In this Wednesday, Aug. 10, 2011 photo released by Tokyo Electric Power Co., building materials are being pulled up by a crane by Unit 1 reactor, seen behind the crane, to build a tent to cover the reactor at the crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, northeastern Japan. Its operator TEPCO said Friday, Aug. 12, they are building a huge tent to cover Unit 1, one of the worst-hit reactors. Officials hope the cover will keep leaked radioactive materials from spreading, prevent rainwater seepage and offer a barrier from further leaks. The tent is being built behind the reactor and not shown in the photo.