PROBABILISTIC ASSESSMENT OF THE FRACTURE-MECHANICS BEHAVIOR OF AN HTR-MODULE PRIMARY CIRCUIT PRESSURE BOUNDARY

In this paper the fracture mechanical behaviour of the primary circuit pressure boundary of a planned HTR-module reactor for electricity and steam generation under normal operation is assessed probabilistically . First and second order reliability methods (FORM-SORM) are used to c alculate failure probabilities. They also allow a simplified analysis of the leak-before-break (LBB) behaviour. No LBB was probabilistically identified for the reactor pressure vessel. However, failure of the p ressure vessel unit in normal operation probably originates from the c onnecting pressure vessel or the steam generator pressure vessel. They show LBB in probabilistic terms.