The Role of Testing Programs in Verifying Structural Integrity of Medium Speed Diesel Generator Components

The reliability of emergency diesel generators is of prime concern to the nuclear power industry. Assurance that these components will perform their intended functions has usually been approached by requiring frequent, and occasionally abusive, testing. The testing procedure is suspected to result in some life reduction to the equipment. A current program addresses the evaluation of structural integrity of diesel generator components through a combination of engine pre- and postoperational testing, design analysis, nondestructive examination, and monitoring to maximize reliability with minimum wear of the engine. This program employs engineering analysis to understand previous problems, to predict future performance of critical components, and to define areas of focus for NDE or monitoring. The analysis also provides conservative in-service inspection intervals and a quantitative basis to extend or eliminate NDE requirements. Engine testing and inspection provide verification of this analysis and at the same time refine the accuracy of the predictions. This paper describes applying this combined analytical and testing-approach to major diesel engine components such as crankshafts, connecting rod bearing shells, and pistons.