Radiation levels around the quake-hit Fukushima No.1 nuclear power plant significantly fell Tuesday afternoon after rising above the safety limit in the morning in the wake of two fresh blasts in the troubled plant, Japan’s top government spokesman said.
“The radiation level near the main gate of the troubled Fukushima No. 1 plant, 230 km north of Tokyo, significantly fell to 596.4 microsieverts per hour as of 3:30 p.m. (0630 GMT), from 8,217 microsieverts per hour near registered at 8:31 a.m. (2331 Monday GMT) and 11,930 microsieverts at 9 a.m. (0000 GMT),” Chief Cabinet Secretary Yukio Edano told a press conference.
The level is almost 700 times less than the levels reported after the separate explosions at the No.2 and No.4 reactors of the plant in the morning.
In particular, the radiation level reached 400 millisieverts per hour near the No.3 reactor in the morning.
On Monday, the radiation level near the No. 3 reactor stood at 3,130 microsieverts or about 3 millisieverts per hour. The amount was 400 times higher than the allowable limit for citizens in a year. 1,000 microsieverts equal 1 millisievert. A single dose of 1,000 millisieverts causes temporary radiation sickness such as nausea and vomiting, and a dose of 5,000 millisieverts would kill about half those receiving it within a month.
At a nationally televised press conference in the morning, Prime Minister Naoto Kan urged people within 30 km of the plant to stay indoors. Residents within a 20-km radius have already been ordered to vacate the area following Saturday’s hydrogen blast at the plant’s No. 1 reactor.
Authorities in Tokyo detected slightly higher-than-normal radiation levels following the incidents, but not at harmful levels, Tokyo metropolitan government said. The wind was blowing from north to south, means from Fukushima Prefecture toward Tokyo, when the incidents occurred at the Fukushima plant.
In Ibaraki Prefecture, north of Tokyo, also reported radiation levels registered 5 microsieverts per hour, 100 times higher than usual, before 8:00 a.m. (2300 Monday GMT).
There are six reactors in Fukushima No.1 nuclear power plant, which was hit by last Friday’s 9.0-magnitude earthquake and tsunami. The two explosions on Tuesday morning came after hydrogen blasts at both of the plant’s No. 1 and No. 3 reactors on Saturday and Monday.
The No.2 reactor’s cooling system was damaged on Monday, causing water levels to rapidly fall and fully exposing its fuel rods for several hours. The three reactors were in critical condition after Friday’s quake, losing their ability to cool down and releasing some radiation, and the operator has been struggling to safely shut down the cores at the three reactors.