, TOKYO, Aug 22 – Workers at Japan’s crippled Fukushima nuclear plant on Thursday scrambled to check hundreds of tanks storing highly radioactive water, after one sprang a leak that is feared to have seeped into the Pacific.
Around 300 tonnes of toxic liquid was believed to have escaped from one of the tanks that hold water used to cool the broken reactors, while operator Tokyo Electric Power Co (TEPCO) warned some of it might have flowed into the ocean.
“We are hurriedly checking if some 300 tanks of the same type holding contaminated water have the same leak problem,” a TEPCO spokesman said.
“We have finished pumping out water from the troubled tank, while we have continued removing the soil soaked by the water,” he said.
Spokesman Tsuyoshi Numajiri said Wednesday that traces of radioactivity were detected in a drainage stream.
“We cannot rule out the possibility that part of the contaminated water flowed into the sea,” he said.
On Wednesday, nuclear regulators said the leak represented a level-three “serious incident” on the UN’s seven-point International Nuclear Event Scale (INES), which measures radiation accidents.
The alert was raised from level one, which indicates an “anomaly”.
It is the most serious single event since the plant was declared to be in a “state of cold shutdown” — effectively indicating it was under control at the end of 2011.
The quake and tsunami-sparked meltdowns at the plant in March of that year were ultimately categorised as level seven on the INES scale. The Chernobyl disaster in 1986 is the only other incident to have been given the most serious ranking.
TEPCO has said puddles of water near the tank were so toxic that anyone exposed to them would receive the same amount of radiation in an hour that a nuclear plant worker in Japan is allowed to receive in five years.
The absence of a water-level gauge on the 1,000-tonne tank made detecting the problem more difficult, experts say.
Thursday’s safety checks on 300 tanks came after Nuclear Regulation Authority (NRA) chairman Shunichi Tanaka on Wednesday voiced concern that there could be similar leaks from other containers.
“We must carefully deal with the problem on the assumption that if one tank springs a leak the same thing can happen at other tanks,” he said.