GAP analysis between single-unit and multi-unit psas for Korean NPPs

초록

On June, 2016, the Nuclear Safety and Security Commission (NSSC) of Korea approved the construction permit for Shin-Kori Units 5 and 6. This means that a total of nine nuclear power plants (NPPs) will be operating within approximatelyfive kilometers of one another on a single site (decommissioning of Kori unit 1 slated for 2017.) The fact that there are twometropoles located at distances of 30 kilometers to the north and southeast of the site is obviously of serious concern to thepublic as well as nuclear experts, particularly considering the recent Fukushima disaster. Furthermore, the simultaneous coredamage at Units 1-3 and hydrogen explosion at Unit 4 spent fuel pool by inter-unit interaction in the Fukushima DaiichiPower Stations has raised a serious issue of multi-unit risk and vulnerability of NPPs to inter-unit interactions. During thelicensing review process for Shin-Kori Units 5 and 6, and even for Shin-Kori Units 3 and 4 earlier, there was a heated debateas to whether multi-unit risk is adequately covered by the current regulations, or otherwise the regulations should be reinforced especially in view of the high-density nuclear power plant sites in Korea.The interest in multi-unit PSA in Korea actually began before the Fukushima accident, with the Ministry of Science, ICTand future Planning (MSIP)’s provision of support for the R&D programs of the Korea Atomic Energy Research Institute(KAERI) to carry out fundamental researches for multi-unit PSA. Recently, as tangible results of such research have becomeavailable, Korea’s nuclear utility has begun conducting a pilot multi-unit PSA on a specific site. At the same time, the NSSClaunched to develop an R&D roadmap for multi-unit PSA so that multi-unit risk can be adequately addressed by the utility. Itis expected that appropriate regulatory measures will be taken by the NSSC once sufficient insights are gained for the multiunit site risk.This paper presents a technical gap between single- and multi-unit PSAs and the particular issues in South Korea asobserved in our preliminary study to assist the NSSC in developing the R&D roadmap.