Fukushima Daiichi Nuclear Power Station 26 May 2012

Media persons and Tokyo Electric Power Co. employees look at the company's tsunami-crippled Fukushima Dai-Ichi nuclear power plant during a press tour in Okuma town, Fukushima prefecture, Japan, Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)

Reactor buildings from left to right, the No. 1, the No. 2, the No. 3 and the No. 4, are seen during a press tour at Tokyo Electric Power Co.'s (TEPCO) Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)

Members of the media and Tokyo Electric Power Co. employees walk in front of the No. 4 reactor building, rear, crippled by the March 11 earthquake and tsunami, at the utility company's Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)

The damaged No. 4 reactor building stands at Tokyo Electric Power Co.'s Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. Japanese Environment and Nuclear Minister Goshi Hosono, accompanied by the media, has visited the crippled Fukushima Dai-ichi nuclear power plant to inspect a reactor building and its spent fuel pool at the center of safety concerns. (Tomohiro Ohsumi, Pool)

Goshi Hosono, Japan's environment and nuclear minister, third from left, wearing a red helmet, along with members of the media, walks on the No. 4 reactor building at Tokyo Electric Power Co.'s (TEPCO) Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. Japan's environment and nuclear minister Hosono visited the tsunami-crippled nuclear power plant Saturday to inspect a spent fuel pool at the center of safety concerns. (Tomohiro Ohsumi, Pool)

Goshi Hosono, Japan's environment and nuclear minister, inspects the No. 4 reactor building at Tokyo Electric Power Co.'s Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan, Saturday, May 26, 2012. The visit by Hosono, apparently aimed at demonstrating the safety of the facility, came amid renewed concerns about conditions at the plant's No. 4 reactor after its operator reported a bulging of the building's wall. (Toshiaki Shimizu, Japan Pool) [Yellow reactor containment dome at center background.]

Workers walk in front of the No. 4 reactor building at Tokyo Electric Power Co.'s tsunami-crippled Fukushima Dai-Ichi nuclear power plant in Okuma town, Fukushima prefecture, Japan, Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)

An inside view of the damaged No. 4 reactor building is seen at Tokyo Electric Power Co.'s tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. (Toshiaki Shimizu, Japan Pool)

The inside of the tsunami-crippled No. 4 reactor building is seen during a press tour at Tokyo Electric Power Co.'s (TEPCO) Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan, Saturday, May 26, 2012.(Toshiaki Shimizu, Japan Pool)

Japan's Environment and Nuclear Minister Goshi Hosono, second from left, inspects a pool containing spent fuel rods inside the No. 4 reactor building at Tokyo Electric Power Co. 's tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan, Saturday, May 26, 2012. The pool, located at the top of the building above the reactor, remains one of the plant's biggest risks due to its vulnerability to earthquakes. (Toshiaki Shimizu, Japan Pool)

A pool for spent fuel rods is seen inside the No. 4 reactor building of Tokyo Electric Power Co.'s tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. The pool, located at the top of the building above the reactor, remains one of the plant's biggest risks due to its vulnerability to earthquakes. (Toshiaki Shimizu, Japan Pool)

The No. 3 reactor building is seen at Tokyo Electric Power Co.'s (TEPCO) Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. Japan's environment and nuclear minister, accompanied by the media, visited the tsunami-crippled nuclear power plant Saturday to inspect a spent fuel pool at the center of safety concerns. (Tomohiro Ohsumi, Pool)

The No. 1, left, and the No. 2, reactor buildings are seen during a press tour at the tsunami-crippled Fukushima Dai-ichi nuclear power plant of Tokyo Electric Power Co. (TEPCO) in Okuma, Fukushima Prefecture, Japan, Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)

Workers carry out radiation screening on a bus for a media tour at Tokyo Electric Power Co. (TEPCO) 's Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, on Saturday, May 26, 2012. Japan's environment and nuclear minister, accompanied by the media, visited the tsunami-crippled nuclear power plant Saturday to inspect a spent fuel pool at the center of safety concerns. (Tomohiro Ohsumi, Pool)

A worker carries out radiation screening on a bus for a media tour at Tokyo Electric Power Co. (TEPCO) 's Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, Japan, on Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)

A worker walks through the building used as crisis management headquarters at the tsunami-crippled Fukushima Dai-ichi nuclear power plant of Tokyo Electric Power Co.'s (TEPCO) in Okuma, Fukushima prefecture, Japan, Saturday, May 26, 2012. (Tomohiro Ohsumi, Pool)