The government and Tokyo Electric Power Co. are boasting success in achieving the first stage in the road map to stabilize the reactors at the Fukushima No. 1 power plant, but experts said big challenges remain as the utility moves to the second phase, the goal of which is to achieve a cold shutdown in three to six months.
In the newly updated plan, released Tuesday, the two sides defined cold shutdown as bringing the temperature at the bottom of the pressure vessels in the stricken reactors to below 100 degrees. They also plan to reduce the amount of radioactive materials being released from the containment vessels and keep the radiation level around the plant to less than 1 millisievert per year by mid-January, which may enable some evacuees to return home.
When the second phase is over, "it will depend on radiation levels in the various areas, but I think we can achieve some specific results even for the evacuation area (within 20 km of the plant)," said Goshi Hosono, state minister in charge of the crisis, stressing that the government will make every effort to decontaminate areas around the plant.