Reliability Study On The Lawrence Livermore National Laboratory Water-supply System

Abstract

We conducted a reliability analysis of the Mocho water-supply system for the Lawrence Livermore National Laboratory (LLNL) to determine if an adequate supply of water would be available in the event of a major fire. We used the digraph fault-tree approach for logic model generation. The initiating-enabling event interval reliability approach was used for a probabilistic evaluation of the Mocho system fault tree. In the event of a major fire, the Mocho system demand unavailability was calculated to be 3.6 x 10-4• We identified 16 single-component failures that would cause failure of the control loop wh ich monitors storage-tank level. These failures would go undetected by monitoring personnel at LLNL. Our recom mended changes would provide a redundant measurement of the tank level, resulting in a decrease of the predicted system unavailability by about a factor of 50.