The head of the UN atomic agency toured Japan's tsunami-wrecked Fukushima nuclear power plant on Wednesday and said he is satisfied with still-contentious plans to release treated radioactive wastewater into the Pacific Ocean. International Atomic Energy Agency chief Rafael Mariano Grossi observed where the treated water will be sent through a pipeline to a coastal facility, where it will be highly diluted with seawater and receive a final test sampling. It will then be released 1 kilometre (1,000 yards) offshore through an undersea tunnel.