22/03 Reactor cooling efforts continue

The Daily Yomiuri

Tokyo Electric Power Co. stepped up efforts Monday to restore electricity at a reactor at a quake-hit nuclear power plant while firefighters and Self-Defense Forces personnel continued spraying water to cool down two other overheating reactors at the complex.

But in a worrying development, gray smoke was seen rising near the temporary fuel storage pool of the No. 3 reactor at the Fukushima No. 1 nuclear power plant at about 3:55 p.m. TEPCO immediately suspended all restoration work and ordered its workers to evacuate the site.

The Nuclear and Industrial Safety Agency said earlier in the afternoon the functions of the No. 2 reactor's central control room air conditioning system and some reactor instruments might be restored within the day.

A TEPCO inspection found that to supply electricity to the No. 2 reactor's central control room, some instruments, such as the backup water system motor and a power-supply unit, needed to be repaired or replaced.

It is expected to take several days to restore the reactor's cooling system, officials said.

The development came a day after TEPCO confirmed electricity had reached the switchboard-cum-transformer at the reactor's turbine building.

TEPCO workers also continued efforts to send electricity from the No. 2 reactor to the No. 1 reactor, and lay cables to the Nos. 3 and 4 reactors. However, work to lay cables to the Nos. 3 and 4 reactors was reportedly running into trouble because of debris from previous explosions and high radiation levels.

Electricity also reached the switchboard of the No. 5 reactor at about 11:30 a.m., and switched the reactor power source from an emergency generator to an outside power source about 90 minutes later, making it technically possible to send electricity to the No. 6 reactor, TEPCO officials said.

Electricity at the Nos. 5 and 6 reactors had been supplied by emergency diesel-powered generators.

At the Nos. 5 and 6 reactors, temperatures reportedly have stabilized at 100 C or lower. Water temperatures in the two reactors' nuclear fuel storage pools also declined to normal levels of 39.5 C and 32 C, respectively, as of 5 a.m. Monday, TEPCO said.

Experts warned the rain might temporarily raise radiation levels in the area because radioactive material that had floated in the air might fall to the ground.

3,700 tons of water sprayed

Meanwhile, a special squad of the Tokyo Fire Department and other firefighters blasted about 1,130 tons of water into the No. 3 reactor's nuclear fuel storage pool for about 6-1/2 hours until 4 a.m. Monday. It was the Tokyo firefighters' third spraying operation at the plant.

The combined amount of water blasted on the No. 3 reactor, including that sprayed by the SDF, reached 3,700 tons by Monday morning, officials said.

The SDF sprayed water on the fuel storage pool of the No. 4 reactor for about two hours starting at about 6:40 a.m. Monday.

The water-spraying operations to date likely have raised water levels in the nuclear fuel storage pools and decreased water temperatures, gradually lowering radiation levels from damaged nuclear fuel rods.

If workers are able to maintain the fuel storage pool water levels, the next focus would be to try to restore electricity from outside to the Nos. 1 to 3 reactors, so as to constantly cool the reactors using their own cooling systems.

Currently, workers are injecting pumped seawater into the reactor pressure vessels in each reactor core.

(Mar. 22, 2011)