Japan may have lost race to save nuclear reactor [View All]

Source: The Guardian

http://www.guardian.co.uk/world/gallery/2011/mar/29/japan-disaster-week-three-in-pictures">• In pictures: Fukushima nuclear emergency - week three

http://www.guardian.co.uk/world/interactive/2011/mar/16/japan-earthquake-and-tsunami-nuclear-sample?intcmp=239">• Interactive: Japan earthquake: Ian Sample on efforts to contain the nuclear accident

Ian Sample , science correspondent | Tuesday March 29 2011 16.53 BST

The radioactive core in a reactor at the crippled Fukushima nuclear power plant appears to have melted through the bottom of its containment vessel and on to a concrete floor below, experts say, raising fears of a major release of radiation at the site.

Richard Lahey, who has worked on the plant at Fukushima, told the Guardian officials seemed to have "lost the race" to save the reactor, but added that there was no danger of a Chernobyl-style catastrophe.

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At Fukushima, workers have been pumping water into three reactors in a desperate bid to keep the fuel rods from melting down. But Lahey, who was head of safety research for boiling-water reactors at General Electric when the company installed the units at the plant, said his analysis of radiation levels suggested these attempts had failed at reactor two.

He said at least part of the molten core, which includes melted fuel rods and zirconium alloy cladding, seemed to have sunk through the steel "lower head" of the pressure vessel and on to the concrete floor below. "The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell," Lahey said. "I hope I am wrong, but that is certainly what the evidence is pointing towards."

Read more: http://www.guardian.co.uk/world/2011/mar/29/japan-lost-race-save-nuclear-reactor