Radiation has seen a steady decline near the damaged Fukushima No.1 nuclear power plant following water-dousing measures taken Thursday, said the Nuclear and Industrial Safety Agency Friday.

According to Measurements taken by the agency around 1.1 km west of the plant's No.2 reactor, hourly radiation dose stood at 279.4 microsievert at 5 a.m. Friday, down from 309 and 292 microsievert around the time when the Self-Defense Forces (SDF) shot water at the reactor to cool down the overheating spent fuel storage pool.

Agency officials said that they will work to restore electricity for No.1 and No.2 reactors Friday, and for No. 3, No.4 reactors Sunday, to chill down the malfunctioned reactors and overheating storage pools.

The storage pools at the power station lost their cooling function after the colossal quake and tsunami hit northeastern and eastern Japan on March 11. It is also no longer possible to monitor the water level and temperature of the pools of the four reactors.

On Thursday morning two SDF CH-47 helicopters dumped water in turn on the damaged No.3 reactor, followed by five fire and rescue trucks equipped with high-pressure water canons shooting around 30 tons of water at the reactor later in the day.