Radiation levels in some unevacuated areas around Japan's crippled Fukushima Dai-ichi nuclear power plant were high enough to trigger "protective action," likely an evacuation, under U.S. radiation exposure guidelines.
The Energy Department used airborne and ground-based monitors to detect radiation that exceeded 12.5 millirems per hour, or 1,200 millirems over a four-day period, in areas outside the 12-mile evacuation zone surrounding the Japanese disaster. Under U.S. guidelines, if exposure to radiation exceeds 1,000 millirems -- a standard unit for measuring radiation -- over four days, then Environmental Protection Agency recommends protective action, an Energy report this week said.
Protective action could consist of staying indoors during a small, short-term release of radiation, but likely would involve evacuating areas before a major release, said Roger Hannah, a spokesman for the Nuclear Regulatory Commission.
A day before the monitoring began, NRC already had urged U.S. citizens and military personnel to move at least 50 miles away from the Fukushima plant. Japanese authorities ordered people within 12 miles of the plant to evacuate.
"Our recommendations are usually very conservative," Hannah said. So while protective action can mean "sheltering indoors" if a minor radiation release is expected, evacuation is the most effective way to ensure that people are not exposed to radiation during a prolonged release, he said.
Japanese emergency workers have been struggling to regain control over the Fukishima nuclear plant since it was severely damaged during the March 11 earthquake and tsunami. Energy sent 33 radiation experts from its National Nuclear Security Administration to Japan on March 15. They joined six others already there to begin sampling for radiation using sensors aboard U.S. military planes and at numerous locations on the ground.
The monitors discovered radiation readings of less than 1.19 millirems per hour along the coast and as far south as Tokyo and Kawasaki, as well as due west of the stricken power plant. But in a swath stretching northwest from the plant, they gathered readings of greater than 12.5 millirems per hour. The high radiation readings were discovered in an area northwest of the 12-mile evacuation zone.
"Given the circumstances, we would have recommended a larger evacuation area," Hannah said.
Energy gathered radiation levels near the Japanese power plant from March 17-19, according to the department's report.
Meanwhile, the Food and Drug Administration announced that its inspectors might block imports of dairy products, fresh produce and infant formula that come from areas around the Fukushima power plant.
Japanese health officials said March 19 they had discovered radioactive iodine at five times acceptable levels in those products during screening March 16-18.
In an unrelated radiation scare on March 22, the American Federation of Government Employees called for the Transportation Security Administration to begin nationwide monitoring of TSA workers for exposure to radiation from X-ray machines used to inspect airline passengers' luggage.
AFGE president John Gage said TSA workers should be given dosimeters, devices that to would track their radiation exposure. He said he made the request after learning TSA has ordered new tests on radiation-emitting equipment after finding errors in earlier results.