ENENEWS
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.
Bringing the fuel under control could take between two and three months if restoration work moved forward as expected, said Takashi Sawada, the group's deputy chairman. The organization based its assessment on information provided by the Japanese Nuclear and Industrial Safety Agency and by Tokyo Electric Power, the plant's operator.