Options for the Separation and Immobilization of Technetium

Serne, R. Jeffrey; Crum, Jarrod V.; Riley, Brian J.; Levitskaia, Tatiana G.

doi:10.2172/1333455

Cited by 5 publications

(7 citation statements)

References 62 publications

(109 reference statements)

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“…The removal of 99-Tc from LAW in a pretreatment step was previously included in the Hanford LAW WTP flowsheet and removed in 2003 Serne et al 2016a). The proposed approach at WTP was the use of an ion exchange resin to remove TcO 4 -.…”

Section: Pretreatment Technologiesmentioning

confidence: 99%

“…The proposed approach at WTP was the use of an ion exchange resin to remove TcO 4 -. A previous summary of alternate 99-Tc capture approaches within the Hanford flowsheet is presented elsewhere (Serne et al 2016a). The most promising and technically mature technologies available to date are discussed below.…”

Section: Pretreatment Technologiesmentioning

confidence: 99%

“…The reduction of 99-Tc from its soluble Tc(VII)O 4 form to a low solubility Tc(IV) species can be utilized to extract 99-Tc from liquid waste streams (Serne et al 2016a). Several candidate reductants exist which can drive the reaction of Tc(VII) including Sn(II) (Asmussen et al 2016b;Duncan et al 2016;Taylor-Pashow et al 2018), Fe (0 or II) (Del Cul et al 1995) and S(0) (Pearce et al 2018).…”

Section: Line 6 -Redox Strike/co-precipitationmentioning

confidence: 99%

“…In this approach a simple chemical form of the reductant would be introduced to the LAW to precipitate 99-Tc. The precipitated 99-Tc would then be filtered out and disposed of in a secondary waste form (for which multiple candidates exist [Serne et al 2016a), or remain in the LAW feed and blended into a grout.…”

Section: Line 6 -Redox Strike/co-precipitationmentioning

confidence: 99%

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Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Skeen

Langston

McCabe

et al. 2020

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An expert panel consisting of the document authors was assembled by Washington River Protection Solutions, LLC (WRPS) and tasked with (1) identifying technical and regulatory limitations to treating and disposing of grouted low-activity waste (LAW), and (2) with identifying and evaluating a wide range of technical solutions to these limitations. The analysis included technologies to allow inventory management and/or improve retention of iodine, technetium, and nitrate either in the waste packages, or within the Integrated Disposal Facility (IDF), and, technologies to ensure regulated organics are below Resource Conservation and Recovery Act of 1976 (RCRA) Land Disposal Restriction (LDR) levels.The expert panel completed their analysis in three distinct phases. In Phase I, the team reviewed the chemical and physical characteristics of the most recent projected supplemental LAW (SLAW) feed vector along with disposal site waste acceptance criteria and the fiscal year 2019 results from Pacific Northwest National Laboratory that identified the level of improvement that would be needed to meet onsite disposal requirements in the IDF (Asmussen et al. 2019a). The two regulatory constraints targeted for technology solutions by the expert panel were (1) current estimates based on performance assessment fate-andtransport modeling indicate that if the entire quantity of LAW currently designated for supplemental treatment were solidified as a cementitious material, nitrate, 99-Tc, and 129-I could exceed groundwater standards after DOE's time of compliance (1,000 years) but within 10,000 years after IDF closure and (2) LAW may contain RCRA LDR organics at levels that require removal to meet LDR concentration-based limits. It should also be noted that the first issue is only applicable to on-site disposal, not offsite at WCS and is based on calculations that assume either a low-performing grout is used, or high-performance grout does not maintain its performance (SRNL-RP-2018-00687). Asmussen et al. (2019a) estimated that the inventory of grouted SLAW could meet IDF groundwater requirements if the release rate of nitrate, 99-Tc, and 129-I were reduced by a factor of approximately 3.2, 10, and 32, respectively versus baseline formulation performance.In Phase II, an extensive list of technologies and engineering approaches was identified and subjected to an initial assessment by the group. Current knowledge associated with technology maturation needs and constraints to implementation at Hanford were recorded in 13 distinct categories. In the final phase of the process (Phase III), the expert panel selected 7 of the 13 categories for qualitative rating and a series of meetings were held between the expert panel to discuss and rate each technology in each category. All ratings were developed by consensus. After the qualitative rating was complete, a numerical scoring criterion for each category was applied and a composite score for the individual technologies was calculated. An uncertainty score was also developed for each technolo...

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Section: Pretreatment Technologiesmentioning

confidence: 99%

Section: Pretreatment Technologiesmentioning

confidence: 99%

Section: Line 6 -Redox Strike/co-precipitationmentioning

confidence: 99%

Section: Line 6 -Redox Strike/co-precipitationmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Skeen

Langston

McCabe

et al. 2020

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“…This includes filtration through a suitable filter to remove suspended particles, acidification to pH 1-4 with HCl [5], H 2 SO 4 [6] or HNO 3 [7]. Above mentioned technetium immobilization may be achieved by several methods, such as evaporation [8], extraction chromatographic methods [9], sorption onto carbon-based materials such as biochar [10], etc. The evaporation technique is a very simple method and is applicable to smaller volumes of samples with low salinity, respectively.…”

Section: Introductionmentioning

confidence: 99%

Surface Complexation Models of Pertechnetate on Biochar/Montmorillonite Composite—Batch and Dynamic Sorption Study

et al. 2020

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The study summarizes the results of monitoring the properties of two types of sorbents, BC1 (biochar sample 1) and BC2a (biochar sample 2), prepared by pyrolysis of bamboo biomass (BC1) and as its composite with montmorillonite K10 (BC2a). The main goal was to study their applicability to the Tc (VII) separation from liquid wastes, using NH4ReO4 as a carrier. The research was focused on determining the sorbents surface properties (by XRF (X-ray fluorescence) method and potentiometric titration in order to determine the properties of surface groups—Chemical Equilibrium Model (CEM) and Ion Exchange Model (IExM) models were applied here). As well as monitoring Tc (VII) (+Re(VII)) sorption, especially to determine equilibrium isotherm, the influence of pH and kinetics. The subject of research was also the dynamics of sorption, including its mathematical–physical modeling. Both sorbents have good properties against Tc (VII), however BC2a, due to the presence of montmorillonite, is more advantageous in this respect. It has a higher sorption capacity and faster kinetic investigation. An important finding is that the optimal pH is 2–3, which is related not only to the protonation of surface groups (they have a positive charge), but also to the negative form of the existence of Tc (VII) and Re (VII): TcO4− and ReO4−.

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Hexagonal close-packed high-entropy alloy formation under extreme processing conditions

et al. 2019

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Options for the Separation and Immobilization of Technetium

Cited by 5 publications

References 62 publications

Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Surface Complexation Models of Pertechnetate on Biochar/Montmorillonite Composite—Batch and Dynamic Sorption Study

Hexagonal close-packed high-entropy alloy formation under extreme processing conditions

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