Comparison of the performance of solvent wash reagents used for the primary cleanup of degraded PUREX solvent
Satyabrata MishraChandan MukhopadhyayaChayan PatraVishnu Anand PanantharayilPuspalata RajeshDasari SivakumarN. DesiganK. DhamodharanP. VelavendanR. RajeevK. A. VenkatesanK. Ananthasivan
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Abstract The effectiveness of the solvent wash reagents such as sodium carbonate and hydrazine carbonate were compared using the lean solvent obtained during reprocessing of high plutonium content fast reactor spent nuclear fuel. The concentrations of the reagents were optimized based on the removal of retained metal ions from the lean solvent and 1.5 M hydrazine carbonate was found to be optimal and superior to sodium carbonate to be adopted as the reagent for primary cleanup of the spent solvent. Both the reagents were found to possess excellent room temperature stability and their performance was not affected upon gamma irradiation which was assessed in terms of capacity to remove di-butyl phosphate from degraded TBP/n-DD system.Keywords:
PUREX
Sodium carbonate
Hydrazine (antidepressant)
Carbonate Ion
M ceric sulfate in dilute nitric acid and mounted for total alpha counting, alpha energy analysis, and gamma energy analysis. Neptunium recoveries of 95% have been obtained while plutonium decontamination factors are 5 x 10/sup 4/. Decontamination factors for uranium americium, curium, and gross fission products are all greater than 10/sup 4/. Uranium, up to 180 g/l in the column feed, does not interfere. The plutonium decontamination factor can be increased by a factor of 10 to 100 by fol lowing the nitric acid-ferrous sulfamate-semicarbazide wash by a wash with 0.1 M NH/sub 4/I in 12 M HCl. This is followed by neptunium elution with 6.5 M HCl containing 0.004 M HF. The method is applicable to the high salt samples from the Redox process as well as Purex process samples. (auth)
Neptunium
Nitric acid
PUREX
Human decontamination
Curium
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Tert-butyl hydroquinone (TBH) has been evaluated as a plutonium reductant for reprocessing and analytical applications. The effect of nitric acid concentration on plutonium reduction efficiency of TBH and its recycling are investigated under conditions prevailing in the uranium purification cycle of the PUREX process. A solvent extraction method has been developed for the separation of trace concentrations of uranium (3–30 µg/mL) from plutonium solution (10–12 mg/mL) obtained on dissolution of plutonium oxide in HNO3 containing traces of HF. The method involves the selective extraction of U(VI) with a mixed solvent comprising 1% trialkyl phosphine oxide (TRPO) + 1.1 M tri-n-butyl phosphate (TBP) + 0.4 M TBH solution in n-dodecane from 3 M HNO3–0.4 M N2H4, while reducing Pu(VI)/Pu(IV) to inextractable Pu(III) using salt-free reductants TBH (organic phase) and hydrazine (aqueous phase). A decontamination factor of ∽150 with respect to Pu has been achieved. This method has been adopted for routine analysis of uranium in PuO2 samples by Inductively Coupled Plasma–Atomic Emission Spectroscopy (ICP-AES).
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Nitric acid
Hydroquinone
Hydrazine (antidepressant)
Tributyl phosphate
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Abstract The effectiveness of the solvent wash reagents such as sodium carbonate and hydrazine carbonate were compared using the lean solvent obtained during reprocessing of high plutonium content fast reactor spent nuclear fuel. The concentrations of the reagents were optimized based on the removal of retained metal ions from the lean solvent and 1.5 M hydrazine carbonate was found to be optimal and superior to sodium carbonate to be adopted as the reagent for primary cleanup of the spent solvent. Both the reagents were found to possess excellent room temperature stability and their performance was not affected upon gamma irradiation which was assessed in terms of capacity to remove di-butyl phosphate from degraded TBP/n-DD system.
PUREX
Sodium carbonate
Hydrazine (antidepressant)
Carbonate Ion
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Practical procedures were demonstrated for partitioning plutonium from uranium in the Purex process with hydrazine-stabilized uranium(IV) nitrate as the reducing reagent for plutonium. Typical partitioning results were 0.04--0.2% loss of plutonium to the uranium product and less than 1 wt% uranium in the plutonium product. With uranium(IV) nitrate as a replacement for ferrous sulfamate, most solids in wastes from the Parex process can be eliminated. No undue hazard is expected from the use of hydrazine as the stabilizing agent. (auth)
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Hydrazine (antidepressant)
Transuranium element
Nuclear reprocessing
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The contaminated solvent from the Purex process is washed with alkaline detergents such as sodium carbonate, which generates a large amount of secondary wastes. Therefore, hydrazine carbonate as a salt-free reagent deserves to be studied in depth. In this study, the Ce(IV), U(VI), and Zr(IV) metal ions in organic phases containing dibutyl phosphate (HDBP) of 30% tributyl phosphate (TBP)–dodecane were washed with hydrazine carbonate. The effects of the oscillation time (1 to 15 min); temperature (25°C to 85°C); cumulative number of washes (one to four times); mass fraction of hydrazine carbonate (0.1% to 20%); volume ratio of the aqueous phase to the organic phase (0.2 to 5); HDBP concentration (0 to 0.4 M); HNO3 concentration (0.05 to 8 M); and concentration of Ce(IV), U(VI), and Zr(IV) metal ions on the removal percentages of Ce(IV), U(VI), and Zr(IV) metal ions in polluted solvents were studied. The results showed that when the organic phase containing 0.02 M HDBP was washed three times with 5% hydrazine carbonate at 25°C, the removal percentages of the Ce(IV), U(VI), and Zr(IV) ions were 96%, 98%, and 94%, respectively. Meanwhile, the retention concentrations of the three in the organic phase were 35, 28, and 78 mg/L, respectively. The increase of the mass fraction of hydrazine carbonate enhances the removal of the metal ions from the organic phase into the aqueous phase. High acid is not conducive to alkaline washing of metal ions. The increase of HDBP concentration not only promotes extraction but also increases the retention capacity of the organic phase and has the most significant effect on Zr(IV). U(VI) promotes the preferential washing of Zr(IV) while Ce(IV) increases the metal retention concentration of Zr(IV) in the organic phase.
PUREX
Sodium carbonate
Tributyl phosphate
Carbonate Ion
Ammonium carbonate
Hydrazine (antidepressant)
Nitric acid
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PUREX
Phosphoric acid
Dodecane
Sodium carbonate
Tributyl phosphate
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The reduction of Pu(IV) using photochemically generated U(IV) has been evaluated as a procedure for possible inclusion in the Savannah River Plant's nuclear fuel reprocessing facility. The ''Purex 2nd Uranium Cycle'' with feed conditions of 400 g/L U, 1 M HNO/sub 3/, and 10/sup -8/ to 10/sup -6/ M Pu was identified previously as the most promising stage for application of a photochemical method. Laboratory tests were conducted under similar conditions to determine if the plutonium could be successfully reduced and separated in a two-phase flowing system. The laboratory scale tests, which used primarily a 0.01 M butanol/0.01 M hydrazine reductant combination, demonstrated that reductive stripping of Pu(IV) using photochemically generated U(IV) is a practical method for removing plutonium from the organic phase. The kinetics of the reductive stripping procedure were found to be determined by the mixing rates of the organic and aqueous phases in this simple laboratory-scale system.
PUREX
Stripping (fiber)
Hydrazine (antidepressant)
Nuclear reprocessing
Transuranium element
Data scrubbing
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Hydrazine (antidepressant)
Transuranium element
Nuclear reprocessing
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ABS>Hot cell demonstration of the Zirflex decladding process coupled with a modified Purex solvent extraction process was completed using specimens of Zircaloy-clad UO/sub 2/ irradiated to levels of 6150-14,600 Mwd/TU. Soluble losses of uranium and plutonium to the decladding solutions were about 0.05%. Centrifugation of the decladding solution is probably necessary to remove up to 1% of the UO/sub 2/ present as fines resulting from the fracture of low (93 to 95%) density pellets; high (96%) density pellets produced few fines. Approximately 5 hours were required to dissolve the UO/sub 2/ core material (14,000 Mwd/TU) in 4M HNO/sub 3/ versus 6 to 7 hours for unirradiated pellets to produce a solvent extraction feed of 100 g U/l and 3M HNO/sub 3/. Gamma decontamination factors for uranium in the Purex CU stream and plutonium in the BP stream were increased by factors of 2 to 10 from the normal 1.3 x 10/sup 3/ and 2.1 x 10/sup 3/, respectively, by pretreatment of the solvent extraction feed with dincetyl monoxime or its degradation product, oxalic acid. Preliminary data indicate radiation damage degrades the solvent, 30% TBP diluted with Amsco 125- 82, upon one pass through the mixer-settler banks with feed solutions irradiated to levels greater than 12,000 Mwd/T causing a decrease in Zr Z'' test by a factor of 15. (nuth)
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Oxalic Acid
Nitric acid
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