Early Tuesday officials said that fuel rods in the number two reactor were again "fully exposed", boosting fears of an eventual partial meltdown.
California's Department of Public Health says it is "monitoring the situation closely," and highlights its Nuclear Emergency Response Program, which sets out measures to be taken in case of a nuclear incident.
Japan is some 5,000 miles (8,000 kilometers) from the U.S. West Coast, and nearer to Alaska in the north. Some experts suggest that, blown along by the fast-moving jet stream, radioactivity could reach North America in 36 hours.
"Some of the radioactivity could carry in the atmosphere to the West Coast of the US," added Cirincione, head of anti-nuclear group Ploughshares Fund.
"Right now the government as a whole has people looking at the situation and asking these questions. We don't have the answers yet. We don't have anything that we can say publicly right now."
This is an unfolding situation and really we can't comment on it very much," he added, while stressing the NRC's basic view that the threat to the United States is minimal.
Source: Discovery.com