FUKUSHIMA – Tokyo Electric Power Co. on Friday started digging up soil tainted with highly radioactive water discharged from a storage tank at its Fukushima No. 1 nuclear plant to test its radiation levels.
The utility will dig areas measuring 12 sq. meters in total to a depth of 40 to 50 cm where pools of leaked radioactive water formed, and then measure levels to determine how far the contamination has spread and how much soil needs to be removed.
Some 300 tons of highly radioactive water recently spewed into the Pacific from one of 26 tanks built in an area just 500 meters from the plant’s seawall. The tanks are surrounded by dikes, but some 120 liters of the water leaked outside of them, making it necessary to collect soil to prevent the contamination from spreading.
Meanwhile, a 15-member team from the Nuclear Regulation Authority visited the Fukushima No. 1 complex Friday to check the storage tank from which the 300 tons of water is thought to have escaped.
The tank may not be the only source of leaked water, as Tepco said Thursday that it had detected high radiation levels around the bottom of two more tanks of the same design, an indicator that water may have leaked from those containers as well.
The nuclear watchdog’s team began the inspection Friday morning, an NRA official said.
Tepco has said puddles of water near the leaking 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 — 100 millisieverts.
Groundwater that mixed with the tainted water has already flowed to the ocean, and Tepco said Friday it has launched an operation to pump it out of 28 wells.
Meanwhile, a memorial service for Masao Yoshida, who headed the complex when the crisis started in 2011, was held in Tokyo the same day. Yoshida, who stepped down as plant chief in December 2011, died of esophageal cancer July 9.
The memorial service was organized by Tepco, and its president, Naomi Hirose, praised Yoshida for “devoting his full strength” to the kind of emergency no one had ever previously experienced in Japan. Naoto Kan, prime minister when the crisis started, said after the event that “it is because of Yoshida that the situation did not further deteriorate.”
Tepco said Yoshida’s radiation dose after the accident was 70 millisieverts, less than the 100-millisievert five-year limit for nuclear workers, and that it believes there was little causal relationship between his radiation exposure and the cancer.