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Japan Suffers its Worst Nuke Plant Accident Ever 283

Cy Guy writes "I'm sure there will be many more stories on this soon, for now, here is the wire story." An update sent in by cheetah: "It appears that someone mixed about 6 times too much uranium into a fuel processing tank. For the latest info click Here"
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Japan Suffers its Worst Nuke Plant Accident Ever

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  • Close, but the particles don't have to be charged.
  • by Anonymous Coward
    I live 60 km away from the accident. Luckily, I'm upwind...

    There's one thing that the Japanese couldn't give a damn about and that's health and saftey. I'm a metallurgist employed in the most prestigous Japanese research institute and my job for today is to degrease some metal swarf for next week's experiments. I ask for some degreaser, expecting something aqueous and safe. I get a dusty old bottle of acetone. I ask for a fume cupboard. I get a blank look. I ask for any ventilation at all. I might as well have asked how to stop all these earthquakes.

    They wear sandals in machine shops. They plasma spray next to 55 gallon drums of inflamable solvents. I've yet to see a face mask or earplugs being used near any of the high volume, high energy processes we use.

    Whenever there's a health and saftey inspector dropping by, he'll phone us a week or so ahead, so that we can make sure he doesn't see anything that might embarass us. We ask him which laboratories he'll be inspecting, then move all the lethal shit to the other labs. I won't mention the azide explosion that put two people in hospital, or the insecticide that made my friend ill for two weeks, or what happened to the kidneys of a chemist working in Toyko.

    Jesus H. Fucking Christ! I'm leaving as soon as I can, in 8 months time.

    And ask for the degreaser, I'm popping home to get the citrus stuff I use on my bike chain. Its safe and its works. There's no chance I can get anyone here to use it.

  • The electrons are mostly from beta decay associated with radioactive by-products of fission. These electrons come away with alot of energy. Compton scattering doesn't transfer too much energy to the electron (think about the mass difference -- photons have none, so it is very hard to exchange momentum and energy with a free electron -- although photons can kick electrons out of atomic orbit with some energy).
  • Plastic explosives produce neutrons?
    If that's all it took, any dork with access
    to explosives could build an H-bomb,
    you still need fissile materials to
    set off a bomb.
  • Water also is a positive feedback loop for a reactor. As the water heats up it expanses and allows more high energy neutrons to escape which causes a slow down in the reaction which generates less heat which cause the water to cool down which moderate more neutrons which speed up the reaction which generates more heat ...... Feedback. That's negative feedback. Postive feedback would be if heated water caused the reaction to grow stronger and would result in a completely runaway reaction. Negative feedback causes a system to stabilize at a given level. Unfortunately, in this case the level is still way too 'hot'. At any rate, water is used as a stabilizer precisely because of this behaviour. Its helpful in keeping a reaction from getting out of hand too easily.
  • If I were in charge I wouldn't tell people the whole truth. Nuclear accidents have a tendency to be downplayed for many years after the actual accident (as in China Syndrome). This helps both calm the people and provide a better outlook at your skills as governer or whatever.

    If there really was a big problem, telling the whole world they were about to die wouldn't be on your agenda. Just let people live in ignorance is soooooooooo much better than the alternative.

    If you don't agree, then I heavily suggest you never vote for me if I decide to run for office.
  • The danger posed by the nuclear meltdown comes in three forms:

    Washing is extremely effective against Alpha radiation, which are just large enough that they can't penetrate your skin. In fact, you get alpha radiation poison either by inhaling the stuff or eating it down.

    Beta is easily stopped by object, it's just a bunch of flimsy electrons anyways.

    Gamma, well, IIRC, uranium based reactors don't create a lot of this stuff, it's them plutonium based reactors that make this stuff in droves...

    Let's say if you can see your outline burned in the ground from gamma radiation, you're screwed. :)
  • Exactly, if this happened next door to me, my first thought would be to get in my car and drive as fast as I could until my gas tank was empty. (Perhaps even steal a faster car.)
    In a populated area the effects of this could be worse then the accident itself.

    I've always worried about that with reagards to Seabrook Station here in New England. Apperently the evacuation plan involves the people coming from the beach to actualy drive towards the plant for a short stretch to get on roads that could handle the traffic. I honestly beleve that police would have to start shooting at people to inforce this.
  • What, I'm a CS major, not a phys major! It's not as if I can do most of this without a couple weeks of research.

    Of course I'm also not afraid to be ignorant(too much)

  • Isaac Asimov's Foundation series had one stage of the Foundation deal directly with this problem. The (dang what was the name of the professor again, Henry Sobol?) answer to having uneducated people deal with the dangers of nuclear reactors was to use theological rules and constructs to instruct them how to use safe nuclear procedure.

    The only difference I assume between this and a tolalitarian society is that the nuclear device is preached as the punisher of not wearing the priestly nuclear suit, rather than the government.
    ^~~^~^^~~^~^~^~^^~^^~^~^~~^^^~^^~~^~~ ~^~~^~
  • Aside from the =amazing= technical ignorance (I can just picture the alpha, beta and gamma radiation sneaking out of the building when no-one's looking), this accident is extremely serious, but highlights something else, too. TEN TIMES background, on a good day, in the surrounding area? What's that been doing to the food chain? It doesn't just sit there and pose for the photographers. My sympathies to the workers & the local population, but maybe this will cut into the pervasive complacency over safety.

  • Another point is that there is no standard design for nuke power plants. Every time we build one, its a whole new design. If someone would settle on a design, then we could study it and make it much safer. Then we could learn from our mistakes and next year (decade, whatever) when we build all the new plants, they'll all be "version 1.2, with bugfixes".

    The US Navy cites this as one of the reasons they don't have problems with their nukes (at least none that they've told us about). The Navy has a singular basic design that they've refined and exacted, plus they've got a talent base that knows how to operate _all_ their reactors.

    Think if all US nuke power plants were the same basic design, then experts from one facility would be instantly usefull in diagnosing problems at another.

    Someone should start a "safe nukes" movement...


  • Not entirly true. IIRC, an H-bomb works on the principle of having hydrogen ( mostly hydrogen, with various amounts of deterium and tritium, which are isatobes of hydrogen ) The trick is to speed up these elements fast enough to cause the colisions to fuse the hydrogen to helium(needs to raise the temp of hydrogen to 4x10^7 K). I know that this was done originaly with a Plutonium sphere, somewhat similer to the fat man bomb. It is theoreticaly posible to do this without a fission reaction(the sun is a good example of this), BUT it would take a lot of work. I believe they use plastic explocives to set off a small fission reaction, which in turn produces the fusion reaction. I believe that the first H-Bombs derived about 80-90% of the effect from the fusion, but now it is a LOT higher. As far as the nutrons go, they realy dont matter, the only thing that you need from the fission reaction is the heat it can produce
  • I could be mistaken, but I remember reading that this blue light is the result of when a particle in a medium travels faster than light in the same medium.

    (before I get flamed: the "speed barrier", c, refers to light in a *vacuum* (which is impossible, btw, thanks to the uncertainty principle). Light travels slower in any medium (but 1 atm air tends to be "vacuumy enough" that it's very close to c).).

    I remember on /. a while back about how someone managed to force light to travel at a snail 60mph or so. If in that medium, something was travelling faster than it, you'd witness this radiation. Probably happened because the particle was bombarded with gamma radiation.
  • Well, last I checked, they had a team draining the water. They had also brought in 300lb of (insert subsatce who's name escapes me here) to try to calm things down a bit, but couldn't figure out how to get a person in close enough to use it.

    Actually, I just checked CNN [] again and the reference to the substance was gone. The site did say that the water had been drained off and that RAD levels were way down.

    Footage at 11.

  • but compared to prior years, 1999 has been pretty tame in terms of 7+ magnitude quakes..
    front story. []
    ch art of quakes in 20th century []: requires login. shows only 11 (i guess it would be 12 including today's quake in mexico) in 1999, with the average being just under 20, and 1943 being the most active year with 41 total 7.0+ quakes.
  • ... were they using 16 kg of the stuff when they know that can produce a criticality?
  • I think this would be against the spirit of the awards, since these people caused so much external damage. Darwin Awards are (IMHO) meant for those who produce a net benefit to society by removing themselves in amusing ways without hurting others.
  • There's also a matter of national pride, and the military angle. Almost every major country has its own designs for nuclear reactors. It keeps the bug utilities happy, and they make generous contributions to politicians. Amazing.

    Instead of light-water reactors, why doesn't everyone use heavy-water ones, like the CANDU? With that design, if you lose cooling water the reaction stops instead of running out of control. Sounds like a good idea to me. Also (until a spate of recent problems; I'm not sure how it is now) CANDU reactors have held many of the top spots for uptime and performance.

  • /* begin sarcasm */

    That reminds me, I heard of a coal mine exploding recently from a buildup of methane gas in Montana.

    I also have a feeling some of the more extreme technophiles/ conservatives are going to chastise us for being alarmed by *this* sort of accident. Generally, after a coal mining mishap, the pattern goes like this:

    1) BOOOM
    2) a number of people are rushed to the hospital
    3) liberals run around screaming "Look how awful coal Is!"
    4) conservatives tilt their Laz-e-boys up a notch, puff on their pipes, and make devastating comments about "Luddites"

    Wait, 3 and 4 don't happen. I'm sorry. I guess hundreds of coal workers dieing every year just isn't as news worthy as 19 Japanese people with radiation burns. Millions of Tobacco smokers dying horrible deaths is maybe as news worthy, but just barely.

    Well then, at least watching the tape of the Space Shuttle Challenger and its seven deaths was enough to convince me never to go up into space. Never mind that that is less than the average number of high school kids that die in drunk driving accidents over a four year period of a high school. Lets have a party!

    /* end of sarcasm */
  • Unlikely. The maximum allowed is 2.5 kg (vs 16 kg).

    Even litres vs gallons wouldn't suffice.

    I wonder if this was software controlled ...
  • here at Yahoo. Looks like an easterly wind with some clouds moving in. God, I don't know whether rain would be good or not...

    (since SLASH isn't displaying the link properly, here it is... sia_loop.html)
  • The reaction from the officials (and the Japanese news outlets) is not surprising; the goverment of any country would downplay the incident. The really bad thing in Japan is that ignoring a problem is the number one approach to problem solving for many (most?) people. And it works great with radiation! You don't see, you don't hear, you don't smell it; it's only in your head anyway - and if you die 20 years later from cancer, you can always blame your smoking co-workers.

    Chilli - less than 100km away from that shit

    PS: It is also no contradiction here to have a kindergarten next to a dioxin emitting waste plant - on the contrary, the kids playing in the contaminated area give everything a much lighter athmosphere (and they probably got a much higher dose while there were being breast fed anyway)

    PSS: Why do you think, I am cynic?

  • Is that politico-speak for "China Syndrome"?

    Not good. Especially with Japan being such a densely populated country.


  • Isn't 18.8% an awfully high enrichment for most reactors other than research reactors?
  • Neutrons aren't worse because they are heavier, they are worse because they have no charge. Alpha and Beta particles are stopped easily because other charged particles act to repel or attract them, depleting their energy. Neutrons can go right on through without much interaction. Also, neutrons are absorbed by normally stable atoms making them radioactive.
    ^. .^
    ( @ )
    ^. .^
  • CNN is now saying that the reaction may still be going on. Citizens are told to stay indoors, and this thing may reach critical mass (imminent self-sustaining meltdown) within hours.

    I'm no expert by any means, but I'm guessing that Japan's geographic isolation is a Real Good Thing right about now...


  • by Anonymous Coward
    Much maligned people the Luddites. Firstly, they fought bravely for their right to work against ruthless employers who were using new technology to throw workers on the scrap heap. Secondly, the Luddites didn't attack employers who used the machines intelligently, ie employed more workers or improved working conditions. They were not anti technology, just against some of it's uses by some people. If being against nuclear power means being associated with people who fought rather than just bendover and take it, then I'm proud to be called a Luddite!
  • Those living within a six-mile radius of the plant were told to stay indoors.

    What?? If the air is contaminated, then staying indoors won't change a thing. If atoms in the air are radioactive, everyone's gonna get it anyway. As for direct radiation from the central, the only thing that can help is: 1) shielding, and 2) distance. Thinking whether you're indoors or outdoors will make a difference is like thinking a layer of normal clothes will protect you from a bullet.

    They wouldn't get me to stay indoors following this. I guess the people from the surrounding village don't really know what's going on.

    If the Japanese Government acts so irresponsibly, this could get a lot worse...

    "There is no surer way to ruin a good discussion than to contaminate it with the facts."

  • The humans in the Matrix served only as a battery. They mention the use of fusion power as well.

    Of course, your unlikely to have accidents putting to much hydrogen into a container (well, unless someone lights a cigarette).

    /. is like a steer's horns, a point here, a point there and a lot of bull in between.
  • If I recall correctly, collecting only 1/3 of all the incident solar radition on domestic American rooftops for a single day produces enough energy to power the US for a whole year.

    Sound effective to me.
  • I don't think that the uncertainty principle has anything to do with the speed of light limit. You can't reach the speed of light because as you approach it, your relitavisic mass approaches infinity, and the more massive you are, the harder it is to accelerate. The uncertainty priniple deals with subatomic particles mostly and for the most part does not apply to large objects, but all objects have to stay under the speed of light.

    Incidentally, the medium to which you refer in your last paragraph is a Bose-Einstien condensate.
  • Replyng to a first poster always kills your karma, but...

    Nuclear power is safe. While these incidents happen, I'm not going to say "how safe is your car?" because that's not what I mean. If you researched, or ever talked to nuclear scientists (this is how I know), there are many designs that are entirely safe. The water method is, as I've been told, a horrible but popular method. Its cheap and efficent, just not safe. There are reactor types that can never reach a point causing such damage as we've seen, here and elsewhere. Nuclear power is not the cleanest, but if scientists rather then polititions run the show, it can be low radiation.

    Secondly, this is a fission reactor. Fission means lower efficency, lower energy, higher levels (not in ammount, but in radiation levels) of waste. Fusion is quite different. Of course, fusion reactors ar not here, at the moment. I've seen graphs from LLNL which predicted the first in 2010, but their project, NIF, was supposed to be done and operational in 2001. I'm told this is likely in 2003 or later. Blame managers and fake scientists, along with accountants who shifted NIF funds, and polititions who gave jobs to companies that could never handle them.

    What is NIF? National Ignition Facility, a project that will be the first fusion laser. Other lasers, like LLNL's Nova laser (which was copied by other contries - Japan, England, France, etc - France even using LLNL's colors), could reach fusion. NIF is far better, though the quality of the laser has degraded due to those damn business/IT-style scientist guys. NIF will be fully safe, and I've talked to a few working on just that, to ensure employees are not harmed.

    So before you spit out all the bs the media talks about, remember the media also calls crackers hackers, the media helped make a polition's campaign dead by saying niggardly, etc. The media is full of.. Read some physics, talk to some scientists, ponder a few questions. Did you know, for one, there have been nuclear bombs made for contstruction? These leave no radiation - it dicipates in 48hours! Guess what, this isn't fiction, it just isn't doable because of the fear and misunderstandings of the public.

    And guess what, Japan screwed up. Not because of technical merits (they have an 'ok' program, but like the rest of the world, they mostly leech off of the US), but because politions got in the way, etc. Don't attack the technology or the scientist, tell your politions to stop screwing tht 14 year old girl and do something to earn his pay.
  • by DHartung ( 13689 ) on Thursday September 30, 1999 @02:40PM (#1647638) Homepage
    Just FYI, nobody is "prepared" for any disaster. The authorities conducted an evacuation and are evaluating the situation before taking rash action.

    Contrary to widespread popular belief, a nuclear reaction is not in itself dangerous. Nuclear reactions are taking place all the time wherever there are radioactive minerals. The danger relates to the amount of radioactivity and the length of time of the reaction.

    [There are dinner plates -- Fiestaware -- that were glazed back in the 30s with radioactive uranium. (Gave it a characteristic orange color.) They're decaying: a nuclear reaction, but it takes a very long time. You don't keep them in the house or eat off of them. But they're safe to own.]

    In this case, a nuclear reaction was caused involving a certain amount of uranium with other amounts of water and nitric acid. The uranium in question would be decaying and emitting radiation as a matter of course; what happened here is that the material was concentrated enough that decaying particles from the uranium atoms strike other atoms and trigger a further reaction. This is simply a "self-sustaining" nuclear reaction.

    This does not compare to Chernobyl. In Chernobyl, a reactor-sized pile of fuel was not only in a self-sustaining reaction, there was an explosion and fire. The damping system was permanently damaged. The roof was blown off the structure (this was one of the biggest errors made by the Russians: no containment structure). The fire was spewing radioactive ash high into the atmosphere. Without containment or control systems, stopping the fire was the only option. Even so, the way in which it was done (involving panic, local and army firemen with no training, and contradictory instructions from various levels of officials), and the criminal choice of not evacuating the town, were of greater importance.

    This chain reaction in Japan, though, is simply exactly what Enrico Fermi caused to happen, for the first time, under the seat of the University of Chicago's football stadium.

    What do you do when you have a critical mass that begins a self-sustaining nuclear reaction?

    Well, two things, basically. You separate the material; or you insert dampers.

    What they're doing here is a process of attempting to separate the material by draining radioactive water (not into the environment, of course, but into a holding tank). This way they can reduce the fuel beneath critical mass and the chain reaction will dissipate naturally.

    No comparison with Chernobyl, really; more like other lesser accidents that have happened, such as Three Mile Island, or Windscale. In terms of human error and botched procedures, though, hopefully this will offer many lessons.
  • People fear that which they do not understand. If the averabe person put 10% of their NIMBY energy into learning about nuclear energy, they'd be lining up to but plant-side property.

    Okay, this is the second time I see that word, and now I'm curious: what does NIMBY mean?
  • DISCLAIMER: I am not a health physicist. I'm a nuclear engineer, but I don't specialize in this area... but I thought some Slashdotters might be interested in what I found in my reference material.

    The CNN Story [] had this to say about the immediate effects on two of the plant workers:

    Hisashi Ouchi, 35, and Masato Shinohara, 39, were listed in critical condition, hospital officials said. The two were in a state of shock with fever and diarrhea.

    Pulling out my trusty copy of Introduction to Health Physics, 2nd edition, by Cember, I find that diarrhea is first mentioned under the heading of Gastrointestinal Syndrome, at a dose of about 10 Grays (1000 RAD) or higher. Effects of this condition are a consequence of "desquamation of the intestinal epithelium"... basically translated as peeling away of the inner layers of the intestine. Other symptoms include (as given in Cember:

    • acute blood changes,
    • ablation of bone marrow,
    • mailaise and fatigue,
    • epilation (skin peeling),
    • severe nausea, vomiting, and diarrhea.

    As a point of reference, Cember lists an exposure of 7 Grays (700 RADs) as being the LD-50/30 dose for humans... i.e., 50% of people die within 30 days of a 700 RAD acute exposure. At the probable dose level experienced by the two workers mentioned above, "...death within 1 to 2 weeks after exposure is the most likely outcome."

    In short, these two workers are in a whole world of hurt, and will probably be dead fairly soon. It's incredible that something like this could happen... was allowed to happen. I can't imagine what kind of flap is going to follow.

  • by chazR ( 41002 ) on Thursday September 30, 1999 @02:40PM (#1647641) Homepage
    At the moment the best information that I have could (charitably) be called 'hearsay and rumour', but here's how I understand it so far:

    1) This was a fuel processing facility, so comments like 'meltdown', 'China syndrome' and 'Chernobyl' are ridiculous.

    2) It is reported that approx. 5 times the correct amount of Uranium was introduced into a chemical treatment vessel.

    3) Two plant workers are 'seriously ill'. 30+ others were 'exposed'

    4) Totally unconfirmed reports have been published of workers 'seeing a blue light' and feeling unwell.

    5) People have been advised to stay indoors and wash off any rainwater they may have been in contact with.

    Point 1: This facility is *not* a nuclear reactor. The worst that is likely to happen is a nasty, rather radioactive, chemical mess that will take a lot of time and effort to clean up. Even if the nuclear reaction (that may or may not have taken place) is still continuing, it will cool down on it's own. It is very difficult to design a reactor to keep a fissile reaction running for any length of time.

    Point 2: It will be some time before we know why too much uranium was allowed into the processing environment. Let's not start blaming anyone until we know the facts.

    Point 3: If you are listed as 'seriously ill' after an being involved with an event like this then you will be extremely lucky to live. My thoughts are with these people and their families.

    Point 4: I don't know whether to believe this. The blue light sounds like Cerenkov radiation. If you start feeling ill just after seeing this, then you are certainly in the 'seriously ill' category. I doubt you'd be talking to reporters. It may have happened, but I'll wait for more information. You need a *lot* of nuclear activity for Cerenkov radiation to be obvious.

    Point 5: Very sensible advice. If it was raining at or soon after the time of the accident, then the rain will absorb a lot of the 'nasties' from the air and wash them to the ground. In these conditions staying inside, closing the windows and avoiding contact with radioactive rain seems to be a good idea. Would you rather get in a car, sit in a traffic jam and wonder how much rain is in the car's ventilation systems? The instinct is to get as far away as possible, but a house is probably safer than a car.

    We need to make sure that the Japanese authorities are given every possible assistance in dealing with this. Then we need to find out how it happened. Then we need to put measures in place to stop it from happening again. It has happened before on several occasions, at least once in US, once in UK and once in what was USSR.
  • I remember reading somewhere that NASA was perplexed by reports from Astronauts about seeing "little white streaks" out of the corners of their eyes while in orbit. Eventually somebody realized they were seeing Cerenkov radiation from the cosmic rays sleeting through their eyeballs. Now that's a Happy Thought!

  • As someone wise once said: "Eathquakes are a message from God.... telling us that the tectonic plates of the earth are shifting."
  • For most of 1997, I lived in Mito, Ibaraki - very nearby the Tokaimura plant. During my stay there, we had headline news regarding accidents at this plant on 3 occasions. When I discussed this with the locals, I received unanimous reactions along the lines of "(yawn) yeah, this kind of thing happens all the time." I think it's worth mentioning that I don't believe the anti-nuke movement has the momentum in Japan that it has in America. Nuclear power facilities there don't seem to be held to the same type of scrutiny that you would expect here. Perhaps this public complancency is a factor in the safety record of this plant.
  • One nice thing about the Canadian style of nuclear reactors is that they run on natural uranium (with heavy water as the moderator), thus eliminating some of these dangerous processing steps.
  • we could build totally fail-safe plants today if we could get past the political obstacles.

    Do tell.

    We could also have disposed of all the spent fuel sitting in pools at nuclear plants by now, except for the anti-nuke political activists who do not
    want to admit that the technical solutions will work

    The only "technical solutions" I've ever heard of involve digging a really big hole, and I'm afraid that I don't trust the stuff to stay buried long enough. If we have to keep it around, I'm for keeping a close watch on it, not hiding it...

  • Yes!

    Which is worse, the (quite) small risk of limited danger from a nuclear accident (I know Chernoble affected alot of the planet, but it's effects have been relatively limited, and are fading with time), or pumping the air full of chemicals and gases that are impossible to contain, affect the entire planet and cannot be gotten rid of?

    Nuclear wast can be contained, it can be stored in containers that withstand impacts of hundreds of miles an hour. Try doing that with several million tons of CO2.

    I'm not saying that nuclear is the answer, but it's better than most of the alternatives.
  • Why would someone hate "nuclear" power. It seems to be a pretty silly thing to stand against since its only free energy. How many people have died in "nuclear" power plants? Do some research and find out. Not more than the number of kids who get shot at high schools. Not even remotely close to the number of deaths from automobiles.

    Here's what "nuclear power" is. Unlimited energy. It doesn't run out. Always there. Itsy bit of matter gets turned into energy and bingo, lights on for a city. There are no green gases floating out, or 3 eyed fishes. And like every other thing on this earth, accidents happen. And of course everyone goes crazy, and posts their signs "Ban nuclear power!".

    It all boils down to one word. Nuclear.
    If it was called BioEnergy, or ThermoFree or something positive, I'm sure it would have caught on. But nope. Some stupid scientist way back when called it the EXACT same name as a Nuclear bomb. Nuclear bombs are bad. Therefore nuclear power is bad.

    If anything, why would someone hate this? I can understand being indifferent about it, but HATING? So many anti-nuclear activists running around with pickets and wasting time. Its just free energy! Calm down!

    Ok. I lied. nothings free. It comes at a cost. A tiny bit of stuff that you dont wanna go near. And the problem with this is?? Lets see, we get energy which run computers, tv's, lights, and we get a bit of crap that we dont like. Let me ask you something. How many chemical weapons were MADE ? Dont tell me that these weapons are less deadly. They were made with the intention to be deadly. If we can bottle all that crap up, i'm sure we can get rid of a tiny bit of nuclear particles. Why not send it to antarctica? No one cares about antarctica.

    Point is.. dont hate something cause of hype. Its just free energy. An accident here, and accident there. Its worth it. And we learn from our mistakes.

    Ps. my grammer sucks and you may not agree with my half witted statements. keep the flames hot.

  • "this thing may reach critical mass
    (imminent self-sustaining meltdown) within hours. "

    This is tosh. It's *not* a reactor. Meltdown means that a reactor's core becomes molten. I still haven't got all the facts ( and neither has anybody), but what seems to have happened is that a chemical process (probably involving uranium salts in solution) received too much uranium.

    This has happened in other countries (including US) before. Somehow, this may or may not have caused a fissile reaction, which may or may not have caused heating which led to an escape of radioactive material.

    It may have been caused by a precipitation of a uranium-rich substance. Whatever it was, it needs a moderator to keep a fissile reaction going. Water will do the job, but not very well. This reaction (if there is one - it could have been an entirely chemical reaction) will almost certainly calm down fairly rapidly. I grant that it will leave a nasty mess.

    For your information, Japan is got 'geographically isolated'. It's rather close to China and Russia.

  • Work into this that the workers actually saw the blue glow, and hypothesize that if it actually is Cerenkov radiation what minimum amount of uranium or nitric acid is required

    Insufficient information. 16kg is certainly enough to sustain a reaction (depending on its physical layout, etc), but it depends on many other factors such as temperature, pressure, poisons present (poison to neutrons, not humans ). Nitric acid is not necessary.
  • What annoys me is how big-time journalists never seem to compare the number of coal-mine fatalities to that of nuclear causes.

    Accidents in coal mines are far, far, far more common than nuclear accidens. More fatalities, too.

    Take a look at some statistics for coal mine fatalities and you'll see what I mean.

    And then there's the oil rig problems...
  • People are going to blow this out of proportion, because the headlines contain the word "nuclear". While this disaster doesn't seem anywhere near the magnitude of TMI, Chernobyl, Windscale, I'm sure the media is going to make it seem like is. I sure hope fusion research doesn't suffer... But seriously, if the public is to be wooed into accepting nuclear technology, we should be more careful with our isotopes.
  • not even god can protect you from asbestos
  • Any knowledgable person out there able to venture an opinion as to how bad this is compared to the Chernobyl disaster?
    I presume it is smaller, but numerically how many times worse was Chernobyl, especially with regard to contamination of the atmosphere, which is measureable in other countries.
  • This is sort of correct, but the conclusion you draw is not entirely accurate. Yes, alphas and betas are stopped fairly easily. Alphas can generally be stopped by a single sheet of paper... or your outer layer of dead skin. Betas are a little more penetrating, they make it past your skin before stopping. Neutrons and gammas are more penetrating yet, they go a good ways inside before they stop.

    The problem is this. While alphas may be slowed down and stopped easily, they give up a lot of kinetic energy as they do so. They are rather massive (basically a helium nucleus), and strongly charged (+2). This is why they stop so quickly, shedding all their kinetic energy in a relatively small space as they slow down. That's why it's not good to inhale alpha emitters... there's a lot of soft tissue in your lungs, and alpha emitters can screw it up royally. But basically, you have to ingest alpha emitters for there to be any damage.

    Betas are different. They're less massive (basically an electron), but are still charged (-1 or +1). Betas are weakly penetrating, but impart a fair amount of energy as they slow down. Generally speaking, the most common hazard from betas is dose to the lens of the eye.

    Neutrons, being uncharged, don't slow down as rapidly as alphas or betas. They do slow down though... either by scattering off light nuclei (hydrogen and carbon... hmm, not much of that in the human body, is there?) or by being absorbed. In the process of slowing down, neutrons have the capability of inducing ionization in the materials through which they're traveling. Or, they can be absorbed, causing nuclear transormations which can lead to emission of other types of ionizing radiations. But as far as risk from neutrons go, it's the induced ionization that is more of a problem.

    Finally, there's gamma radiation (high energy photons). These are very penetrating, probably passing all the way through your body, but probably causing some damage along the way. The damage from gammas is not usually direct, however. A gamma may, when passing close by a nucleus, spontaneously disappear and be replaced by an electron and a positron. If a gamma undergoes scattering off an electron, the electron could be released. In both these cases, you've had a release of charged particles that will interact with the material around them.

    So what I'm getting at, basically, is that all radiation presents a risk. The amount of risk is dependent on the type of radiation, the amount of radiation, the energy of that radiation, where the radiation is, the properties of the material the radiation's traveling through, etc. etc. etc. It's pretty hard to say that any one type is worse for you than another... it all depends.

  • Methinks the earthquakes during the war may have led more then a few people to worry about new high powered enemy weapons causing earth quakes. :)

    Anyway - that's off the nuclear subject.

    Though that reminds me that there are several nuclear power plants built nicely in the middle of fault lines. (New Brunswick, California, a few other jurisdictions too).

    Seems we need to contact geologists a little more.
  • Latest info (at 1212 UT) can be read in this BBC report []

    They seem to have drained of the water (where to?) which should stop any further nuclear rection.

    Unfortunately, it seems as if more people than previously thought have been contaminated, including rescue workers.

    The early reports of 'a blue flash' now sound more like a chemical (?hydrogen?) explosion.
  • You would get a significant dose of photons as well.
  • Hi,

    I worked in an (unnamed) Chemical plant under construction, and there were valves that should have been Fail Closed which were Fail Open. Why? The EPC (Engineering Procurement Contractor) had ordered the wrong valves, and someone had switched the designation to cover it up. Because of Due Diligence, we discovered it and were able to make proper safeguards.

    It's likely that a valve designed to regulate the flow of a slurry of Uranium Oxide (or PuO2, but that'd be a national secret if they were purifying Pu) failed open.
  • (dang what was the name of the professor again, Henry Sobol?)
    Hari Seldon, father of pychohistory.
  • The last reports I heard seemed to suggest that the blue flash *may* have been due to a chemical explosion. I hope it wasn't Cerenkov radiation. That would indicate a significant nuclear reaction under water.
  • OK, first of all, energy-efficient alternatives have this way of getting scrapped in favor of wasteful ones in the name of "creating jobs" and because the more "wasteful" industries are big business. Racist stereotypes of Mexicans + heavy pressure from the lumber (and other) industries = criminalization of hemp. Oddly, there was once a (IIRC, WWII) propoganda film called "Hemp for Victory." Interesting, huh?

    If someone were to develop a clean, cheap, efficient source of power, it would never hit the market thanks to Big Oil. When managed properly, hydroelectric, wind/solar, and even nuclear power can be quite effective. Locally, we use a good bit of hydro and nuclear power, and I haven't seen problems.

    OTOH, one of the big problems with nuclear energy is the question of "where to put the waste." Locally, the people who run a nearby salt mine thought that abandoned parts of the mine would be perfect. But while they were in the process of getting this approved, some very bad things happened. Specifically, the abandoned mine began to collapse (whether due to a rare earthquake or a potentially-less-stable mining technique that was used there, I don't know). Water began flooding in at the rate of thousands of gallons a minute, eroding the salt, causing the mine to collapse further, and contaminating what was once a good source of groundwater with a very large quantity of salt. I was in college at the time, and found out that the dorm I lived in might have its foundation cracked sometime between five and 50 years from now if they can't find some way to stop the water. In nearby towns, there are areas where the land has just dropped six feet.

    I'd rather not think about how much worse all this would have been if there HAD been nuclear waste in there. Ick.

  • by Tau Zero ( 75868 ) on Thursday September 30, 1999 @03:33PM (#1647678) Journal
    You want guaranteed safety? Look at some of the designs for gas-cooled reactors with pelletized carbide fuel. They can be designed so that "thermal broadening" cuts off the chain reaction before the fuel gets near melting; if you turn off the cooling fans, physics would shut them off.
    The only "technical solutions" I've ever heard of involve digging a really big hole, and I'm afraid that I don't trust the stuff to stay buried long enough.
    Depends what you bury. Fission products (the actual waste) have half-lives of 50 years or less. You could bury that or keep it around at your option; the Pyramids are as old as 5000 years, and in that time all of the cobalt 60 and strontium 90 and other ugly stuff would have all turned cold. It isn't going away overnight, but it doesn't have to. Radioactivity is actually an advantage compared to chemical poisons which might not degrade for millenia, or elemental toxics like mercury which will be toxic forever.
  • Isn't it obvious? Someone let Mr. Sparkle into the plant.
  • As our population and technology has grown (and by all counts, will continue to do so for the foreseeable future), our electricity needs will continue to skyrocket. Upcoming electric cars, higher power computers, smart appliances, industrialization of the third world... yup, gonna need more power, Scotty.

    Unfortunately, while all these needs grow, the available power generation capacity is not. True, new petrochemical sources are found every year, but there is obviously a limit to how much can be done there. Nuke plants are just not going to happen (popular opinion aside, the expense of maintaining safety and etc. is high and only going to grow after this disaster.) Hydroelectric and wind are only useful in a few discrete (and often scenic) areas of the world. Coal is a good long-term solution, although dirty and environmentally unsound. Coal, too, will run out, but not for a very long time.

    The only truly scalable solution is the sun. Eventually we will have no choice but to go off-planet and build massive solar collector farms on the moon (and later, in space) to get this power and beam it (via microwaves) down to Earth.

    I suppose one could use scare-tactics to drive investment into space exploration for the eventual goal of building these things, but there's really no need. As the petrochemicals get used up, and as nuke plants become less and less tolerated, the cost of energy will (slowly) rise. Eventually it will get to the point where it'll be profitable to invest in space. (I hope it's sooner rather than later, 'cause it'd be cool to see in my lifetime.)

    Conservation of energy will really just delay the inevitable. Just like the squeaky wheel getting the grease, the space solution will only come about when the cost of developing the answer is less than the expected costs of terrestrial energy consumption. So use up that energy! Save the world by using up all the kilowatts you can!

    Seriously, though, the practical answer is to support space development. Go see and vote for congresscritters that support space. ;-)

  • There is one existing standard reactor design. It is referred to as the System 80+, designed by Combustion Engineering of Windsor, Connecticut. CE was, decades ago, involved in the development of the standard Navy design. It is now out of the military market, and a part of Asea Brown Boveri.

    The design is NRC approved, and is an outgrowth of the very successful, and accident/incident free Palo Verde plant(s) (3 reactor site) in Nevada. For a U.S. site, the design does not need to go through the lengthy and costly 'per site' approval process, provided the location is geologically sound. If not, no deal - but then again, no one would build a reactor on the San Andreas fault line. :)

    Other existing plants of this design (or a contractual tailoring thereof for seismic, economic or political reasons dictated by the customer) are located at Yonggwang (2 of 6 units on the site) and Ulchin (2 of 6 units now being constructed) in S. Korea. The remaining units at these sites are Candu (Canadian), Framatome (French) or Westinghouse ... The variety is due to single-mode failure clauses and legal requirements for diversification. Understandable due to the ~$4 billion per unit price tag.

    Future projects might include N. Korea, China, and frankly, wherever there's a market. Few people are building new plants these days due to FUD and startup costs.

    As for the 'safe nukes' project, I'm all for it. Step 1 is to educate the public about the risks, costs and processes involved, and how they compare to fossil hazzards and background radiation from folks own basements and such.
  • That's just so much fear-mongering.

    Nuclear technology is just that. Technology.
    Yes, it has the potential to cause a lot of harm - this is why Billy-Joe and Bubba don't get to run the plants. It takes training and an education. Any shmoe can shovel coal. Do you want to breate the exhaust? Would you rather have been down wind of that Union Carbide disaster in India in the mid 80's? The coal ash that leaves a traditional fossil plant is more radioactive than anything vented into the atmosphere in the U.S. - this includes 3 mile island.

    NukeTech is highly regulated. Accidents happen because people a) make mistakes, and b) cut corners. The benefits of nuclear power are huge, but the technology must be respected, and funded well enough to implement proper respect.

    The funding of nuclear facilities (in the US and abroad) is inadequate. They are expected to function like traditional fossil plants, but everyone knows they need a much more steady hand - both on part of the operators and management.

    France derives 60-75% of it's electrical power from nuclear sources. They respect it, regulate it intelligently and fund is adequately. They have never, ever had a nuclear accident.

    People hear the word 'nuclear' and envision giant mushrooms on the horizon, or picture pulsating, glowing goo creeping towards them. Feh!

    People fear that which they do not understand. If the averabe person put 10% of their NIMBY energy into learning about nuclear energy, they'd be lining up to but plant-side property.
  • Light vs. Heavy water has little to do with stopping the reaction. But there is a design issue.

    Most designs rely on electrical power being available in order to shut themselves down. This is a design decision, and there are multiple backups and unneeded (IMO) complexity. Others require power to keep the reaction going. This way, all you do is cut power, and the control rods fall (gravity) into the core (rather than being forced up into it by a motor) and the chain reaction grinds to a halt.

    A standard design is naturally more expensive than a custom one, because in a standard design, a uniform environment for the reactor must be part of the design rather than part of the location.
    This is much like providing a standard interface for the reactor 'code', instead of hardcoding values into the given location. So to apply the reactor to a new site, the location interface is changed but the 'code' is the same, instead of redesigning the reactor to match the location...

    National pride is a small issue, except to the French, and to customers who hire foreign contractors (designers, engineers) rather than use internal expertise (natural resentment there).

    BTW, the top spot is now the Yonggwang#4 reactor with, I believe, a complete fuel cycle of 2 years with an AVERAGE output of 114% of design.
  • by Anonymous Coward
    Yahoo is following [] the story on this page.
  • Just as a clarification, this is not the worst nuclear accident ever, it is the worst accident ever in Japan.

    The 1986 Chernobyl meltdown is still the worst nuclear accident ever - in the world.

    This (Japanese) accident did not happen at a nuclear power facility, but rather in a Uranium processing plant. Much too much (7 times) Uranium was added to a mixing tank, resulting in a chain reaction. As of present reports (21:00 EST) the reaction is under control and clean-up has begun.

    Approximatelly 40 people have been hospitalized for radiation exposure, of this 2 are critical. The Japanese government has evacuated a 0.35 km radius around the plant, and is considering expanding the evac to 0.5 km. For those not reading the U.S. vs S.I. discussion, this is about 0.3 mile proposed radius.

    As of latest report, Godzilla has not yet made an appearance. Area residents (300,000 people) are advised to remain indoors and minimize open air infusion into their residences (close windows, vents, etc). The accident occured at 09:30 Friday local time, 120 km N.E. of Tokyo with winds from the ENE direction clocking now at 15 knots.
  • IIRC, modern fusion bombs use extremely powerful plastic explosives to set off the fusion component. Using a fission bomb to trigger a fusion bomb was the old way of doing it, but I don't think that we still do that.
  • The CNN article [] was clearer on the subject. They were told to stay indoors because the water that had leaked from the plant had evaporated and it started to rain radioactive rain. My god, that sounds ugly.

    "There is no surer way to ruin a good discussion than to contaminate it with the facts."

  • by konstant ( 63560 ) on Thursday September 30, 1999 @10:20AM (#1647725)
    I have a feeling some of the more extreme technophiles/conservatives are going to chastise us for being alarmed by this sort of accident. Generally, after a nuclear mishap, the pattern goes like this:

    1) BOOOM
    2) a number of people are rushed to the hospital
    3) liberals run around screaming "Look how awful nukes are!"
    4) conservatives tilt their Laz-e-boys up a notch, puff on their pipes, and make devastating comments about "Luddites"

    But look folks, nuclear technology really is a technology unlike most others. Only genetic modification has as much potential for literally wiping out the human race if somebody forgets to carry the two. We all know from experience that even experts make miscalculations, and that sometimes the results are hazardous. Generally, these are tragic but containable. They are what you might call "acceptable losses" on the path towards improving the lot of our species.

    But I'll be damned if waking up each morning to a pitcher of radioactive milk is acceptable to me. Just a single reactor in Russia threw the world's food supply into havoc for months. And mistakes like Chernobyl have happened before and will happen again. Every once in a while somebody fucks up. It's just that, with nukes, the ramifications are so very large!

    The reason that we don't see more accidents like this in Japan is not because nuclear energy is, on the whole, safe. It's because most people have extreme NIMBY reactions to nuclear facility proposals. People are scared of nuclear technology, and I think rationally so. The development of a clever scientific pet trick is not enough justification for its deployment. We do not have to do everything that we can do.

    I'm sure that statement alone will be enough to moderate me down on slashdot ;)

  • It isn't nuclear power that's scary; it's radiation. Radiation, like the Ebola virus, fills us with irrational dread. It there, but you can't see it, you can't feel it, hear it, or taste it, but it can contaminate you and then you die!!

    There are rational arguments against nuclear power, most of them economic: Fuel refining had such a high energy cost that plant operations only recouped the energy balance some time around 1980 (that's really a number pulled from my fundament. I read it from a book written by a DOE employee and I read it over five years ago, so give or take a 5 years, and just accept that my point is it took a long time -- I'd love it if you'd go look it up and tell me exactly). The plants are very expensive to run (although the industry claims this is mostly due to overregulation). The waste problem remains intractable (and thus expensive). Even so, the rabid "anti-nuke" feeling out there is a product of a primal fear, not of reason.

    All of that said, my brother is a Navy Nuke and the one thing he is certain of is that he won't work in civilian nuclear power. He (and I guess a fair portion of the nuclear Navy) feels the civilian nuclear industry just doesn't have their act together.

    As for the alternatives discussed above:

    Oil is being extarcted faster than it is being made. It will run out, all other things being equal. I suspect, however, that the release of all of that carbon into the atmosphere will disrupt things enough before the oil runs out that it will finally dawn on us how stupid we are being. Same for coal. I would believe that our supplies of oil and coal will last for centuries. Why? Because we only go after easy supplies now. As those supplies run out, the price rises and it becomes economical to go after "hard" supplies. Such a thing happened to make pressurized water drilling economically feasible. Eventually the same will happen for more extraordinary measures.

    At some point, though, I think the rising cost of that oil will finally make solar comepletely economical. It is quite possible to power your home and break-even within the life of a mortgage right now. That's not enough to make a bank or an industry happy, but that's not too bad. Solar and wind have one major technological problem. Batteries. They suck. But you need them or some such thing because the sun isn't always over your home and the wind isn't always blowing. Grid-interitied solar systems coupled with traditional power generation would really improve things right now. We could shut down all the nukes and a significant number of coal plants (the highest emission ones, perhaps?) if people put grid-interied systems on their homes that met only 10% of their energy needs. You can do that right now, today, for less than $10,000.

    Personally, I'm very much in favor of small hydro systems. The huge Grand Coulee style projects cause major environmental havoc, but small community-scale projects cause much less and that harm is known to be less than the harm of burning fossil fuels. Such hydro system can only meet a tiny fraction of our energy needs, however.

    As for radiation, yep. It's scary. But I think it should be impossible to get out of high school without knowing what radition is and how it interacts with living tissue. I think people should know that, like the Palmolive commercial, they "are soaking in it" every day of their lives. That their own bones are radioactive. They should well understand how and why exposure harms us and what kind of levels exist in nature, and how much exposure is dangerous. But then, I also think you shouldn't get out of high school without knowning how the bond market works, how to get a mortgage, how to balance your checkbook, and that Carson City is the capital of Nevada. Guess I'm a dreamer...
  • See: tm


    Limit for working adults: 5 REM (0.05 sievert) / year

    Limit for unborn child: 0.5 REM (0.005 sievert) / year

    Limit for minor child: 0.1 REM (0.001 sievert) / year

    So any adult a mile from the plant is getting his Maximum Recommended Annual Dose every fifteen hours; children go well over the limit in two hours.

    Yours WDK -

  • Photons have mass-energy, and momentum by the equation E = pc. A one-MeV gamma ray has more mass-energy than an electron (511 KeV). This can give a little electron a very big kick. I'd quote you the equation for the conservation of energy and momentum if I could remember that part of PHY 242.

    Beta radiation doesn't penetrate a significant thickness of metal. Gamma photons do; most of the electrons which produce Cerenkov radiation in a reactor are secondary particles produced by the primary gamma emissions.

  • ABC News []

    CNN []

    Yahoo News []

    It also looks like the US military's going to be called in.
  • Actually, I didn't mention nuclear power. There's a lot of fuel for that also, as there are uncollected radioactives everywhere. And as an S-type asteroid probably has an assortment of metals [], there will be some with a lot of fissionables. As well as a lot of tritium and other possible fusion fuels on the Moon's surface.
  • Oh, you still think that oil is from plants? []

    Well, no matter. There's a lot of hydrocarbons out there also. We discussed Titan hydrocarbons already []. Comets have been observed spewing hydrogen and carbon for some time. Volatiles seem to have been driven out of the inner Solar System, so might have to send robots to Saturn to fetch some. Unless we use an Orion drive or fusion torch; then the travel time will be on a human scale.

  • Consider the atoms pretty much stable, like mousetraps with two ping pong balls on each in a large room. Throw a ball in the room and a few might set each other off. Now concentrate the atoms together into critical mass and the first ball thrown will trigger an ever growing action. Balls will be popping all over the place into a meltdown.
  • by Outland Traveller ( 12138 ) on Thursday September 30, 1999 @10:34AM (#1647765)
    I know that I'm ignorant about what is going on over there right now, as I've only read the Reuters wire and a CNN report.

    However, from this information it appears that Japan:

    1. Is not prepared for this kind of disaster
    2. Is not reacting to it in an aggressive fashion.

    It is strange to me that given the repeated nuclear safety problems they have had over there that they do not have a plan in place to deal with a nuclear emergency. Why are they asking the US Military for aid? What kind of aid are they looking for? It seems like they don't even know what kind of help they need.

    Also, the action that appears to be taken so far seems to contrast starkly with the Russian firefighters who gave their lives to try and stop the Chernobyl disaster. Some officials are saying that they don't know whether or not the reaction will become self sustaining or not. It seems to me that if there is a chance this emergency could turn into something similar to a reactor meltdown people should go in there and do everything they can to smother the reaction before it becomes any worse. Taking a "wait and see" attitude with something like has the possibility of frigthening consequences.

    Some people have questioned the value of telling people to remain indoors. This was probably done to avoid a widespread panic that would clog all the roads and hamper efforts to bring the situation under control.

    Perhaps we'll get more useful information in the days ahead.
  • You think that's ugly?

    From CNN: The workers at the plant reported seeing a blue light, and then they became ill.

    If there was enough radiation to see Cherenkov radiation IN THE AIR, then those guys aren't just sick, they're dead.

    All around, this sounds like a very ugly situation.


  • Last report I heard was that there were possible still ongoing "criticality incidents" but that workers could not re-enter the plant becauske of 4000x the 'normal' radiation, but that when they could go in, they would drain the water from the tank where the stuff was being processed (35 lbs instead of the normal 5lbs) in order to stop further reactions.
    Scary shit.

  • I'm not a physicist, but for no particular reason I have been on a tour of a reactor, and still seem to remember some related elementary foo...

    How much do you remember about nuclear fission (which, presumably is what happened in this incident, since the conditions would seem completely inadequate for fusion)?

    The splitting of an atom can free neutrons, sending them in various directions. Depending upon various conditions (such as the amount of fissionable material, the presence or absence of materials that either absorb or reflect the neutrons, and so forth), these neutrons may or may not collide with other atoms. These collisions can induce more splitting, leading to the possibility of a self-sustaining chain-reaction.

    Incidentally, the NY Times/Associated Press [] article mentions that the workers thought they saw a blue glow. Dunno about you folks, but this reminded me of Cerenkov radiation. For more info on that, see this page [].
  • by cancrman ( 24472 ) on Thursday September 30, 1999 @10:39AM (#1647773) Homepage
    You make it sound like nuclear technology is inherently evil. Ummmm....It's not. Yes it's true that it has its downsides, but so do a hell of a lot of other things. I'll just touch on a few here

    Oil -> Air Pollution -> We all die slowly and eventually run out of fuel
    Coal -> Air Pollution -> We all die slowly and eventually run out of fuel
    Hydro -> Environment Damage -> Fish all die (& everything that eats those fish)
    Solar/Wind -> Not effective -> We all freeze
    Nuclear -> /Possible/ accidents -> We all die slowly

    So, sure nuclear energy can fuck us up. But so can a lot of other things that we are already using. Nuclear power is a clean, cheap, & long lasting source of energy. Ok, I wouldn't want one in my backyard. But it is still a necessary evil at this point.

    I can see through time -Lisa Simpson
  • by Jeffrey Baker ( 6191 ) on Thursday September 30, 1999 @10:41AM (#1647779)
    The amount of radiation released by this accident is tiny compared to the millions of tons of slightly radioactive fly ash spewed out of the smokestacks of coal-fired power plants in China.

    China consumes ~25% of the world's coal production.


  • The injured in the plant said they saw a 'Blue Light'. I know very little about nuclear. In fact, any one can explaint this to me?

    p.s. As far I know, that 'blue' in Japanese should be color between Green and Light Blue.
  • It works like this:
    Uranium (even highly enriched in U235--the fissile isotope) has a very long half life and thus isn't very radioactive. From a radiation standpoint, it's not too difficult to handle. I operate a nuclear research reactor, and I have held new fuel elements in my hands. Anyway, the way nuclear fission works is that a neutron hits a U235 atom and it splits apart into two lighter fragments and releases on average 2.4 neutrons, and also lots of energy and radiation. These neutrons then go off and start other fission reactions -- a self-sustaining chain reaction. There are many factors that control whether the reaction is self-sustaining, such as the amount of U235 present, geometry (a tight sphere will react more readily than a bunch of spread-out lumps), moderation, etc. Sub-critical means the reaction isn't self-sustaining. This is the "normal" state of things (there are always fissions happening, but at a very low level). Critical means it is exactly self-sustaining. It means a steady state. Supercritical means it's more than self-sustaining -- the rate of reaction is increasing.
    Anyway, criticality accidents have happened all too many times before. The usual result is that the people who were initially exposed die of massive radiation exposure, but it's probably not much of a danger to people beyond that. This is entirely different from a "meltdown" or "China Syndrome" accident. Criticality accidents are usually (I think) caused by a change in geomerty that wasn't supposed to happen. I remember hearing about one in which fissile material mistakenly made it into a centrifuge. It was sitting at the bottom of the centrifuge in a subcritical geometry. When they turned it on, it got flung up against the walls of the container, and for a brief instant passed through a supercritical geometry and then went subcritical again. Of course, this killed the operator of the centrifuge. When they sent people in to investigate, one of the things they did was to turn off the centrifuge (since nobody who witnessed the accident was alive, they didn't really know what had happened). Of course, this caused it to go critical again for a brief moment, severely injuring the rescue party.
  • MSNBC has a good article [] on Criticality. Doesn't quite explain how it differs from a total meltdown or fision blast, but it does explain how it happens and gives a little history.


  • (Man, did this thread ever attract lots of comments! Take a few minutes to write, and half a dozen people slip in.)

    Briefly: The critical state is where each fission event emits neutrons which create, on average, one more fission (a "chain reaction", like falling dominoes). "Fast" (high-energy) neutrons are not as easily captured by U-235 nuclei as "thermal" neutrons (neutrons which have energies similar to the kinetic energies of particles in bulk materials). This last part is important.

    As for what really happened, we're going to be at the mercy of relatively unsophisticated reporters and editors for some time, but it appears that some spent enriched fuel was being reprocessed chemically to separate it from fission waste products. Since the fuel is normally in the form of uranium oxides (extremely high-melting), it must be dissolved in acid to make it soluble at room temperature. Most acids are far from pure (they contain a lot of water), and the hydrogen in acid or water is a good moderator for neutrons. The uranium alone wasn't a problem, but adding it to a solution with lots of neutron-slowing hydrogen raised the neutron capture efficiency to the point where the tank went critical; in effect, it became a nuclear reactor. This is accompanied by lots of pretty blue Cerenkov-radiation light and killer doses of neutrons.

    The reaction will stop when the solution gets too concentrated (not enough hydrogen to slow the neutrons) or too spread-out (too many lost neutrons to continue the reaction). Throwing in a neutron absorber like boron would fix it too. If the Japanese have a bomb-disposal robot capable of getting to the tank and dumping some boric acid into it, that would probably get rid of the immediate problem. Then the difficulty becomes one of cleanup.

    Of course the big problem is how the workers got 8 times the usual quantity of uranium into the tank against all procedures. Somehow I don't think they were being as orderly and efficient as the stereotype of the Japanese would suggest.

    Nope, I don't work in the biz, but I've spent lots of time listening to old pros talk shop.

  • by dattaway ( 3088 ) on Thursday September 30, 1999 @10:58AM (#1647797) Homepage Journal
    The way I see much of the controversy over nuke plants is that they directly compete with coal plants, coal mines, and the many jobs coal creates, or the more expensive alternative, petroleum fired generators. Humans have an affinity towards energy, so it looks like we will be generating it one way or another. Pick your weapon.

    A coal plant is opening up 15 miles from where I live. This is good for me as my payscale suddenly shot up as they were looking for workers. Tell you the truth, I would rather have a nuke down the street. It all has to do with the air I breathe and the massive amounts of ground being dug that were a great habitat for wildlife and hunting.

    Not that I'm complaining, electricity will be very cheap for manufacturing plants. Good paying jobs will be abundant and those who already are employed will see property values skyrocket. The price of land has doubled for the last few years.
  • by Anonymous Coward
    They were hoping Gojira would appear.
  • The Japanese government is reporting that the solution in question is uranyl nitrate enriched to 18.8 weight percent U-235 in a concentration of about 370gU/l. There are about 50L of solution (16kg of uranium) in a stainless steel tank with about a 50cm diameter and 3mm wall thickness, to a depth of about 26cm. Outside the wall is a 2.5cm-thick water bath.

    k-effective for this is about 1.04. Removing the water bath lowers k-effective to about 1.0, so it's a good first step. If you don't understand any of the above, you may safely return to your state of antinuclear hysterical panic.
  • Is it just me, or have we disasters than usual this year? I mean..

    -> Severe doughts on the eastern coast of the US. Floods in the midwest. Floods in the East from Floyd (a good bit of New Jersey and North Carolina was still underwater last I heard).
    -> Three major earthquakes almost on top of one another: Turkey, Greece, Taiwan.
    -> Political unrest and instability in Russia. Political unrest in the Middle East. Kosovo. East Timor. Other places that haven't gotten so much coverage (which I naturally can't remember)
    -> More stuff I've forgotten.
    -> This.

    And the following events haven't even happened yet!

    -> Massive civil disruption by Christian fundamentalists and cults of all descriptions who believe the end of the world is imminent.
    -> Computeres miscalculating the date and causing planes to fall out of the sky, eletricity to shut off.
    -> Microsoft releasing Windows '00.

    Clearly these are Signs! The only thing for sensible people to do is to get a lifetime's supply of cookies and HIDE UNDER THE BED until the clock rolls over!


    Sorry, just trying to lighten the mood a little..

    But in all seriousness this has not been a good year. I think the only disaster that hasn't happened yet is launching of nukes -- or perhaps a tornado in downtown NYC.

  • For Slashdot?

    Assume 16kg of high quality Uranium, reactor grade, and essentially unlimited amounts of nitric acid in solution.

    I think that's what reports indicate happened.

    Work into this that the workers actually saw the blue glow, and hypothesize that if it actually is Cerenkov radiation what minimum amount of uranium or nitric acid is required.


  • It's the light emitted by water when it is bombarded by intense gamma radiation. the same thing you see in physics textbooks when they show pictures of nuclear waste under water. Uraniaum will not normally produce this, but when it fissions, most of the energy is emitted as gamma rays and xrays. the guys who were unlucky enough to see this are screwed, I don't think it's possible to survive standing in front of a nuclear pile that suddenly goes critical. They must have absorbed a massive dose, because it appears they started feeling ill immediately. Not a good sign.

    ^. .^
    ( @ )
    ^. .^
  • didn't work for me.

    Try p?cp1=1#BODY [] instead.


  • by Crusty Wizard ( 60219 ) on Thursday September 30, 1999 @01:34PM (#1647828)
    Here's a brief description of the primary types of radiation and their relative harmfulness.

    1) Alpha radiation. Alpha particles are helium nuclei, big and slow; they can be stopped by a sheet of paper, but if you inhale alpha emitters, they can tear up your lung cells. So don't do that.

    2) Beta radiation. Beta particles are energetic electrons, and can penetrate a bit better than alpha particles, but you should be okay if you're in the next room.

    3) Gamma radiation. Gamma rays are *very* energetic photons; these are the ones that'll get ya. You need a good amount of dense shielding to absorb these.

    4) Neutrons. Energetic neutrons from radioactive decay both perpetuate the chain reaction, and cause direct damage like beta particles, only worse because they're heavier.

    The people close to this one will probably have gotten a good zap of gamma radiation, and will be in a world of hurt. But unless radioactive *material* (such as the uranium itself) escapes into the surrounding air, nearby civilians should be okay unless there is inadequate shielding against gamma rays.

    In a nutshell, this is Really Bad, especially for the people closest, but the Earth is not about to collapse into a molten ball...
  • by Anonymous Coward on Thursday September 30, 1999 @11:28AM (#1647830) easier to achive than you think.

    (Snarl, network here is on the fritz, apologies if this comes through multiple times - connection reset by peer before anything actually gets submitted, I'm assuming...)

    Anyone working at a nuke plant, especially a fuel processing plant, knows this. This incident appears to have been caused by stupidity of truly mind-boggling proportions.

    If you're ever working with heavy isotopes (i.e. fissionables) in solution, the water or other solvent in which the compounds are dissolved can act as a moderator, and the amount of uranium or other fissionable matter required for criticality drops precipitously.

    I did a few summer terms at a research reactor at a university. This reactor was often used to create compounds for medical use as well as other research. Preventing this type of incident was discussed in one of the most heavily-underlined-and-boldfaced sections of text in the book.

    Any time you have to work with heavy unstable isotopes in solution, it's imperative that you know exactly what you're dealing with. That means you need to know both the nuclear (cross-sectional) and the chemical properties of both solvent and solute, AND the shape of the container, AND the concentrations expected at any stage in the dissolution.

    Those latter two are particularly counterintuitive - but are glaringly obvious in hindsight, as they're significant factors in the mean distance (i.e. free path) between particles of the heavy isotope in the solution, a key determinant in criticality.

    To give an example of what can go wrong - take a beaker of water and drop in a spoonful of brown sugar. Pretend the sugar is fissionable.

    At the start, you have a subcritical mass of brown sugar. Safe enough to hold in your hand. At the end, the sugar is distributed evenly enough through the water that even with the water's moderating effect, it's subcritical. Safe enough to work with.

    Walk away from the beaker and come back in 5 minutes. Observe that there are regions in the beaker of varying concentrations. At least one of these concentrations will be the "right" concentration to minimize the mass required for criticality. If the volume of that region is large enough, it goes critical in that region and it's game over.

    For an even better version of this game, imagine you can stir it quickly enough so that this is never a risk. Mix it in a baking pan, so that the liquid is never deeper than 1cm, and most of the neutrons fly out the top and bottom of the pan. Give it to your friend, who pours it into one of those nice flasks with the spherical bottoms. The spherical shape allows many more neutrons to be absorbed. Your last thought is that "Safe enough to work with" only means "safe enough to work with in this container". Game over.

    Or just carelessly leave the pan under the fume hood over the weekend. Or toss it in the freezer, and discover that as it freezes, the capacity to hold the material in solution changes, and some of it precipitates out. In either case, don't expect to get any work done on Monday morning, though.

    Of course, now that I've gone through the hard ways to have this accident (about which anyone working in this environment would still know), putting seven times as much solute in the solution would also be a good way to screw it up.

    Scary thought: If they could see the Cerenkov radiation - and weren't looking at the tank - it means the radiation flux through the fluid in the eyeball was high enough to cause a visible blue glow. That's a lot of radiation.

    Remember all those "how to build your own atomic bomb" plans, that all worked out to "this won't give you a nuclear detonation, but it'll make one unholy hell of mess"?

    The Japanese have just become the test case. While we're not talking about levelling cities or nuclear explosive yield, in terms of the physics involved - an uncontrolled chain reaction in a critical mass - the Japanese have arguably just nuked themselves, in the same sense that the Americans nuked them twice earlier this century.

    It's a banner week for Darwinian Stupidity in the sciences, folks. First we lose a $125M space probe because two engineering teams didn't know the difference between metric and Imperial measure, and then a couple of Japanese fuel processing guys manage to top our blunder by accidentally building and activating something that's the fundamental equivalent to the core of an atomic bomb.

  • by Tau Zero ( 75868 ) on Thursday September 30, 1999 @11:48AM (#1647831) Journal
    Nobody's gotten this entirely right yet... the blue light is Cerenkov radiation, which is created when charged particles like electrons (NOT neutrons) move through a medium faster than light travels through it. (Obviously this cannot be done in free space, but it can in water, in glass, and other media.) Much like an object moving through air faster than the speed of sound creates a sonic boom, a charged particle going faster than the local speed of light creates a "photic boom". Just FYI, some electronic devices such as Travelling Wave Tubes work on not-dissimilar principles.

    How do the electrons get moving so fast? When a gamma ray bounces off an electron, the electron can recoil at high speed. This phenomenon is called Compton scattering, if I'm not mistaken.

  • Moderator...

    Just as a comment, I've heard that atomic scientists once used Cerenkov radiation to locate beams in cyclotrons... by sticking their heads inside the machines! I can't be sure of the truth of this or not (having no primary source), but it would be funny if the Doctor Science comment about "sticking your head into the beam of a linear accelerator" had some basis in fact.

  • guess you better not live near the highway, you might get run over.

    Better not live near trees, might get squished by one in a windstorm.

    Better not live near a river, it might flood.

    Better not live on land, oops, earthquake....

    Everybody's gotta live somewhere. Have a little compassion for those whom you call ignorant.
  • Chernobal is still critical.....burning away through the ground towards the water table.
    Not by a long shot. The PBS special on it some years ago publicly put the lie to that one. Some of the fuel did melt, but it formed a slag with the sand which surrounded the core and melted into glass. This glass flowed lower in the building, where it hardened (the reactor was not critical without a moderator, and the graphite moderator burned away).

    The hardened mix of fuel, waste isotopes, cladding and sand was named Chernobylite. The PBS show had footage of a piece of a hardened flow being shot off by a Russian marksman, then being placed in a shielded container by a small wheeled robot. That stuff is hard as rock; it isn't going anywhere.

"I prefer the blunted cudgels of the followers of the Serpent God." -- Sean Doran the Younger