Study Background

This is an U.S. Nuclear Regulatory Commission (USNRC) sponsored study, initiated in response to the accident at the Fukushima Dai-ichi Nuclear Power Station in Japan. The March 11, 2011, Great East-Japan earthquake and tsunami devastated parts of the northeast coast of Honshu Island. The earthquake and tsunami knocked out offsite power to the station and all but one of the station’s backup power generators. The power loss initiated a sequence of events that resulted in meltdowns of three of the station’s six reactor cores; hydrogen explosions that severely damaged four reactor buildings and blocked access to their spent fuel pools; and, according to Japanese government estimates, the release of about 1017 becquerels (~ 3 million curies) of iodine-131, 1016 becquerels (~300,000 curies) of cesium-137, and approximately 1016 becquerels (~300,000 curies) of cesium-134 into the atmosphere. The accident was rated as a Level 7 (major accident) event on the International Nuclear and Radiological Event Scale, on par with the 1986 Chernobyl accident.

Cleanup from the Fukushima accident will be a lengthy and costly effort. The plant owner/operator (TEPCO), in consultation with the Japanese government, has developed a roadmap for decommissioning the damaged units at the plant. This roadmap calls for the commencement of removal of spent fuel from the pools in the damaged reactor buildings within 2 years, commencement of removal of fuel debris from reactor containments within 10 years, and completion of plant decommissioning within 30-40 years. Additionally, the Japanese government estimates that up to about 2,400 square kilometers (930 square miles) of land might need to be decontaminated to reduce radiation exposures to acceptable levels. The cost of decommissioning and decontamination is likely to run into the tens of billions of US dollars (trillions of Japanese yen) and could generate millions to tens of millions of cubic meters of waste.

Two Japanese government-sponsored inquiries have assessed the causes of the Fukushima accident. The first, which was commissioned by former Japanese Prime Minister Naoto Kan, issued an interim report in December 2011 and plans to issue a final report in the fall of 2012. The interim report is critical of TEPCO and the Japanese nuclear regulator for being unprepared for the earthquake and tsunami. A second inquiry, which was mandated by the Japanese Diet was released July 2012.

Governments in other countries have also initiated inquiries to determine if changes in nuclear plant operations or regulations are needed. In the United States, the U.S. Nuclear Regulatory Commission organized the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident to assess whether improvements were needed in that agency’s processes and regulations. The Task Force issued its report in July 2011; it concluded that although there are no imminent risks from plant operations and licensing activities, enhancements to safety and emergency preparedness are warranted. The Commission recently approved the Task Force’s recommendations for near-term enhancements and is now considering the recommendations for longer-term enhancements. The Task Force and Japanese inquiry reports will be important inputs to this National Research Council study.

The initial recommendation for this National Research Council study was made by the Blue Ribbon Commission on America’s Nuclear Future in its report to the U.S. Secretary of Energy:[1]

“[T]he Commission recommends that the National Academy of Sciences (NAS) conduct a thorough assessment of lessons learned from Fukushima and their implications for conclusions reached in earlier NAS studies[2] on the safety and security of current storage arrangements for spent nuclear fuel and high-level waste in the United States.”

In mandating this study, Congress added additional tasking involving assessments of reactor safety and security and the adequacy of existing regulations.

The congressional mandate also directs that the study be coordinated with the Japanese government if possible. National Research Council staff has made initial contacts with officials from the Japanese Atomic Energy Commission, Japanese Atomic Energy Agency, Japan Science and Technology Agency, Nuclear and Industrial Safety Agency, Science Council of Japan, and the Japanese Embassy to assess the Japanese government’s interest in cooperating on this study.

[1] Blue Ribbon Commission on America’s Nuclear Future, Report to the Secretary of Energy, January 2012. Available at
[2] Safety and Security of Commercial Spent Nuclear Fuel Storage (U) (2004); Safety and Security of Commercial Spent Nuclear Fuel Storage: Public Report (2006).