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NRC approves TerraPower construction permit
Today, the Nuclear Regulatory Commission announced that it has approved TerraPower’s construction permit application for Kemmerer Unit 1, the company’s first deployment of Natrium, its flagship sodium fast reactor.
This approval is a significant milestone on three fronts. For TerraPower, it represents another step forward in demonstrating its technology. For the Department of Energy, it reflects progress (despite delays) for the Advanced Reactor Demonstration Program (ARDP). For the NRC, it is the first approval granted to a commercial reactor in nearly a decade—and the first approval of a commercial non–light water reactor in more than 40 years.
Yan Wang, Zhijian Zhang, Anqi Xu, Huazhi Zhang
Nuclear Technology | Volume 198 | Number 3 | June 2017 | Pages 327-341
Technical Paper | doi.org/10.1080/00295450.2017.1297174
Articles are hosted by Taylor and Francis Online.
Quantitative risk values for nuclear power plants (NPPs) can be obtained by conducting a probabilistic safety assessment (PSA). However, people cannot judge the risk level without comparing the risk values from PSA with the standards of acceptable risk in society. Acceptable risk standards are affected by many factors, and those factors are preferentially considered in specified applications. There are many methods used to establish acceptable risk, and a comparative method is easily understood and accepted by the public. In the United States, both qualitative safety goals and quantitative health objectives (QHOs) for the current generation of light water reactors are established by a comparative method and are described in the Safety Goals Policy Statement published by the U.S. Nuclear Regulatory Commission. The evaluations of Level 1 PSA or Level 2 PSA are enough for most regulatory decisions and engineering practices.
In order to use PSA as a useful tool for regulation, establishing surrogate safety goals based on QHOs is necessary. But, there is no clear derivation process. First, this paper introduces the process of how to derive QHOs from qualitative safety goals and a model of quantitative health risk. Then, models using core damage frequency (CDF) and large early release frequency (LERF) based on the QHOs are introduced. The situations of nuclear power for each country—the number of plants, the types of reactors, the weather conditions, the population distribution, and the off-site emergency response plan—are different for each country. This paper considers two representative situations. The first situation is that a society has only a single NPP. The maximum consequence method is used to determine the surrogate safety goals for this situation. The second situation is that a society has multiple types of NPPs and the off-site environments of the plants are different from each other. The statistical tolerance intervals method is used to determine the surrogate safety goals for this situation. Data of individual early fatality and cancer fatality risk in China from 2004 to 2013 are collected and analyzed, and then, Chinese, U.S., Korean, and Japanese QHOs are compared. Chinese QHOs and some data from the reference are used to establish surrogate safety goals for the two situations, which are compared with existing surrogate safety goals CDF = 1E-04 per reactor and LERF = 1E-05/reactor-year.