Safety analysis of a like-NET shielding blanket system

The contribution of failures in the driver shielding blanket system to the overall risk associated with operating a Next European Torus (NET)-like fusion test reactor is evaluated and compared with the assumed safety design targets. The analysis is based on the system study methodology developed by ENEA and CEA for the NET Overall Plant Accident Scenarios identification and risk evaluation. A low-pressure, low-temperature water-cooled blanket with the addition of lithium salt (LiNO₃) were studied. Different design options have been considered, mainly based on the number and layout of the primary cooling loops. The identified process source terms come from the tritium and the activated corrosion products carried by the primary coolant. Different active and passive barriers (e.g. containment barriers, ventilation, stack filters) have been considered to evaluate accident releases to environment. Expected frequencies of initiating events and unavailability of safety systems have been estimated by means of the fault-tree technique; expected probabilities of accident sequences have been estimated by means of the event-tree technique. Reliability data from the data bank adapted for the fusion environment have been utilized. The results of the analysis are presented