Application of likelihood evaluation method for an integrated safety analysis

One of the most significant issues in South Korea is management of spent fuels (SFs) due to relatively narrow territory and low public acceptance on safe and reliable controls on radioactive wastes. Currently, a low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju province has been operated since 2015. However, high-level radioactive wastes such as PWR SFs have been temporarily stored in SF pools with active cooling systems in nuclear power plant (NPP) sites. In addition, a shortage of the temporary storage capacity is anticipated by 2024 for Hanbit and Kori NPPs. In order to recycle the valuable materials in SFs and to reduce the amount of wastes, Korea Atomic Energy Research Institute (KAERI) has been developing a pyroprocess technology as a dry process compared to a wet process. In a pyroprocess, it is essential to ensure safety of operations due to the high radiological consequences of radioactive materials on facility workers as well as public and the environment. In a risk matrix of 3 by 3, three types of consequences and likelihoods, respectively, are divided based on 10 CFR 70.61. In this study, a likelihood evaluation method is applied by distinguishing failure frequency index numbers and failure probability index numbers according to f-type and p-type events, respectively