System 80+ standard plant design reduced off-site radiological impacts

The minimization of potential radiological consequences to the public is one of the most important international issues for nuclear power plant design and operation. While specific criteria and emphasis on long-term vs. short-term effects may vary from country to country, there is a clear international desire to ensure that potential post-accident radiological impacts are minimized. This can be seen through a review of requirements proposed in programs such as the US Advanced Light Water Reactor (ALWR) Utility Requirements Document (URD) program, the European Utility Requirements program, the Korean Standard Requirements program, and the People's Republic of China nuclear power program. This paper identifies and compares specific criteria from the various programs and summarizes related numerical results for the System 80+ Standard Nuclear Power Plant. For the first two hours after a postulated large-break LOCA, the conservatively-calculated design basis dose to an individual at the site boundary for System 80+ is less than 1.72 Sv to the thyroid and less than 0.026 Sv to the whole body. Corresponding acceptance criteria are 3.0 Sv and 0.25 Sv, respectively. The System 80+ Total Effective Dose Equivalent (TEDE) dose for the same LOCA and two-hour time frame is 0.09 Sv, significantly less than the NRC's acceptance criterion of 0.25 Sv TEDE. The core damage frequency (CDF) for System 80+ is calculated to be between 1.9E-6 and 3.5E-6 events/year, depending on the assumptions used and reviewed by the US Nuclear Regulatory Commission (NRC). The probability of a large release (0.25 Sv whole body in the first 24 hours) is 5E-8 events/year for a site boundary radius of 800 meters. The probability of a corresponding small release (0.01 Sv whole body in the first 24 hours) is 3E-7 events/year. The potential dose at any distance from the plant is reduced by more than two orders of magnitude for System 80+ relative to the plants analyzed when the NRC established current emergency planning requirements. In fact, the dose at the System 80+ site boundary is less than that at the outer limit of the 10-mile emergency planning zone for the plants originally analyzed. These significantly lower predictions of potential offsite doses suggest that a re-evaluation of current emergency planning requirements should be initiated. The System 80+ analysis has also shown that the size of the food ingestion emergency planning zone justifiably could be reduced in area by a factor of about ten. (author)