Submitted for Publication in the Ceramic Transactions for the Symposium on Waste Management Science and Technology in the Ceramic and Nuclear Industeies (Paper B5-048-00)

摘要

Vitrified high-level waste (HLW), poured into stainless steel (SS) canisters, will be packed into a double-barrier waste package (WP) consisting of Ni-base alloy and SS. The internal WP environment, causing corrosion of the vitrified waste form, may enrich with iron compounds from WP and pour canister corrosion. In this study, the modified product consistency test (PCT), with regular leachant exchanges, was used to determine the leaching rates of simulated HLW glasses [West Valley Demonstration Project (WVDP) Ref. 6 and Defense Waste Processing Facility (DWPF) Blend 1] in the presence of aqueous solutions of FeCl_2 and FeCl_3 at 90 °C. These conditions were selected to simulate an internal WP environment containing steel corrosion products and oxidized by radiolysis. Substantially high initial boron and alkali release rates, approximately a factory of 50 to 70 times greater than those in deionized water, were measured in 0.25 M FeCl_3 solutions. The initial leaching rate for boron was found to be pH-dependent and decreased as the leachate pH was increased. The slope of the regression of log leaching rate with pH was linear and almost identical for the two simulated waste glasses.