Effects of Alpha Decay on the Properties of Actual Nuclear Waste Glass
- PDF / 2,004,745 Bytes
- 8 Pages / 414.72 x 648 pts Page_size
- 47 Downloads / 178 Views
EFFECTS OF ALPHA DECAY ON THE PROPERTIES OF ACTUAL NUCLEAR WASTE GLASS
T. BANBA*, S. MATSUMOTO*, S. MURAOKA*, K. YAMADA**, M. SAITO**, H. ISHIKAWA**, AND N. SASAKI** *Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-11, Japan "**Power Reactor and Nuclear Fuel Development Corporation, Tokai, Ibaraki 319-11, Japan ABSTRACT An 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 24 4 CmO2 was melted 244 at 1200'C for 2 hrs. The radioactivity concentration of Cm was 1.0 x 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 x 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 x 101 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. INTRODUCTION
A variety of different types of radiation can affect chemical and physical properties of glasses. Nuclear waste glasses represent a system in which many different types of radiation can coexist. The radiation effects involved result from the emission of alpha and beta particles, gamma rays and neutrons from the decaying radionuclides. Most of the effects involving atomic displacements are induced by passage of these particles through the glass. It is generally assumed that the primary source for radiation damage in nuclear waste glasses is from displacement. According to Weber and Roberts, alpha decay produces several orders of magnitude more displacements than any other radiation source [1]. Therefore, most of the studies on radiation effects in waste forms have emphasized alpha-decay effects. The shortlived actinide-doping technique using simulated high-level waste glasses has been most frequently employed for this purpose. A lot of available data on alpha-decay effects in simulated waste glasses have been obtained from these previous studies [e.g. 1,2]. However, there are few data on alpha-d
Data Loading...
