Since at least a decade, a lot of efforts have been devoted to the design and the evaluation of effectiveness of Passive Safety Systems, within the design strategy for both advanced and innovative reactors. However, main activities have dealt with thermalhydraulic and mechanical aspects of the design. Moreover, as far as the reliability related to the passive safety systems is concerned, the largest amount of work has been employed for the development of methods and tools for the sensitivity and uncertainty analysis, mainly on the models and the codes adopted for the safety assessment. Scope of this research, carried out by ENEA in collaboration with University of Pisa and Polytechnic of Milano since 1999, is the identification of a methodology allowing the evaluation of the reliability of passive systems as a whole, in a more physical and phenomenal way. The paper describe the study, named REPAS (Reliability Evaluation of PAssive Safety systems) carried out by the partners and finalised to the development and validation of such a procedure. The main sources of physical failure are identified and a probability of occurrence is assigned. The reliability analysis is performed on a passive system which operates in two-phase, natural circulation. The selected system is a loop including a heat source and a heat sink where the condensation occurs. The system behaviour under different configurations has been simulated via best-estimate code (Relap5 mod3.2). The results are shown and can be treated in such a way to give qualitative and quantitative information on the system reliability. Main routes of development of the methodology are also depicted.
|Titolo:||The REPAS Study: Reliability Evaluation of Passive Safety Systems|
|Data di pubblicazione:||14-apr-2002|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|