"US government officials told the NY 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 US helicopters flying humanitarian missions some 60 miles north of damaged Japanese reactors were coated with particulate radiation. The aircraft were washed off."
BUT:
"officials said there was no indication that any of the military personnel experienced ill effects from the exposure, comparing it to "natural background radiation" that all people are exposed to daily."
.