Rain to cause major problems at Fukushima!

TEPCO cuts back on water due to expected rains
The Yomiuri Shimbun

Tokyo Electric Power Co. has launched efforts to reduce the amount of radioactive water being generated at its crippled Fukushima No. 1 nuclear power plant, given that its water decontamination system has not been functioning properly and the rainy season has officially arrived in the area.

The efforts began following the Meteorological Agency's announcement Tuesday that the rainy season has begun in the Tohoku region, which includes Fukushima Prefecture, where the plant is located.

TEPCO workers are covering the roofs of reactor buildings that were blown off in hydrogen explosions after the March 11 disaster to keep rainwater out, and the utility has cut back on the amount of cooling water being injected into the reactors.

The highly radioactive water accumulated at the Fukushima power station after leaking from damaged reactors. If it cannot be disposed of smoothly, it is feared it may overflow trenches and storage tanks before the end of the month.

But reducing the water being poured into the damaged reactors puts the plant operator in dilemma, since if the volume of water is reduced, temperatures in the reactors will likely rise. In fact, temperatures inside the No. 3 reactor have already risen slightly.

The amount of water being injected into the Nos. 1 and 2 reactors was reduced by half a ton per hour Tuesday for the second straight day to 3.5 tons per hour and four tons per hour, respectively. But plant workers have continued pouring 10 tons per hour into the No. 3 reactor because of high temperatures inside, TEPCO said.

Other measures to deal with expected heavy rain include installing sandbags around the reactor facilities, and covering roofs and doors with steel sheets.

Contaminated water in an operational trench for the No. 3 reactor reached its highest level when it rose to 12 centimeters below the top of the trench at 7 a.m. Wednesday. If decontamination does not proceed smoothly, the polluted water could overflow by next Wednesday, or even earlier if rainwater gets in.

Water levels in the same trench rose by 6.5 centimeters a day when an extratropical cyclone passed over the plant at the end of May, the utility said.

The Meteorological Agency has forecast precipitation for the coming month in the southern Tohoku region will be less than normal, but warned there was the possibility it would rain more heavily toward the end of the rainy season.

Radiation of 430 millisieverts per hour was detected near the No. 2 reactor at the Fukushima plant, TEPCO said Wednesday.

The extremely high radiation level was measured at a mezzanine floor between the first floor and the basement of the No. 2 reactor building. This figure is the highest ever recorded in the building.

Highly radioactive water is believed to have leaked from the damaged reactor pressure suppression chamber in the basement, a TEPCO official said.

TEPCO workers entered the basement for the first time since the March 11 disaster Tuesday and measured radiation on the stairway on the northwestern side of the building.

(Jun. 23, 2011)