Getter Incorporation into Cast Stone and Solid State Characterizations

Updated Liquid Secondary Waste Grout Formulation and Preliminary Waste Form Qualification

“…The iQID radiography image of a cross section of T15-4, leached for 406 days in VZPW, shows the 99 Tc to be present in discrete spots throughout the sample, as shown in Figure A.5. From previous analysis of LAW Cast Stone monolith cross sections containing Sn-A, the chemical makeup at the "hot spots" results from the 99 Tc being present with a modified Sn-A (Asmussen et al 2016a). A similar chemistry can be expected at the "hot spots" observed in the T15-4 sample.…”

“…Determining the distribution of 99 Tc within the monolith samples following leaching can assist in understanding the leaching trends. Previous work has shown 99 Tc to be evenly distributed throughout the monolith samples in unleached LAW Cast Stone (Asmussen et al 2016a). Following leach testing, this distribution of 99 Tc can change with both a congregation at the outer monolith wall and an appearance of discrete "hot spots" of 99 Tc appearing after long-term leaching (>3 year) of LAW Cast Stone (Asmussen et al 2016b).…”

“…From previous analysis. This particular monolith, T2, when imaged by autoradiography show discrete "hot spots" resulting from 99 Tc being associated with the Sn(II)-apatite getter (Asmussen et al 2016).…”

“…For T2, Xypex was added to the initial dry blend before homogenization. Aliquots of previously prepared simulant spiked with 99 Tc and 127 I were reacted with I getter (Ag-zeolite) and 99 Tc getter (Sn-apatite) for T3 and T6, respectively, for at least 48 h before mixing the simulant-getter slurry with the other dry ingredients (Asmussen et al 2016). LSWG monolith test batches were then prepared over the course of eight days: non-99 Tc-spiked LSWG monoliths (T7 in Table 4.1) were prepared first, then six days later 99 Tc-spiked LSWG monoliths from batches T1, T2, T4, and T5 were prepared, and finally T3 and T6 monoliths were prepared on day eight.…”

Options for the Separation and Immobilization of Technetium

“…However, more study is needed to resolve what Tc species is present in the resulting solution from the Reillex stripping reactions. The Sn(II)Cl 2 reductive precipitation approach results in a solid containing mixed valences of Sn(IV)/Sn(II) with a Tc(IV) co-precipitate (see Asmussen et al (2016) for details. It is Tc(IV) that is required to make mineral structures including goethite, spinel, rutile, pyrochlore, and perovskite.…”