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....

The Hanford Site, in southeast Washington State, is preparing to disposition approximately 56,000,000 gallons (56 Mgal) of radioactive and chemically hazardous wastes currently stored in underground tanks at the site. Tank wastes will be divided into a high-activity fraction and a low-activity fraction for subsequent treatment and disposition. A waste processing and treatment facility, the Waste Treatment and Immobilization Plant (WTP), will include the high-level waste (HLW) vitrification facility (WTP HLW Vitrification Facility) for immobilizing the high-activity fraction and a low-activity waste (LAW) vitrification facility (WTP LAW Vitrification Facility) for immobilizing the low-activity fraction. Both facilities will use vitrification technology to immobilize the Hanford tank wastes in a glass waste form.The volume of LAW to be treated and disposed of following waste retrieval and WTP operations will exceed the planned processing capacity of the WTP LAW Vitrification Facility. ORP-11242, River Protection Project System Plan, 1 estimates a shortfall in LAW treatment capacity of approximately 56 Mgal, approximately 50% of the projected LAW volume. 2 To maintain the planned tank waste processing mission schedule, the U.S. Department of Energy (DOE) will require additional LAW treatment capacity (termed "supplemental LAW") external to the WTP process. LAW must be solidified by a treatment technology before the waste can be permanently disposed of in an approved DOE on-site disposal facility or a commercial (state or U.S. Nuclear Regulatory Commission [NRC]-licensed) off-site mixed low-level waste disposal facility. A decision on the approach to supplemental LAW treatment, processing, and disposal has not yet been made. SRNL-STI-2023-00007 Revision 0 Volume I | viii SRNL-STI-2023-00007 Revision 0 Volume I | ix The FFRDC team makes the following recommendation: DOE should expeditiously secure and implement multiple pathways for off-site grout solidification/ immobilization and disposal of LAW in parallel with the direct-feed low-activity waste (DFLAW) vitrification process.