Comparison and Evaluation of Analytical Structural Solutions With EPRI Safety Valve Test Results

Abstract

All operating plant licensees and applicants are required to verify the acceptability of plant specific pressurizer safety valve piping systems for valve operation transients by testing per NUREG-0737 (issued November, 1980) and all subsequent U.S. NRC generic follow-up letters. Of particular concern was the operability of the safety valves and the acceptability of the downstream piping when subjected to the dynamic thermal hydraulic loadings associated with these transients. To aid in this verification process the Electric Power Research Institute (EPRI) conducted an extensive program testing different safety valves subjected to varying operating conditions. Downstream piping loads associated with the various loading cases were also measured. This paper presents and compares analytically determined solutions for the structural response of the test configuration to actual test results. A brief description of the methods used to generate the thermal hydraulic loads is presented but the major emphasis is on the piping dynamic response. Discussed are the piping and support modeling techniques, the dynamic solution methods and the load application methods employed. Analytically calculated piping stresses, support loads, displacements, and valve nozzle loads are compared to the test results.