System study application to the safety analysis of the exhaust and tritium systems of a fusion reactor

Abstract

Abstract A general methodology system study developed in order to analyze new facilities is firstly applied to the safety analysis of a fusion reactor. After defining successively the missions and functions, it has been possible to identify the systems which are able to fulfil these functions. Two systems were studied first, as examples: the exhaust and the tritium systems. These systems are divided into subsystems, units, down to single components. Thus, it is now possible to identify the interactions and interfaces, both inside and between the tritium and exhaust systems. Finally, this methodology allows are to perform a reliable and exhaustive safety analysis. For both the analyzed systems, the framework of the study is split into the following tasks: initial information collection, functional analysis, failure scenarios identification and description, reliability data assessment, accident sequence quantification, consequence seriousness evaluation, and risk assessment. The consequence seriousness is split into ‘consequence categories’ and for each of these the occurrence probabilities are evaluated by summing the corresponding ones carried out by event trees. This makes it possible to determine the risk by category of consequences. Results concerning risk contribution from direct failures are presented and compared with design safety targets for public and workers.