The Department of Homeland Security’s front-line agencies, “out of an abundance of caution,” said this week that they are increasing their monitoring of vessels and cargo that arrive from Japan but are using
standard protocols to resolve any radiation alert that may arise.

According to an announcement by the Coast Guard and Customs and Border Protection, the Coast Guard will track vessels that transit the 50-mile zone that was established around the Fukushima nuclear plant.
The agency will conduct additional screening at sea before ships arrive at a U.S. port. The Coast Guard “will follow long-standing resolution protocols” if they detect radiation.

From the Journal of Commerce