Physical property changes of crystalline and non-crystalline SiO2 due to neutron irradiation and recovery by subsequent annealing

• Published in: Journal of nuclear materials 2007-08, Vol.367-370, p.730-735
• Main Authors: YANO, Toyohiko, FUKUDA, Kunio, IMAI, Masamitsu, MIYAZAKI, Hiroyuki
• Format: Article
• Language: English
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2007.03.090

Physical property changes of quartz and vitreous silica due to neutron irradiation and recovery by subsequent annealing were examined. Specimens were fast-neutron-irradiated up to a fluence of 3.0X1023n/m2 at 140 deg C, and 6.9X1023n/m2 at 300 deg C. Vitreous silica shrunk 0.8% in length after both irradiations. On annealing, the length started to increase above 200 and 500 deg C for the lower and higher fluence specimens, respectively, and gradually increased with increasing annealing temperature. Quartz expanded in an anisotropic manner, with larger expansion along the a-axis as compared to the c-axis, due to the irradiation. Length and lattice parameter of quartz started to reduce for annealing over 300-500 deg C, and were almost fully recovered at 800 deg C in the lower fluence case, and 1000 deg C in the higher fluence case. Thermal diffusivity reduced 10% in vitreous silica and 60-70% in quartz by the irradiation. Recovery of thermal diffusivity of vitreous silica and quartz by annealing resembled the corresponding length change.