Anion Scavengers for Low-Level Radioactive Waste Repository Backfills

Abstract

Minimization of 129/− and 99 TcO4 − transport to the biosphere is critical to the success of low level radioactive waste (LLRW) storage facilities. Here we experimentally identify and classify potential sorbent materials for inclusion in LLRW backfills. For low pH conditions (pH 4-5), Cu-sulfides and possibly imogolite-rich soils provide Kd's (distribution coefficients) of roughly 103 mL g−1 for /−, and 102 mL g−1 for TcO4 −. At near neutral pH, hydrotalcites, Cu-oxides, Cu-sulfides, and lignite coal possess Kd's on the order of 102 mL g−1 for both /− and TcO4 −. At high pH (pH>10), such as might occur in a cementitious LLRW facility, calcium monosulfate aluminate Kd's are calculated to be roughly 102 mL g−1 for both both /− and TcO4 −.