围板连接螺栓的辐照促进应力腐蚀裂纹研究

Study on Irradiation-Assisted Stress Corrosion Cracking of Baffle-Former Bolts

在压水堆(PWR)中,堆芯部件围板连接螺栓的材质是奥氏体不锈钢,长期处于强中子辐照区域。当辐照超过一定限值后,即使应力水平很低,但由于辐照过程中的缺陷、相转变、晶界偏析以及应力变化等原因,材料的塑性逐步丧失,辐照促进应力腐蚀裂纹(IASCC)随之发生。使用高纯度材料、控制水质和改进连接结构可以有效地减缓围板螺栓辐照促进应力腐蚀裂纹的产生。

Baffle-Former Bolts in PWR are made of austenitic stainless, locating in the area of strong Neutron irradiation for a long time. When Neutron irradiation exceeds the limit, even if the stress level is very low, the plasticity of the material will lose step by step because of the defects, phase transformation and grain boundary segregation, and then Irradiation-Assisted Stress Corrosion Cracking takes place. Techniques for mitigating IASCC is put forward： using high purity materials, quality control of water, and improvement of structure.