Modification of K-HRA Method for Fire Human Reliability Analysis

This study focuses on incorporating fire scenarios into the diagnosis error probability calculation of the existing KHRA methodology, addressing the impact of the shift technical advisor's absence during fire incidents. Based on operator interviews, it was determined that the shift technical advisor was absent from the main control room for approximately 30 minutes to establish and stabilize the fire brigade. During this period, the joint human error probability doubles between 10 and 30 minutes, as determined by the NUREG/CR-1278 methodology. Accordingly, the nominal diagnosis error probability in K-HRA was adjusted to account for fire-related scenarios. In addition to modifying the nominal diagnosis error probability, the fire human reliability analysis incorporated fire-specific considerations into performance shaping factors. These include the simultaneous use of fire procedures with abnormal/emergency operation procedures, partial or complete human-system interface damage due to cable failures, and insufficient training related to reactor shutdown during fires. This research highlights the integration of fire conditions into the K-HRA framework, particularly addressing the shift technical advisor's absence. Future studies aim to compare the diagnosis error probability derived from the existing K-HRA and Fire human reliability analysis methodologies during the quantification of human failure events, such as operator manual actions. This work contributes to advancing fire-specific reliability assessments for nuclear power plant safety.

Keywords: Fire Human Reliability Analysis, Detailed Analysis, Diagnosis Error Probability, K-HRA Method.