Uncertainty analysis for source term evaluation of high temperature gas-cooled reactor under accident conditions; Identification of influencing factors in loss-of-forced circulation accidents

Honda, Yuki; Sato, Hiroyuki  ; Nakagawa, Shigeaki  ; Ohashi, Hirofumi 

There is growing interest in uncertainty analysis for probabilistic risk assessment (PRA). The focus of this research is to propose and trial investigate the new approach which identify influencing factors for uncertainty in a systematic manner for High Temperature Gas -cooled Reactor (HTGR). As a trial investigation, this approach is tested to evaluation of maximum fuel temperature in a depressurized loss-of-forced circulation (DLOFC) accident and failure of mitigation systems such as control rod systems from the view point of reactor dynamics and thermal hydraulic characteristics. As a result, 16 influencing factors are successfully selected in accordance with the suggested procedure. In the future, the selected influencing factors will be used as input parameter for uncertainty propagation analysis.