EVOLVED GAS ANALYSIS FOR HIGH-ALUMINA HIGH LEVEL WASTE FEED

摘要

The melting rate of high-level waste (HLW) glass strongly affects the vitrification process and the efficiency of immobilization of nuclear waste. A key factor influencing the melting rate is the conversion of the dry melter feed to glass within the batch blanket or "cold cap," a layer of melter feed floating on a pool of molten glass in an electrical glass-melting furnace. Such conversion involves numerous reactions, which typically generate gases. Using thermogravimetry coupled with gas chromatography-mass spectrometry, we performed analyses of multiple gas-evolving reactions and evolving gases (H_2O, CO_2, NO and O_2). We further developed a simple model, via the least squares method, which correlates the overall mass loss rate to the gas evolution rates of each gas with constant fitting coefficients. The agreement with the measured mass loss rate is nearly perfect. The fitting coefficients can be used to determine the amount of mass loss equivalent to each evolving gas.