Tainted water suspected of being leaked to sea from nuclear plant

The Nuclear Regulation Authority said on July 10 that it is strongly suspected that water contaminated by radioactive substances is spreading into the sea from the disaster-hit Fukushima Daiichi power plant. The agency expressed the view at its regular meeting where it discussed the issue of the detection of high levels of radioactive substances in water in a monitoring well on the plant site and at a port near the plant. The agency's chairman, Shunichi Tanaka, who hails from the city of Fukushima, expressed his intention to set up a task force, saying it is necessary to identify the cause of the leakage and to take countermeasures at an early date. The agency plans to ask Tokyo Electric Power Co., the operator of the plant, to complete the work to set up a shielding wall that would prevent contaminated water from leaking into the sea. According to Tokyo Electric Power, or TEPCO, water taken on July 9 from the monitoring well between the sea and the building housing turbines for the No. 2 reactor contained 11,000 becquerels of cesium 134 and 22,000 becquerels of ceisum 137 per liter. The density of cesium 134 was about 111 times higher than the level in water taken July 5 while that of cesium 137 was about 105 times higher. In addition, 2,300 becquerels of tritium per liter were detected in seawater taken on July 3 from the port near the power plant. Tanaka and four agency members concluded it is highly likely that highly concentrated contaminated water is leaking into the ground and then spreading into the sea. TEPCO said highly concentrated tainted water seeped into the ground from a work hole near the No. 2 reactor building in April 2011, resulting in the detection of the radioactive substances in waters in the well and near the port. The Nuclear Regulation Authority, however, questioned TEPCO's argument, noting the level of tritium taken from groundwater away from the hole was higher than that in water near the hole, and noted the need to quickly identify the contamination source.