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Liquid Nitrogen Injection Underground Last Defense

  1. Apr 24, 2011 #1
    Only assuming that the worst will happen and that will include the complete breaches through the bottom of the sealed containment of all four reactors, wouldn't it be possible, first, and then prudent, second, to be ready to cool these molten masses with liquid nitrogen being injected underground while capturing the gases with a type of canopy or other containment system? I know that any possible solution at this point would be most difficult to procure. It would be easier to be ready for this possible outcome now.
  2. jcsd
  3. Apr 24, 2011 #2


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    I don't believe such breaches have occurred or will occur. Injecting liquid nitrogen is not feasible, since liquid nitrogen requires a cryogenic vessel. It would be liquid in the ground.
  4. Apr 24, 2011 #3
    Thank you. How difficult or feasable to build circum containment under/around vessels now? Its hard to really get accurate info at present especially with Jp gvmnt cracking down on 'illegal' info! I'm finding.
  5. Apr 24, 2011 #4


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    The plant foundations are on bedrock. One complication would be boring or tunneling through rock.
  6. Apr 24, 2011 #5
    As I understand it, the plant is elevated unlike Chernobyl where filling the containment vessels were possible, this option isn't available on the slope of the fukushima plant. 7 on a scale of 1-7 brings the worst possible outcomes to mind, doesn't it?
  7. Apr 24, 2011 #6


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    The INES 7 rating is based on the release of I and Cs isotopes from 3 reactors cores, and at least one spent fuel pool. As far as we know, the reactor pressure vessels (RPVs) are intact, and I expect containments are flooded to the extent possible. Hence I don't expect corium, but the fuel is heavily damaged. I don't believe the fuel melted, but more likely the cladding is heavily oxidized/corroded and cracked or broken, and there may be significant fuel washout or dissolution.
  8. Apr 24, 2011 #7
    I imagine that there is a lot that is being reported to only the highest global authority that is making it harder for even the most educated of second guessing impossible. I think the Japanese government owes the most complete description known to all the peoples of the world. I'm sorry this is coming off more as a blog than technical data or report on my part. But of course we are all interested in how long until the eventual depletion of volitles entering the earth's biosphere. Thank you for your info. I saw a lot of number crunching and tears during the Exxon Valdez spill, that too was an environmental catastrophe, but without the radionuclides. Now I will have to call Muktuk Nuktuk..
  9. Apr 24, 2011 #8


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    If by blog, you mean crackpottish nonsense....
  10. Apr 25, 2011 #9
    It's tempting to think of molten reactor core material as a "lava like" substance you could cool by spraying something on it. However:

    Reactors #2 and #3 have nominal thermal outputs of 2.4 billion watts. At this point the thermal output has probably diminished to "only" 0.3%, but that's still 7.2 megawatts per reactor.

    Note this is not residual heat like molten lava from a volcano -- it is being continuously generated from nuclear decay.

    Liquid nitrogen's latent heat of vaporization is 199.1 kilojoules per kilogram. That's the heat energy 1 kg of LN2 would carry away if vaporized.

    7.2 megawatts is 25.9 million kilojoules per hour, continuously. A huge semi tanker truck can carry about 30,000 liters (about 24,000 kg) of LN2. This equates to 24000*199 = 4.77 million kilojoules per truck.

    So even if injecting LN2 into the ground picked up no heat from the earth, and the LN2 perfectly vaporized and carried away 100% of the possible nuclear decay heat, it would take: 25.9 million kj/hr / 4.77 million kj/truck = 5.4 trucks per hour, continuously.

    That's for a single reactor. To cool four reactors would take about four times that many, or 20 trucks per hour. That's probably far beyond the maximum world manufacturing capacity for liquid nitrogen.
  11. Apr 25, 2011 #10
    Thank you. Continuously meaning generations? 40Million years? (Just to put this in complete perspective!) And for the record, do you know what solution the brightest minds have come up with so far for the long term? Breaking down the cores, transporting to underground, safer locations? Or just restoring as much order as possible to damaged facilities?
  12. Apr 25, 2011 #11
    Not feasible there. Soviet union could do that during Chernobyl - using up all liquid nitrogen of western part of soviet union, that is to say, most of liquid nitrogen it had - using it also to deep freeze the *ground* under the reactor, actually. That minimizes steam formation when hot fuel lava reaches that ground.
    Japan can't possibly do something similar, they can't just take all their liquid nitrogen and throw at it. The calculations above are correct. It is a lot of liquid nitrogen. In the ballpark of all of liquid nitrogen in Japan.
    When Chernobyl is discussed in the west, it is always downplayed just how many resources were thrown at it. It is always presented as a worst possible disaster, most ineptly handled - but it wasn't so. Move it to capitalist country, and it will be a lot worse, because it'd be handled by the utility owning the reactor, with a little help.

    With the 'drywells' flooded, there's no way anything is melting anywhere. If there's any risk of steam explosion, it'd happen long before it hits the ground.
    Last edited: Apr 25, 2011
  13. Apr 25, 2011 #12
    The decay heat gradually diminishes: http://en.wikipedia.org/wiki/Decay_heat

    Spent fuel is usually stored in pools for several years. After that it can be stored in dry casks.

    Note this is necessary because of a high wasteful "once through" fuel cycle, which not only squanders most of the energy but creates highly radioactive waste which requires long-term storage: http://en.wikipedia.org/wiki/Nuclear_fuel_cycle

    There are other well-known solutions which reduce high level waste to a small amount: http://en.wikipedia.org/wiki/Integral_Fast_Reactor

    So technical solutions exist which could largely eliminate the waste problem, but for a variety of reasons haven't been used. And regardless of that it wouldn't change the 440 nuclear plants currently in operation worldwide.
  14. Apr 25, 2011 #13
    how so? You get same amount of fission products for the energy you get out. Except the fission products aren't immobilized anymore in small containers (pellets, and then, rods).
  15. Apr 25, 2011 #14


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    The power is decaying exponentially. After 2 months the power will be down to around 1 MW. After one year, ~300 kW. After 10 years, ~30 kW. After 100 years, 5 kW. After 1000 years, 1 kW.

    Most of the long-term decay heat is produced by only a few isotopes though (sr-90, cs-137, am-241 and pu-239) which can be chemically separated and allowed to decay by themselves in a small shielded container.
  16. Apr 25, 2011 #15
    small, VERY WELL COOLED shielded container. Think about it, it'll be making same power, if you concentrate it, you have higher power density, smaller surface area for cooling it...
  17. Apr 25, 2011 #16
    Mobile, Super-Cooled, Shielded Containers with a decaying payload launched into the sun would be something new, ridding the earth of all the contamination, right? It seems that such an endeavor would serve mankind better than colonizing the moon, no? I'm sure this is elementary and there are reasons its not feasable, probably safety, cost?
  18. Apr 25, 2011 #17


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    It's not hard to cool 10 kW, in a steel cask natural convection would be sufficient.

    No. The Earth is a big place. There's plenty of room to tuck away hazardous materials where they can't harm anyone for thousands of years. Launching waste is risky, expensive, and pointless. Also it would take quite a large rocket to send any significant amount of material into the sun. There is no such thing as a "decaying solar orbit". In order to crash into the sun, you have to use thrusters to actively decelerate. It takes more delta-v to decelerate from Earth into the Sun than it does to leave the solar system entirely.
  19. Apr 25, 2011 #18
    Sweet Jeeeebers, NOOOOOO! Just imagine a company like TEPCO winning the contract for that project. Just imagine an "incident" happening anytime between the launch(or even much before) and the payload vessel's deceleration so it can free fall into the sun(sort of).

    Don't think about this anymore. Ever.
  20. Apr 25, 2011 #19
    Its not quite exponential because of decay chains ,

    it will still be 5 MW after 1 year :

    http://mitnse.com/2011/03/16/what-is-decay-heat/ [Broken]
    Last edited by a moderator: May 5, 2017
  21. Apr 25, 2011 #20
    Newer reactor designs like IFR and I think some Gen IV designs burn fission waste as fuel, converting it to a much smaller amount of waste with shorter life.

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