AP913 reliability-based maintenance method for US nuclear power plants

This article, aimed at readers with a basic knowledge of industrial maintenance and nuclear power generation, presents the contents of the AP913 (Advanced Process 913) method developed by INPO (Institute of Nuclear Power Operations) for the maintenance of US nuclear power plants. INPO has published a recommendation guide entitled "Reliability Process Description AP913", which provides a framework for implementing an equipment reliability procedure to help US operators improve the safety and availability of their plants. The first section provides the origins of this approach and sets the context for the operation of nuclear power plants in the USA. As AP913 is specific to nuclear power plants, the operation of pressurized water and boiling water plants is briefly described. In this same section, and given that nuclear power generation involves risks, the elements essential to mastering the AP913 process will be recalled. They concern the regulatory bodies for the operation of US nuclear power plants, the safety and reliability of US pressurized-water nuclear power plant operation, the safety and safeguard systems of a nuclear power plant, the concept of defense-in-depth, probabilistic safety assessments (PSAs), the Maintenance Rule and the IAEA's INES scale. The second section outlines the six general steps required to carry out the asset management process for a nuclear power plant. It is the combination of all these steps that constitutes the AP913 process. Similar to Nowlan and Heap's MBF reliability-based maintenance method, developed in 1978, three steps concern the assessment and identification of critical components, the implementation of preventive maintenance and the continuous improvement of equipment reliability. Three additional steps ensure consistency for the overall asset management process: performance monitoring, corrective action, long-term planning and life-cycle management. This second section explains the content of the actions and questions to be asked, identified by their mark in the detailed AP913 flowchart. Following this procedure is essential if maintenance is to comply with AP913. The third section reports on the implementation of AP913 at several nuclear sites. The results show that increases in safety, reliability and availability have indeed been achieved. On the other hand, the volume of monitoring, preventive maintenance and replacement work is increasing very significantly. The fourth section takes as an example the volumetric and chemical control system (RCV) of a pressurized water power plant, which performs critical functions in normal and incidental operation. Maintenance tasks for a motor-operated valve are proposed, based on an AMEC maintenance and table framework and MBF-inspired selection logic.

The article concludes with a summary of the specific...