The Tohoku earthquake, which occurred at 2:46 p.m. (Japan time) on Friday, March 11, 2011, on the east coast of northern Japan, is believed to be one of the largest earthquakes in recorded history. Following the earthquake on Friday afternoon, the nuclear power plants at the Fukushima Daiichi, Fukushima Daini, Higashidori, Onagawa, and Tokai Daini nuclear power stations (NPSs) were affected, and emergency systems were activated. The earthquake caused a tsunami, which hit the east coast of Japan and caused a loss of all on-site and off-site power at the Fukushima Daiichi NPS, leaving it without any emergency power. The resultant damage to fuel, reactor, and containment caused a release of radioactive materials to the region surrounding the NPS. Although the United States was not directly affected, our nuclear power industry will take important lessons from this accident.

The American Nuclear Society (ANS) formed a special committee, The American Nuclear Society Special Committee on Fukushima (the Committee), to examine the Fukushima Daiichi accident. The Committee was charged to provide a clear and concise explanation of the accident events, health physics, and accident cleanup, as well as safety-related issues that emerged. The Committee also evaluated actions that ANS should consider to better communicate with the public during a nuclear event.

The Committee used publically available source materials from the Japanese industry and government as well as reports from those entities to the international community, as indicated in the sections “References” and “Bibliography.” The Committee views do not reflect any major inconsistencies regarding accident events, health physics, and accident cleanup. The safety-related issues identified by the Committee are consistent with what has been noted in the reports already issued from many regulatory agencies. Finally, the Committee focused on risk communication and crisis communication as major issues that ANS as a professional society needs to address in the future.

The Committee worked from May 2011 to December 2011. Because the accident forensics, accident cleanup, and associated off-site health effects are ongoing, the Committee will continue to update the detailed accident-related information at the ANS Web site ( as new measurements, facts, insights, and regulatory developments are gained. An embedded topical meeting, International Meeting on Severe Accident Assessment and Management: Lessons Learned from Fukushima Daiichi, will be held as part of the ANS Winter Meeting in November 2012.