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Title: Assessment of the Mechanisms for Sr-90 and Tru Removal from Complexant-Containing Tank Wastes at Hanford

Abstract

Small-scale tests (~20 mL) were conducted with samples from Hanford underground storage tanks AN-102 and AN-107 to assess the mechanisms for removing Sr-90 and transuranics (TRU) from the liquid (supernatant) portion of the waste. The Sr-90 and TRU must be removed (decontaminated), in addition to Cs-137 and the entrained solids, before the supernatant can be disposed of as low-activity waste. Experiments were conducted with various reagents and modified Sr/TRU removal process conditions to more fully understand the reaction mechanisms. The optimized treatment conditions--no added hydroxide, addition of Sr (0.02M target concentration) followed by sodium permanganate (0.02M target concentration) with mixing at ambient temperature--were used as a reference for comparison. The waste was initially two orders of magnitude undersaturated with Sr; the addition of nonradioactive Sr(NO₃) ₂ saturated the supernatant, resulting in isotopic dilution and precipitation of Sr-90 as SrCO₃. The reaction chemistry of Mn species relevant to the mechanism of TRU removal by permanganate treatment was evaluated, along with the importance of various mechanisms for decontamination, such as precipitation, absorption, ligand exchange, and oxidation of organic complexants. For TRU removal, permanganate addition generally gave the highest DF. The addition of Mn of lower oxidation states (II, IV, and VI) alsomore » resulted in good TRU removal, as did complexant oxidation with periodate and addition of Zr(IV) for ligand exchange. These results suggest that permanganate treatment leads to TRU removal by multiple routes.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
15020527
Report Number(s):
PNWD-SA-6239
TRN: US0504624
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Separation Science and Technology, 40(1-3):171-183
Additional Journal Information:
Journal Volume: 40; Journal Issue: 1-3
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ABSORPTION; DILUTION; ION EXCHANGE; OXIDATION; PERIODATES; PERMANGANATES; PRECIPITATION; REACTION KINETICS; REMOVAL; HANFORD RESERVATION; STORAGE FACILITIES; RADIOACTIVE WASTE STORAGE; STRONTIUM 90; TRANSURANIUM ELEMENTS; pretreatment; radioactive waste; precipitation; strontium; permanganate; separation; decontamination

Citation Formats

Hallen, Richard T, Geeting, John GH, Lilga, Michael A, Hart, Todd R, and Hoopes, Francis V. Assessment of the Mechanisms for Sr-90 and Tru Removal from Complexant-Containing Tank Wastes at Hanford. United States: N. p., 2005. Web. doi:10.1081/SS-200041906.
Hallen, Richard T, Geeting, John GH, Lilga, Michael A, Hart, Todd R, & Hoopes, Francis V. Assessment of the Mechanisms for Sr-90 and Tru Removal from Complexant-Containing Tank Wastes at Hanford. United States. doi:10.1081/SS-200041906.
Hallen, Richard T, Geeting, John GH, Lilga, Michael A, Hart, Todd R, and Hoopes, Francis V. Tue . "Assessment of the Mechanisms for Sr-90 and Tru Removal from Complexant-Containing Tank Wastes at Hanford". United States. doi:10.1081/SS-200041906.
@article{osti_15020527,
title = {Assessment of the Mechanisms for Sr-90 and Tru Removal from Complexant-Containing Tank Wastes at Hanford},
author = {Hallen, Richard T and Geeting, John GH and Lilga, Michael A and Hart, Todd R and Hoopes, Francis V},
abstractNote = {Small-scale tests (~20 mL) were conducted with samples from Hanford underground storage tanks AN-102 and AN-107 to assess the mechanisms for removing Sr-90 and transuranics (TRU) from the liquid (supernatant) portion of the waste. The Sr-90 and TRU must be removed (decontaminated), in addition to Cs-137 and the entrained solids, before the supernatant can be disposed of as low-activity waste. Experiments were conducted with various reagents and modified Sr/TRU removal process conditions to more fully understand the reaction mechanisms. The optimized treatment conditions--no added hydroxide, addition of Sr (0.02M target concentration) followed by sodium permanganate (0.02M target concentration) with mixing at ambient temperature--were used as a reference for comparison. The waste was initially two orders of magnitude undersaturated with Sr; the addition of nonradioactive Sr(NO₃) ₂ saturated the supernatant, resulting in isotopic dilution and precipitation of Sr-90 as SrCO₃. The reaction chemistry of Mn species relevant to the mechanism of TRU removal by permanganate treatment was evaluated, along with the importance of various mechanisms for decontamination, such as precipitation, absorption, ligand exchange, and oxidation of organic complexants. For TRU removal, permanganate addition generally gave the highest DF. The addition of Mn of lower oxidation states (II, IV, and VI) also resulted in good TRU removal, as did complexant oxidation with periodate and addition of Zr(IV) for ligand exchange. These results suggest that permanganate treatment leads to TRU removal by multiple routes.},
doi = {10.1081/SS-200041906},
journal = {Separation Science and Technology, 40(1-3):171-183},
number = 1-3,
volume = 40,
place = {United States},
year = {2005},
month = {2}
}