Progress in the development of a PIE-PIT for the ITER Tokamak

The ITER Tokamak Postulated Initiating Event and Potential Impacts Table (ITER Tokamak PIE-PIT) is a matrix that shows the potential impacts on the ITER Tokamak Plant Confinement States from postulated initiating events. A ranking scheme has been applied to this Tokamak matrix in order to sort its 162 event sequences by severity and risk. The safety-related parameters or factors influencing the ranking have been the frequency of every PIE and its severity, the severity of the final Plant Confinement State and the reliability of confinement barriers and other safety-related systems. Results denote a strong presence at the top of the ranking of the sequences involving ingress of coolant (water and cryogenic coolant) as well as sequences involving failure of fuelling system components. Comparison with the bounding events sequences identified in other safety studies shows adequate coherence. The implementation of the PIE-PIT methodology for ITER allows ranking of accident sequences to cross-check other safety analyses and to give an overview from the probabilistic and deterministic points of view.