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Surge-line thermal stratification: Displacements and fatigue damage computations

Conference · · Transactions of the American Nuclear Society; (USA)
OSTI ID:5229503

Slow, unexpected displacements have been experienced in most pressurized water reactor (PWR) surge lines. Sometimes, these displacement lead to gap closure at the pipe whip restraints. These movements occur because of thermal stratification. This movement has the potential to increase stresses to valves, which may exceed the material yield stress. To understand this phenomenon, Framatome, Commissariat a l'Energie Atomique, and Electricite de France have undertaken large programs for the study of (1) thermal-hydraulic tests with a half-scale Plexiglas surge line, (2) thermal-hydraulic computations of permanent states and transients with a two-dimensional model, and (3) mechanical analysis of displacements and computation of fatigue damage due to stratification. This paper deals with the last subject. Avoiding stratification in piping by process modifications is difficult because of the high flow rate needed. Alternative solutions for coping with stratification effects are discussed.

OSTI ID:
5229503
Report Number(s):
CONF-890604--
Journal Information:
Transactions of the American Nuclear Society; (USA), Journal Name: Transactions of the American Nuclear Society; (USA) Vol. 59; ISSN TANSA; ISSN 0003-018X
Country of Publication:
United States
Language:
English