After gauges repaired last week revealed that fuel in Fukushima Daiichi's unit 1 reactor had melted completely and settled at the bottom of its pressure vessel, Tokyo Electric Power Co. announced today that the damage inside units 2 and 3 may be just as extensive.
Earlier estimates placed the amount of damaged fuel in those reactors at 35 percent and 30 percent, respectively. But TEPCO told reporters that new data from the central control room indicates conditions are significantly worse. Bloomberg and other media outlets quoted TEPCO spokesmen as saying fuel in both units had melted enough to drop to the bottom of the pressure vessels. The company described damage to the pressure vessels now cradling the fuel as “limited.”
The announcement brings the utility's damage assessment more in line with U.S. regulators' earlier estimates of fuel damage in the units. TEPCO's announcement also revealed more information about the time line following the loss of external and backup power at the plant. The company said fuel began melting in units 2 and 3 by the second or third day of the station blackout, the Guardian newspaper reported. TEPCO estimates fuel in unit 1 melted after 16 hours.
Despite damage to the reactors being more extensive than originally announced, TEPCO officials said the newly revealed status of the damaged fuel did not significantly worsen the plant's outlook. The melted fuel accumulated at the bottom of the pressure vessels is completely submerged, the Guardian reported, and TEPCO indicated temperatures inside are below dangerous levels.