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back to article Japanese gov makes Fukushima evac zone compulsory

Japanese authorities have elected to make a recommended evacuation zone around the damaged Fukushima Daiichi nuclear powerplant compulsory and ordered residents of some communities beyond the zone to evacuate, despite the fact that radiation levels beyond the plant fence are dropping steadily and are nowhere such as to cause …

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Hmm, who to believe?

In the blue corner, a journo who spent the week after the tsunami saying the situation couldn't possibly get worse. And every time he said it, things got worse.

In the red corner the people who are having to deal with it on the ground

Tricky one that.

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Stop

Wuh?

It got worse?

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not much choice

Since the journo is basing his story on the facts delivered by the people on the ground, you're not leaving us with much of a choice is it?

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WTF?

Bollocks

Ok on one hand we have reports that not all of the reactors have been stabilised (one with large cracks in the casing) with potential remaining for meltdown, leading the government to escalate the severity of the incident ...

... and on the other hand we have Lewis telling us its all fine and they're scaremongers because the current reported radiation levels *outside* of the plant are low.

Hmmm.

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Anonymous Coward

title

Large cracks in the casing? Yet can still hold pressure...

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They're melting down the cores

If you had bothered to look at facts before you started ranting, you would've seen that the temperatures of all three cores have been hovering somewhere between 100 and 200°C for the past weeks. Hardly a temperature at which your beloved meltdown would be possible.

Same goes for the 'leaky' #2 containment. The spilling has been dammed off and They're planning to close the leak in the coming weeks.

You know, it's not for nothing that the govt send recovery-crews into the evacuation zone a while ago. They would've never risk the lives of people to recover dead bodies. That's a basic fact of all rescue/recovery work.

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Ahhhh, good. Lewis is back

<sarcasm>

with his hard-hitting Fair and Balanced(TM) factual reporting.

</sarcasm>

Sponsored by the Nuclear Energy Institute, I presume?

http://www.nei.org/

Or perhaps the UK Nuclear Industry Association:

http://www.niauk.org/

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Happy

@ Anonymous Coward - Sponsored by Czech radon spa & wellness Jachymov

http://www.laznejachymov.cz/en/programms/detail/radonova-kura//

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BP Gulf of Mexico Accident

How does this measure up against the oil drilling accident last year?

11 people killed during the accident

countless animals and sea organisms killed by the oil pollution

livelihoods wrecked

continuing human and wildlife ill-effects from the lingering pollution.

Measured on the same scale as a nuclear accident, that's got to be a 10 surely??

And, it was caused by cost cutting / incompetence not an almost unprecedented natural disaster...

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Sssh!

Be quiet! They're sleeping the sleep of the righteous. They don't want to be reminded of last year's disasters, especially not in the context of pleading for a bit of perspective on the part of the fearmongers, most especially not when last year's disasters weren't made out of nuclear demons, which every God-fearing righteous person knows are the satraps of Satan. How dare you seek to snatch the torches and pitchforks from their hands?

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Personal experience re: radiation casualties

My family in Eastern France was heavily affected by the Chernobyl fallout.

One of my cousins died of leukemia as a result of the fallout. Doctors determined that the source of radiation was a rainstorm when he was outside.

My aunt, who works a small farm, was similarly affected and had to have her thyroid removed. So where thousands of other people in the region.

The point is, it's not just about the radiation levels measured, but also the risk of localized high exposure due to atmospheric transport. The later is much worse and rather unpredictable. Eastern France was heavily impacted by highly localized concentrations of fallout, some of which was higher than the Ukraine evacuation zone. There are still places where you can't use the milk or grass to this day.

And, before you say "this isn't Chernobyl - it's not a burning reactor" - sure, but it's stuff that has a nasty tendency to evaporate (e.g. h2o). It may not be quite as bad, but if it takes 9 months to clean, how much is going to evaporate, esp with a ready heat source (never mind the weather).

Of course, Lewis believes it's perfectly safe, which is easy to preach when you're 6000 miles from the danger. IMHO, it's much better for the locals to play it safe, even overly safe, rather than be sorry after the fact.

Not bashing Lewis or even nuclear power, but I also think that a dose of reality is required and nothing is more real than death.

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Just FYI...

H[2]O isn't radioactive. It doesn't matter how much water evaporates, because the evaporating water isn't the problem--it's the stuff that's floating around in that water, which is not especially inclined just to bugger off into the air whenever it likes. The vapor pressure of heavy ions in water is not very impressive.

The Chernobyl fire, I wish to add, was no ordinary graphite fire. The RBMK-1000 is a very large reactor, and contains hundreds of tons of graphite. When graphite burns, it burns extremely hot, and when hundreds of tons of it are on fire, all full of molten reactor parts, it's not a pretty picture. Evaporating water vapor is no good at carrying relatively dense radioactive materials into the air, but a plume of graphite-powered hellfire that burns for nine or ten days is quite adept at sending particles of soot and dust, contaminated with radioactive substances because that soot came directly from the same flaming heap that contains the remains of the fuel rods, high into the atmosphere. You will never find a fan that's as good at moving air as that fire was, nor a better way of dispersing dust laden with little bits of radioactive materials than a big, hot column of fire.

The end result is that a nontrivial fraction of the mass of the fuel went straight into the atmosphere--It actually produced about four hundred times more fallout than the Hiroshima bombing! For Fukushima Daiichi to reproduce this effect would require the construction of quite an impressive bonfire.

Your closing line, by the way, is kind of ironic since the only deaths recorded at either of the Fukushima sites have been from blunt force trauma of one sort or another.

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This isn't Chernobyl.

...but not entirely because it isn't a burning reactor, though it also isn't Chernobyl because of that. This isn't Chernobyl because the wind swept the fallout plume straight out over the planet's widest ocean, which diluted the fallout so thoroughly by the time it reached North American shores that even the New Scientist didn't try to pretend it was anything other than barely detectable with the most sensitive instruments available. I don't pretend it is remotely desirable to contaminate even the planet's largest ocean with radioactive debris; on the other hand, I also don't imagine the problem to be more than the large-scale, though low-mortality, industrial accident that it is.

It's also not Chernobyl because evaporation of water is not going to produce radioactive steam: water contains fallout but, absent direct neutron activation which is not happening here, does not become fallout. Since the radioactive particles in the water, mostly isotopes of cesium and iodine, are heavier than the water molecules themselves, the water won't carry the fallout with it as it evaporates. (Evaporative purification also lies at the heart of most processes used in the desalination of seawater. Also, I'm not any kind of chemist, but I'm pretty sure a chemist wouldn't slap me for describing it the way I just have.)

I don't believe Mr. Page is arguing that it's "perfectly safe" or that people in the vicinity of the Fukushima plant should behave exactly as they ordinarily would; any large-scale industrial accident is likely to contaminate the surrounding countryside, and Fukushima is no different. As far as I can tell, Mr. Page has been arguing around two major points: first, that this accident has at no point approached the scale of the Chernobyl disaster; and, second, that as with every nuclear accident since the Chernobyl disaster, this is a large-scale industrial accident which, for no good or sensible reason whatsoever and to great human and economic cost, is being treated as though it portends the very wrath of God.

That may sound like a sarcastic and cynical exaggeration, but it is nothing of the sort; as Mr. Page and many others have, over the last month, been at great and lengthy pains to illustrate, when an oil rig blows up and dumps enough oil into the water to all but slaughter an entire sea, it's old hat to anyone not directly affected before the headlines have even had time to die down. But when it comes to a nuclear incident -- *every* nuclear incident, no matter the details -- the gloves come off, the forebrains are shut down, and people behave exactly as did Middle Ages peasants when confronted with the terrible specter of Satan walking up and down in the land.

Compared to that, what's a brand-new dead and toxic sea? Compared to that, what's a mere ten thousand or so people killed and as many over again left unaccounted for in a completely forgettable natural disaster on an utterly disinteresting scale equalled by only a very few such totally banal events in recorded human history?

But there's a bigger problem. One way or another, whether the peak oil theorists turn out right or the AGW folks get their way, we're almost certainly going to be burning less oil fifty years from now than we are right now, and the decline will continue as time grinds on -- and natural gas is finite, too, even if there is a fair bit more of it left to dig up. (And even if the oil'll never run out and global warming isn't and ice cream rains from the skies, it's still not like exhaust fumes are *good* for anybody.)

We obviously can't wait fifty years to start bringing new generation capacity online, whichever mix of technologies we turn out to use. Wind and solar might be to a point in fifty years where they can sustain a significant amount of baseload power generation, or they might not; I'm not knowledgeable enough even to pretend I have a guess one way or another. But I do know they aren't there right now and aren't going to be ten or twenty years from now, either.

Right now, solar and wind put together don't even supply three percent of the world's actual energy consumption, and they still haven't gotten over the problems of the sun going down every night and the wind going this way and that: wind and solar are *interruptible*, which is a pretty big problem (especially for forests, and also for cities) when it means you can't run your space heater at the coldest time of the night, and a very big problem when it means a hospital can't run the extremely power-hungry equipment it uses to keep people not dead, and a goddamned enormous problem when it starts telling on our capacity to keep people fed.

So, because wind and solar are interruptible and because there are many processes, some immediately or eventually critical to human life, which aren't, we can't implement those technologies without putting a separate, conventional technology in place to supply power when the clean'n'green plants are forced offline by utterly ordinary environmental conditions. (Or, at any rate, we can't do that unless we *want* a lot of people to die pretty damn quick, and a lot more to die a lot sooner than they otherwise would.)

Right now, natural gas is often used to backstop wind and solar, because natural gas can be made to work much more reliably; on the other hand, if we're talking about a future in which carbon emissions are radically curtailed -- and, one way or another, it seems that we are -- then we can't assume natural gas or any other petrochemical fuel will be available or acceptable as a backstop technology. That leaves dams, needing rare (and mostly already populated) favorable geography, and tending to kill far more people than any reactor when they fail; geothermal, needing favorable geography and just not up to much in terms of raw output; wave power, which I'm still convinced is nothing more than some engineer's perverse joke that got far too far out of hand; and nuclear, which is reliable and renewable and can be made to be quite clean -- but only, I'm convinced, once we start coming up with governments with brains and backbone enough to say, and make stick, that some things are too damned important and too damned dangerous to be used for making money on.

Because that, I remain firmly convinced, is the root of the problem. A company like TEPCO isn't doing nuclear; they're doing money, and nuclear is just a tool with which they've chosen to do it. If that tool isn't fit for purpose, it'll be ground down until it does the job -- which, again, lest we forget, as with any for-profit corporation, is money. That's why they fucked it up, both in Japan and at TMI. (Windscale and Chernobyl do not figure into this particular evaluation; graphite piles without meaningful secondary containment -- even a mope like me can say those people did not start to know what the fuck they were doing.) If we can replace the private nuclear industry we have now with people who are just doing nuclear, who are very good at nuclear and absolutely unshakeable on the point of maximum possible safety, and who don't have to worry about money at all, we almost certainly won't have these problems.

Of course I didn't come up with all that myself; unless I'm very much mistaken, it is another point lately made in these Pages, with the suggestion that the people required be drawn from the engineering departments of the various nuclear navies, and employed by a tax-funded agency with absolute, unquestioned, and *sovereign* responsibility over every reactor and every significant mass of active material in a jurisdiction coterminous with the boundaries of the nation in which it's organized. (In the US, this might be a third civilian uniformed service, but one I think without precedent in the breadth of its authority and responsibility -- if done right, at least.)

Not that I'm well equipped to evaluate such a proposal on the merits, of course; I'm basically nobody, but I'm a reasonably clever nobody, and in light of the problems with zero-emissions generation technology, it sounded like a damn good idea to me.

I don't want to seem unsympathetic about the harm the Chernobyl disaster did your family and many others. I don't know, of course, but I like to hope I'd say the same thing if I lived downwind from a nuclear plant, or if I lived downwind of Fukushima. (Though admittedly I'd have to be living on an anchored ship or a stationary houseboat or something.)

And I agree that a dose of reality is required. Here's hoping my attempt at same has been helpful.

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Who, then, shall do it?

"If we can replace the private nuclear industry we have now with people who are just doing nuclear, who are very good at nuclear and absolutely unshakeable on the point of maximum possible safety, and who don't have to worry about money at all, we almost certainly won't have these problems."

I agree with your comments, and am in sympathy with them, except for the part about replacing what we have now. Because if it isn't a business making energy, it's either a government or a priesthood of some sort. Neither governments nor priesthoods have a good record of staying on-mission.

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I'm open to a better suggestion

I would sure as hell rather entrust the responsibility to a government agency than to a for-profit corporation with a powerful incentive against maximal safety built into its very nature. I certainly do not want a nuclear priesthood. I don't like any of those options particularly, but government is the one of them I dislike least, and this is far from a perfect world. But I'd love to hear about any plausible fourth alternative you've come up with.

And, to clarify, I'm not talking about handing over the entire generation industry to the Nucleonics Service or whatever it'd end up being called; to vaguely paraphrase whoever I ripped off the idea from, everything from the turbine hall out can belong to a company and be run for profit, but the reactors themselves *must* be operated and maintained by an agency which, all the way up the line, is made out of people who are there to do nuclear, instead of using nuclear to do money.

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Anonymous Coward

Hand it over to the scientists and the prices become uncompetitive

Hand it over to the scientists and the industry dies because the prices become uncompetitive, because the prices are determined by construction and operation costs, not by fuel costs.

Dead in the water (so to speak) either way. Might as well accept it sooner rather than later.

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@ Aaron Em - the fourth alternative

The problem is perhaps not so much who should be entrusted with responsibility to run the nuclear industry but who is available to staff it and how many people have any real understanding of the science behind it.

While the UK had been up with the world leaders in the early days of the nuclear engineering,.in the decades since North Sea Oil and the Dash for Gas the industry has been in serious decline. Other than a small number of graduates who see a career in weaponry, there has been hardly any new blood going into the industry.

As in other areas, rigorous democratic accountability would provide appropriate safeguards. But this requires both that processes and procedures should be open to inspection by the 'thousand eyes' of the general public and also that people as a whole have sufficient comprehension of the issues and the technology to make sense of what they see.

Now that nuclear weapons are somewhat outdated there is no longer any great need for secrecy. The problem then comes down to how to teach the basics of nuclear science to the general public and to encourage a new generation of engineers and scientists. If comments on El Reg are a guide, this is likely to be a long haul.

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Scientists?

I'm talking about handing it over to the engineers.

David Pollard's point, on the other hand, I find compelling.

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Joke

"I certainly do not want a nuclear priesthood"

But... "Church of the Children of Atom" sounds nice...

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Naah

Got better things to do than worship a lump of two-hundred-year-old unexploded ordnance, thanks.

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Terminator

Time to consider just building the reactors on large floating platforms

Easy Cooling, easy failsafety, lots of shielding around, easily defended against terros and greens.

Rogue waves, electricty transport, damage due to sea environment and fuel rod logistics would be a problem though.

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Heart

THAT'S BRILLIANT

LET ME JUST GO CALL THE NOBEL COMMITTEE

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Stop

The scary thing about cancer...

@Si 1 "...anyone who gets cancer doesn't automatically sue the government and Tepco for billions of yen?"

The scary thing about cancer, is that at least 30% of the population is going to come down with cancer anyways.

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E 2

The fat lady has not sung yet.

What I said in the title.

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Flame

"oil drilling accident last year?"

That oil drilling accident was rather messy wasn't it. Still, at least till the Yanks and their hangers-on cut down on their gas guzzlers so that there's enough affordable oil left for petrochemical feedstocks for them and maybe a bit left over for the rest of the world, the world has little option but to continue drilling for oil. No cheap oil, no cheap petrochemicals, no cheap transport. No cheap petrochemicals, no agribusiness. No cheap petrochemicals, no cheap plastic. No cheap transport, no globalization. No globalization, no global finance business. Think about it for a nanosecond or two.

Meanwhile, are there any alternatives to nuclear electricity? Starting with nice low tech low cost options like basic energy efficiency measures in commercial and industrial premises in the West? No, you're quite right, it can't possibly be done, it would probably involve creating local jobs for local people.

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And then

after the wind mills are installed , we have weather like we've had in the past 2 months

Nothing like a nice blocking high pressure system to generate electricity from wind

perhaps if we put green party supporters in hamster wheels we could generate power

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Not without precedent

"perhaps if we put green party supporters in hamster wheels we could generate power"

Well, they were building treadmills in prisons as far back as two centuries ago. Obviously far ahead of their time!

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FAIL

WTF does this have to do with radioactive hot springs in Iran or background radiation in Madras?

So Mr. Page dug up the places on Earth where people are exposed to the highest known levels of naturally occurring background radiation, then proceeded to conclude that everything is fine in Fukushima?

More false parallels. The radiation in Fukushima isn't coming from hot springs in the ground or any other naturally occuring, steady, low-level emissions source. It's coming from a fucking man-made nuclear power plant that suffered multiple explosions, contaminated tap water as far as Tokyo, spewed radioactive cesium all over the ground, and is still not under control. Periodic massive spikes in radiation exposure have occurred, uncontrolled leakage of radation into the ocean has occurred, and the plant lies in ruins, shattered concrete and twisted rebar all over, containment bolts blasted loose, etc.

http://www.youtube.com/watch?v=rpN8VQ_UL4c

Like it or not, any part of that plant could suffer an unforeseen malfunction at any time.

Mr. Page's argument is tantamount to standing in a wildfire evacuation zone saying "the smoke exposure here is less than what someone gets who smokes a 2 packs a day of unfiltered cigarettes in Iran every day for a year, and I don't see the government of Iran banning cigarettes. Therefore this evacuation zone is bullshit. Pay no mind to the negligible soot in the air or the houses burnt to the ground a few miles down the road."

Am I glad that things in Fukushima appear to be gradually coming under control, and radiation doses are (thankfully) not catastrophically high to the surrounding population? Most certainly. It is my most fervent hope that Fukushima comes under control soon and the whole thing is either shitcanned under concrete or safely rebuilt and run under even higher safety standards in future. Japan has little choice but to use nuclear power on a large scale. And once things come under control, no doubt we will be treated to more self-congratulatory crowing and preening from the likes of Messrs. Orlowski and Page.

But dodging a bullet doesn't mean getting shot at is safe. And long-term, nuclear power is not less dangerous than coal, oil, wind, solar, etc. It is immeasurably more risky and dangerous. The argument is not about how many people have or have not died or gotten ill due to nuclear accidents, or how effective safety precautions have been thus far over the brief period of time that humanity has used nuclear power. The argument is about looking at the ramifications of the worst-case scenario. Chernobyl gave us a good long look at that, and now Fukushima has given us another glimpse.

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Eh... So, what *is* the worse that can happen?

Quoted: "And long-term, nuclear power is not less dangerous than coal, oil, wind, solar, etc. It is immeasurably more risky and dangerous."

But based upon what? Quantify it for me. In what way is nuclear *more* dangerous long term? Or, because it's immeasurable, that it can't be measured, but surely -- nod, nod, wink, wink -- it's more. It.. it's just GOT to be!

As far as I can tell, the question about "What's the worst that could happen"? Is not answered, especially not from the people who are fretting about the worst that can happen, but being scared about the answer to that question is already worse than what has happened.

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Can we get a missed-the-point icon please?

WTF does this have to do with radioactive hot springs in Iran or background radiation in Madras?

Simple: the naturally occurring radiation exposure in those locations is higher than at Fukushima but no one is being evacuated from there. Oh, I forgot that's "natural" radiation so it's alright.[/SARCASM]

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Grenade

Missed the point?

Cpt Blue Bear: "Simple: the naturally occurring radiation exposure in those locations is higher than at Fukushima but no one is being evacuated from there. Oh, I forgot that's "natural" radiation so it's alright.[/SARCASM]"

No, it's not that simple. It is unlikely that the hot springs in Iran will suddenly display a temporary spike in radiation thousands of times normal or start spewing radioactive cesium all over the ground. My point, which you clearly missed in your blind haste to triumphantly thump your chest, was not that naturally occurring radiation in the two locales Mr. Page dug up on Wikipedia was any the less harmful for being naturally occurring. My point was and is that the Fukushima plant is not under control and has blown up several containment buildings (but not to worry, says Mr. Page, that's a design feature) and has spewed tons of radioactive water into the sea (but not to worry, says Mr. Page, if you pee in a large enough swimming pool no-one will notice) and has in general exhibited no signs of stability just yet (but not to worry, says Mr. Page, we should look for our guidance on radiation safety levels to countries where stoning adulterers and pooping in the street are still the norm). The reason there is an evacuation zone in Fukushima and not Madras is there is a nuclear plant that just blew up and puked radiation all over the place in Fukushima, and not Madras. As to whether the Iranians or Indians should evacuate areas where the populace is exposed to higher than normal levels of radation, that is another question entirely. It is a question of resources, policy, governance, etc. for those countries, and has fuck-all to do with whether or not it is safe to go scarfing down the cesium-tainted produce outside the gates of a nuclear power plant with three reactors suffering compromised fuel integrity and unknown containment integrity. I hope that makes it "simple" enough for you, Captain.

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Boffin

(untitled)

It is on the other hand highly unlikely that the background radiation in those places will ever subside. This in contrary to Fukushima....

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More Axe Grinding by Mr. Lewis

The evacuations are probably not so much for the current levels of radiation, but to reduce the loss of life if any one of many possible catastrophic situations releases far higher amounts of radiation.

But it is more convenient for Mr. Lewis axe grinding arguments if he simply ignores this possibility.

We are several weeks into the disaster and they have barely made any progress towards getting this actually under control. The entire plant is too radioactive for the workers to actually do much to fix the problem. Robots had to be used recently just to make a survey, and they found lethal levels of radiation in large areas of the plant.

We still risk a huge steam explosion spraying huge amounts of lethal radiation if molten material ever contacts ground water.

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WTF?

Fascinating

"We still risk a huge steam explosion spraying huge amounts of lethal radiation if molten material ever contacts ground water."

[Citation needed]

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And how do you imagine that steam explosion is to come about...

five weeks or more post shutdown?

Take ten minutes and think about how much heat's actually being generated now - and how much was generated in the hours immediately following shutdown, when fuel rods failed, but (from the isotopes found) little or no actual fuel melted.

Then think how, if there wasn't enough heat to penetrated reactor vessels then, quite how you'd produce enough now.

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As long as things are out of full control, there are catastrophic consequences possibile

If the pile continues to melt and/or oxidize, the nuclear materials can concentrate below the control rods and thus the reactor can reach critical levels and get so hot it melts through the concrete / steel enclosure. This could happen in a fairly catastrophic way.

It would then hit ground water and make a huge explosion.

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FAIL

Oh for feck's sake

Why don't you try learning about how this reactor works instead of spouting nonsense?

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Geoffrey Swenson - simply not so

Geoffrey,

No, that's simply not the case.

even were the remaining fuel to slump to the bottom of the RPV, it's now simply not generating enough heat to cause significant damage - as I said, in the order of 5MW.

Even some very basic heat transfer calculations would tell you that the rate of heat removal (conduction and subsequent convection) into the containment would easily remove that, with even interior temperatures got getting much over the normal operating temperatures (in the order of 300C).

I'll point out that Three Mile Island saw worse conditions, including slumped fuel, without significant penetration into the RPV wall - something of the order of 10mm in a 200mm wall thickness. A BWR is less prone to this than a PWR, simply because the bottom head of the RPV has multiple penetration spigots (for control rods etc), which prevent the formation of a single mass, even were there to be a full-scale melting of the core.

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I hope you're right about this

While I have a long disused degree in mechanical engineering I don't know the specifics of this particular plant in a way that I could make accurate-enough heat transfer estimates. I was only quoting the concerns of one of the scientists interviewed on the Rachel Maddow show during her coverage of the early unfolding disaster.

I did know that TMI was way worse, in some ways, than what we were originally led to believe. The reactor reached a state that was predicted o be at risk of a melt down. The only thing that saved us from that consequence was these calculations about how the pile would melt and go back to criticality were too conservative, so the melting and the concentration of nuclear material in the resulting unplanned experiment was considerably less than the predictions.

I don't know for sure if we would get as lucky for this ongoing unplanned experiment into new modes of nuclear-related heat transfer and degradation. I also wonder what is going on with all of the corrosive salt from the desperation seawater cooling used right after the disaster, which is something that we have no experience of whatsoever.

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A question to Andydaws

Every now and again somebody raises the fear that if the fuel melts it can lead to a criticality excursion.

I just don't see how it could possibly happen in a LWR with low-enriched fuel (even if it will all melts and pools down at the bottom - where will the moderator be?) but would appreciate if Andy could opine on that. Thanks.

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Boffin

Vladimir,

Quite right.

Recall, there are two forms of criticality - on fast (unmoderated) neutrons, and "thermal" neutrons. The capture cross sections of uranium and plutonium for fast neutrons are much smaller than those for thermal neutrons -in the order of 500-1000 barns for thermal neutrons (dependent on the exact energy), and 1 barn for fast neutrons.

Which means that you need much higher enrichment for fast criticality than thermal. For a fast reactor you need around 40% enrichment, for a typical typical thermal plant 2-3% (and there are some designs will run on unenriched uranium, 0.7% u235).

It's very hard to see how you'd still have moderation in a bolus of melted fuel, so if it were to be critical, it'd have to be on fast neutrons - and since the fuel is only 3% enriched, that's not about to happen.

Ideas of ongoing criticality depend on the idea that the fuel is still in a configuration that allows adequate moderation - again, it's hard to see how that would be the case where the fuel is uncovered (there'd be too much neutron leakage above the core, and probably inadequate moderation due to boiling around the parts of the elements still covered.

The other argument was that there was criticality within the spent-fuel ponds - again, hard to imagine how, given that the fuel there would be heavily contaminated with absorbent poisons (that's why it would have been taken out as spent).

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Silver badge

Thanks, Andy

That is quite clear now.

I wonder, what the downvoter on your post meant - does he disagree with the theory or numbers (in that case why not explain what the problem is) or is he just cross that you have taken his mental scary toy away...

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Happy

You're welcome.

As to the downvoter, God knows....

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FAIL

Given that Mr Page always knows -

to his own satisfaction at least - what is safe and what is not, and that he has deemed the region within a radius of 20 km from the Fukushima Daiichi plant to be quite safe, I suggest that he be issued a white coverall and put to work in the teams attempting to deal with the disaster in situ. And do please put a stamp in his passport preventing him from visiting Chennai !...

Henri

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@ mhenriday

As I've said before, if Reg readers will be so good as to organise a fund for airfares and subsistence, and assuming he is also willing, I'd be happy to join Lewis Page in a trip for a couple of weeks in the 20 km zone.

Perhaps those with political/diplomatic connections might also do a bit of groundwork so that we could be allowed to deliver water and feed to those of the farm animals that have been abandoned and aren't yet dead.

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Stating the obvious

I don't understand.. perhaps I am too "illogical"....why there is so much self righteousness from the pro- nuclear side. OK yes, the world will recover from this, yes, other forms of power also have risks, etc, balance of risks and gains in energy policy...

But to be honest it wasn't very good was it? It's kind of amusing watching people falling over themselves to avoid saying this!

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Happy

There's plenty of surplus food for him to find

Why should we bother with his substinence, he can hunt for his own food, or eat the crops that are not being harvested if he really thinks they are that safe.

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I'm up for that, too

Can we have an allowance to drink sake under the cherry trees in Fukushima province?

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precautionary

With regard to this article, surely the reason for the evacuation isn't because of the current levels of radiation, but because there's a possibility of a large sudden increase in radiation if something goes rapidly very wrong at one of the reactors. Or as the Japanese government put it - it's "precautionary".

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Stop

Why doesn't TEPCO rotate its workers with workers at its other plants every 2 weeks?

Why doesn't TEPCO rotate its workers with workers at its other similar plants every 2 weeks?

It is an outrage that they've got these guys there, making them sleep in their contaminated suits, lying next to one another on a gymnasium floor, no proper food, no proper sleep.

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