Collection and analysis of component failure data from JET systems: neutral beam injectors and power supply

Objective of the on going activity is to develop a fusion specific component failure database with data coming from operating experiences gained in various fusion laboratories. The activity started since 2001 with the study of the Joint European Torus (JET) Vacuum (VS) and Active Gas Handling Systems (AGHS). Two years later the Neutral Beam Injectors (NBI) and Power Supply (PS) systems were considered and, in this last year the Ion Cyclotron Resonant Heating (ICRH) system is under evaluation. Number of failures/malfunctions occurred in the years of operations, failure modes and, where possible, causes and consequences of the failures, were identified, as well as whole sets of components which the anomalies are related to. Components were classified and counted in order to find out amount of similar components, related total operating hours and related demands to operate (for components operating in intermittent way). Main reliability parameters (such as failure rate and corresponding standard errors and confidence intervals) associated to the components were estimated too. In this paper results obtained for the NBI and PS are presented in detail, as well as an overview of the activity