Abstract
The useful life of a power plant is defined by business and economic factors. Degradation of major capital intensive systems/components that occur late in service life pose particularly difficult issues because their remaining amortization time may be insufficient to avoid a significant impact on the cost of electricity. Life cycle management (LCM) is a method of understanding and evaluating such options in order to arrive at optimum useful life of a unit.
LCM is a rational decision making process which integrates economic and technical data to develop, support, and assess the economic impact of those issues which affect plant service life. The LCM cost-benefit analysis process addresses indirect and direct costs and the technical and economic uncertainties associated with maintenance, replacement, and refurbishment. It remains a dynamic program over the life of the plant. The LCM process incorporates age-related degradation into deterministic or probabilistic evaluations. Sensitivity analyses are used to illustrate the impact of uncertainties. This process allows the most cost-effective action to be determined.
This paper describes the methods and presents two examples of an LCM evaluation of a service water system at a nuclear power plant which uses seawater as the cooling fluid. The full evaluation is presented in EPRI Report TR- 102204, April 1993. Cost-benefit analyses were developed by quantifying the age-related degradation for various lining and replacement materials, determining their probabilistic service life distributions, and developing repair/replacement alternatives. For each alternative, the maintenance requirements, life expectancy, and their associated costs were determined. The probabilistic approach and sensitivity analyses demonstrated the confidence in and the economic value of each alternative. To determine the effect of license renewal and to fully appreciate the value of the repair/replacement alternatives, the Present Value of Revenue Requirements (PVRR) costs were determined with and without a 20-year license renewal.
The component aging evaluations and cost-benefit analyses were integrated to produce a comprehensive Life Cycle Management Plan for the service water system. This plan is supportable and provides the basis for cost-effective recommendations for improved system performance as well as justification for operating the modified system for an additional 20-year license renewal period.
