The latest timetable for bringing a nuclear fuel meltdown at the Fukushima No. 1 nuclear power plant under control shows the situation is no longer in the critical condition it was immediately following the accident, but many issues remain unsolved.
The government and Tokyo Electric Power Co. have revised the timetable for the seventh time in the eight months since the crisis began. Data suggests the reactors and radioactive material are under control, and the power plant will achieve a cold shutdown once required conditions are confirmed.
However, the status of the molten nuclear fuel is unclear. It is not known how the fuel, believed to have partially melted through pressure vessels of the reactors and into containment vessels, has dispersed and how much lies in water.
It is questionable to assess the situation as nearly a cold shutdown. Usually, to achieve a cold shutdown, all fuel rods should be cooled under water, and nuclear fuel, pressure and containment vessels should be intact and in good condition.
The situation at the nuclear plant does not meet this definition. Is it appropriate for the government and TEPCO to call the current status nearly a cold shutdown?