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French nuclear specialists agree Fukushima “could still explode”, corium a threat — Reactors remain in meltdown says expert, molten lava could break through at any point

Published: March 11th, 2012 at 4:47 pm ET
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Title: One year after catastrophe, Fukushima remains a threat
Source: FRANCE 24
Author: Charlotte BOITIAUX
Date: 11/03/2012

One year after catastrophe [...] the crippled nuclear plant remains a danger zone. Two specialists tell FRANCE 24 why it could still explode. [...]

Plant director Takeshi Takahashi [...] admitted [last week] the station [...] was still “rather fragile”.

[...] Two French specialists decode Takahashi’s statement. [...]

Stéphane Lhomme, head of the French anti-nuclear organisation l’Observatoire nucléaire

  • [Lhomme] says that TEPCO is seriously playing down potential dangers
  • “Their declarations are over-confident, and moreover, simply not true”
  • “The plant is neither stable nor fragile”
  • Current situation [is] “catastrophic. Even if the thermal power in the four damaged reactors has been considerably reduced, they are still in meltdown and therefore still noxious”
  • Speaking with an alarmed tone, he says “of course the global situation is slightly better than it was a year ago. But the corium, a lava-like fuel-containing material that lies at the bottom of the containers, remains a real problem.”
  • Lhomme argues that at several thousand degrees, this molten lava could break through the cask at any point and destroy the concrete beneath the container, reaching soil and water located beneath the surface
  • “If it comes into contact with water, the corium would spark a series of massive vapour cloud explosions”

Thierry Charles, security director of the French Institute of Radio-Protection and Nuclear Safety (IRSN)

  • [Charles] agrees that the remaining corium could pose a threat
  • “We don’t even know how much corium each cask contains”
  • “Or how much could get through several metres of concrete”
  • Charles is more optimistic than his colleague
  • “The Japanese authorities have already done plenty to tackle the problem. They have injected a cement substance into the floor of the plant, removed the debris, blocked off potential seepage points, cleaned the floors and dressed Reactor 1 in a metal cover in order to limit any fallout”

Read the report here

Published: March 11th, 2012 at 4:47 pm ET
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25 comments

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  2. Wired: ‘Healthy debate’ about location of Fukushima corium — Lava can melt a foot of concrete per hour — Cooling with water may not stop corium flow April 18, 2013
  3. French Nuclear Experts: Did corium pierce steel liners of Fukushima reactors? How deep did it erode concrete? (VIDEO) February 3, 2013
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March 11th, 2012 | Category: Did China Syndrome (Fuel Outside Containment) Occur?, Fukushima Daiichi
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25 comments to French nuclear specialists agree Fukushima “could still explode”, corium a threat — Reactors remain in meltdown says expert, molten lava could break through at any point

  • anne anne
    March 11, 2012 at 5:15 pm

    The tent isn't metal; it's polyester. And there is at least one window that vents radiation continuously, seen especially every single night, all night long on the TEPCO cam:

    New plan to stop radioactive leak
    2011-08-12
    "The tent is made up of airtight polyester. It will stand 54 metres tall and stretch 47 metres in length. It is held up by a metal frame…."
    http://www.news24.com/World/News/New-plan-to-stop-radioactive-leak-20110812


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  • TheWorldIsBlind
    March 11, 2012 at 5:27 pm

    what did they build infront of reactor 3??


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  • Lacsap Lacsap
    March 11, 2012 at 5:28 pm

    'The Japanese authorities have already done plenty to tackle the problem'.

    Japanese authorities is that the government? I'm confused.. Shouldn't that be TEPCO?


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    • john lh john lh
      March 11, 2012 at 8:10 pm

      Our Asia culture and language is like Opium, always make people living in dream! Those terms can lead you to any place to feel good, but never take any liability.


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  • xdrfox
    March 11, 2012 at 5:36 pm

    Lava breaking threw, we talked about that last March !


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  • Heart of the Rose Heart of the Rose
    March 11, 2012 at 5:43 pm

    The French specialists have done very little visual analysis..and are behind the curve.
    May 12 2011
    http://www.youtube.com/watch?v=QuVrMlBS50s
    The problem is not solved until containment is proven.
    March 5 2012..
    http://www.youtube.com/watch?v=MfHe3fZUDPI
    I fail to see containment at this time.


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  • lam335 lam335
    March 11, 2012 at 5:48 pm

    re: "dressed Reactor 1 in a metal cover in order to limit any fallout”

    DIdn't they say the tent was made of some kind of polyester material? My understanding is that it is mainly fabric, not metal.


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  • Anthony Anthony
    March 11, 2012 at 5:50 pm

    This is exactly how I see a corium melt-through. Once it contacts underground wet gravel layers and groundwater it WILL GENERATE MASSIVE STEAM It has to, it is thousands of degrees! If this activity lacks venting, enormous buildup of underground steam would surely result. This situation is compounded as there are multiple coriums on the loose.


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  • talktalk
    March 11, 2012 at 7:36 pm

    Some Questions….

    “If it comes into contact with water, the corium would spark a series of massive vapour cloud explosions”

    what is with the cooling water? does it not reach the lava? and why not? or if, why this don't cause vapor explosions? and what is with all this fog we can see on some of the webcam footage?

    And what kind of ground is under the building structure? is it rock or is there a layer of clay? May be there is a tiny chance that the lava will burn clay to ceramics (ceramics would build fissures and the surface of the lava would rise again so that the chance to cool it will rise? – I guess the hope to separate the lava from environmental contacts is gone anyway… so I'm talking about the best in the worse…)

    Are there really a lot more other options than trying to cool the plants plus a load of hope?


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    • JoyB
      March 11, 2012 at 10:54 pm

      The way I'm envisioning from following reports beginning last late-May/early-June (and forward), is that the cooling water has been hitting (and occasionally missing) the top surface of the corium flow masses, then escaping via fissures and seeps into the turbine building basements, electrical and pipe trenches, and some eventually seeps out of the cliff, primarily near the intake piping.

      The ground under the Daiichi facility has been continually wracked by earthquakes through the entire year, sometimes 6 a day. The rock is fractured and partially "liquified" (if unit-3 is sinking as it appears to be, this would be why, however the towers are still vertical). Steam and boiling water has been 'erupting' from the ground near the plants since late May. That's why they used the steel plates they'd been amassing to seal off the cliff to cover the ground around units 1 and 2 instead. Some shielding for the workers.

      Now they have begun laying concrete in the lagoon and a large area under and around the intakes. They say to 'cover' what's already there, but I think more in prep for what's coming. Basic fluid dynamics, and molten corium is fluid like lava. And has taken as many levels of viscosity. It's hot enough to actively melt rock where it's in contact with rock, but it would rather follow gravity's path of least resistance. It will go faster through material easier to melt. It will follow fissures and water seeps. It will tend to go where the water leads it, but always downhill. The turbine buildings are downhill, on the ocean side.

      The groundwater is rising (sign another big quake is building), that's an issue too. But I think the ground is too fractured and pulverized now to hold super-pressure, and the corium's been occasionally in contact with water for months. IOW, no big blow-out. Should be impressive when it hits the sea, though…


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      • majia
        March 12, 2012 at 12:14 am

        EXCELLENT ESSAY Joy, at Enformable

        Fukushima Anniversary: Theatre of the Absurd
        http://enformable.com/2012/03/fukushima-anniversary-theatre-of-the-absurd/

        Did you see Prof Neutron's comment the other day?

        He said that unit 4 spent fuel pool was the only remaining problem.

        Prof Neutron's position seems rather optimistic to me and it sounds like at least one of the above article's "specialists" agrees.

        What do you think it will be like when corium hits ocean,as you indicate in your comment (pasted below):

        [you write[: "But I think the ground is too fractured and pulverized now to hold super-pressure, and the corium's been occasionally in contact with water for months. IOW, no big blow-out. Should be impressive when it hits the sea,though… "

        Will the radiation levels be like they were in December or worse?

        Also, what do you think of Potrblog's spallation thesis?

        Solar flares meeting Fukushima fallout seems to me probable but I'm no expert…


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      • talktalk
        March 12, 2012 at 10:28 am

        thanks for your details! now i got it a bit clearer… so the underground pressure ist rising due to the water cooking nuclear lava and it is just a question by chance, if the ground can stand the pressure ore not and with each quake the chance went worse…

        so besides cooling and hope a preparedness strategy would be a good idea?

        and another question, a bit off topic I guess, what about the platic swirls in the pacific ocean? aren't they in the fallout zone? and what is more likely, plastic particles collecting hot radioactive particles and providing them for the food chain, or hot particles sinking to ground and gone away in the mud of the ocean floor?

        What about Greenpeace? are there any Measurements from the plastic swirls?


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  • jackassrig
    March 11, 2012 at 10:20 pm

    Great pressure underground. If that damn mess is allowed to let down to atmospheric pressure all the water will flash and a great explosion and cooking everything in sight.


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