Application of electrochemical methods to aqueous reprocessing of spent nuclear fuel

Kosyakov, V.N.; Marchenko, V. I.

doi:10.1134/s1066362208040012

Cited by 7 publications

(3 citation statements)

References 22 publications

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“…The reductant used in the key step of the PUREX DOI: 10.1134/S1066362215040050 process, separation of Pu and Np from U, is tetravalent uranium (either fed from the outside in the form of a nitric acid solution or generated electrochemically within the stripping apparatus [7]) in a mixture with hydrazine, and the agent used for reducing Pu in the step of its final purification is hydroxylamine existing in acidic aqueous solutions in the protonated form, NH 3 OH + . The drawbacks of the first reducing system are the presence of salt-forming hydrazine decomposing to form HN 3 and NH 4 NO 3 and large excess consumption of U(IV) due to its oxidation with nitrous acid in the solvent phase.…”

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Organic reductants of Pu and Np ions in wet technology for spent nuclear fuel reprocessing

Marchenko

Alekseenko²,

Dvoeglazov

2015

Radiochemistry

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Scientific, technical, and patent information on the use of organic compounds as reductants of Pu and Np ions in wet technology for spent nuclear fuel reprocessing is summarized and correlated. Organic derivatives of hydrazine and hydroxylamine, and also oximes and urea derivatives at relatively low acidities and temperatures reduce Np(VI) to Np(V) and Pu(IV) to Pu(III). As the acidity and temperature are increased, Np(V) is slowly reduced to Np(IV). Alcohols, aldehydes, hydrocarbons, and acetic acid were identified among products of oxidation of the organic compounds in nitric acid medium. The above-named organic reductants can be used in different steps of the PUREX process: separation of Pu and Np from U in the first extraction cycle, purification of U to remove Np in the second cycle of uranium purification, and Pu stripping in the step of its final purification. Laboratory experiments performed on countercurrent extraction installations of mixersettlers and of centrifugal contactors demonstrated the possibility of reaching high separation factors of U from Pu and/or Np and high degrees of plutonium concentration to obtain Pu strips containing up to 150 g L -1 Pu.

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Organic reductants of Pu and Np ions in wet technology for spent nuclear fuel reprocessing

Marchenko

Alekseenko²,

Dvoeglazov

2015

Radiochemistry

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“…Recent research has focused on this process by using electrochemical methods to control the oxidation state of elements in reprocessing. Electrochemical methods are used because they do not require any special reagents and the electrolysis potential can be controlled precisely and easily [7]. To prepare 2AF feed using electrochemical methods, organic reagents (DMHAN and MMH) contained in 1BP solution need to be electrolyzed first and second the oxidation states of plutonium and neptunium need to be adjusted.…”

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confidence: 99%

Adjustment of valence state of Pu and Np in nitric solution containing N,N-dimethylhydroxylamine and monomethylhydrazine by electrolysis

Zhang¹,

Guoan²,

Cong³

et al. 2012

Radiochimica Acta

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A study of the electrochemical behaviors of N,N-dimethylhydroxylamine (DMHAN) and monomethyl hydrazine (MMH) in nitric acid solution on Pt electrodes were carried out by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) methods. The diffusion coefficients of DMHAN and MMH were obtained by CV. The values are found to be 0.53 × 10 −6 cm 2 /s D (DMHAN) and 0.88 × 10 −5 cm 2 /s D (MMH) . The equilibrium potentials ( + 0.47 V vs. SCE for DMHAN and + 0.31 V vs. SCE for MMH) were also measured using Tafel curves. Various valence states of Pu and Np in HNO 3 solution containing DMHAN and MMH in the electrolytic process were investigated by an electrolytic cell using a platinum as the anode and a titanium plate as the cathode. In this procedure, MMH was first electrooxidized on the Pt anode and Np(V) was reduced to Np(IV) on the Ti cathode. After MMH was entirely consumed, the accumulation of HNO 2 (due to the electrochemical reduction of nitric acid on the Ti cathode) caused a significantly fast catalytic reaction of DMHAN with HNO 3 to form HNO 2 . HNO 2 can oxidize Pu(III) to Pu(IV) quickly. As a result, both oxidation states of Pu and Np were found to be tetravalent in the post-electrolysis solution. A convenient method to keep the post-electrolysis solution at 70 • C was used to adjust the oxidation state of Np in it's pentavalent state while retaining the tetravalent state of Pu. This study developed an electrolytic process for the preparation of 2AF feed (the feed of Pu purification cycle) in APOR (Advanced Purex Process Based on Organic Reductants) process by electrochemically oxidizing Pu(III) and selectively adjusting the valence state of neptunium to either Np(IV) or Np(V).

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“…The majority of papers concerning redox reactions that involve Np(VI) ions deal with oxidation or reduction of Np(VI) with chemical reagents [1,2], by electrochemical method [3], or with radiolysis products [4,5]. All the above redox reactions were mainly studied in solutions of perchloric and nitric acids, alkalis, carbonates, and bicarbonates.…”

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Behavior of Np(VI) in HNO3 solutions containing potassium phosphotungstate K10P2W17O61

et al. 2012

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Application of electrochemical methods to aqueous reprocessing of spent nuclear fuel

Cited by 7 publications

References 22 publications

Organic reductants of Pu and Np ions in wet technology for spent nuclear fuel reprocessing

Organic reductants of Pu and Np ions in wet technology for spent nuclear fuel reprocessing

Adjustment of valence state of Pu and Np in nitric solution containing N,N-dimethylhydroxylamine and monomethylhydrazine by electrolysis

Behavior of Np(VI) in HNO3 solutions containing potassium phosphotungstate K10P2W17O61

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