A massive leak of uranium waste was reported August 26 at a nuclear plant operated by the government-run Power Reactor and Nuclear Fuel Development Corp. (PNC) in Tokai, Ibaraki Prefecture.
PNC officials said they believe that radioactivity from the leak is limited to the radioactive waste storage facility in the Tokai nuclear complex, although no precise survey has been conducted.
The complex is located some 115 km northeast of Tokyo.
PNC attributed the leakage to corrosion and decay of some of the 200-liter steel drum containers in the facility as a result of rainwater.
About 2,000 drums of low-level radioactive waste have been stored there for roughly 30 years.
The facility, which opened in August 1967 to store waste from uranium enrichment, consists of five 4-meter-deep, box-shaped concrete dugouts. Although the dugouts have concrete lids, rainwater has been seeping inside since the start of use.
Recent surveys showed the water in some of the dugouts to be as deep as 2.5 meters. Uranium has been detected in the water, with radioactivity density in some samples reaching as high as 10,000 times the maximum limit for emissions into the environment, PNC sources said.