Dr. Jeff Masters at the Weather Underground (a meteorology site) ran a NOAA computer model to answer the question. The answer is yes—but, not in quantities to be of concern for human health.

HysplitRadSpread.gif
  • http://www.wunderground.com/blog/JeffMasters/show.html

Dr. Masters links to a more refined model by the Austrian weather service, also showing the spread of the materials across Japan and the Pacific.