Safety system study of a fusion reactor confinement

The study of confinement in the NET (Next European Torus) plant, as a safety system study, involves a functional analysis that not only identifies the functions whose losses have safety-related consequences, but also quantifies the consequences in a semiprobabilistic way. The results of this study will permit the designers to improve the NET. The failures that are identified as having safety-related consequences (namely, direct failures of the confinement) have been classified in homogeneous groups called initiating events. The use of layout models of the building and of the confinement units permits the risk for each initiating event to be quantified with the help of risk-event trees. From a primary activity release (process release) in one room, it is possible to know in the surrounding rooms and in a second row of rooms the activities and their probabilities of occurrence. Therefore the risk in each room can be assessed on the basis of the state of each barrier encountered by the release