Fukushima Daiichi

Discussion in 'Earth Science' started by Trippy, Aug 5, 2013.

  1. Trippy ALEA IACTA EST Staff Member

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    I'm having one of those moments that leaves me wondering wether or not there's something I'm missing.

    I was reading about the latest woes TEPCO have been having at Fukushima and it seems to me they're missing thed obvious solution.

    The little that I have been able to gather is that the problem they are having is one of groundwater containment. They pumped some chemical into the ground that hardens to make the soil impermeable, btut, it's only effective at depths >1.8m and there are concerns about it overtopping as the groundwater continues its inexorable trek from the hills behind the plant to the ocean in front of it.

    It seems to me that there's an obvious solution.

    Dig two paralell trenches around the plant (or around reactors one and two).
    Fill the outermost trench as a slurry wall. For bonus points you can line it with geotextile.
    Fill the innermost trench with pea gravel and place a pumping well every twenty meters or so.
    Trench depth is dependent on soil hydraulic conductivity.
    The basic idea is the slurry wall diverts flow around the affected area, while the pumping setts up a negative hydraulic gradient containing any groundwater contamination in much the same way a negative pressure environment contains airborne contaminants
    Pump, condense, store, dispose.

    It seems such an obvious solution to me that it leaves wondering what I have missed.
     
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  3. spidergoat Valued Senior Member

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    Why don't they just throw some Jello™ in there?
     
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  5. Gage Registered Senior Member

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    You should draw it on a map, to make sense of it. I think we read the same article. From what I got out of it was their worried about the groundwater rising and breaking the underground barrier of the slurry pool which will cause the slurry to rise and seep into ocean. Right? Either way the worse part it seemed to me was they can't even get robots near the reactors it's so radioactive. 3 of the 6 reactors are in meltdown, apparently all their doing is pouring water on it to keep it from leaking anywhere else then storing all of it in containers which they ran out of. This shit is going to take years to clean up.
     
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  7. leopold Valued Senior Member

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    japans atomic commission should have its head examined for allowing fukishima to be built in such a vulnerable place to begin with.
     
  8. iceaura Valued Senior Member

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    It was no worse than the locations of dozens of other plants in various countries - it was not normally upwind or upstream of any major cities, it had a large source of emergency cooling water handy, it did not put any significant bodies of fresh water at risk, etc.

    If you are going to build those things, you have to pick a location - there are very few good ones.
     
  9. KitemanSA Registered Senior Member

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    I read somewhere that FD 1 thru 4 were originally planned to be up the hill behind them at about the elevation of 5 & 6 which both worked just fine. They apparently moved them down hill to save on cooling water pumping costs. Having lowered the plant about 50m, they then installed a 5(?)m sea-wall. Dumb, da dumb, dumb, DUUUMB!
     
  10. Trippy ALEA IACTA EST Staff Member

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    Seconded.
     
  11. billvon Valued Senior Member

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    It was a pretty good site compared to the other possibilities.

    Consider it this way. If the earthquake had been centered IN Japan, then putting it on the top of a high hill would be "such a vulnerable place." If the disaster had been the biggest typhoon Japan had ever seen, then putting it in a remote valley would be "such a vulnerable place." It's easy in hindsight to claim that it was a bad design choice, but that's only because of the specific disaster that hit the plant.
     
  12. Trippy ALEA IACTA EST Staff Member

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    It's been suggested to me a couple of times that there isn't the space between the plant and the ocean. I can see two replies to that.

    1. It doesn't require much space. The slurry wall and the drainage trench only need to be a meter wide (If that).

    2. That explains why it hasn't been done on the ocean side, what about the other three sides? If you're willing to accept pumping a quantity of sea water, and include that in your calculations, then installing the slurry wall on the other three sides combined with installing an appropriate drainage trench network is still going to be effective at isolating the plant from the groundwater.
     
  13. Gage Registered Senior Member

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    165
    draw it
     
  14. KitemanSA Registered Senior Member

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    They need to drill three lines of wells, one as close to the ocean as possible, one just inland of the reactors, and one near the inland boundary of the site.
    Pump the ground water out at the boundary to reduce the groundwater flow. Filter it and inject it back into the ground at the ocean edge. Pump out all available water at the middle line (inland of the plants). This will drive any leaked contamination back inland and allow it to be pumped out and treated. It would also reduce the amount of ground water leakage into the plants.
     
  15. iceaura Valued Senior Member

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    From the sound of things they may be facing narrow and fairly rapid flows somewhere, rather than a general seepage. If that's so, lines of wells would only work by luck - they would have to find the leak or leaks, and the flow or flows, to make committing too much of their resources a good bet.

    It's also possible their problem is quite deep - that a trench capable of intercepting its progress toward the ocean would have to be dug down a long ways - well below, say, sea level.

    Nothing worked "just fine" at 5 and 6 - they too lost cooling power, etc. They were simply lucky in that they had been shut down for inspection rather than operating at power as 1,2,and 3 were, did not share piping allowing gas flow from the meltdowns as 4 did, and in the case of 5 did not suffer shake acceleration exceeding their design limits as a couple of others did.

    We should mention in that respect the other Fukushima plant - Daini not Daichii - that despite getting hit with smaller waves etc came within one backup diesel generator of losing cooling power to its several reactors, which were in trouble. (Reactor 3 was down to one emergency seawater pump for a rapidly overheating core). Only very competent response by plant workers and the good luck of that one remaining generator operating at full power without breakdown and that one pump in 3 holding out kept Daini out of the headlines.
     
    Last edited: Aug 8, 2013
  16. Buddha12 Valued Senior Member

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    Just remember that Japan is on a plate that is constantly creating earthquakes throughout Japan so no matter where you build a power plant you are just going to have to take that into consideration. So if they moved this power plant inland they could have had a 8.0 earthquake to destroy it there too. In Japan they are having minor earthquakes almost monthly.
     
  17. Trippy ALEA IACTA EST Staff Member

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    I could grant you that - channelized through old streambeds and their associated gravels. Even that's not insurmountable though, my recollection is that resistivity testing should be able to identify that.

    The impression I have (for what that's worth) is that the problem (or part of it anyway) is that the chemical they've used to seal the pores and create a barrier is only really effective at depths greater than 1.8m and that they were concerned about overtopping of this underground barrier.
     
  18. KitemanSA Registered Senior Member

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    They lost power to the plant but unlike #4, their emergency power worked. If the emergency diesels for 1 thru 4 had worked, there wouldn't have been the giant mess. The PLANTS might have been toast, but the landscape would still be clean.
     
  19. KitemanSA Registered Senior Member

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    The plants survived the 9.0 earthquake, they failed due to inadequate tsunami protection. There were a number of plants along the coast that all saw pretty much the same 9.0 earthquake. NONE of them failed, except Daiichi which had inadequate tsunami protection. (This isn't to imply the others all have adequate protection, just that they may not have been fully TSUNAMI tested this go around.)
     
  20. iceaura Valued Senior Member

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    A couple of the reactors were severely damaged by the quake itself. The luck of having so many of the reactors at Daichii shut down for maintenance was critical - the several factors of extraordinary good luck involved in saving Fukushima from the disaster it could have been should never be overlooked.
    None of those plants were shaken as hard, nevertheless Dainii apparently came within one overworked functioning generator, one seawater pump in reactor 3, and the commendable competence of the plant employees at the scene

    (as well as the extreme good luck of having the quake hit during weekday working hours, with thousands of employees rather than tens at the scene to string the miles of heavy cable for power etc. The odds of that were 4:1 against, and with only the evening or weekend crew at hand reactors 1, 2, and 4 would probably not have been stabilized in time)

    of suffering a similar series of meltdowns, depending on the role of the quake damage in Daichii's problems (the quake at Dainii was much weaker). We don't know what happened due to the quake at Daichii yet - as with Three Mile Island, it will be a couple of years before we even find out exactly what happened to the cores of a couple of those reactors, and can reconstruct the sequence of events with more than informed guesswork and estimation to guide us.

    The reactors and plant at Dainii failed just as Daichii did, except apparently from tsunami damage only and without losing their cooling systems for as long a period. They remain damaged essentially beyond repair. . Your notion that no nukes "failed" except Daichii's is bizarre - Daini's four reactors are a total loss, and three of the four reactors came within last resort emergency measures of melting down.
     
    Last edited: Aug 22, 2013
  21. KitemanSA Registered Senior Member

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    Repeated investigations from numerous organizations have ALL come back with the statement that the units survived the earthquake essentially undamaged. It was the tsunami and subsequent explosions that resulted in all the damage.
     
  22. KitemanSA Registered Senior Member

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    Fine, I admit that I was a bit lax on the use of the term "failed". I did mean melted down/ failed containment.
     
  23. KitemanSA Registered Senior Member

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    As far as I know, the complex north of Daichi on the coast closer to the epicenter did NOT fail because it was up on a bluff above the tsunami danger.

    The point being that earthquake risk is basically solved, and was back in the 60s and 70s. We are better at it now, so things are looking up. Daichi was due to poor tsunami requirements, and failure to learn from others (didn't install the catalytic hydrogen burners as recommended).
     

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