Experimental data developed to support the selection of a treatment process for West Valley alkaline supernatant

Bray, L.A.; Holton, L.K.; Myers, T.R.; Richardson, Graham M.; Wise, Barry M.

doi:10.2172/5336229

Cited by 17 publications

(21 citation statements)

References 4 publications

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“…Technetium is expected to be present as pertechnetate in most tank wastes, because this is the most stable fonn in oxygen-saturated solutions of any pH in the absence of complexants or ligands that stabilize other oxidation states (Pourbaix 1966). Technetium removal from West Valley alkaline supemate simulants by a number of different ion exchangers was investigated in FY 1983 at Pacific Northwest National Laboratory (PNNL) (Bray et al 1984). Only charcoal and two organic anion exchange resins removed Tc effectively from the simulants.…”

Section: Needmentioning

confidence: 99%

Technetium in alkaline, high-salt, radioactive tank waste supernate: Preliminary characterization and removal

Blanchard¹,

Brown²,

Conradson³

1997

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SummaryThis report describes the initial work conducted at Pacific Northwest National Laboratory to study technetium (Tc) removal fiom W o r d tank waste supernates and Tc oxidation state in the supemates. Filtered supernate samples fiom four tanks were studied: a composite double shell slurry feed (DSSF) consisting of 70% fiom Tank AW-101, 20% from AP-106, and 10% fiom AP-102; and three complexant concentrate (CC) wastes (Tanks AN-107, SY-101, ANS SY-103) that are distinguished by having a high concentration of organic complexants. The work included batch contacts of these waste samples with ReillexTW€PQ (anion exchanger fiom Reilly Industries) and ABEC 5000 (a sorbent from Eichrom Industries), materials designed to effectively remove Tc as pertechnetate fiom tank wastes. A short study of Tc analysis methods was completed. A preliminary identification of the oxidation state of non-pertechnetate species in the supernates was made by analyzing the technetium x-ray absorption spectra of four CC waste samples. Molybdenum (Mo) and rhenium (Re) spiked test solutions and simulants were tested with electrospmy ionizationmass spectrometry to evaluate the feasibility of the technique for identifying Tc species in waste samples.The highlights fiom the work are as follows:* Both ReillexTH-HPQ and ABEC 5000 are effective for Tc removal from the composite DSSF waste (70% AW-IOl), exhibiting 93% and 91% removal, respectively, on the first contact. Neither Rei1lex"cHpQ nor ABEC 5000 are effective for Tc removal from the three CC wastes studied. Technetium removal from the CC wastes was in all cases less than 50%. Removal of Tc from these wastes will require either an alternative process such as electrochemical deposition or addition of a feed adjustment step to oxidize the Tc species to pertechnetate.The Tc in CC waste is very resistant to oxidation to pertechnetate in acidified samples generally required for Tc analysis. A vigorous oxidation with C e O was found effective for this purpose, but is time consuming. X-ray absorption near edge spectroscopy indicates that the dominant species in CC waste is not pertechnetate. It also shows that the non-pertechnetate specie(s) in the CC wastes probably has an oxidation state of +IV.The batch contacts, oxidation study, and XANES data all indicate that for the tested wastes containing relatively large (> 10 g total organic carbon per liter), amounts of organic complexants, more than half of the total Tc is not pertechnetate.Inductively coupled plasma-mass spectrometry identified Re species, including polyoxyanions, in simulants and test solutions and was usefid for following the Re species through various changes in solution chemistry. Penhenate, a good surrogate for TcOi, was easily detectable in a CC waste simulant at 200 m a , somewhat higher than the concentration of Tc in CC wastes.

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Section: Needmentioning

confidence: 99%

Technetium in alkaline, high-salt, radioactive tank waste supernate: Preliminary characterization and removal

Blanchard¹,

Brown²,

Conradson³

1997

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“…Technetium removal from West Valley alkaline supernate simulants by a number of different ion exchangers was investigated in FY 1983 at PNML (Bray et al, 1984). Only charcoal and two organic anion exchange resins removed Tc effectively from the simulants.…”

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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“…TIE-96 is a modified version of the IE-96 and is capable of removing strontium and plutonium, in addition to cesium, from alkaline solutions (Bray et al 1984;Bray and Hara 1991). Both of these materials have been commercially available for several years.…”

Section: Materials Selection and Preparationmentioning

confidence: 99%

Performance evaluation of 24 ion exchange materials for removing cesium and strontium from actual and simulated N-Reactor storage basin water

Brown¹,

Carson²,

DesChane³

et al. 1997

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This report describes the evaluation of 24 organic and inorganic ion exchange materials for removing cesium and strontium from actual and simulated waters from the 100 Area 105 N-Reactor fuel storage basin. The data described in this report can be applied for developing and evaluating ion exchange pretreatment process flowsheets. Cesium and strontium batch distribution ratios (h's), decontamination factors (DF), and material loadings (mmol 8') are compared as a function of ion exchange material and initial cesium concentration.The actual and simulated N-Basin waters contain relatively low levels of aluminum, barium, calcium, potassium, and magnesium (ranging from 8.33E-04 to 6.40E-05 m, with slightly higher levels of boron (6.63E-03 M) and sodium (1.62E-03 M). The I3%s level is 1.74E-06 Ci L-' which corresponds to approximately 4.87E-10 M Cs. The initial Na/Cs ratio was 3.33E+06. The concentration of total strontium is 4.45E-06 M. while the %r radioactive component was measured to be 6.13E-06 Ci L-'.Simulant tests were conducted by contacting 0.067 g or each ion exchange material with approximately 100 mL of either the actual or simulated N-Basin water. The simulants contained variable initial cesium concentrations ranging from 1.00E-04 to 2.57E-10 M Cs while all other components were held constant.For all materials, the average cesium & was independent of cesium concentration below approximately 1 .OK06 M. Above this level, the average cesium I(d values decreased significantly. Cesium I(d values exceeding 1 .OE+07 mL g-' were measured in the simulated N-Basin water. However, when measured in the actual N-Basin water the values were several orders of magnitude lower, with a maximum of 1.24E+05 mL g-' observed. Several materials, including a potassium cobalt hexacyanoferrate (KCoHex), inorganic zeolites, crystalline silicotitanates, biotite micas, pharmacosiderites, and phlogopites exhibited substantial affinity for cesium. The nonspecific cation exchange materials did not show an appreciable affinity for cesium in the basin water.Because of the high levels of nonradioactive strontium and calcium, the strontium I& results were much lower (e.g., between 1 .OE+03 and 1 .OE+05 mL g-') than those for the cesium. The strontium I(d and loading were inversely correlated to the cesium concentration (increasing with decreasing concentration from 1.OE-04 to 1 .Os09 M Cs). The data suggest that either the two ions compete for similar ion exchange sites or the higher cesium loading perturbs the strontium sites such that the strontium exchange process is hindered.... SummaryThis report describes evaluations of the radionuclide uptake capability of several newly produced ion exchange materials under actual waste solution conditions and compares the results obtained with these materials to those obtained with other commercial and experimental exchangers. The ion exchange materials are being evaluated for their performance in treating water from the 105 N-Reactor basin at Hanford. Actual and simulated basin water was us...

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Experimental data developed to support the selection of a treatment process for West Valley alkaline supernatant

Cited by 17 publications

References 4 publications

Technetium in alkaline, high-salt, radioactive tank waste supernate: Preliminary characterization and removal

Technetium in alkaline, high-salt, radioactive tank waste supernate: Preliminary characterization and removal

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

Performance evaluation of 24 ion exchange materials for removing cesium and strontium from actual and simulated N-Reactor storage basin water

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