STUDY ON LBB BEHAVIOR OF NUCLEAR PRIMARY PIPES AFTER LONG-TERM THERMAL AGING

摘要：

　　The leak-before-break(LBB)analysis is a high level safety assessment method for pressurized vessels and pipes containing defects.The key technology of LBB safety assessment is the crack stability analysis and the determination of critical crack length.In this paper,on the basis of experimental data of a pipe material,the evolution of the fracture toughness after long-term thermal aging at 280 and 330 ℃ were estimated using the Argonne National Laboratory(ANL)procedure.Three-dimensional finite element analysis models were built to make elastic-plastic fracture mechanics analysis for the postulated circumferential through-wall cracks with different sizes in the nuclear primary pipe.According to the J-integral tearing modulus(J-T)method,the critical crack length were obtained and LBB curves of circumferential through-wall cracked pipes were constructed.Effects of the fracture toughness and operating temperature of nuclear primary pipe on critical crack length and LBB curves were also investigated.The results show that the pipe material is sensitive to thermal aging embrittlement during long-term service,which results in the critical crack length and LBB curve significantly decreasing due to degradation of fracture toughness.The non-conservative(unsafe)results will be produced if LBB analysis does not take into account of the effect of thermal aging.Compared to the results at 280 and 330 ℃,the pipes suffer more serious thermal aging embrittlement and the degree of non-conservative in LBB analysis become larger when operating at a higher temperature.

关键词： Thermal aging Fracture toughness Critical crack length Leak-before-break curve

作者: Xuming Lv Shilei Li Hailong Zhang Yanli Wang Fei Xue Xitao Wang

作者单位: State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing, State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing, Suzhou Nuclear Power Research Institute,Suzhou 215004,China

会议类型: 国际会议

会议名称: Energy Materials 2014(第一届能源材料国际会议)

会议地点: 西安

会议语种:英文

页码: 501-508

在线出版日期: 2014-11-04（万方平台首次上网日期，不代表论文的发表时间）