TEPCO Revises Fukushima Reactor Meltdown Guesstimates

TEPCO revises nuclear fuel damage ratios. The operator of the troubled Fukushima Daiichi nuclear plant in northeastern Japan has reassessed its estimates of fuel damage in reactors No.1 to No.3. Tokyo Electric Power Company on Wednesday announced new estimates of damage after the country's nuclear safety agency questioned the accuracy of the initial assessments. The utility has revised the estimated fuel damage in the No.1 reactor from 70 percent to 55 percent, saying radiation levels were not correct.

TEPCO also says that it acted inappropriately in excluding fuel damage of less than 5 percent in calculating total damage ratios for the No.2 and No.3 reactors. As a result, the utility revised upward its estimates of damaged fuel in the No.2 and No.3 reactors by 5 percentage points each to 35 percent and 30 percent respectively. The company released its initial estimates as of March 15th, based on radiation levels in the reactors and their containment vessels.

Earlier this month, the Nuclear and Industrial Safety Agency raised the crisis level at the Fukushima plant to the highest 7 on the international scale, based on its estimate of the volume of released radioactive substances. TEPCO says the corrected estimates will not affect the agency's crisis rating.