Developments of analyses on grid-to-rod fretting problems in pressurized water reactors

This paper briefly summaries the recent developments of grid-to-rod fretting (GTRF) wear analyses, as well as the remaining challenges. Attention is given to the aspects of spring/dimple geometry design, fretting wear, turbulent flow, vibrations and material behaviors such as creep, swelling and corrosion. These factors are closely related to the loss of spring force and the wear damage of fuel claddings. Due to enormous number of publications for each factor, this brief review is not intended to be completely comprehensive. The goal is to understand how these factors affect the GTRF problem and give a big picture of it. Significant progress has been made in understanding each individual factor, which provided guidelines to the design of next generation fuel plant. However, state of art uncertainty analyses are needed to evaluate their contributions under the in-reactor conditions. Analyses to couple those factors together are challenging yet necessary to completely understand and eliminate the GTRF induced fuel failures.