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. According to Japanese media reports on Thursday night, there seems to have been a partial or substantial meltdown of the fuel rods in the No.1 reactor at Fukushima. This news emerged yesterday as Tokyo Electric Power Co released successive statements describing what technicians had found when they started examining and correcting gauges and other monitoring equipment at the reactor. NHK, the Japanese TV broadcaster owned by the government, reported on its English website last night: "Tokyo Electric Power Company says the No.1 reactor at the Fukushima Daiichi nuclear power plant is believed to be in a state of "meltdown". "The utility company said on Thursday that most of the fuel rods are likely to have melted and fallen to the bottom of the reactor. Earlier in the day, it found that the coolant water in the reactor is at a level which would completely expose nuclear fuel rods if they were in their normal position. "The company believes the melted fuel has cooled down, judging from the reactor's surface temperature." So its back to square one at reactor No.1. Tepco might have to cover the whole thing with lead and concrete, but what about the ground under the reactor? This news was somehow missed in reports in Australia today of the earlier leaks found by Tepco and by reports that radioactive substances exceeding the legal limit has been detected in pasture grass and vegetables in Tochigi and Ibaraki prefectures, neighboring Fukushima Prefecture (and closer to Tokyo). ABC AM mentioned the partial meltdown in a report at the end of the program this morning. Also missed news that the Japanese government, fresh from botching completely the evacuation of people from around Fukushima, has now ordered the prefectural government to organise the destruction of all animals inside the exclusion zone for fear they may be radioactive. This act of bastardry from a government that forgot to allow farmers and families to take animals or make arrangements for their most prized assets to be moved to safety, so panicked were they after March 11. Earlier this week the Japanese Prime Minister, Naota Kan confirmed that the government had abandoned the June, 2010 Strategic Energy and Growth plan that called for the greater reliance on nuclear power by 2030. By then nuclear power was supposed to be providing half Japan's energy needs a year. That won't change from the current 20% or so,  depending on how many reactors currently operating, are forced to close for safety reasons. Three reactors at the five reactor plant of Chubu Electric at its Hamaoka plant, south of Tokyo, are being shut down for safety reasons, or until the company can improve safety at the plant that is considered the most vulnerable in Japan to damage in a major quake. It sits on a subduction zone, and has no sea wall or defences high enough to protect it against a major tsunami. Work started yesterday on shutting down the reactors and placing them in suspension. It means that 14 of Japan's 54 reactors are currently closed (such as all six at Fukushima), closing, like the Chubu trio, or closed and being inspected or about to be inspected for safety reasons. But by the end of this month that figure will rise to 35, or about two-thirds, of Japan's commercial reactors will have been shut down by the end of May. And another five will have to shut from June onwards through summer for regular safety inspections. That means that if the power companies keep these 40 reactors offline for the time being, Japan will have about 75% of its reactors shutdown this (northern) summer. No wonder the government and business are very nervous about the economy and employment over the summer when in and around Tokyo alone there will be a 15% (minimum) shortfall in electricity supplies.

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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):

    [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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