Tailoring Inorganic Sorbents for SRS Strontium and Actinide Separations: Optimized Monosodium Titanate and Pharmacosiderite Phase I Final Report

HOBBS, DAVID

Savannah River Site (S.C.)

关键词: Removal;    Acceleration;    Testing;    Sodium;    08 Hydrogen;   

DOI  :  10.2172/835578
RP-ID  :  WSRC-TR-2004-00322
RP-ID  :  AC09-96SR18500
RP-ID  :  835578

美国|英语

来源: UNT Digital Library

【 摘 要 】

This report summarizes experiments and engineering evaluations conducted in a project funded by the Department of Energy, Office of Environmental Cleanup and Acceleration to develop improved sorbent materials for strontium/actinide separations at SRS. From the results of Phase 1 activities of the project, we offer the following conclusions and recommendations. Chemically modified monosodium titanate (MST) samples exhibited significantly increased actinide removal performance compared to the baseline MST. Testing results indicate that the modified MST offers the possibility of reduced MST concentrations and shorter contact times compared to the baseline MST. Preliminary calculations indicate that the use of the optimized MST sorbent will provide significantly increased waste throughput in the ARP facilities should shorter batch contact times and reduced MST concentrations be realized. The maximum throughput increases are realized using a 0.1-micron pore-size filter media in these facilities. Evaluation of the impacts of incorporating MST into DWPF operations indicates that both the baseline MST and optimized MST (4X decrease) quantities can be accommodated from Chemical Processing Cell (CPC) and glass formulation perspectives. We recommend that the MST materials be tested to determine the effects, if any, that introduction of MST has on slurry rheology, antifoam effectiveness, potential generation of hydrogen and processing time in the CPC. Evaluation of the impacts of MST and titanosilicate analog of pharmacosiderite (TSP) materials determined that the use of these materials showed no significant impacts on the SWPF and Saltstone facility. Based on the promising enhanced actinide removal performance of the chemically modified MST samples, which could have significant positive impacts on the SWPF, ARP and perhaps an in-tank deployment for Sr/actinide removal, we recommend that the Department of Energy continue funding to develop chemically modified MST materials. Dried MST exhibited poorer strontium and alpha removal kinetics, which may adversely impact process cycle times and waste feed throughput. Thus, we recommend that pretreatment facilities not use dried MST. Samples of TSP, sodium nonatitanate (SNT) templated-MST and pH-adjusted MST materials did not exhibit significantly improved strontium and actinide removal performance compared to the baseline MST. Thus, we halted further development of these materials. Nb-SNT exhibited evidence of chemical instability upon contact with strongly alkaline salt solutions for several days. The chemical instability could have significant impacts on downstream operations in the SWPF and DWPF.