Developing Optimum Single Fuel Channel Replacement Procedures With Anticipatory Piping Stress Analysis

Abstract

The replacement of a fuel channel is a maintenance procedure that is mandated as part of the periodic fuel channel inspection requirements. To accomplish a Single Fuel Channel Replacement during a planned outage, positioning assembly hardware must be removed from the target fuel channel as well as adjacent fuel channels to provide adequate working space. In addition, feeder pipes must either be disconnected or displaced a minimum distance from the target fuel channel. Piping and component stress analysis is required to determine the consequences of removing hardware and the tolerable amount of deflection on specified components. The analysis determines the movement limits for feeders and end fittings to ensure that maintenance activities do not exceed component allowable stresses. By considering all potentially desirable combinations of maintenance configurations beforehand, optimum maintenance strategies can be devised by comparing the results of the stress analysis for specific configurations. This paper demonstrates the gains in efficiency that can be achieved during major reactor maintenance projects such as the Single Fuel Channel Replacement by adopting this collaborative approach.