Snubber aging assessment

Snubbers are safety-related devices used to restrain undesirable dynamic loads at various piping and equipment locations in nuclear power plants (NPPs). Each snubber must accommodate a plant's normal thermal movements and be capable of restraining the maximum off-normal dynamic loads postulated for its specific location. The effects of snubber aging and the environments and mechanisms that degrade snubber performance need to be better understood. This paper describes the Phase II Nuclear Plant Aging Research Program in-plant aging research conducted to enhance the understanding of snubber aging and its consequences. Pacific Northwest Laboratory staff and their subcontractors, Lake Engineering and Wyle Laboratories, visited eight sites (encompassing thirteen plants) to conduct interviews with NPP staff and to collect snubber aging, testing, and maintenance data. The research methodology, evaluations, results, conclusions, and recommendations are described in the paper. Effective methods for service-life monitoring of snubbers are included in the recommendations.