Investigation of the Character of Stored-Energy Release from Graphite Irradiated at High Temperature

Abstract

The results of an investigation of the stored energy in GR-280 graphite irradiated at 560°C to neutron fluence ~3·1026 m–2 are presented. The measurements were performed by means of differential scanning calorimetry with constant heating rate 20°C/min. The release of the stored energy reaches a maximum at annealing temperature 1100°C. The maximum output is equal to 0.34–0.48 J/(g·°C). The total stored energy released in the annealing temperature range 560–1300°C does not exceed 183 J/g. A kinetic analysis of the spectrum of the stored energy was performed. This analysis established that increasing the radiation temperature from 450 to 560°C results in almost complete vanishing of individual vacancies, redistribution of the migration of di-vacancies, and evolution of a cluster structure upon post-radiation annealing in the range 560–1300°C in the direction of processes with lower activation energy.