Effects of Alpha Decay on the Properties of Actual Nuclear Waste Glass

Abstract

AbstractAn accelerated experiment using the actinide doping technique was performed to investigate the effects of alpha decay on the properties of actual nuclear waste glass at high radiation doses. A fully radioactive borosilicate waste glass, containing the actual high-level radioactive liquid waste generated from the Tokai Reprocessing Plant of PNC, was prepared by JAERI, and a powder mixture of the ground fully radioactive glass and 244CmO2 was melted at 1200°C for 2 hrs. The radioactivity concentration of 244Cm was 1.0 } 1010 Bq/g-glass at the date of preparation. The homogeneity of curium-doped glass samples was confirmed by the density measurement, heat load measurement and alpha autoradiography. The properties of the irradiated samples were investigated by the mass spectrometer for helium determination, the optical microscope, the electron probe microanalyzer, the densitometer, the Soxhlet and MCC-1 leach testing apparatus. By measuring the amount of helium released from the curium-doped glass samples, more than 99% of helium remained in the matrix at room temperature. The density of the sample slightly decreased with the increase of cumulative alpha decays and the decrease of 0.77% was observed at a dose of 1.55 } 1018 alpha decays/g, corresponding to an equivalent age of 150000 yrs. Optical and scanning electron micrographs showed that no cracks were observed on all samples having up to a dose of 1.5 } 1018 alpha decays/g. The leach rates, based on weight loss, in both the Soxhlet (100°C, 7 days) and MCC-1 (90°C, 28 days) tests did not significantly change with alpha decay dose.