Radiation has been detected n rain water in the US

"Massachusetts, Pennsylvania, Nevada and other Western states are among the states that have reported minuscule amounts of radiation.

Nuclear-plant operators Progress Energy Inc. and Duke Energy Corp. in North Carolina and South Carolina Electric & Gas Co. also said they have detected trace amounts of radiation.

Nuclear experts and health officials said there is no public-health risk. The U.S. Environmental Protection Agency said people are exposed to much more radiation on an international airline flight." 

Except that radiation in a flight last for the time of the flight, Cs-137,Cs-134,Strontium-90 and Plutonium, uranium ...will remain around for a long time and keep releasing radiation.