Tokyo. March 22, 2011. Abnormally high levels of radioactive substances have been detected in seawater near the quake-crippled nuclear power plant in Japan, its operator said early Tuesday, cited by AFP. Five kinds of radioactive materials, including iodine-131, cesium-134 and cobalt, released by damaged fuel rods, were detected in the sea.
Tokyo Electric Power Co. (TEPCO) said the level of iodine-131 was 126.7 times higher and cesium-134 was 24.8 times higher than government-set standards. Cesium-137 was 16.5 times higher
The government limit is based on the amount of radioactive material that can be consumed by a person for a year, which is 1 millisievert. Although iodine-131 has a radioactive half-life of eight days, cesium-137's half-life is about 30 years.
In a phenomenon called biological concentration, radioactive materials in seawater will become more concentrated in fish and marine plants.
The substances were detected in seawater which was sampled Monday about 100 kilometres (60 miles) south of the Fukushima No.1 plant.
