A protester is detained by police officers in front of the head office of Tokyo Electric Power Company, Inc. (TEPCO) during an anti-nuclear march in Tokyo March 31, 2011. Pressure mounted on Japan on Thursday to expand the evacuation zone around its stricken nuclear power plants after high levels of radiation were found outside the zone and radioactivity in seawater reached more than 4,000 times its legal limit. [Photo/Agencies]

A protester shouts slogans as he raises his fist toward to the head office of Tokyo Electric Power Company, Inc. (TEPCO) during an anti-nuclear march in Tokyo March 31, 2011. [Photo/Agencies]