SPRR-300研究堆随堆辐照石墨的中子辐照效应

Neutron irradiation effects of graphite serving in SPRR-300 reactor

随SPRR-300研究堆约30 a的长时间运行,位于活性区附近的石墨箱体经历了长期的中子辐照。在长期服役的石墨箱体上取样,研究了其热学、力学以及微观结构变化,并与商用IG110,NG-CT-10石墨进行了对比。研究结果表明,经长时间低剂量率的中子辐照后,SPRR-300堆内随堆辐照石墨的晶格中出现了明显的辐照损伤缺陷,这些缺陷主要为位错环、层错、孔洞和微裂纹等,并出现了一定程度的非晶化。这些辐照损伤缺陷直接或间接地引起了石墨热学、力学性能的变化,主要表现为热膨胀系数、热扩散系数、抗压强度和抗弯强度的下降以及弯曲弹性模量的上升。

During the long period service in the SPRR-300 research reactor, the graphite box in the vicinity of the core has been irradiated for about 30 years. In this paper, we take samples from the graphite box and investigate the changes of the thermal, mechanical properties and microstructure, compare them with those of the commercial IG110and NG-CT-10 graphite. We find that after the long-time service, the low fluence neutron irradiation has induced tremendous irradiation damage defects in the crystal structures of the SPRR-300 graphite. These defects are mainly dislocation loops, stacking faults, voids, microcracks, et al. A degree of amorphization has also been observed.Comparing with those of the IG110 and NG-CT-10 graphite, the coefficients of thermal expansion, thermal diffusivity,compression strength and the flexural strength of the SPRR-300 graphite decrease while the modulus of elasticity in flexure increase. The changes of the thermal and mechanical properties of the SPRR-300 graphite may due to the irradiation-induced defects.