REGDOC-2.4.1 COMPLIANT LOSS OF FLOW TRIP COVERAGE ANALYSIS

Abstract

This paper describes the loss of flow trip coverage analysis which was performed as part of New Brunswick Power’s REGDOC-2.4.1 implementation plan. The loss of flow (LOF) initiating event is one of the limiting events in terms of the potential impact of aging on safety margins. Event identification and classification identified the loss of Class IV power and single pump trip initiating events as anticipated operational occurrences (AOOs). AOO LOF events were analyzed using industry developed guidance for the realistic operating envelope methodology, in conjunction with fuel and fuel channel fitness for service criteria. The LOF AOO events were also analyzed as design-basis accidents (DBAs) using industry guidance for the limit of operating envelope (LOE) methodology, in conjunction with fuel and fuel channel integrity criteria. The pump seizure initiating event was analyzed as DBA. The analysis covered operation to end-of-life and a wide range of power levels including full power. Adjusted operation following setback was also analyzed. Limit of modelling envelope analysis was performed to show that the methodology has sufficient conservatism to cover code accuracy.