核电站用三元乙丙橡胶辐照老化研究

Study on Irradiation Aging of EPDM for Nuclear Power Plants

针对核电站核安全壳内1E级电气连接器的高辐照工况,研究核电站用三元乙丙橡胶(EPDM)在受到高辐照剂量辐照后物理性能和电气性能的变化,分析其辐照损伤机理,建立其辐照老化数学模型,以预测其耐辐照老化性能。结果表明:随着辐照剂量的增大,EPDM硬度略增大,硬化程度小于10%;拉伸强度略有降低,拉伸强度下降率不超过20%;拉断伸长率明显下降,当累积辐照剂量达到1.1 MGy时,拉断伸长率降低近60%,根据阿累尼乌斯公式推导出EPDM拉断伸长率自然对数值与累积辐照剂量线性相关;未压缩EPDM试样经辐照后压缩永久变形率减小,辐照对提高EPDM抗压缩变形性能有一定作用;随着辐照剂量的增大,EPDM介电强度明显提高,体积电阻率增大,表面电阻率变化不大,辐照对EPDM电气绝缘性能有一定的改善作用。

Based on the high irradiation service condition of 1 E grade electrical connector in containment of nuclear power plant,the physical and electrical properties of EPDM for nuclear power plants after heavy irradiation were studied,the mechanism of irradiation damage was analyzed,and the mathematical model of irradiation aging of EPDM was established to predict its irradiation aging resistance.The results showed that,with the increase of irradiation dose,the hardness of EPDM increased slightly and the hardening degree was less than 10%,the tensile strength decreased and the rate of decline did not exceed 20%,and the elongation at break decreased significantly.When the cumulative total irradiation dose reached 1.1 MGy,the elongation at break decreased by nearly 60%.According to Arenius formula,it was deduced that the logarithm of the elongation at break of EPDM was linearly correlated with the cumulative total irradiation dose.The compression permanent deformation rate of uncompressed EPDM sample decreased after irradiation,indicating that irradiation had a certain effect on improving the compression deformation resistance of EPDM.With the increase of irradiation dose,the dielectric strength of EPDM increased obviously,the volume resistivity increased,and the surface resistivity changed little,indicating that irradiation could improve the electrical insulation performance of EPDM to a certain extent.