Evening Report

From NEI’s Japan earthquake launch page:

UPDATE AS OF 7:00 P.M. EDT, MARCH 24

Restoration of electric power at reactors 1, 2 and 4 at the Fukushima Daiichi nuclear power plant has led to the reconnection of important reactor instrumentation, the International Atomic Energy Agency said.

Cooling water continues to be injected into reactors 1, 2 and 3. Reactors 5 and 6 at Fukushima Daiichi remain safely shut down. Both reactors were undergoing maintenance at the time of the earthquake.

Radiation dose rates inside the containment vessels of reactors 1 and 2 have decreased slightly, IAEA said.

External power has been reconnected to the common used fuel storage pool at the plant and cooling started on March 24 at 5:05 AM EDT, according to Japan’s Nuclear and Industrial Safety Agency.  About 60 percent of the used uranium fuel rods at Fukushima plant are stored at this facility.

Radiation monitoring continues

Air samples collected at on-site monitors at the Fukushima Daiichi plant March 19-23 show that only iodine-131 was found to be in excess of Japanese government limits. Radiation dose rates measured on site March 21-23 have decreased from 193 millirem to 21 millirem per hour. Radiation dose rates at the plant’s site boundary ranged from 1 millirem to 3 millirem per hour on Thursday.

At distances between 34 and 73 kilometers to the west of the Fukushima Daiichi nuclear power plant, the dose rate ranged from .06 millirem to .69 millirem per hour.

Considerable variation in the levels of reported iodine-131 and cesium-137 continues in 10 prefectures, IAEA said. Food, milk and drinking water sampling has been most thorough and extensive in the Fukushima and Ibaraki prefectures, IAEA said.

Seawater samples collected at several points 30 kilometers from the coastline near the Fukushima Daiichi nuclear power plant found measurable concentrations of iodine-131 and cesium-137, IAEA said. The iodine concentrations were at or above Japanese regulatory limits. The cesium levels were well below those limits.

For more information on iodine-131, see NEI’s fact sheet Health Impacts of Iodine-131.