Snubber reduction for enhanced plant reliability

Nuclear power plants coming on line since the late 1970s tend to have a large number of snubbers and struts on piping systems to provide protection against seismic and other dynamic loads. Considerable effort has been expended by industry to reexamine ASME code requirements, regulatory standards, and design practices for piping to identify those items that could lead to the identification and removal of unnecessary snubbers. This paper provides a summary of three related efforts in snubber reduction. The first study consisted of a pilot program of snubber reduction of three typical lines from a recently operating boiling water reactor (BWR) plant. The second effort consisted of developing and obtaining approval for a licensing application that identifies methods and criteria to be used for a snubber reduction evaluation of an operating plant. The third effort consisted of developing generic industry guidelines for snubber reduction of operating power plants. This work has also identified recommendations for industry activities to justify code and regulatory changes that will allow snubber removal beyond the guidelines presented