中子与γ射线辐照对B4C/环氧树脂屏蔽材料性能的影响

Neutron and gamma irradiation effects on properties of a B_(4)C/epoxy resin shielding material

中子与γ射线辐照对屏蔽材料性能的影响直接关系到了核设施的运行安全性。本研究以B4C/环氧树脂屏蔽材料作为研究对象,对比了在1 MGyγ射线及叠加1.19×10^(15)cm^(−2)中子辐照两种辐照环境下屏蔽材料力学性能、断口组织形貌、特征化学产物及热稳定性能的变化规律。结果表明:持续约11.6 d的γ射线辐照及叠加持续约3 h的中子辐照后屏蔽材料力学性能持续降低,但均未降低到辐照前的50%以下,屏蔽材料在此条件下产生了辐照降解,但未发生失效。与单独的γ射线辐照相比,叠加中子辐照后屏蔽材料1H-NMR图谱δ=7附近峰的强度没有明显变化,说明未继续发生苯环上C‒H键的断裂。屏蔽材料热失重50%质量损失温度T_(50%)由辐照前的526.3℃降低到了γ射线辐照后的453.2℃及γ射线叠加中子辐照后的463.9℃,屏蔽材料辐照后热稳定性降低。

The effects of neutron and gamma radiation on shielding materials directly influence the safety of nuclear facilities.In this study,a B4C/epoxy resin shielding material was fabricated.The mechanical properties,fracture microstructural morphology,characteristic groups,and thermal degradation of the shielding material under two different irradiation conditions,1 MGy gamma and superimposed 1.19×10^(15)cm^(−2)neutron radiation,were compared.After gamma irradiation for 11.6 d and superimposed neutron irradiation for 3 h,the mechanical properties of the shielding material continued to decrease;however,they did not decrease to 50%of those before irradiation,and radiation degradation occurred instead of material failure.Compared with separate gamma irradiation,the peak intensity in the 1H-NMR spectra of the shielding material nearδ=7 did not change significantly after the additional neutron irradiation,indicating that there was no further degradation of the C‒H bond on the benzene ring.At 50% loss in mass,the temperature decreased from 526.3℃ before irradiation to 453.2℃ after gamma irradiation and 463.9°C after gamma superimposed neutron irradiation,demonstrating the decrease in thermal stability.