is certainly brittle. And it's possible that when the fuel is in that configuration that you can get a re-criticality. It's also possible in any of the fuel pools, one, two, three, and four pools, that you could get a criticality, as well. So there’s been frequent enough high iodine indications to lead me to believe that either one of the four fuel pools or the Unit 3 reactor is in fact, every once in a while starting itself up and then it gets to a point where it gets so hot that it shuts itself down and it kind of cycles. It kind of breathes, if you will."
 
andybwell said:
No sign of stabilizing the situation.

I don't see what this comment is based on. For me if the last phrase of the comment was "situation seems stable at the moment" it would be worth exactly the same.
 
clancy688 said:
Why? If it melts there's no water. If there's no water, there's no moderator for a chain reaction.
If it's unused fuel, a criticality is more likely. But why should it melt then? There are no fission products generating heats inside those.

With 3 or 4 full reactor loads in each pool, melted fuel could very easily gather together into a shape that makes _some_ of it go prompt critical; explosive disassembly etc etc... Even just 10 kg of Uranium fissioning all at once can ruin your day in a very comprehensive manner.

Bombs don't need moderation. Some advanced designs do use reflectors. Uranium is such a reflector.

Unused fuel would melt from the heat generated by the used fuel that's burning, surely? So would the borated plastic sheets that serve as neutron absorbents for the fuel racks...
 
zapperzero said:
With 3 or 4 full reactor loads in each pool, melted fuel could very easily gather together into a shape that makes _some_ of it go prompt critical; explosive disassembly etc etc... Even just 10 kg of Uranium fissioning all at once can ruin your day in a very comprehensive manner.

Bombs don't need moderation. Some advanced designs do use reflectors. Uranium is such a reflector.

Unused fuel would melt from the heat generated by the used fuel that's burning, surely? So would the borated plastic sheets that serve as neutron absorbents for the fuel racks...

No, it couldn't. Bomb's do not need moderation but they do need 90+% enriched U-235 or Pu-239. Even fresh fuel only has maximum 5% enrichment. The average ~0.8% fissile material remaining in spent fuel could not form a critical mass without correct moderation and geometry, even ignoring the parasitic absorbers also present.
 
andybwell said:
"you can’t put the concrete at the top (of 4) because you will collapse the building and it’s so radioactive, you can’t lift the nuclear fuel out. I used to do this as a living and Unit 4 has me (Arnie Gundersen!) stumped."

Gundersen used to what as a living, exactly?

http://atomicinsights.com/2011/02/arnie-gundersen-has-inflated-his-resume-yet-frequently-claims-that-entergy-cannot-be-trusted.html
 
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It's like we're living in an imaginary World.
The Government knows that if they don't tell you, there won't be a problem.
Covering it in mud and clay is like sticking your head in the sand. Or is it like the three monkeys, hear no evil, see no evil, speak no evil? Or how about just sweeping it under the rug.

No matter how it's produced, cesium will eventually enter the environment. Become part of the food chain and we will eat it, breath it, or absorb it into our derma.

Now that everyone has determined the hazards, and the potential for exposure and spread throughout our planets environment. Ask yourself, do I really know how much cesium has been dump on the planet?

Lets say for instance that after WWII there was a race for technological dominance. The cause was to spread freedom to win out over the evil cruel empires, this was called "the Cold War".

In that great effort, scientist developed a cloaking device to make it's surveillance aircraft virtually invisible to enemy detectors. This miracle discovery was a top secret fuel additive. Code named "Panther Piss" now known as cesium.

Let say that after 30 years of operation, 30 billion pounds of this fuel was burned in the upper atmosphere and then it was discovered that cesium enters the food chain.

What do they say to the governed? The answer is SILENCE.
 
Sled Head said:
It's like we're living in an imaginary World.
The Government knows that if they don't tell you, there won't be a problem.
Covering it in mud and clay is like sticking your head in the sand. Or is it like the three monkeys, hear no evil, see no evil, speak no evil? Or how about just sweeping it under the rug.

No matter how it's produced, cesium will eventually enter the environment. Become part of the food chain and we will eat it, breath it, or absorb it into our derma.

I don't know how you live knowing that every time you eat salad, you consume Potassium-40. That every second in your body 4000 radioactive decays happen, and some of them damage your genes in your cells. HORROR.

Now that everyone has determined the hazards, and the potential for exposure and spread throughout our planets environment. Ask yourself, do I really know how much cesium has been dump on the planet?

Yes. It's not very hard to calculate caesium content in all spent fuel in F1. Total release can't be more than that.

Lets say for instance that after WWII there was a race for technological dominance. The cause was to spread freedom to win out over the evil cruel empires, this was called "the Cold War".

In that great effort, scientist developed a cloaking device to make it's surveillance aircraft virtually invisible to enemy detectors. This miracle discovery was a top secret fuel additive. Code named "Panther Piss" now known as cesium.

Let say that after 30 years of operation, 30 billion pounds of this fuel was burned in the upper atmosphere and then it was discovered that cesium enters the food chain.

What do they say to the governed? The answer is SILENCE.

Nonsense. Caesium is not a poisonous material.
 
Wikipedia says "Although the element is only mildly toxic, it is a hazardous material as a metal". That is for the non radioactive metal.
 
r-j said:
Wikipedia says "Although the element is only mildly toxic, it is a hazardous material as a metal". That is for the non radioactive metal.

It is not in the metallic form, so it doesn't matter.

Sodium in metallic form is dangerous, reacts vigorously with water, plenty of videos of sodium explosions on youtube. At the same time kitchen salt - which is a sodium compound - is quite inert. Same with cesium.
 
Does the dangerous radioactive cesium form inert compounds as well?
 
r-j said:
Does the dangerous radioactive cesium form inert compounds as well?

Cesium reacts very much as the other alkaline metals such as sodium or potassium, forming similar compounds.
Indeed, the metal is taken up by plants and animals in substitution for potassium, which is why potassium soil enrichment has been proposed as a way to reduce the crop contamination in the affected areas. It is also possible to flush the cesium from the body, as the replacement time in muscle tissue is about 3 months, unlike the calcium equivalents such as strontium that get incorporated into bone.
 
petergreat said:
I don't understand. How can a nuclear plant accident produce more radioactive fallout than an atmospheric nuclear explosion? No nuclear test has ever triggered panic around the global fearing radioactive dust spread by wind.

There are more radioactive materials such as coolant, structure and fuel material.
It's more radioactive than nuclear weapon in amount.
 
law&theorem said:
There are more radioactive materials such as coolant, structure and fuel material.
It's more radioactive than nuclear weapon in amount.

I think after 140 posts the original question has been thoroughly answered. :biggrin:
 
r-j said:
Does the dangerous radioactive cesium form inert compounds as well?

In general, chemistry of the radioactive isotopes is not different from the chemistry of the non-radioactive ones.
 
If Fukushima incident is not very threatening, would it be safe to live in tokyo (several hundreds km away)? I wonder if there will be some long term effects just like the nuclear remains in chernobyl...
 
luben said:
If Fukushima incident is not very threatening, would it be safe to live in tokyo (several hundreds km away)? I wonder if there will be some long term effects just like the nuclear remains in chernobyl...

Afaik, there are several well settled areas on Earth where background radiation is comfortably above that needed to give a 20 mSiv/yr dose. Deleterious effects have not been documented in those cases, either short or long term.
So there is a real measure of hype in the current Fukushima coverage.
My guess is that the risks of living in Tokyo, where a large earthquake is reasonably probable within the next three decades, is not materially altered by the contamination from Fukushima.
 
Mother Nature built a naturally occurring radioactive isotopoe, C14, into our DNA for some reason.

See Asimov's "At Closest Range"
 
etudiant said:
Afaik, there are several well settled areas on Earth where background radiation is comfortably above that needed to give a 20 mSiv/yr dose.
Where are these places? Is the radiation from cesium?
 
r-j said:
Never you mind, I found it.

http://sums.academia.edu/Mortazavi/...f_the_problem_and_the_need_for_future_studies

Ramsar in Iran is the poster child for high radiation sites, but there are similar situations in China, India and Brazil. These all involve large areas, not point sources. Afaik, the radioactivity driver is usually thorium bearing minerals, not cesium, whose short half life makes it decay in a blink of an eye geologically speaking.