USS Ronald Reagan Aircraft Carrier Sails Into Radioactive Cloud

The Pentagon is expected to announce that sailors on the USS Ronald Reagan, an aircraft carrier were exposed to radiation when the carrier sailed into a radioactive cloud off the coast of Japan, according to a New York Times report.

U.S. government officials told the Times that sailors and other military personnel onboard were exposed to a month's worth of radiation in an hour's time. They added that helicopters flying humanitarian missions 60 miles north of damaged Japanese reactors were coated with particulate radiation. The aircraft were washed off.

Despite the scare, officials said there was no indication that any of the military personnel experienced ill effects from the exposure, comparing it with "natural background radiation" that all people are exposed to daily.

A second hydrogen explosion rocked a stricken nuclear power plant in Japan where authorities have been scrambling to avert a meltdown after last week's devastating earthquake and tsunami.

The big fear is of a major radiation leak from the complex in Fukushima, 150 miles north of Tokyo, where engineers have been battling since the weekend to prevent a meltdown in three reactors.

The core container of the No. 3 reactor was intact after the explosion, the government said, but it warned that those still in the 13-mile evacuation zone to stay indoors. The plant operator, Tokyo Electric Power Co., said 11 people had been injured in the blast.

U.S. warships and planes helping with relief efforts moved away from the coast temporarily because of low-level radiation. The U.S. Seventh Fleet described the move as precautionary.