UPDATE AS OF 11:30 A.M. EDT, MONDAY, MARCH 28:
Radiation levels in the seawater near the Fukushima Daiichi nuclear power plant remained high on Monday, but dropped considerably from the levels reported on Sunday. Monday's sampling near the plant's south discharge outlet showed that radioactive iodine levels were 250 times normal, reduced significantly from 1,850 times normal.
Radiation dose rates also remained elevated in the turbine buildings of reactors 1, 2, 3 and 4. Tokyo Electric Power Co. on Monday said that workers had found similarly high radiation levels in water in drainage conduits outside reactors 1 and 2. The company said that rubble at reactor 3 prevented measures from being taken there on Monday.
TEPCO is pumping contaminated water from the basement of the turbine building at reactors 1 and 2 to the main condenser. The company also continued to pump fresh water into reactors 1, 2 and 3, using electrical-driven pumps rather than diesel-powered fire pumps.
Levels of radiation at the plant's main gate ranged from 12.5 millirems per hour to about 20 millirem per hour (125-200 microSieverts/hour). The U.S. Nuclear Regulatory Commission's annual limit for occupational exposure is 5,000 millirem.
For more information about radiation, see NEI's Web page on health and radiation safety.