Quantitive Risk Assessment of the Model Representing Latest Japanese Hydrogen Refuelling Stations

Current safety codes and technical standards related to Japanese hydrogen refueling stations (HRSs) have been established based on qualitative risk assessment and quantitative effectiveness validation of safety measures for more than ten years. In the last decade, there has been significant development in the technologies and significant increment in operational experience related to HRSs. We performed a quantitative risk assessment (QRA) of the HRS model representing Japanese HRSs with the latest information in the previous study. The QRA results were obtained by summing risk contours derived from each process unit. They showed that the risk contours of 10-3 and 10-4 per year were confined within the HRS boundaries, whereas those of 10-5 and 10-6 per year are still present outside the HRS boundaries. Therefore, we analyzed the summation of risk contours derived from each unit and identified the largest risk scenarios outside the station. The HRS model in the previous study did not consider fire and blast protection walls, which could reduce the risks outside the station. Therefore, we conducted a detailed risk analysis of the identified scenarios using 3D structure modeling. The heat radiation and temperature rise of jet fire scenarios that pose the greatest risk to the physical surroundings in the HRS model were estimated in detail based on computational fluid dynamics with 3D structures, including fire protection walls. Results show that the risks spreading outside the north-, west-, and east-side station boundaries are expected to be acceptable by incorporating the fire protection wall into the Japanese HRS model.