From the Santos Republic:
Radioactive materials spewed out from the crippled Fukushima No. 1 Nuclear Power Plant reached North America soon after the meltdown and were carried all the way to Europe, according to a simulation by university researchers.
The computer simulation by researchers at Kyushu University and the University of Tokyo, among other institutions, calculated dispersal of radioactive dust from the Fukushima plant beginning at 9 p.m. on March 14, when radiation levels around the plant spiked.
The team found that radioactive dust was likely caught by the jet stream and carried across the Pacific Ocean, its concentration dropping as it spread. According to the computer model, radioactive materials at a concentration just one-one hundred millionth of that found around the Fukushima plant hit the west coast of North America three days later, and reached the skies over much of Europe about a week later.