Reactions of the Uranium Carbides with Nitric Acid<sup>1</sup>

Ferris, L.M.; Bradley, Mildred J.

doi:10.1021/ja01086a016

Cited by 43 publications

(20 citation statements)

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“…We were unable to separate and detect mellitic acid by IC and CE methods as they exhibited strong retentions. We could not detect benzoic acid by either IC or CE confirming similar reported observations [32]. Further efforts were not made to detect the presence/absence of aromatic acids or soluble spieces in the pyrohydrolysis distillate.…”

Section: Formation Of Organic Acids During Pyrohydrolysissupporting

confidence: 89%

“…The reaction between UC and 6 M HNO 3 has been reported, which describes that significant amounts of mellitic and oxalic acids were found among the reaction products [31]. However, a capillary electrophoresis separation of a dissolver solution of uranium carbide in nitric acid ensured the presence of oxalic acid whereas it could not detect any mellitic, trimellitic and benzoate anions in the dissolver solution [32]. Based on (i) the retention times of organic acid anions during IC separation from literature, (ii) the various hydrocarbons evolved during hydrolysis and (iii) the organic acids formed during reaction with acids, it was intended to consider the separation of chloride, fluoride, other common anions along with the anions of formic, acetic, propionic, butyric, oxalic, succinic, benzoic, tartaric, citric and mellitic acids with a view to identify the organic acids from the sample chromatogram.…”

Section: Selection Of Organic Acidsmentioning

confidence: 99%

“…The CE method reported for the analysis of dissolver solution of UC in nitric acid was not followed because the method was mainly used for separating oxalic, benzoic and mellitic acids along with uranium and no attempt was made to detect organic acids such as formic, acetic etc. [32]. Since the present study is focused on identification of lower organic acids (formic to butyric acids) which are expected to have close retention factors compared to that of chloride and fluoride ions.…”

Section: Capillary Electrophoresis (Ce) Separationmentioning

confidence: 99%

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Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

et al. 2014

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Identification of various soluble organic acids formed during the pyrohydrolysis of uranium-plutonium mixed carbide [(U,Pu)C] was carried out using ion chromatography. This has significant importance as the soluble organic acids can cause severe interferences during the ion chromatography separation and determination of Cl − and F − in the pyrohydrolysis distillate of (U,Pu)C. Determination of Cl and F is important in the chemical quality control of nuclear materials as these two elements can cause corrosion and hence, their concentrations in all nuclear materials are restricted to certain specified values. Since the pyrohydrolysis distillates contain both inorganic and organic acid anions, for the sake of separating and identifying organic acid anions from the common inorganic anions, three independent isocratic elutions using varying concentrations of NaOH eluent were employed for the separation of weakly, moderately and strongly retained anions. It was observed that pyrohydrolysis of (U,Pu)C also produced soluble organic acids as in the case of nitric acid dissolution of UC. The present investigation revealed the presence of formic, acetic, propionic, butyric, oxalic acid anions in the pyrohydrolysis distillate of (U,Pu)C in trace or ultra-trace concentrations. The presence of each organic acid identified in the chromatogram was confirmed with spike addition as well as by separating them by capillary electrophoresis method. The presence of lower aliphatic acids viz. formic and acetic acids was reconfirmed by carrying out an independent separation with tetraborate eluent. It is suggested that nitric acid being formed during pyrohydrolysis could be responsible for the formation of organic acids. Based on the findings, an ion chromatography separation method has been proposed for the interferencefree determination of chloride and fluoride in pyrohydrolysis distillate of (U,Pu)C.

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Section: Formation Of Organic Acids During Pyrohydrolysissupporting

confidence: 89%

Section: Selection Of Organic Acidsmentioning

confidence: 99%

Section: Capillary Electrophoresis (Ce) Separationmentioning

confidence: 99%

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Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

et al. 2014

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“…These organics, in particular carboxylic and mellitic acid [5,6], can then complex the uranium and plutonium ions in the resulting solution making their extraction significantly less effective and consequently wasting valuable fissile material. Therefore, in order for carbide fuels to be reprocessed in the same manner as oxide fuels, and hence be simpler and less expensive to introduce, the problem of organics in solution must be addressed.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Shepherd

Fairweather

Heggs

et al. 2015

Computers & Chemical Engineering

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Uranium carbide is a candidate fuel for future nuclear reactors. However, for it to be implemented in a closed fuel cycle, an outline for its reprocessing is necessary. One proposed method is to oxidise the uranium carbide into uranium oxide which can then be reprocessed using current infrastructure. A mathematical model describing the heat and mass transfer processes involved in such an oxidation has been constructed. The available literature was consulted for reaction coefficients and information on reaction products. A stable and convergent numerical solution has been developed using a combination of finitedifference approximations of the differential equations. Completion times of approximately 3-30 hours are predicted given a spherical pellet with a radius of 9.35 under varying initial conditions. The transient temperature distribution throughout the system is predicted, with a maximum temperature of 1458° observed from an initial temperature of 500° at an oxygen concentration of 3.15 .

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“…He suggested that the direct dissolution of carbide fuels may serve as the best head-end step to get a suitable feed solution for solvent extraction. However, the direct dissolution of the carbides yields, apart from carbon dioxide, a host of organic compounds including oxalic acid and mellitic acid, which affect the extraction of plutonium into TBP [2,3]. Additional steps are therefore required to destroy these organic species.…”

Section: Introductionmentioning

confidence: 99%

Chemical Head-end Steps for Aqueous Reprocessing of Carbide Fuels

1990

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The organic compounds formed during the dissolution of carbide fuels in nitric acid adversely affect the extraction of plutonium by tributyl phosphate. This work was undertaken as a preliminary study of the effect of refluxing the dissolver solutions obtained by dissolution of uranium carbide in 13 Μ nitric acid on the subsequent solvent extractions steps. The extraction of plutonium from carbide dissolver solutions by 30% TBP in ndodecane and the subsequent stripping and partitioning of Pu from the organic phase loaded with uranium and plutonium were studied. The results obtained were compared with those obtained with control solutions containing uranyl nitrate and plutonium(IV) nitrate with concentrations of uranium, plutonium and nitric acid similar to those of the dissolver solutions. The distribution ratios obtained with the dissolver solution and the control solution were comparable, indicating that the dissolver solution obtained after refluxing for 20h may give a feed solution suitable for PUREX process. Similarly, extraction and partitioning experiments were carried out with (U, Pu)C dissolver solutions and the results were similar to the results obtained with uranium carbide dissolver solutions.As an alternative chemical route for the destruction of carbonaceous materials in the UC dissolver solution, the effectiveness of sodium dichromate as an oxidizing agent was also investigated in terms of the percentage carbon remaining after treatment of the dissolver solution with sodium dichromate. The treatment resulted in destruction of nearly 97% of the initial carbon present in the carbide fuel.

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Reactions of the Uranium Carbides with Nitric Acid¹

Cited by 43 publications

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Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Chemical Head-end Steps for Aqueous Reprocessing of Carbide Fuels

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Reactions of the Uranium Carbides with Nitric Acid1

Cited by 43 publications

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Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

Study on the identification of organic and common anions in the pyrohydrolysis distillate of mixed uranium-plutonium carbide for the interference free determination of chlorine and fluorine by ion chromatography

Mathematical modelling of the pre-oxidation of a uranium carbide fuel pellet

Chemical Head-end Steps for Aqueous Reprocessing of Carbide Fuels

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Reactions of the Uranium Carbides with Nitric Acid¹