A Framework to Identify the Catalog of Important Tasks Reflecting Interorganizational Characteristics Regarding the Deployment of Portable Equipment

One key difference between the traditional probabilistic safety assessment (PSA) and multi-unit PSA (MU-PSA) is that the MU-PSA must consider interorganizational characteristics arising from deploying portable equipment. In this study, a systematic framework is proposed for the detailed sub-task analysis of human failure events (HFEs) involving portable equipment through utilization of STAMP (Systems-Theoretic Accident Model and Processes) and STPA (Systems-Theoretic Process Analysis). A case study was performed for a typical multi-unit emergency response involving a portable diesel generator. Through the proposed framework, detailed sub-tasks were identified for the HFE (“Failure of deploying the portable diesel generator”) in a form of unsafe control actions through a systemic approach. The results showed that the potential hazards that may not currently be analyzed in the traditional HRA enough include failed convocation of offsite workers, interorganizational communication between important EROs, and multi-unit decision making error on installing PDGs if there are conflict due to limited number of PDGs available. Results of the detailed HFE analysis using the proposed framework may be used as a basis to allow more realistic application of the HRA involving deployment of portable equipment (e.g., multi-unit accidents and beyond design-basis external events) that are better representative of the interorganizational characteristics.