Safety assessment of the International Fusion Materials Irradiation Facility

This paper deals with the safety assessment of the lithium target of the International Fusion Materials Irradiation Facility, to evaluate the most important risk factors related with the system operation and to verify the fulfillment of the safety criteria. At first a well structured Failure Mode and Effect Analysis (FMEA) procedure allows for the hazard assessment, by detailing on a component-by-component basis all the possible failure modes and identifying their effects on the plant. Additionally a systems analysis, applying the fault tree technique, is performed in order to evaluate, on the probabilistic standpoint, all the relevant and possible failures of each component required for system safe operation and assess the unavailability of the lithium target system. The last task is pertaining to the thermal hydraulic transient analysis of the target lithium loop, including operational and accident transients. A lithium target loop model is developed, using the RELAP5/Mod3.2 thermal hydraulic code, which has been modified to include specific features of IFMIF itself. Main conclusions are that target safety is fulfilled: hazards associated with lithium operation are confined within the IFMIF security boundaries and environmental impact is negligible, and the plant well answers to the simulated transients being able to reach steady conditions in a situation of safety