The government's Nuclear and Industrial Safety Agency (NISA) demanded the health ministry raise the allowable radiation exposure limit to 350 millisieverts effectively for emergency workers trying to bring the crippled Fukushima nuclear power station under control shortly after the ministry lifted the legal exposure limit to 250 millisieverts from 100 millisieverts on March 14, 2011, it has been learned.
NISA demanded the change to the radiation exposure limit after receiving a request from Tokyo Electric Power Co. (TEPCO), the operator of the troubled Fukushima No. 1 Nuclear Power Plant, according to NISA's internal documents disclosed after an organization specializing in issues of radiation exposure requested the materials through information disclosure laws. The internal documents disclosed are NISA's internal memos and solicitation documents TEPCO, Toshiba Corp. and Hitachi-GE Nuclear Energy, Ltd. sent to NISA.
It was already known that then Prime Minister Naoto Kan talked about the possibility of raising the exposure limit to 500 millisieverts at the Prime Minister's Office three days after it was raised to 250 millisieverts. But it is the first time that specific exchanges between the government ministries and agencies concerned have been revealed through internal documents. Read More