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Recent emphasis on increasing the availability of nuclear emergency diesel generators (EDG's) has motivated the industry to re-evaluate the maintenance philosophies utilized for these units. Improving availability, while maintaining or enhancing the existing levels of reliability, has become the challenge to nuclear utilities. In order to meet quantified reliability and availability objectives, a renewed approach to maintenance is required. The direction taken includes the initiation of a diagnostic data monitoring and trending program to assess those parameters where such methods have proven to be effective. In addition, prescribed inspections based on historical findings are recommended where needed. Periodic reviews are proposed to provide further program improvement.

The advent of the microprocessor has revolutionized technology worldwide with digital (microprocessor based) systems found throughout industry. While digital systems have been used in nuclear safety-related applications, uniform methodology has not been followed, precipitating regulatory guidance. While acknowledging the advantages of digital technology, the U.S. Nuclear Regulatory Commission (NRC) has noted that potential failure modes not previously considered are introduced with its application. Adapting traditional supply methodology is necessary to address design and quality assurance issues related to the common mode failure potential of computer software and electromagnetic interference. A participatory approach is described to apply a digital speed governing system to nuclear emergency diesel generators. This governing system is a proposed replacement for existing mechanical and analog electronic governing technology.

Culminating several years of disciplined effort, this paper describes the engineering program preceding the introduction of the Transamerica Delaval R5 diesel engine to the marketplace. This engine enters the large-bore medium-speed class rated at 634 kW/cylinder (19.0 bar bmep at 514 rpm). Careful design, followed by an aggressive test strategy has produced an engine of sound integrity. Mechanical endurance testing was followed by a thorough inspection of all major components, revealing excellent wear rates. This paper includes basic engine design, residual fuel testing, emissions and performance information.