Asia-Pacific

May 13, 2011

Fukushima nuke plant ‘in a state of meltdown’

According to Japanese media reports, there seems to have been a partial or substantial meltdown of the fuel rods in the No.1 reactor at Fukushima.

Glenn Dyer — <em>Crikey</em> business and media commentator

Glenn Dyer

Crikey business and media commentator

So bored has Australia’s media become with the impact of the March 11 earthquake and tsunami in Japan and their impact on the Fukushima nuclear power station that a major development seems to have been missed overnight.

4 comments

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4 thoughts on “Fukushima nuke plant ‘in a state of meltdown’

  1. rubiginosa

    Where are the groundwater monitoring results?

  2. michael r james

    Correct, Glen. I also heard it on BBC radio early am today (this is a BBC world broadcast–out of Bonn for some reason– that digital ABCNewsRadio switches over to at about 1am I think; for insomniacs like me it is a very good way to stay plugged into very current events worldwide as it appears to be live; during unfolding events they even broadcast live telephone reports from citizens in places like Libya, Syria etc.).

    For Crikey readers I will reproduce a relevant bit of my Rooted blog (4-5 days after the tsunami):
    (blogs.crikey.com.au/rooted/2011/03/16/japans-nuclear-crisis-the-technical-facts/)

    [These (hydrogen) explosions are not enough to breach the concrete and stainless steel shell of the inner core but the detection of caesium-137* and iodine-131 indicates that at least part of the fuel rods have been exposed and damaged. (Water levels inside the core are unknown because the gauges have failed, itself indicating damage.) If left exposed for too long the fuel pellets melt and fall to the bottom of the core. If it continues all the fuel melts into a pool at the bottom of the core, continues to overheat—and at some point with loss of neutron moderation (absorbtion) in the molten pool it becomes self-accelerating—until nothing can contain it and it burns through the core, ie. the China Syndrome.

    Contact with other material or any liquid, along with accumulated hydrogen will result in explosive dispersal of the highly radioactive material—not as a nuclear bomb—but a far worse kind of dirty “bomb” in terms of radioactive contamination of hundreds or thousands of square kilometres depending on prevailing winds. As time moves on the likelihood of this kind of catastrophic event becomes less and less likely because the energy released by the fuel diminishes quickly. Some experts believe the dangerpoint for such a total meltdown has been passed but Tuesday’s events make any outside assessment very problematic.]

    To clarify a bit more, the only major worry is if the melted core restarts criticality, ie. starts generating new fissioning due to all the uranium fuel melting together. Being the heaviest metal it sinks while other metals and moderators or absorbers float on it. So it depends on what kind of a melt it is; if only partial and a soup of all the various components it will probably not be able to reach criticality, so the heat comes from the residual radioactive products of the core at the time of shutdown. (And yes, just to pre-empt bloggers, when moderator separates from fuel it reduces efficiency of fissioning since the neutrons need slowing down for more capture by the uranium fuel, more fission.)

    This is what happened at Three Mile Island (melted down to a blob which melted through the first level of containment before stopping, but did not restart criticality). The major difference with TMI is that the cooling systems remained functional and so heat was adequately removed. (They still had to wait years before accessing and dealing with the melted core.) The cooling is what remains so dysfunctional at Fukushima.

    (*The media today have propagated an error in reporting the leaks were detected by measuring “caesium-134” when I pretty certain they mean 137; I suspect someone has misread a seven written in euro style as a four.)

  3. zut alors

    On ABC Brisbane radio the 7am bulletin ran the story about the destruction of animals (those which hadn’t slowly starved to death in enclosures or cages) but I heard nothing more on this elsewhere today.

    With a 15% (approx) cut in electricity this summer the Japanese will be able to attest how impractical and unliveable modern highrise buildings are due to lack of natural ventilation and their total dependence on airconditioning. Who will be able to work in such airless, overheated structures?

  4. Harvey Tarvydas

    Dr Harvey M Tarvydas

    A place in history surely for Glen’s pungent media critique
    “So bored has Australia’s media become with the…”
    So true Glen, thank God for Crikey, Glen Dyer and commenters of the calibre of @MICHAEL R JAMES – Posted Friday, 13 May 2011 at 3:10 pm
    and so many others.
    Thank you!

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