Assessment on the Success Criteria and the Human Error Probability of the Power Uprated Plant

Numerous power uprate applications for nuclear power plants (NPP) were approved (109 applications) in the United States since 1970, while the first NPP power uprate is planned for Kori 3 and 4 / Yonggwang 1 and 2 in Korea. There are three categories of power uprate ; (1) MUR (Measurement Uncertainty Recapture power uprate), which is less than 2 percent and can be achieved by implementing the enhanced techniques for reactor power calculations ; (2) SPU (Strech Power Uprate), which is typically up to 7 percent and does not involve major plant modifications ; (3) EPU (Extended Power Uprate), which is usually as high as 20 percent and requires significant modifications to the major BOP equipment. USNRC requires licensees to evaluate the effect of power uprate on the plant specific PSA results for EPU by issuing the regulatory guidance RS-001, but it does not require the PSA evaluation for SPU and MUR plants. There is no established regulatory guidance for the PSA evaluations of power uprated plants in Korea. Since the power uprates for Kori 3 and 4 / Yonggwang 1 and 2 will be SPU, there is no general guidance for their PSA evaluations. But, after reviewing many reference foreign documents related to the PSA evaluations for EPU, we discovered that the main changes related to the power uprates were as follows. (1) The decay heat removal success criteria (2) The dynamic operator actions (3) The fission product inventories This paper discusses the changes of the plant specific level 1 PSA for Kori 3 and 4 / Yonggwang 1 and 2 by SPU, and it is mainly focused on the changes of the success criteria and the human error probabilities in the PSA model