"The worst case scenario is that the fuel rods fuse together, the temperatures get so hot that they melt together in a radioactive molten mass that bursts through the containment mechanisms and is exposed to the outside. So they spew radioactivity in the ground, into the air, into the water. Some of the radioactivity could carry in the atmosphere to the West Coast of the United States." ~ Joe Cirincione, Ploughshares Fund
According to a report posted on PrisonPlanet.com, the radiation could take 7 days to reach the US from Fukushima. The following is the typical wind trajectory. The whole story is not being disclosed in the media, because the information is changing, and they don't want to cause unnecessary panic.
Who would have known that this country would suffer two major disasters in less than 70 years.