Officials of Tokyo Electric Power Co (TEPCO) said Thursday that radioactive water containing strontium-90 leaked out of the stricken Fukushima nuclear power plant into the sea.
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years. Its presence in the human body can cause bone cancer, cancer of nearby tissues and leukemia.
TEPCO officials apologized at a news conference for the leakage which occurred early Thursday morning, TBS reported. TEPCO said the leak was from a pipe attached to a temporary decontamination system, and the water had already gone through some of the cleansing process.
The water, once it has been used to cool the reactors, contains massive amounts of radioactive substances such as cesium and strontium, and is put into the water-processing facility so it can be recycled for use as a coolant.
The water is believed to have leaked out for about two hours before it was stopped shortly after 2 a.m., TEPCO said, according to TBS.
TEPCO said it believed that up to 12 tons of waste water containing strontium leaked into the sea.
This is not the first time that strontium has leaked from the Fukushima plant. Last November, radioactive strontium was found in soil in three locations in Tokyo, peaking at 51 becquerels per kilogram. In December, about 150 liters of waste water containing strontium flowed into the sea.
Fukushima’s makeshift water-treatment system has been hit by a series of problems since the government declared the plant was in cold shutdown last December.