Nuclear Disasters of the Past

So, Three-Mile Island was the worst nuclear accident on US soil. How many deaths are epidemologically attributed to the accident. Well, one study I was quoted in passing by a co-worker was that 50-100 deaths resulted from the accident. All these deaths alas, were due to the increased coal mining and pollutants from the increase in coal fired electrical production. 

Who wants to guess that the aftermath of the recent earthquake and reactor incedents have similar “fallout?”

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18 comments

  1. Boonton says:

    Off the bat you have the workers who are directly fighting the reactors who are getting lifetime doses of radiation in an hour or so. We saw that in Russia where many of the workers didn’t last a year but we don’t know how much more attention Japan is paying to worker safety. The US plane that can detect radioactive plumes in the air (used to monitor nuclear bomb tests by countries like N. Korea), is picking up real radiation well beyond the plant itself.

    On the positive side Japan seems to have a much more efficient gov’t that is really concerned about safety. In contrast when it happened in Russia valuable time was squandered by trying to pretend everything was under control. If the evacuation was done correctly the eventual number of cancer deaths may be minimal. On the other hand evacuations are not free. They may not show up as cancer deaths but deaths will happen from heart attacks, injuries, people who might have been resqued if emergancy workers could have just concentrated on the quake rather than managing an evacuation etc.

    From what I’ve been reading, it’s not just about a melt down. The fuel itself puts out a lot of heat. The Economist says the spent fuel rods themselves put out the heat of a jet engine at full throttle alone, why is why they sit in a giant bath of water. If the water is gone the protective coating around the rods will melt away and if the rods are exposed to air they will basically start burning sending the material up in the smoke.

    Take aways so far:
    1. Multiple backup systems can be less fool proof than they may seem at first glance when you realize probabilities of failure are not independent of each other.

    2. The problem is not just the reaction itself. A reactor that has been fully shut down still needs multiple systems working to prevent a massive release. In this respect I wonder if the ‘pebble’ based reactor you’ve been pushing as fool proof may simply be a bit less risky.

    I don’t think its Russia but its pretty bad, Three-Mile Island was triva in comparision. I’m a bit skeptical of your ‘study’. How does the study purport to ‘know’ how much coal mining happened because of 3-mile island versus the simple fact that coal is very cheap and nuclear plants are often uneconomical.

  2. Mark says:

    Boonton,
    The workers are all wearing dosimeters. When they get their annual not lifetime dose, they are no longer working on site. The point is, while we don’t know how much radiation the workers are getting, they do.

    Chernobyl is completely off the map as far as scale of problem and radiation release. The Chernobyl reactor was carbon (graphite) moderated. Only one (UK, now shut down) reactor in the entire western world was a graphite pile. Carbon graphite piles suffer from having to anneal out Wigner energy (crystal defects due to neutron bombardment needs to be heat treated out otherwise the defects build until explosively released). It was during an annealing cycle that the accident occurred … and the graphite pile burned for weeks. Additionally, the Soviet bloc reactors don’t enrich their as much as the West. That meant their power/heat coefficient was positive not negative like in the West. In English that means that as the reactor gets hotter in the Soviet bloc the reaction tended to want to put out more power, in the West, as a reactor heats … the reaction itself is damped because the neutron absorption efficiency is going down not up. The point is, this is a lot more (by many orders of magnitude) like 3-Mile Island than Chernobyl and there is little reason to believe that situation will change.

    What does “melt-down” mean to you? I’m curious.

    If the water is gone the protective coating around the rods will melt away and if the rods are exposed to air they will basically start burning sending the material up in the smoke.

    No. That’s not what happens. The “protective coatings” are steel rods. The problem is if they heat up too much some hydrogen (some of which it Tritium) is released from the rust protection coating. Tritium has a 12 year half life … but only a three day biological half life.

    How does the study purport to ‘know’ how much coal mining happened because of 3-mile island versus the simple fact that coal is very cheap and nuclear plants are often uneconomical.

    Estimates of that should be fairly uncomplicated and straightforward. As you know the costs of Nuclear plants are “up front” … and the power output of the 3-Mile Island plant is known. How much coal would be required to replace is quite calculable and not “unknowable.”

    There’s been a lot of scare reporting, it seems to me and a lot of mis-reporting confusing millisieverts with microseiverts. Those 3 orders of magnitude are significant.

    The US plane that can detect radioactive plumes in the air (used to monitor nuclear bomb tests by countries like N. Korea), is picking up real radiation well beyond the plant itself.

    So? There is a wide margin between what is detectable and what is even biologically significant at any level to what is dangerous.

    Multiple backup systems can be less fool proof than they may seem at first glance when you realize probabilities of failure are not independent of each other.

    I’m curious. Why were the reactors shut down at all? If they hadn’t been shut down, then the backup systems would have had power. Have you seen a (reliable) report saying why the shutdown was required?

  3. Boonton says:

    What does “melt-down” mean to you? I’m curious.

    To me a melt down means fission reaction is happening in an uncontrolled, unstoppable manner. One mental vision I’ve had from what I’ve read is the material melting because its ‘natural heat’ cannot be removed via the water system and the material ‘pooling’ underneath where the fission reaction starts thereby making it hotter. I’d imagine, though, at some point this ‘pool’ has to spread out enough for the reaction to case and that it isn’t so hot that it ‘melts all the way to china’.

    Tritium has a 12 year half life … but only a three day biological half life.

    Yes so let’s say you ingest 4380 tritium atoms. I’m figuring only about 1.5 of those atoms will actually decay and release radiation while inside your body before 3 days pass and half of them leave. So another 3-6 days you’d probably see maybe just another atom decay before the amount of tritium in your body goes to near zero. But you’re assuming a single instance of exposure. Imagine living in an area coated with tritium. Yes every 3 days half the atoms are leaving your body, but you’re replacing them with new atoms. A 3 day bio-half life is not really important for you then, it’s the 12 year half life since you’re not going to lower your exposure until you either move or the amount of tritium disappears.

    Estimates of that should be fairly uncomplicated and straightforward. As you know the costs of Nuclear plants are “up front” … and the power output of the 3-Mile Island plant is known. How much coal would be required to replace is quite calculable and not “unknowable.”

    OK, I thought the study was assuming the slowdown in Nuclear power after 3-Mile Island was all caused by the accident and therefore was estimating how much coal was burned post 3-Mile Island that would have been replaced IF nuclear had continued growing at the pace it did. That would be problematic because nuclear suffers from cons other than the radiation concern…In a world of cheap natural gas, cheap coal it’s not very economical givin the massive investment it requires and the long payback period.

    More importantly, though, I suspect this estimate is based on straight lining radiation death. From http://www.bbc.co.uk/news/health-12722435, 5,000 mSv would result in death of 1/2 exposed in less than a month. From that you could straight line back to calculate a number of people who supposedly die from regular background radiation each year or additional deaths from tiny increases in background radiation (such as from burning coal). But this has never been proven. It very well might be that the curve is more of an inverted ‘j’ shaped where tiny amounts of radiation might actually be kinda of good then the benefit drops to zero as soon as you leave ‘normal background’ amounts and then starts shooting down into ‘negative benefit’ (i.e. harm) for higher levels of exposure.

    It also views time as irrelevant….exposure to a given amount of radiation in a day is the same as being expoosed to the same amount spread over a year. I’m not sure this has been established and it may be false. Taking your radiation in tiny amounts over time may give you body the breathing room it needs to kill the mutated cells that you get from it while taking it all at once overwhelms your body and let’s a few cells with the cancer mutations loose.

    I’m curious. Why were the reactors shut down at all? If they hadn’t been shut down, then the backup systems would have had power. Have you seen a (reliable) report saying why the shutdown was required?

    what I’ve heard and am not sure about is that the reactors shut down but they still require several days to cool, hence the need to keep the water circulating. If that’s so then there must be a massive amount of heat from the reaction. On top of that even non-reacting material must be cooled in water because of the heat it gives off naturally.

    So what would have happened if the reactor wasn’t shut down and the power wasn’t cut *but* the wave wiped out the pumps? Would the reactor have been able to shut down manually if hit by the wave? would the heat have just been a worse problem? The pumps were able to work a while after shutdown via power, then diesal, then battery.

  4. Mark says:

    Boonton,
    Hmm. It occurred to me that the hydrogen released is probably not tritium, but just plain hydrogen. It’s a chemical heat reaction that produces the hydrogen. The fear then would be that the gas release carries particles of other radioactive stuff with it.

    A “melt-down” is not a “china-syndrome fantasy” but is basically an event in which the reactor heats up to a point at which fuel “moves”, that is the rods containing the nuclear material warp or change shape due to heating.

    5,000 mSv would result in death of 1/2 exposed in less than a month.

    That’s 5 Sv causing death in half exposed. And … 600 microSv is an x-ray. … So … googling “seiverts and three-mile island” we see that at Three-Mile Island the exposure to which the people around were exposed was 60 microSv. To put that in context about a tenth of an x-ray. So, you should begin to see why your epidemiology finds more death from coal than the exposure. Right (and if you don’t agree to that this is a “religious” argument, i.e., in the sense that nothing I say will convince you of anything on this topic).

    OK, I thought the study was assuming the slowdown in Nuclear power after 3-Mile Island was all caused by the accident and therefore was estimating how much coal was burned post 3-Mile Island that would have been replaced IF nuclear had continued growing at the pace it did.

    No. It was the increase in coal because of the removal of the one plant from operation. Hence your economics of future coal is not important. My suggesting for the future however depends on future plant construction and is, I admit, far more speculative.

    About the reactor shut down and why? The reason for the question is that, if the reactors where not shut down, they’d then still have generated power for the pumps.

    BTW, my daughter asked about the accident and Chernobyl. I told her to laugh outright at people making the comparison. The release of material so far in Japan is likely measured in grams … Chernobyl released 30 tons of radioactive stuff into to the atmosphere. Those who can’t tell grams from tons deserve a little scorn.

  5. Boonton says:

    A “melt-down” is not a “china-syndrome fantasy” but is basically an event in which the reactor heats up to a point at which fuel “moves”, that is the rods containing the nuclear material warp or change shape due to heating.

    Question then, is this due to the fuel being ‘naturally hot’ or the fuel being hot due to fission happening? Can the fuel then ‘move’ to the point where it is close enough to its fellow fuel that the fission reaction then starts up and cannot be stopped?

    Maybe you can clear up some confusion I have with the language. If you have a radioactive material in a container, that material will emit radiation which your body could asorb if you happen to be standing next to it. In that case the danger can be simply addressed by making sure you don’t stand by it too long or if you do you have shielding to block its rays. On the other hand if that container of radioactive material explodes and spreads out like baby powder, then yes standing near it exposes you to its rays but it’s also getting on your clothes, you’re breathing it in etc. Even when you walk away and go home for the night you’re carrying that material in your body which is getting damaged by the radiation it gives off. Hence we see pictures of the workers in full body suites with breathing masks on. This isn’t because the suits offer much protection from the actual radiation, it’s that they keep the radioactive material from getting on or in the worker’s bodies.

    This morning the radio says that they think they might have ‘stabalized’ some of the reactors and the ‘containment’ hasn’t been breached. But if the containment hasn’t been breached why the need for the body suits and how is California picking up trace amounts of radiation? Certainly some material must have been released in the explosions? How could that happen if the material is still fully ‘contained’???

    About the reactor shut down and why? The reason for the question is that, if the reactors where not shut down, they’d then still have generated power for the pumps.

    Possibly but then what would happen in the alternative case where the reactors were not shut down but the pumps were nevertheless disabled by the wave? (And since this reactor is so hot even after a shutdown couldn’t it be generating some residual power even then? The pumps certainly take a trivial amount of output from the thousands of homes the reactor was supplying. I wouldn’t be surprised if the pumps were fed first by the reactor itself, then by the general electric grid and last by battery backup with the wave destroying the actual lines from the reactor/grid to the pumps.

    Chernobyl released 30 tons of radioactive stuff into to the atmosphere. Those who can’t tell grams from tons deserve a little scorn.

    Indeed but how much are we talking about here? Grams or tons?

  6. Mark says:

    Boonton,
    What do you mean by “naturally hot”? A U235 atom is has a half life and will fission on its own at some rate. If it captures neutron (and “thermal”, i.e., cold moderated neutrons) are far more likely to be captured … then it will be less stable and far more likely to fission sooner. So, it can move “closer” to other fuel elements, but you also need a moderator. And … the cross section (probability) of neutron capture is heat dependent …

    Radioactivity release without a containment breach is possible. Neutrons emitted by the reaction leave the containment vessel and can be captured by other nuclei, which in turn can the new isotope unstable itself.

    Locate the XKCD graphic on radioactivity.

  7. Boonton says:

    I suppose what I mean by ‘naturally hot’ is that the fuel rods are giving off heat even when the reactor is ‘turned off’ because as you say the U235 atom has a half life and will fission on its own at some rate. From what I understand the reactor is not just about storing a bunch of U235 atoms and basking in the heat they give off but about forcing them to fission even faster by making sure they get hit with lots of neutrons. This happens on a simple level from the fact that if you get a lot of atoms close together the neutrons released from on ‘natural fission’ are more likely to impact other atoms thereby causing more fission.

    So in my mental image of a ‘meltdown’ the fuel starts to melt or warp and collects into some type of pool. Because you not got a bunch of U235 atoms close together the ‘natural fission’ starts feeding a reaction where more and more fission happens undirected by the plant operators thereby making the pile hotter and hotter. Where things go from there I don’t know.

    Radioactivity release without a containment breach is possible. Neutrons emitted by the reaction leave the containment vessel and can be captured by other nuclei,

    I think I remember reading about this in relation to ‘neutron bombs’. A neutron bomb might hit something like a tank with lots of neutrons which will get ‘asorbed’ by the tank’s metal….sort of like a sponge asorbing water. The tank will then slowly give off that radiation over a few days or so making it deadly to use by its crew. The impression I got, though, that this was rather short lived. The radiation dissipates quickly.

    So then the question is what exactly is California picking up? Are they seeing atoms that got hit by radiation from the reactor…radiation that would have normally been asorbed by the water and steel/concrete building surrounding the reactor…which then travelled to CA by the wind and sea? Or are they seeing actual tiny bits of the reactor itself that either blew or boiled off during one of the multiple explosions?

    Next question, today they are saying the pool that the ‘spent fuel rods’ sit in is boiling. If even the ‘used up’ fuel rods put out enough heat to boil a large pool of water why wouldn’t they tap that for additional generation power? How about space probes that use radioactive material as ‘fuel’? It seems to me like nuclear waste could be tapped for electrical power while it’s sitting around waiting to get burried in Yucca Mountain or whereever it’s going to finally go….

    Finally as a side note, I notice quite a few people, including you, have been asserting that if electric based cars are going to take off big time, nuclear will need to be tapped much more to supply the increased demand on the grid. This doesn’t seem to be thought out well to me….

    1. The largest plants ‘want’ to operate 24-7 but demand varies dramatically shooting up at day and dropping very low at night. It seems that there’s a lot of potential to tap unused night time capacity. Since convincing half the population to stay up all night and sleep all day probably isn’t going to happen, electric cars would seem like the next best way to pull off a chronological transfer since most people would charge their electric cars as they sleep.

    2. You could just burn gas to charge the cars! Well not quite but gas cars are basically a very tiny power plant if you think about it. Tiny plants tend to be very inefficient and loose a lot of energy to heat loss. Huge plants, on the other hand, benefit from being more efficient. Apples to apples, if you had a 50 mile extension cord it would be more efficient to run your car off of that letting a monster boiler at the power plant generate the power burning coal, gas or oil rather than your little engine doing it. Hence subways and trains are able to tap efficiencies by letting the power plant do the work rather than running their own locomotives…..

    So if tomorrow we suddenly coverted so many cars to electric thereby saving 100 units of oil, but you weren’t allowed to use new nuclear capacity to fuel them, you could power those electric cars with less than 100 units of oil (or coal or whatnot) burned at massive plants. I suppose the downside would be that you’d loose energy sending it over the power lines from the plant to the homes and then from the homes to the batteries in the cars….but could you get that energy loss to equal the energy loss that’s incurred from having your power come from thousands of tiny engines? I bet you could. After all it’s almost always more efficient for a home to draw its electric from the grid rather than using a gas or oil boiler to generate its own domestic electric.

  8. Mark says:

    Boonton,
    While the reactivity will go up by “putting all the fuel” close together, that doesn’t mean it will be higher than in a well designed reactor, because you won’t have any moderator any more. Neutrons coming directly out of a fission event are “hot” they have a lot of kinetic energy. That means their wavelength is very short. A colder neutron, so called “thermal neutrons”, which have a much lower kinetic energy have a longer wavelength an a much higher chance of interaction with a nuclei. This is why for a fission device (bomb) you need very very highly purified U235 because you want to be putting lots of moderator in there.

    The tank will then slowly give off that radiation over a few days or so making it deadly to use by its crew. The impression I got, though, that this was rather short lived. The radiation dissipates quickly.

    Depends on the element. For many elements the half-life is minutes, which means the those parts of the tank will be clean in a very short time (minutes). Iodine is an example of an element that has a longer half life.

    So then the question is what exactly is California picking up? Are they seeing atoms that got hit by radiation from the reactor…radiation that would have normally been asorbed by the water and steel/concrete building surrounding the reactor…which then travelled to CA by the wind and sea? Or are they seeing actual tiny bits of the reactor itself that either blew or boiled off during one of the multiple explosions?

    Look at the reactor core as a human body with its digestive tract. You are a torus, stuff you eat isn’t really “inside” you in the same way that your blood and organs are. A core release is like a release of blood or organs. A coolant release is an more like the flu. Now, the coolant (water) is going to be somewhat radioactive after time due to absorption of neutrons … a higher percentage of the H and O are going to be other isotopes than the ordinary … and have their respective activity and half life. If you release this steam (or as noted the steam under high temperatures likes to react chemically with stuff and be hydrogen (an event which can happen at non-nuclear power plants … but there the water isn’t “hot” in the radioactive sense). That is very different than releasing heavy metals and stuff. Chernobyl as noted was the core burning. Carbon moderator and core material were being released to the atmosphere directly.

    At the troubled Fukyama (sp?) reactor I understand against mfg (Westinghouse) recommendations the practice was to occasionally remove for inspection all the fuel rods for inspection and observation. The recommended (US) practice is only to remove fuel rods when they are spent. This was in process at the time of the accident and is why the rods are so hot.

    But yes, the waste material at Yucca is going to be hot. Not hot enough for modern power generation, which heats the water beyond the critical point (see the phase diagram for water … follow the phase line between gas/liquid out from the triple point. See where it vanishes? … that’s where modern power plants live. Quite amazing really.). The point is the spent fuel doesn’t have the umph to live in that world any more. And as noted in that discussion from that MIT paper its both expense to continue processing, and because a certain “interesting” amount of the U238 has taken on neutrons to become Plutonium, which has other bomb/terrorist related issues … means storing it is what is recommended. (Hint: Drill).

    The reason we don’t want to use small gas engines to generate electricity is because it would be more efficient to use that gas to directly drive your car at that point … and small motors (electric and gas) are less efficient than large ones.

  9. Boonton says:

    Sounds good. So iodine aside, are the materials that have been made radioactive by being explose to neutrons coming from the core going to be a problem for a long period of time (say over a year)? Or is the only time you have a long term serious problem from a nuclear reactor when you actually have the core itself breached and the actual metals in there being expelled into the air?

    The reason we don’t want to use small gas engines to generate electricity is because it would be more efficient to use that gas to directly drive your car at that point … and small motors (electric and gas) are less efficient than large ones.

    True but many homes use gas for heat which is also used for electricity generation in larger plants. Some still use coal which is a major source of electricity. Home electric generation, though, has not really been economical unless you’re talking about being far from the grid, or as a backup to the grid. I think in theory you could have a massive increase in electric based battery cars that is fed by currently unused capacity and topping that off with non-nuclear fossil fuels and still see a net reduction in CO2 emmissions.

    Perhaps a ‘street car’ approach might be something worth considering. You keep the gas engine, you keep the battery but certain roads (like major interstates) would have ‘3rd rails’ on them. The cars could tap that rail for electric power both to charge its battery and run the trip. On smaller roads the car would revert to its regular gas/battery based operation. The advantage would be that you could stop trying to discover a way to make batteries charge very rapidly or have very large capacities.

  10. Mark says:

    Boonton,
    The materials from a core release are going to be both more active and many longer lasting and biologically more problematic (heavy metals when eaten tend to go to your bones and stay for decades whereas deuterium or tritium is going to be out with a half life of three days). So the problem is one of scale and impact.

    Look at it from an simple energy balance. You have to replace with electricity the energy burned in petroleum cars today. That’s more energy than the grid has capacity to provide. Running full out on off hours isn’t going to fix that.

  11. Boonton says:

    Hmmmm and what has become of your assertion that supply could easily double without adding capacity?

    I think you’re under estimating how important off hours are. Baseline power plants run all the time but there’s a huge swing in demand between day and night (as well as random swings during, say, heat waves). Swing production (like gas plants) can turn on and off but doing so costs energy as well as wear and tear. Simply making demand more even would allow the utility to use more baseline production and less of the expensive swing production. More electric cars would do it, so would serious battery innovations that could effectively do the same thing.

    Worse case, though, you can burn the fossil fuels that would have burned in cars in added plants. Since large plants are more efficient than small cars, you’d still see net energy savings if you could avoid losing it in the transmission and conversion to battery storage.

  12. Mark says:

    Boonton,
    You need much more than double to run those cars. That’s the problem.

  13. Boonton says:

    Hmmmm, what if you bypassed the battery and went to a combo gas / street car approach where cars would pull electric from certain streets that had power lines installed? You’d get rid of the energy loss of having to carry all your electric around in battery form.

  14. Mark says:

    Boonton,
    That’s an urban only solution.

  15. Boonton says:

    Or maybe not, think about interstates and major highways. You may rather roll this out on roads that have fewer rather than more people on them as pedestians.

  16. Boonton says:

    OK back to nukes…..

    1. It seems that your pebble reactor misses a point. The inability to melt down eliminates your risk of releasing the actual reactor core materials (unless, I suppose, someone manages to blow the thing up), but you’re telling me that you can get radioactive materials just by the radiation from the reactor itself….

    2. In the debate over Yucca Mountain, I remember one of the concerns was water rotting away the containment vessels. One proposed solution was to pack the vessels tightly together and let the natural heat from the radioactive provide a heat barrier that would evaporate water droplets before they could impact the metal. It seems that spent fuel can still put out enough energy to be somewhat interesting…. Why not build a large boiler type operation to let the spent rods sit for a few years or even decades? Extract some useful work out of them for a bit more while letting htem cool a bit and let R&D work on the waste issue?*

    * I also recall hearing another idea floated of burying the material really deep and letting it’s ‘natural heat’ melt the rocks around it in order to sink very deep into the earth. If that’s true then this material really must put out an interesting amount of heat even when fully spent. No?

  17. Mark says:

    Boonton,
    Yes, radiation can stimulate other materials to be radioactive. This process is the source of most medical radioactive materials, btw. The point is that the core release is the far more dangerous (like Chernobyl) which is why it is the concern. Making a reactor in which the fuel and core are intrinsically safe, so a situation like Japan were diesel and battery backups were lost … would then pose no danger.

    I think the reason is people don’t want to use waste as secondary heat sources is that their radiation release and associated needs to control and engineer around that are high compared to the heat available.

    The MIT study which recommended sinking deep holes and putting the material in there did not suggest that it would “melt rocks” around the borehole. I don’t think the waste is hot enough to melt rock.

  18. Boonton says:

    OK so google says iodine’s half life is about 8 days which means in 40 days 97% or so will be gone. Assuming you don’t have a core release, what’s the worse possible case in terms of material that’s stimulated to be radioactive? It sounds to me like 6 months and all the radiation is gone so the challenge is just to keep people out of the area that has material for a while. It’s not the million year challenge posed by core material or waste.