Technetium partitioning for the Hanford Tank Waste Remediation System:  anion exchange studies for partitioning technetium from synthetic DSSF and DSS simulants and actual Hanford wastes (101-SY and 103-SY) using Rellex-HPQ resin

Schroeder, Norman C.; Radzinski, Susan D.; Ball, Jason R.; Ashley, Kenneth R.; Cobb, Steven L.; Cutrell, Brent; Adams, John M.; Johnson, Coy; Whitener, Glenn D.

doi:10.2172/1400218

Cited by 28 publications

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“…Due to the performance requirements for the low activity waste glass, almost all of the 137 Cs and 9 0 Sr and approximately 80% of the technetium ( 9 9 Tc) must be removed from the low activity waste stream and sent to the high activity waste stream. 2,3 The procedure for removing technetium was ion exchange of pertechnetate, TcO 4 -, the most thermodynamically stable form of technetium at high pH. While ion exchange is effective for many tanks, it fails for Complexant Concentrate (CC) waste tanks, including tanks SY-101 and SY-103, which contain the organic complexants nitrilotriacetate (NTA), ethylenediaminetetraacetate (EDTA), citrate, and gluconate.…”

Section: Manuscript Textmentioning

confidence: 99%

Identification of the Non-Pertechnetate Species in Hanford Waste Tanks, Tc(I)−Carbonyl Complexes

Lukens

Shuh

Schroeder

et al. 2003

Environ. Sci. Technol.

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Immobilization of the high-level nuclear waste stored at the Hanford Reservation has been complicated by the presence of soluble, lower-valent technetium species. Previous work by Schroeder and Blanchard has shown that these species cannot be removed by ion-exchange and are difficult to oxidize.The Tc-K edge XANES spectra of the species in Tanks SY-101 and SY-103 were reported by Blanchard, but they could not be assigned to any known technetium complex. We report that the XANES spectra are most likely those of Tc(I) carbonyl species, especially fac-Tc(CO) 3 (gluconate) 2-. This is further supported by EXAFS and 9 9 Tc-NMR studies in nonradioactive simulants of these tank wastes.2 KEYWORDS Technetium, Hanford, high level waste, nuclear waste BRIEFS The soluble technetium species that have caused problems for the remediation of high level nuclear waste at Hanford are most likely Tc(I) carbonyl complexes.

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Section: Manuscript Textmentioning

confidence: 99%

Identification of the Non-Pertechnetate Species in Hanford Waste Tanks, Tc(I)−Carbonyl Complexes

Lukens

Shuh

Schroeder

et al. 2003

Environ. Sci. Technol.

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“…Various ion exchange materials have shown the ability to remove technetium as pertechnetate from various simulated solutions (Marsh et al, 1994a;Marsh et al, 1994b;Marsh et al, 1994c;Marsh et al, 1995). Much of the recent research concerning technetium removal has focused on the ReillexTM-HPQ resin (Schroeder et al, 1993;Schroeder et al, 1994;Schroeder et al, 1995a;Schroeder et al, 1995b) and ABEC 5000 sorbent . tanks SY-101 and SY-103 were shipped from Hanford to LANL for Tc removal experiments with ReillexT"-HPQ.…”

Section: Needmentioning

confidence: 99%

Technetium removal column flow testing with alkaline, high salt, radioactive tank waste

Blanchard¹,

Kurath²,

Golcar

et al. 1996

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@ This document was printed on recycled paper. (9197)t r SummaryThis report describes two bench-scale column tests conducted to demonstrate the removal of Tc-99 from actual alkaline high salt radioactive waste. The waste used as feed for these tests was obtained fromlhe Hanford double shell tank AW-101 , which contains double shell slurry feed (DSSF). The tank sample was diluted to approximately 5 M Na with water, and most of the Cs-137 was removed using crystalline silicotitanates. The tests were conducted with two small columns connected in series, containing 10 mL of either a sorbent, ABEC 5000 (Eichrom Industries, Inc.), or an anion exchanger Reillex?-HPQ (Reilly Industries, Inc.). Both materials are selective for pertechnetate anion (TcO4-). The process steps generally followed those expected in a full-scale process and included 1) resin conditioning, 2) loading, 3) caustic wash to remove residual feed and prevent the precipitation of Al(OH)3, and 4) elution. A small amount of Tc-99m tracer was added as ammonium pertechnetate to the feed and a portable GEA counter was used to closely monitor the process. Analyses of the Tc-99 in the waste was performed using ICP-MS .with spot checks using radiochemical analysis. Technetium x-ray absorption spectroscopy ( U S ) spectra of 6 samples were also collected to determine the prevalence of non-pertechnetate species [e.g. Tc(IV)].Some of the relevant flow test parameters are given in Table S The 1525% of the Tc-99 that was not extracted corresponds to a Tc-99 level in the effluent of 1.65 X 10-2 Cum3 to 2.75 X 10-2 Ci/m3. This is 5.5% to 9.2% of the NRC Class A limit of 0.3 Ci/m3. The concentration in the final waste form would likely be higher.The relatively high fraction of non-pertechnetate Tc-99 in the AW-101 waste suggests that this phenomenon may be common in the tank wastes. It was expected that significant fractions of non-pertechnetate Tc-99 would be restricted to tank wastes with a high organic content. The DSSF from AW-101 contains a relatively low amount of organic ( approx. 2.5 g TOC/L in tank).As indicated by the So values, the effective Tc-99 capacity of the Reillexm-HPQ is greater than that for the ABEC 5000 material. The difference between the h50 values for the Tc-99m tracer data and the actual Tc-99 data is attributed to the non-pertechnetate fraction in the waste.Both materials are efficiently eluted, but the ABEC 5000 material is eluted with deionized water which would contribute a relatively small amount of other components to a final waste form.Few operational problems were experienced with either material, although a small portion of the ReillexT"-HPQ bed on the second column was observed to float in solution and preparation of the ABEC 5000 column was tedious because of the difficulty in removing entrained air from the bed. It is suggested that a larger particle size would alleviate this problem.--

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“…Ion exchange processes for technetium are undergoing vigorous investigation in a number of U.S. laboratories for application to high-level liquid alkaline waste treatment (Schroeder et al 1995;Blanchard et al 1997). …”

Section: Ion Exchange and Solvent Extractionmentioning

confidence: 99%

Decontamination of alkaline solution from technetium and other fission products and from some actinides by reductive coprecipitation and sorption on metals

Peretrukhin¹,

Silin²,

Тананаев³

et al. 1997

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SummaryEffective decontamination of alkaline solutions and Hanford Site tank waste simulants from technetium has been accomplished by reductive coprecipitation with iron(II1) hydroxide. Addition of 1 M (NH4),Fe(S04), to 0.5 to 4.0 M NaOH to a final concentration of 0.1 to 0.15 M coprecipitates more than 99% of the technetium from 0.5 to 1.0 &j NaOH and 98 to 96% from 2.0 to 4.0 M NaOH. Similar results were obtained by reduction of Tc(VII) with 0.1 to 0.15 &j hydrazine and subsequent addition of FeCI, to a final concentration of 0.15 M. Inclusion of four complex-fonning agents rO.01 &j phosphate, 0.1 M EDTA (ethylenediaminetetraacetate), 0.03 M citrate, and 0.1 M glycolate (HOCH,CO;)] to the alkaline solution decreases technetium coprecipitation with iron hydroxide to 85% under otherwise similar conditions. Inclusion of 0.04 M NqCrO, drastically decreases reductive coprecipitation of Tc(VII) in 0.5 to 4.0 M NaOH. Iron(I1) salt, added to a 0.07 M excess over that of chromate, completely reduces chromate and provides greater than 99% coprecipitation of technetium with product iron(II1) and chromium(II1) hydroxides. Technetium(VI1) reduction by hydrazine is slow in the presence of chromate in alkaline solution, and technetium coprecipitation is incomplete in these conditions. Decontamination of an alkaline Hanford Site tank waste simulant, containing 0.04 &j chromate and eleven salts and complex-forming agents, by adding 1 M iron(I1) salt solution was studied.Coprecipitation of 15 to 28% of the technetium and more than 99% of the plutonium occurred in the Fe/Cr(III) hydroxide precipitate produced by adding 0.05 to 0.10 _M iron@). Chromate reduction was incomplete. About 75% of the technetium was coprecipitated, and the chromate was completely reduced, after adding 0.2 _M iron@) salt.Technetium(VI1) capture from 0.5 to 4.0 M NaOH was insignificant or incomplete on coprecipitation carriers Pe(OH),, Cr(OH),, Mn(OH),, Co(OH),, Co(OH),J obtained by the Method of Appearing Reagents under conditions providing complete capture of Np(V) and Pu(V1). Under the same conditions, cesium-137 capture is insignificant and strontium-90 capture is incomplete with these metal hydroxide carriers. Sodium diuranate coprecipitation from 0.5 to 4 M NaOH removed about 15 to 60? -of the technetium; sodium uranate coprecipitation removed 98 to 99% of the 90Sr, and 1 to 12% of the l3'CS.Reductive sorption of Tc(VI1) on metals (Zn, Cry Sn, and two Pb alloys) from 0.5 to 4 M NaOH and from alkaline waste simulant provided poor decontamination of these solutions. In contrast, greater than 98% of the plutonium(V1) was sorbed on chromium from 0.5 M NaOH at a surface area to volume ratio of 1.6 cm-'.

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Technetium partitioning for the Hanford Tank Waste Remediation System: anion exchange studies for partitioning technetium from synthetic DSSF and DSS simulants and actual Hanford wastes (101-SY and 103-SY) using Rellex-HPQ resin

Cited by 28 publications

References 0 publications

Identification of the Non-Pertechnetate Species in Hanford Waste Tanks, Tc(I)−Carbonyl Complexes

Identification of the Non-Pertechnetate Species in Hanford Waste Tanks, Tc(I)−Carbonyl Complexes

Technetium removal column flow testing with alkaline, high salt, radioactive tank waste

Decontamination of alkaline solution from technetium and other fission products and from some actinides by reductive coprecipitation and sorption on metals

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