LEVEL-1 PSA STUDIES FOR THE ASTRID REACTOR

摘要

In the framework of the French Act of the 28th of June 2006 about nuclear materials and waste management, ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration), a GENIV and actinides incineration demonstration prototype, is to be commissioned in the 2020 decade to demonstrate the progress made in SFR technology on an industrial scale by qualifying innovative options, especially relative to safety and operability. More specifically, we aim for a level of safety at least equivalent to the EPR's one (third generation), with progress made in SFR-specific fields. So, the integration of safety issues in the early phase of the design of ASTRID is necessarily expected. For this purpose, CEA and its partners AREVA and EDF perform a level-1 PSA to support the preliminary design of ASTRID reactor. This paper presents the PSA approach and current studies for the assessment of safety systems and the future work to be done for the 2013-2014 period. The preliminary preparation of PSA studies is presented : objectives and scope of the early design phase PSA, definition of core damage states, selection and grouping of initiating events, assessment of safety functions and related systems. Work under progress is also presented: modelling of event trees, construction of fault trees of safety systems, transient calculations of accident sequences with the CATHARE2 code and reliability data assessment. The main objectives of a level-1 PSA performed at the conceptual design stage are an early assessment of the safety architecture of the reactor and the most effective ways for improvement, but also the identification of dominant accident sequences and comparison with alternative designs. So, after the elaboration of a simplified level-1 PSA model for nominal state and main internal initiators, various alternative designs will be evaluated from the viewpoint of PSA in order to support the design choices for ASTRID.