Meanwhile, plant operator Tokyo Electric Power Co. turned on the lights in the control room of the No. 2 reactor the same day, and was analyzing and trying to remove pools of water containing radioactive materials in the turbine buildings of reactors 1 to 3.
The iodine-131 in the seawater was detected at 8:30 a.m. Friday, about 330 meters south of the plant's drain outlets. Previously, the highest amount recorded was about 100 times above the permitted level.
If a person drank 500 ml of water containing the newly detected level of contamination, it would be the equivalent of 1 millisievert of radiation, or the average dosage one is exposed to annually, the NISA said.
"It is a substantial amount," NISA spokesman Hidehiko Nishiyama told a news conference. (read more)