Japan Plant Fuel Melted Partway Through Reactors: ReportFriday, April 15, 2011
Nuclear fuel has melted in three reactors at Japan's Fukushima Daiichi nuclear power plant and fallen to the lower sections of their container vessels, raising the specter of overheated material compromising a container and causing a massive radiation release, the Atomic Energy Society of Japan said in a report released on Friday (see GSN, April 15).
The group played down the possibility of a container breach, though, noting that only a small amount of fuel had melted so far and affected material had assumed a granulated structure and remained relatively cool, Kyodo News reported. The six-reactor plant was crippled by the 9.0-magnitude earthquake and devastating tsunami that hit Japan on March 11; the confirmed death toll from the events now exceeds 12,000 people.
The melted fuel was thought to have dispersed uniformly across the lower portions of the containers of reactors No. 1, No. 2 and No. 3, making the material highly unlikely to resume the fission process in a "recriticality," according to the organization, which said fuel rods in all three reactors had been harmed. Fuel in the No. 1 and No. 2 reactors has made contact with air, while the No. 3 reactor's rods have remained underwater, the group said...
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...Plant personnel pressed ahead in efforts to prevent additional radioactive material from escaping the site, deploying steel barriers around a No. 2 reactor pipeline and proceeding with the insertion of nitrogen gas into the No. 1 reactor to prevent additional hydrogen blasts. Pressure in the No. 1 reactor has fallen to a certain degree, pointing to the possible escape of air, but radiation in the area has remained largely unchanged...
http://www.globalsecuritynewswire.org/gsn/nw_20110415_5020.php