Spraying of water resumes at crisis-hit Fukushima nuke plant

TOKYO, March 21, Kyodo

Fire trucks resumed spraying water early Monday at the crisis-hit Fukushima Daiichi nuclear power plant as part of efforts to cool its overheating reactors and fuel pools.

The operation to cool the No. 4 reactor's spent-fuel pool began Sunday, while the No. 3 unit has so far been doused with over 3,700 tons of water since the unprecedented effort by Self-Defense Forces personnel, firefighters and others to lower the temperature in its fuel tank from outside its damaged building began Thursday.

External power reached the power-receiving facilities of the No. 2 and No. 5 reactors on Sunday, paving the way for plant operator Tokyo Electric Power Co. to restore their systems to monitor radiation and other data, light the control room and cool down the reactors and their spent-fuel storage pools.

The No. 5 and 6 reactors, which have been relatively less problematic than the plant's four others, stopped safely Sunday with the temperature of the water inside falling below 100 C, achieving so-called ''cold shutdown.''

After a magnitude 9.0 quake and ensuing tsunami knocked out power March 11 at the plant on the Pacific coast of Fukushima Prefecture about 220 kilometers northeast of Tokyo, the No. 1, No. 2 and No. 3 reactors, which were operating at the time of the quake and halted automatically, lost their cooling functions.

Their reactor cores are believed to have partially melted and seawater has been pumped into them to prevent the fuel from being exposed. A series of blasts have severely damaged their buildings as well as the No. 2 reactor's containment vessel in its pressure-suppression chamber.

Plutonium-uranium mixed oxide fuel, known as MOX, in the No. 3 reactor poses the greatest risk of releasing highly toxic plutonium in the event of a meltdown. The fuel in the reactors is uranium.

The remaining No. 4, No. 5, and No. 6 units were under maintenance at the time of the earthquake, but the No. 4 reactor is different because some of the fuel was not in the reactor core but in the spent-fuel pool, which also lost its cooling function and lost the roof of its building.

==Kyodo

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