Dynamic analysis of the process water system at the Savannah River Site

This paper describes the seismic analysis of the primary system of a reactor (called the process water system) at the Savannah River Site. This analysis was performed because the previous analysis was judged to contain inaccuracies that could affect conclusions regarding the adequacy of the system. In this analysis, modelling accuracy was improved in the following areas: inclusion of connecting heat exchangers and their supports, inclusion of additional piping connected to the heat exchangers, and consideration of actual support stiffnesses. This piping system contains design and construction details that, while found on commercial nuclear plants, are not common practice. These details include welding supports to elbows, very flexible connecting equipment, supports that were not properly designed to accommodate thermal expansion, and nonlinear supports that restrain the pipe in only one direction. Analysis approaches to these details are described