Study of issues in S-CO2 direct-cycle micro modular reactor due to long-term operation

Abstract

This study discusses several problems that S-CO$_2$ direct-cycle Micro Modular Reactor will face in a long-cycle operating environment. The problems addressed are mechanical performance degradation and the exposure dose of maintenance workers. First, the performance degradation mechanisms that components of the S-CO$_2$ system experienced are classified, and models to simulate them are collected. In this process, an additionally required S-CO$_2$ compressor performance degradation model was newly developed. Using the developed degradation models, transient analysis was performed for the S-CO$_2$ direct-cycle Micro Modular Reactor. The effects of the component deterioration of the part-load operation and frequency control performance were confirmed for the first time. A plate-out analysis was conducted to estimate the occupational dose. As a result, it is confirmed that the level of occupational dose of the 10MWe scale S-CO$_2$ direct-cycle micro modular reactor (KAIST-MMR) is acceptable to adopt on-site maintenance strategy.