The aircraft carrier USS Ronald Reagan is among several US vessels off the coast of Japan on a humanitarian mission in response to Friday`s massive 9.0 earthquake and resulting tsunami.
"The source of this airborne radioactivity is a radioactive plume released from the Fukushima Dai-Ichi nuclear power plant," said a statement posted on the website of the US 7th Fleet.
"The maximum potential radiation dose received by any ship`s force personnel aboard the ship when it passed through the area was less than the radiation exposure received from about one month of exposure to natural background radiation from sources such as rocks, soil, and the sun," it added.
Tests on three helicopter aircrews returning to the carrier after conducting missions near Sendai meanwhile "identified low levels of radioactivity on 17 air crew members," the statement said.
"The low level radioactivity was easily removed from affected personnel by washing with soap and water. They were subsequently surveyed, and no further contamination was detected," it added.
Tens of thousands of residents have already been evacuated from a zone within a radius of 20 kilometers (12 miles) from the Fukushima No.1 plant, 155 miles (250 kilometers) northeast of Tokyo.
The 7th Fleet`s statement, which followed earlier media reports about crew members being exposed to radiation, said it had detected "low level contamination in the air and on its aircraft operating in the area."
The Ronald Reagan "was operating at sea about 100 miles northeast of the power plant at the time," the statement said, without specifying when the exposure took place.
The Ronald Reagan and other Fleet ships in the area "have moved out of the downwind direction from the site to assess the situation and determine what appropriate mitigating actions are necessary," it added.
(U.KR-IFB/M016/H-AK)
Editor: Priyambodo RH
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