EPRI is benchmarking practices at European plants to identify successful on-line maintenance strategies that could be useful when applying on-line maintenance on a smaller scale than in the United States.

U.S. nuclear power plants routinely apply on-line maintenance to improve plant reliability, safety and economic performance (see EPRI report 1018422). Recognizing these achievements, a number of non-U.S. nuclear utilities are exploring the expanded use of on-line maintenance in their plants.

While U.S. plant practices and organizations are structured to support a large amount of maintenance on-line (about 70%), such large-scale adoption may not be optimum in all cases. EPRI is benchmarking on-line maintenance approaches at non-U.S. plants to identify and characterize mature alternative approaches that may be more appropriate on a smaller scale.

Trillo Nuclear Power Plant

EPRI identified three possible candidate plants for benchmarking: the Cofrentes boiling water reactor plant in Spain, the Trillo pressurized water reactor plant in Spain, and the Leibstadt boiling water reactor plant in Switzerland. The benchmarking has a broad scope: extent of on-line maintenance applied, organization and staffing, work scheduling and planning approaches, regulatory considerations and configuration risk methods, and maintenance practices. The benchmarking is conducted through a combination of written questions and on-site interviews with plant personnel.

Benchmarking interviews have been completed at Cofrentes and Trillo. Information gathered from these interviews confirms that the on-line maintenance approaches at these plants differs from those in the United States. For example, the Cofrentes on-line maintenance program, in place since 1997, addresses about nine systems/divisions per year (about 18 systems/divisions per 24-month fuel cycle). Most U.S. plants conduct some on-line maintenance on all plant systems that can be safely taken out of service while the plant is on-line without impacting power production. The Cofrentes on-line maintenance system scope deliberately targets low configuration risk and high feasibility activities.

	Cofrentes Nuclear Power Plant

Trillo’s program, in place since 2000, consists of ongoing on-line maintenance of non-safety and safety-related equipment, and focused on-line maintenance of safety system trains with significant design-based redundancies organized in a one-year scheduling cycle. The ongoing on-line maintenance of safety-related items includes largely non-intrusive tasks like surveillances and calibrations. Because Trillo’s front-line safety systems have four redundant trains, more intrusive on-line maintenance of major components in these systems is conducted in two annual on-line outages of an individual train.

Because the on-line maintenance processes at Cofrentes and Trillo incorporate voluntary risk management elements and the overall on-line maintenance program approach and content has been standardized and stable, the need for situation-dependent decisions is reduced and a very predictable, efficient approach has been achieved in both plants. This is reflected in the relatively low staffing required at both plants to support on-line maintenance scheduling, planning and coordination.

The information gathered from the on-line maintenance plant benchmarking will be published in an EPRI report and is expected to be of high interest to plants initiating use or expanding use of on-line maintenance. For more information, contact Ken Huffman at 704.595.2555 or khuffman@epri.com.