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核压力容器是压水堆核电站的关键设备,其所用钢材经受严重的中子辐照作用后会引起脆化,因此核压力容器用钢的韧性和脆性断裂抗力是反应堆安全运行的重要考核依据。因为核压力容器钢的K_(IC)比K_(Id)和K_(Ia)都大,考虑到压力容器受到动载荷和材料性能恶化等因素而萌生裂纹,所以设计上采用K_(IC)、K_(Id)和K_(Ia)中的最低点作为设计韧性指标,即用ASME附录G中的参考断裂韧性K_(IR)与T—RT_(NDT)曲线作为防止脆断依据,此曲线是A533.B1、A508.2和A508.3三种钢的K_(IC)、K_(Id)和K_(Ia)与温度关系的下包络线。由此可知,核压力容器钢的动态断裂韧性是反应堆安全设计和寿命评定、事故分析的关键数据之一。
Nuclear pressure vessel is the key equipment of PWR nuclear power plant. The steel used for it will cause embrittlement after being subjected to severe neutron irradiation. Therefore, the toughness and brittle fracture resistance of steel for pressure vessel are the important basis for the safe operation of the reactor. Because K_ (IC) of nuclear pressure vessel steel is larger than K_ (Id) and K_ (Ia), considering crack initiation caused by dynamic load and deterioration of material properties, K_ (IC) and K_ (Id) and K_ (Ia) as the design toughness index, that is, the reference fracture toughness K_ (IR) and T-RT_ (NDT) curve in Appendix G of ASME are taken as the basis for preventing brittle fracture. B1, A508.2 and A508.3 K_ (IC), K_ (Id) and K_ (Ia) and the temperature of the lower envelope. It can be seen that the dynamic fracture toughness of nuclear pressure vessel steel is one of the key data of reactor safety design, life assessment and accident analysis.