Fukushima Daiichi NPS February-May 2012

The combination of two photos shows the Fukushima Dai-ichi nuclear power station in Fukushima Prefecture before, top, and nearly one year after a devastating earthquake and tsunami hit Japan's northeast on March 11, 2011 and sent three of its reactors into meltdown. The top photo was taken in October, 2008 while the bottom photo was taken on Feb. 26, 2012. (Kyodo News)

Tsunami-crippled four reactors, from left, Unit 1 to Unit 4, are seen at Fukushima Dadi-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan Sunday, March 11, 2012. Japan on Sunday was remembering the massive earthquake and tsunami that struck the nation a year ago, killing just over 19,000 people and unleashing the world's worst nuclear crisis in a quarter century. The photo was taken about three kilometers (1.9 miles) away from the plant. (Kyodo News)

Cranes stand around tsunami-crippled four reactors, from left, Unit 1 to Unit 4, at Fukushima Dadi-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan Sunday, March 11, 2012. Japan on Sunday was remembering the massive earthquake and tsunami that struck the nation a year ago, killing just over 19,000 people and unleashing the world's worst nuclear crisis in a quarter century. The photo was taken about three kilometers (1.9 miles) away from the plant. (Kyodo News)

Severely damaged reactor Unit 3 is seen at the tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan, Sunday, March 11, 2012. Japan on Sunday was remembering the massive earthquake and tsunami that struck the nation a year ago, killing just over 19,000 people and unleashing the world's worst nuclear crisis in a quarter century. (Kyodo News)

Reactor Unit 2 stands at the tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan, Sunday, March 11, 2012. Japan on Sunday was remembering the massive earthquake and tsunami that struck the nation a year ago, killing just over 19,000 people and unleashing the world's worst nuclear crisis in a quarter century. (Kyodo News)

Severely damaged ducts, fences and buildings are seen in the seaside compound of the tsunami-crippled Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima Prefecture, Japan, Sunday, March 11, 2012. Japan on Sunday was remembering the massive earthquake and tsunami that struck the nation a year ago, killing just over 19,000 people and unleashing the world's worst nuclear crisis in a quarter century. (Kyodo News)

In this aerial photo taken from the Asahi Shimbun helicopter, cranes surround the tsunami-damaged Fukushima Dai-ichi nuclear power plant reactors, from right, Unit 2, covered by light blue walls, Unit 3, center, and Unit 4, in Okuma, Fukushima Prefecture, northeastern Japan, Monday, May 28, 2012. The prime minister during Japan's nuclear crisis last year said Monday he had to use an emergency law that never anticipated major radiation leaks and lacked experts capable of giving him guidance. (Tom Curley)

In this aerial photo taken from the Asahi Shimbun helicopter, reactors of the tsunami-damaged Fukushima Dai-ichi nuclear power plant stand in Okuma, Fukushima Prefecture, northeastern Japan, Monday, May 28, 2012. Reactors are, from right, Unit 1, covered with a beige cover, Unit 2, covered with a square white cover, Unit 3 and Unit 4, showing their damaged frames at the bottom of cranes. (Tom Curley)

In this aerial photo taken from the Asahi Shimbun helicopter, the tsunami-damaged Fukushima Dai-ichi nuclear power plant is seen in Okuma, Fukushima Prefecture, northeastern Japan, Monday, May 28, 2012. The prime minister during Japan's nuclear crisis last year said Monday he had to use an emergency law that never anticipated major radiation leaks and lacked experts capable of giving him guidance. (Tom Curley)