July 5, 2011
Radioactive cesium-137 was found in Tokyo’s tap water for the first time since April as Japan grapples with the worst nuclear disaster in 25 years. The level was below the safety limit set by the government.
Cesium-137 registered at 0.14 becquerel per kilogram in Shinjuku ward on July 2 and none was discovered yesterday, compared with 0.21 becquerel on April 22, according to the Tokyo Metropolitan Institute of Public Health. No cesium-134 or iodine-131 was detected, the agency said on its website.
“This is unlikely to be the result of new radioactive materials being introduced” into the water supply, Hironobu Unesaki, a nuclear engineering professor at Kyoto University, said today by telephone. That’s “because no other elements were detected, especially the more sensitive iodine,” he said.
Japan is battling radiation leaks into the air, soil and water after an earthquake and tsunami on March 11 knocked out cooling systems at Tokyo Electric Power Co.’s Fukushima Dai-Ichi nuclear station, resulting in the meltdown of three of the six reactors at the plant.