and those there should consider departing - see below.
March 18, 2011
The U.S. Department of State warns U.S citizens of the deteriorating situation at the Fukushima Daiichi Nuclear Power Plant. The United States Nuclear Regulatory Commission (NRC) recommends that U.S. citizens who live within 50 miles (80 kilometers) of the Fukushima Daiichi Nuclear Power Plant evacuate the area or take shelter indoors if safe evacuation is not practical. The State Department strongly urges U.S. citizens to defer travel to Japan at this time and those in Japan should consider departing. On March 16, 2011, the Department of State authorized the voluntary departure from Japan of eligible family members of U.S. government personnel in Tokyo (Tokyo Capital Region), Nagoya (Aichi Prefecture), Yokohama (Kanagawa Prefecture), and the prefectures of Chiba, Fukushima, Gunma, Ibaraki, Iwate, Miyagi, Nagano, Niigata, Saitama, Shizouka, Tochigi, Yamagata, and Yamanashi. Separately, because of infrastructure damage from the earthquake and resulting tsunami, voluntary authorized departure is authorized for the eligible family members at Misawa AB (Aomori Prefecture). This Travel Warning replaces the Travel Warning dated March 16, 2011.
In response to the deteriorating situation at the Fukushima Daiichi Nuclear Power Plant, the United States Nuclear Regulatory Commission (NRC), the Department of Energy, and other technical experts in the U.S. Government have reviewed the scientific and technical information they have collected from assets in country, as well as what the Government of Japan has disseminated. Consistent with the NRC guidelines that would apply to such a situation in the United States, we are recommending, as a precaution, that U.S. citizens within 50 miles (80 kilometers) of the Fukushima Daiichi Nuclear Power Plant evacuate the area or to take shelter indoors if safe evacuation is not practical.
http://travel.state.gov/travel/cis_pa_tw/tw/tw_5390.html