Members of a local government council check an outlet of a so-called groundwater bypass system as they inspect the crippled Fukushima Dai-ichi Nuclear Power Station earlier this week. Kyodo/Landov hide caption

itoggle caption Kyodo/Landov

Tokyo Electric Power Co (TEPCO) workers work on waste water tanks at Japan's Fukushima Daiichi nuclear plant in the town of Okuma, Fukushima prefecture in Japan on June 12, 2013. Noboru Hashimoto /AFP/Getty Images hide caption

itoggle caption Noboru Hashimoto /AFP/Getty Images

As they inspected an underground storage pool near the crippled Fukushima Daiichi nuclear power plant earlier this month, Tokyo Electric Power Co. President Naomi Hirose (4th from left) and other officials wore protective suits and masks. Radioactive water stored in some of the pits has leaked. Tokyo Electric Power Co./Reuters /Landov hide caption

itoggle caption Tokyo Electric Power Co./Reuters /Landov

Care managers tend elderly people in March 2012 in Minamisoma, Japan. The home's residents were evacuated eight days after the Fukushima Dai-ichi nuclear power station was crippled by the March 11, 2011 tsunami. Koji Sasahara/AP hide caption

itoggle caption Koji Sasahara/AP

Smoke rises from Unit No. 3 of the stricken Fukushima Dai-ichi nuclear plant after the March 11, 2011 earthquake and tsunami. Anonymous/AP hide caption

itoggle caption Anonymous/AP

This photo, taken by a remote-controlled endoscope and released by Tokyo Electric Power Co., shows structures assumed to be small size piping or cable conduit inside the beaker-shaped containment vessel of No. 2 reactor at the damaged Fukushima Dai-ichi nuclear power plant. Tepco/AP hide caption

itoggle caption Tepco/AP

Workers in protective suits and masks wait to enter the emergency operation center at the crippled Fukushima Dai-ichi nuclear power station on Nov. 12, 2011. David Guttenfelder /AFP/Getty Images hide caption

itoggle caption David Guttenfelder /AFP/Getty Images

Japan's Parliamentary Secretary for the Cabinet Office Yasuhiro Sonoda drinks a glass of decontaminated water taken from puddles inside the buildings housing reactors 5 and 6 at the Fukushima No. 1 plant.

Jiji Press/AFP/Getty Images hide caption

itoggle caption Jiji Press/AFP/Getty Images