PNNL

Abstract

Performance tests were conducted using novel getter materials that can immobilize or delay the transport of radioiodine that would be released during physical and chemical degradation of solidified low-level waste packages. The results showed that metal-capped novel getters such as Hg-thiol and Ag-thiol Self-Assembled Monolayers on Mesoporous Silica (SAMMS), designed specifically to adsorb soft anions such as I-, had very high affinities for adsorption of radioiodine (Kd ~1x104 – 4x105 ml/g). The iodide adsorption performance of these novel getters was from one to two orders of magnitude better than many natural mineral and modified mineral getters. These data indicate that the novel getter materials are capable of significantly retarding the mobility of radioiodine leaching from physically and chemically weathered low-level waste glass packages during various physical and chemical weathering reactions expected during long-term disposal in the vadose zone.