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Vol.6 No.4previous AA 82-SP13 (83-84-85-86)-NT67-68

Academic Articles
Technical Note Vol.6No.4 (2015) p.107 - p.117
 

Main Factors for Fatigue Failure Probability of Pipes Subjected to Fluid Thermal Fluctuation

 
Hideo MACHIDA1, Masaaki SUZUKI2, Naoto KASAHARA2
 
1 TEPCO Systems Corporation, SHIBUSAWA CITY PLACE EITAI, 2-37-28 Eitai, Koto-ku, Tokyo 135-0034, Japan
2 The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
 
Abstract
It is very important to grasp failure probability and failure mode appropriately to carry out risk reduction measures of nuclear power plants. To clarify the important factors for failure probability and failure mode of pipes subjected to fluid thermal fluctuation, failure probability analyses were performed by changing the values of a stress range, stress ratio, stress components and threshold of stress intensity factor range. The important factors for the failure probability are range, stress ratio (mean stress condition) and threshold of stress intensity factor range. The important factor for the failure mode is a circumferential angle range of fluid thermal fluctuation. When a large fluid thermal fluctuation acts on the entire circumferential surface of the pipe, the probability of pipe breakage increases, calling for measures to prevent such a failure and reduce the risk to the plant. When the circumferential angle subjected to fluid thermal fluctuation is small, the failure mode of piping is leakage and the corrective maintenance might be applicable from the viewpoint of risk to the plant.
 
Keywords
Fracture Mechanics, Fatigue, Thermal Stress, Probabilistic Method, Crack Growth, Piping, Nuclear Power Plant
 
Full Paper: PDF EJAM Vol.6 No.4 pp.107-117 "Main Factors for Fatigue Failure Probability of Pipes Subjected to Fluid Thermal Fluctuation"















Article Information
Article history:
Received 30 July 2014
Accepted 26 January 2015