http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?hpU.S. Sees New Threats at Japan’s Nuclear Plant
By JAMES GLANZ and WILLIAM J. BROAD
Published: April 5, 2011
United States government engineers sent to help with the crisis in Japan are warning that the troubled nuclear plant there is facing a wide array of fresh threats that could persist indefinitely, and that in some cases are expected to increase as a result of the very measures being taken to keep the plant stable, according to a confidential assessment prepared by the Nuclear Regulatory Commission.
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The document, which was obtained by The New York Times, provides a more detailed technical assessment of the conundrum facing the Japanese as they struggle to prevent more fuel melting at the Fukushima Daiichi plant than Japanese officials have provided, though it appears to rely largely on data shared with American experts by the Japanese.
Among other problems, the documents raises new questions about whether pouring water on nuclear fuel in the absence of functioning electronic cooling systems can be sustained indefinitely. Experts have said the Japanese need to continue to keep the fuel cool for many months until the plant can be stabilized, but there is growing awareness that the risks of pumping water on the fuel present a whole new category of challenges that the nuclear industry is only beginning to comprehend.
The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to 1 mile from the units,” and that pieces of highly radioactive material fell between two of the units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed.
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Note, I have edited this post at the request of the moderators (removed a paragraph.) Please read the whole article. There is a LOT of information.