"This is a situation in which people may be called in to sacrifice their lives"

That quote comes from the Gregory Jaczko, head of the Nuclear Regulatory Commission, the U.S. agency responsible for regulating nuclear power.  He believes the situation in Japan may be far worse than the Japanese are admitting, and the quote continues: "...It's very difficult for me to contemplate that, but it's… it may have reached that point."

In the mean time, the U.S. has evacuated all its military personnel to a radius of 50 miles around the reactors, whereas the Japanese evacuation radius is only 12 miles. 

Read more in this LA Times article