The government’s Nuclear and Industrial Safety Agency said Wednesday evening that the containment vessel of the troubled No. 3 reactor at Japan’s disaster-hit plant, located 230 km north of Tokyo, may not have been severely damaged.
”The possibility of the No. 3 reactor’s containment vessel at the Fukushima No. 1 nuclear power plant having suffered severe damage is low,” the agency told a press conference, pointing out that the radiation level at the plant has already dropped.
Chief Cabinet Secretary Yukio Edano also made simliar remarks earlier in the day. According to the nuclear agency, the radiation level reached 10.85 millisievert per hour at the plant’s main gate at 12:30 p.m. (0330 GMT), but it significantly fell to 1.47 millisievert at 4:20 p.m (0720 GMT).
White smoke was observed from the No. 3 reactor around 8:30 a.m. (2330 Tuesday GMT) and the government suggested in the morning that the vessel may have suffered damage and radioactive vapor spread outside.
The power station’s operator Tokyo Electric Power Co. (TEPCO) said the vapor was steam caused by water evaporating from the reactor’s storage pool for spent fuel rods, which is heating up.
The No.3 reactor was already hit by a hydrogen explosion on Monday, which blew away the roof and the walls of the building housing the container of the reactor and injured 11 people. However, the reactor’s container was not damaged.
There are six reactors in the Fukushima No.1 nuclear power plant, all designed by US giant General Electric. Cooling functions of the No. 1, No. 2 and No. 3 reactors were damaged following Friday’s magnitude 9.0 earthquake and tsunami, and TEPCO continues emergency efforts on preventing a fuel rod meltdown by cooling the reactors.
The government planned to drop water on the reactor using Self-Defense Forces helicopters to avert the fuel rods’ exposure in the afternoon, but the mission was forced to postpone due to excessive radiation levels above the facility.