Aging mitigation and improved programs for nuclear service diesel generators

Recent NRC sponsored aging research work on nuclear service diesel generators has resulted in a recommendation that an improved engine management program should be adopted for aging mitigation and reliability improvement. The center of attention should be to ensure diesel-generator operational readiness. This report emphasizes a ''healthy engine concept'' and recommends parameters to be monitored to determine engine condition. The proposed program and approach recommended in this report represent balanced management where diesel generator testing, inspections, monitoring, trending, training, and maintenance all have appropriate importance. Fast-starting and fast-loading test of nuclear service diesels causes very rapid wear of certain engine components. This report documents this aging and wear mechanism and recommends ways to largely eliminate this unique aging stressor. Current periodic intrusive maintenance and engine overhaul practice have been found to be less favorable for safety assurance than engine overhauls based on monitoring and trending results or on a need to correct specific engine defects. This report recommends that the periodic overhaul requirements be re-evaluated. Diesel generator research on aging and wear is sponsored by the US Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research. The research reported in this report was conducted by Pacific Northwest Laboratory (PNL), which is operated for the Department of Energy by Battelle Memorial Institute. 23 refs., 3 figs., 8 tabs