The leaked water was among the most severely contaminated that Tepco has reported in the aftermath of the March 2011 disaster at the Fukushima Daiichi plant, when damage caused by an earthquake and a tsunami led to meltdowns in three of the plant’s reactors. Each liter of the water contained, on average, 230 million becquerels of particles giving off beta radiation, the company said. About half of the particles were likely to be strontium 90, which is readily taken up by the human body in the same way that calcium is, and can cause bone cancer and leukemia.
That means the water was about 3.8 million times as contaminated with strontium 90 as the maximum allowed under Japan’s safety standards for drinking water. It also showed levels much more radioactive than a worrisome groundwater reading that Tepco announced earlier this month. That reading — five million becquerels of strontium 90 per liter — which was detected at a location closer to the ocean than the latest spill, prompted criticism of Tepco because the company waited five months to report it publicly.
Critics have assailed the company since the accident, saying that it has been slow to acknowledge problems at the stricken plant and that it has disclosed too little information about the conditions inside. Even so, the government has left the company largely in charge of the cleanup work there.