On the Use of Multi-Attribute Utility Theory to Quantify the Desirability of Hydraulic Control Unit Maintenance of a Boiling Water Reactor

Report Date: August 2002
Appendices: No

Abstract

The role of maintenance in a nuclear power plant is to ensure that plant equipment is kept at a proper level of functionality, thus increasing the level of overall plant safety. In a deregulated electricity market, nuclear power plants must remain competitive with conventional utilities in the production of electricity. Consequently, nuclear utilities must find ways to improve their operations and reduce costs without sacrificing the level of overall plant safety and relationships with its stakeholders. One area of operations in which nuclear utilities can gain a competitive edge is in the maintenance of its power plants. By reducing the frequency of preventive maintenance and shifting the performance of selected maintenance items on-line, the utilities are able to reduce costs without significant impact to plant safety and relations to stakeholders.

This study focuses on the maintenance of hydraulic control units (HCUs) in Tokyo Electric Power Company’s (TEPCO) boiling water reactors (BWRs). Using Multi-Attribute Utility Theory (MAUT), TEPCO decision makers can obtain a rank-ordering of multiple decision options based on their current preferences toward safety, cost, and stakeholder relations. In the case of HCU maintenance, the decision options considered are performance of HCU maintenance in the following conditions: 1) on-line with outage duration unchanged, 2) off-line with outage duration unchanged, 3) on-line with outage duration shortened, and 4) off-line with outage duration shortened. Because these options could have varying effects on safety, cost, and stakeholder relations, the use of MAUT facilitates decision making by providing a methodology that considers the effect of multiple factors simultaneously.

The literature search produced some useful information with regard to the maintenance practices of utilities from different countries, leading to a better understanding of maintenance philosophy, regulation, and routine in Japan. In addition, the search provided a wealth of information on the HCU maintenance practices of US utilities and the predominant failure modes observed in the system.

Through the use of performance indices, the desirability of each maintenance option can be quantified. The results of the study indicate that the best option is to perform on-line maintenance of the HCUs under the condition of a shorter outage. This option yielded the lowest overall performance index, indicating the lowest expected “disutility” among the other decision options.

Program:     NSP Nuclear Systems Enhanced Performance

Type:     TR 

RPT. No.: 12