Studies of transuranic waste storage under conditions expected in the Waste Isolation Pilot Plant (WIPP). Progress report, December 15, 1978--March 15, 1979

Abstract

Thermal decomposition of waste matrices currently appears to be less important than previously reported. Low dose-rate experiments (4 x 10/sup 5/ nCi/g) are generating some gas, but not enough to permit quantification of the gas evolution rates. Some catalyzed thermal degradation may be occurring for polyethylene and cellulosics. The low-temperature and the low dose-rate experiments require additional prolonged exposure time because their gas evolution rates are so low. These experiments simulate most closely the conditions that real wastes would experience. WIPP lithostatic pressure (1.5 x 10/sup 4/ kPa) on the solid waste is estimated to generate gas at 10 to 300% of the rate of similar but nonpressurized experiments. Experiments that are prepressurized to 1 x 10/sup 4/ kPa deuterium show a decrease of 50 to 60% in the rate of hydrogen evolution. Self-pressurization up to 830 kPa by radiolytically evolved gases does not change the rate of additional gas production. Current data appear to indicate that radiolytic gas evolution rates may be dose-rate dependent. The rates of gas evolution by radiolysis are temperature dependent, but the magnitude of the effect diminishes with time. G(gas) for polyvinyl chloride is tentatively estimated to be 8 to 11 gas molecules per 100more » eV. Thermogravimetric analyses of bitumen in air and nitrogen are reported. Additionally, the assessment and detailed characterization of the LASL TRU waste inventory has been completed and final data are presented. 6 figures, 9 tables.« less