![Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima](https://l450v.alamy.com/450vfr/2e6e67a/international-atomic-energy-agency-iaea-fact-finding-mission-team-leader-and-britians-top-nuclear-safety-official-mike-weightman-answers-questions-from-reporters-after-a-meeting-with-goshi-hosono-special-adviser-to-japans-prime-minister-naoto-kan-at-the-prime-ministers-official-residence-in-tokyo-june-1-2011-japan-underestimated-the-risk-of-tsunamis-and-needs-to-closely-monitor-public-and-workers-health-after-the-crisis-at-the-fukushima-daiichi-nuclear-plant-the-team-of-international-safety-inspectors-said-in-a-preliminary-review-of-the-worlds-worst-nuclear-disaster-since-chernobyl-2e6e67a.jpg)
Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima
![Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima](https://l450v.alamy.com/450vfr/2cwh81h/japans-nuclear-and-industrial-safety-agency-nisa-director-general-kenkichi-hirose-r-speaks-during-a-joint-news-conference-with-japans-nuclear-safety-agency-official-hidehiko-nishiyama-in-tokyo-april-12-2011-japan-raised-the-severity-of-its-nuclear-crisis-at-the-fukushima-daiichi-nuclear-plant-to-a-level-7-from-5-putting-it-on-par-with-the-chernobyl-nuclear-disaster-in-1986-reuters-yuriko-nakao-japan-tags-politics-disaster-2cwh81h.jpg)
Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima
![Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima](https://l450v.alamy.com/450vfr/2e62rx1/hidehiko-nishiyama-responsable-de-l-agence-japonaise-de-surete-nucleaire-assiste-a-une-conference-de-presse-sur-la-centrale-nucleaire-de-fukushima-daiichi-de-tokyo-electric-power-co-a-tokyo-le-30-mars-2011-l-eau-de-mer-pres-du-reacteur-n-1-du-complexe-nucleaire-de-fukushima-daiichi-paralyse-contenait-de-l-iode-radioactif-a-3355-fois-la-limite-legale-a-declare-mercredi-l-agence-japonaise-de-surete-nucleaire-et-industrielle-des-plans-structuraux-de-la-centrale-nucleaire-de-fukushima-daiichi-a-partir-de-l-dans-le-sens-des-aiguilles-d-une-montre-les-reacteurs-n-2-n-3-et-n-4-sont-vus-derriere-lui-reuters-issei-kato-japon-tags-environnement-d-energie-de-catastrophe-2e62rx1.jpg)
Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima
![Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima](https://c8.alamy.com/compfr/2cya0rb/japans-nuclear-safety-agency-official-hidehiko-nishiyama-speaks-during-a-news-conference-on-tokyo-electric-power-co-s-fukushima-daiichi-nuclear-power-plant-in-tokyo-march-30-2011-seawater-near-the-crippled-fukushima-daiichi-nuclear-complexs-no-1-reactor-contained-radioactive-iodine-at-3355-times-the-legal-limit-japans-nuclear-and-industrial-safety-agency-said-on-wednesday-structural-drawings-of-fukushima-daiichi-nuclear-power-plant-from-l-to-r-no-1-no-2-and-no-3-reactors-are-seen-behind-him-reuters-issei-kato-japan-tags-disaster-environment-energy-2cya0rb.jpg)
Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima
![Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima](https://l450v.alamy.com/450vfr/2cwepd9/japans-nuclear-safety-agency-official-hidehiko-nishiyama-speaks-during-a-joint-news-conference-with-japan-nuclear-safety-commission-in-tokyo-april-12-2011-japan-raised-the-severity-of-its-nuclear-crisis-at-the-fukushima-daiichi-nuclear-plant-to-a-level-7-from-5-putting-it-on-par-with-the-chernobyl-nuclear-disaster-in-1986-reuters-yuriko-nakao-japan-tags-politics-disaster-energy-2cwepd9.jpg)
Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima
![Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima Japan's nuclear safety agency official Hidehiko Nishiyama speaks during a news conference on Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Plant, in Tokyo March 30, 2011. Seawater near the crippled Fukushima](https://l450v.alamy.com/450vfr/2cx9h3p/hidehiko-nishiyama-responsable-de-l-agence-japonaise-de-surete-nucleaire-s-exprime-lors-d-une-conference-de-presse-sur-la-centrale-nucleaire-de-fukushima-daiichi-de-tokyo-electric-power-co-qui-s-est-tenue-a-tokyo-le-30-mars-2011-l-eau-de-mer-pres-du-reacteur-n-1-du-complexe-nucleaire-de-fukushima-daiichi-paralyse-contenait-de-l-iode-radioactif-a-3355-fois-la-limite-legale-a-declare-mercredi-l-agence-japonaise-de-surete-nucleaire-et-industrielle-le-dessin-structurel-du-reacteur-no-2-de-la-centrale-nucleaire-de-fukushima-daiichi-est-vu-derriere-lui-reuters-issei-kato-japon-tags-environnement-d-energie-de-catastrophe-2cx9h3p.jpg)