Fukushima Radiation Release Exceeds NRC Design-Basis Limit

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U.S. Nuclear Regulatory Commission (NRC) regulations require nuclear license applicants to show that their plants can withstand a series of design-basis accidents without releasing radiation that would exceed a given level. In particular, the whole-body dose for someone standing at the site boundary for the worst two hours of the accident cannot exceed 25 rem, or 250 milli-Sieverts (mSv).

The dose rate for such a design-basis accident would be 125 mSv per hour.

In comparison, the dose rate near reactor Unit 3 at Fukushima Dai-Ichi has reportedly reached 400 mSv per hour. The Fukushima accident is therefore now a beyond-design-basis accident, at least in NRC terms.

Posted in: Japan, Nuclear Power Safety Tags: , ,

About the author: Dr. Lyman received his PhD in physics from Cornell University in 1992. He was a postdoctoral research scientist at Princeton University's Center for Energy and Environmental Studies, and then served as Scientific Director and President of the Nuclear Control Institute. He joined UCS in 2003. He is an active member of the Institute of Nuclear Materials Management and has served on expert panels of the Nuclear Regulatory Commission. His research focuses on security issues associated with the management of nuclear materials and the operation of nuclear power plants, particularly with respect to reprocessing and civil plutonium. Areas of expertise: Nuclear terrorism, proliferation risks of nuclear power, nuclear weapons policy

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