LEACH TESTING OF SIMULATED HANFORD WASTE VITRIFICATION PLANT REFERENCE GLASS, HW-39

The Hanford Waste Vitrification Plant (HWVP) has conducted leach testing up to one year in duration on a former HWVP reference glass (HW-39-2) using the MCC-1 and MCC-3 leach test methods. Glass surface area to leachate volume (SA/V) ratios of 10, 530,2000, and 20,000 m-1 were investigated. Elemental concentrations in the leachates increased with increasing SA/V ratios at comparable (SA/V)*t values. The (S A/V)-t scaling method provides an estimate of long-term concentration conditions that will occur as a result of the glass dissolution. However, the concentration conditions at given (SA/V)*t values obtained using higher SA/V values do not correlate well with those obtained using the low SA/V values. Thus, the (S A/V)-t scaling technique appears to be adequate to provide a general indication of the dissolution characteristics of HW-39-2 glass up to an SA/V 2000 m-1 but fails when the SA/V value is increased to 20,000 m-1. Results from previous testing with a modified MCC-3 leach testing technique were similar to the results generated from the MCC-1 and MCC-3 techniques used in this study. The modified MCC-3 test is a partial leachant replacement MCC-3 leach test in which leachate samples are removed at different time intervals, and the leachant lost through sampling is replaced. The modified MCC-3 test method generated data very similar to that generated by the standard MCC-1 and MCC-3 techniques.