Follow-on Report of Analysis of Approaches to Supplemental Treatment of Low-Activity Waste at the Hanford Nuclear Reservation (Supporting Information Vol. II)

Abstract

Drawing on these advantages, grouts have been used throughout the DOE complex at the Hanford Site, Savannah River Site (SRS), West Valley Demonstration Project (WVDP), Oak Ridge Reservation, and Idaho National Laboratory (INL), along with extensive use in the commercial nuclear industry. Specifics on these efforts are provided in Section A.3. This appendix reviews information on grout relevant to the alternatives discussed in Section 3.3. Each subsection opens with a high-level summary of the detailed information provided. An overview of the basis for grout waste forms is provided in Section A.2. A review of research and development (R&D) efforts relevant to Hanford LAW since the analysis required by Section 3134 of the National Defense Authorization Act for FY 2017 (NDAA17), documented in SRNL-RP-2018-00687, Report of Analysis of Approaches to Supplemental Treatment of Low-Activity Waste at the Hanford Nuclear Reservation, and that address the "next steps" in that report, is provided in Section A.3. A technology overview and relevant considerations are included in Section A.4. A.2 GROUT BACKGROUND A.2.1 Grout FormationRevision 0 Draft DRAFT Volume II | A-4 Revision 0 Draft DRAFT Volume II | A-5Several dry reagents could be used in a grout waste form depending on the waste to be immobilized and the required processing characteristics. The work to date using these reagents for Hanford LAW is summarized in Section A.3.3. Ensuring the quality of the reagents cannot be a forgotten requirement; for example, field spoil piles of fly ash at Hanford do not have the traceability nor purity required for waste immobilization. Brief descriptions of the most general cement reagents for immobilizing liquid waste are as follows. Revision 0 Draft DRAFT Volume II | A-6 Slag cement requires activation by NaOH, Na2SO4, Na2CO3, or Na silicate/other chemicals and is used as a partial replacement for portland cement in numerous construction applications (Wang et al., 1995). The slag cement is a byproduct in an iron-making blast furnace and is made by water quenching from a molten state (~1,550 °C). The resulting slag is then size reduced to a powder to increase the reactive surface area. Slag cement is 95 to 100% silicate glass, with minor components consisting of Al, Ca, Mg, Fe.• Slag cement and blends: Slag cements are the commonly used reagents used for immobilizing alkaline (Na) salt liquid waste streams, because slag hydration is activated by the waste liquid and the resulting phase assemblage typically results in a lower hydraulic conductivity (permeability) than that of portland cement. Slag cement also results in a chemically-reducing environment, which is advantageous for chemically immobilizing selected radionuclides and hazardous constituents in alkaline media.• Super sulfated slag cements: These blended cements consist of mixtures of BFS and calcium sulfate with a small quantity of portland cement used as the "activator" (Gruskovniak et al., 2008). This class of materials is also gaining interest for waste immobilization....