Coextraction of Uranium and Technetium in TBP-Systems

Jassim, T.N.; Liljenzin, Jan‐Olov; Lundqvist, Robert; Persson, G.

doi:10.1080/07366298408918455

Cited by 36 publications

(17 citation statements)

References 5 publications

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“…During the reprocessing of nuclear fuel, the irradiated fuel is first dissolved in nitric acid: under such non-reducing process conditions, Tc is oxidised to the +7 oxidation state, which is the most stable oxidation state of Tc in solution, and forms strong pertechnetic acid HTcO 4 . This acid is easily dissociated to form H + and the oxo-anion TcO 4 À , that may interfere with uranium, plutonium and zirconium in the reprocessing of nuclear fuels [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Density and activity of pertechnetic acid aqueous solutions at T = 298.15 K

Moeyaert

Abiad

Sorel

et al. 2015

The Journal of Chemical Thermodynamics

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Section: Introductionmentioning

confidence: 99%

Density and activity of pertechnetic acid aqueous solutions at T = 298.15 K

Moeyaert

Abiad

Sorel

et al. 2015

The Journal of Chemical Thermodynamics

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“…It is interesting that maximum of [Tc] coincides in position with the maximum of the HNO 3 concentration and is close to the maximum of [U(VI)]. Probably, accumulation of Tc in the block is caused by coextraction of Tc(VII) with U(VI) [11].…”

Section: Extraction Decontamination Of U From Tcmentioning

confidence: 90%

Stripping of Pu and Tc from tributyl phosphate solutions with carbohydrazide

Alekseenko¹,

Marchenko²,

Dvoeglazov³

et al. 2012

Radiochemistry

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Stripping of Pu from 30% tributyl phosphate solutions with carbohydrazide was studied. The degree of the Pu stripping drastically decreases with an increase in acidity and increases with an increase in the carbohydrazide concentration and in temperature. The Pu(IV) reduction rate in the two-phase system is sufficiently high to perform the reductive stripping of Pu with carbohydrazides both in mixer-settlers and in centrifugal extractors. Stripping of Тс at high phase ratio (O/W = 30) with carbohydrazide, hydrazine, and U(IV) in a mixture with hydrazine was studied. At low acidity (<1 M HNO 3 ) and 30-35°C, carbohydrazide allows more than 80% stripping of Tc from 30% TBP solutions even at high volume ratio of the phases.One of the lines in improving aqueous technology for SNF reprocessing is search for new effective reagents for performing redox processes involving Pu and Np ions [1]. The results of our previous studies [2,3] show that carbohydrazide (NH 2 NH) 2 CO can be a candidate reagent for the Pu and Np reduction. Its advantages are high rate of the reaction with Pu(IV) and Np(VI) in aqueous solution, resistance to oxidation in HNO 3 solutions, and the absence of HN 3 among products of its reactions with HNO 3 and HNO 2 . Furthermore, thanks to a high rate of the reaction with HNO 2 , the use of carbohydrazide (CH) does not require introduction of any antinitrite agent (hydrazine) for stabilization of lower valence states of U, Pu, and Np.Another possible application of carbohydrazide is decontamination of U from Tc by the reduction of Tc(VII) to nonextractable Tc(IV) in the final step of the extraction reprocessing of SNF, because specifically 99 Tc (along with 106 Ru) is the nuclide determining the purity of the final uranium product.The goal of this study was to examine the possibility of using carbohydrazide in two-phase extraction systems with TBP for the Pu and Tc reduction and to perform laboratory trials of the reductive stripping of Pu under the conditions of the first extraction cycle and of the U decontamination from Tc in the step of extraction refining of U.The experimental procedure was as follows. A temperature-controlled separating funnel was charged with an aqueous nitric acid solution of carbohydrazide of known concentration, and an equal volume of a 30 vol % solution of TBP in n-dodecane, containing 0.9 to 1.1 g l -1 Pu(IV), was added. The contents were mechanically stirred for a definite time, after which the phases were separated by settling, and the Pu concentration in the organic phase was determined radiometrically, and that in the aqueous phase, spectrophotometrically. In each experiment, we also determined the concentration of H + ions in the aqueous phase by potentiometric titration. The Pu distribution ratio D and the degree of Pu stripping α were calculated by the formulas D = [Pu] org /[Pu] aq and α = (1 -[Pu] org /[Pu] org,init ) × 100%, where [Pu] org and [Pu] aq are the Pu concentrations in the organic and aqueous phases after the phase separation, and [Pu] org, init is the P...

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“…Therefore, the donor groups of CMPO and TBP have been considered to be coordinated through hydrogen bonding to the oxygen atoms of HTCO4 [7,18], Accordingly, the extraction mechanisms of the Tc-CMPO and Tc-TBP systems are considered to be almost the same. On the other hand, the solvation number of two for CMPO, differs from that for TBP, which is three [2,4,6,7,12,13] or four [5,8]. If the number of coordination sites between HTCO4-CMPO and HTCO4-TBP is the same, at least one CMPO should behave as a bidentate extractant [20] in order to compensate for the lack of solvation number.…”

Section: Acid Dependencementioning

confidence: 94%

“…Furthermore, in present nuclear fuel reprocessing plants, Tc as impurity can cause a significant problem with the extraction of U and Pu. In this regard, the solvent extraction behavior of Tc [1-7, 12, 13] and Re [8][9][10][11][12][13] by using TBP has been investigated. Transuranium elements were found to be effectively separated from acidic nuclear wastes by the TRUEX process [14] using the mixture of CMPO and TBP, which was developed at Argonne National Laboratory.…”

Section: Introductionmentioning

confidence: 99%

Solvent Extraction of Tc(VII) and Re(VII) from Nitric Acid Solution with the Mixture of CMPO and TBP

1993

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The distribution mechanism of Tc(VII) and Re(VII) between nitric acid Solution and n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) / tributyl phosphate (TBP) in n-dodecane or decalin was studied. By using distribution coefficients of Tc(VII) and Re(VII), acid concentration dependence and CMPO concentration dependence were confirmed. The distribution coefficient from a mixed CMPO-TBP system was found to be larger than the sum of those obtained from a CMPO system and a TBP system. This enhancement of Tc extraction was discussed in terms of formation of mixed Tc-CMPO-TBP complexes.

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Coextraction of Uranium and Technetium in TBP-Systems

Cited by 36 publications

References 5 publications

Density and activity of pertechnetic acid aqueous solutions at T = 298.15 K

Density and activity of pertechnetic acid aqueous solutions at T = 298.15 K

Stripping of Pu and Tc from tributyl phosphate solutions with carbohydrazide

Solvent Extraction of Tc(VII) and Re(VII) from Nitric Acid Solution with the Mixture of CMPO and TBP

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