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Dugua, Jacques.
Ugine-Kuhlmann, 75 - Paris (France)1980
Ugine-Kuhlmann, 75 - Paris (France)1980
AbstractAbstract
[en] Preparation of ammonium diuranate easy to handle with spherical grains of mean diameter between 40 to 100 microns, of unpressed apparent specific weight between 2 to 2.8 g/cm3 and with a SO4 ion content between 0.5 to 1 %. It is obtained by reaction of uranyl sulfate on ammonia and precipitation at a pH value between 6.6 to 7.2
[fr]
Preparation de diuranate d'ammonium de manutention aisee forme de grains spheriques de diametre moyen 40 a 50 microns, de masse volumique apparente de 2 a 2,8 g/cm3 (pour la poudre non tassee) avec un taux en ions SO4 compris entre 0,5 et 1%. Il est obtenu par action de l'ammoniaque sur le sulfate d'uranyle et precipitation de la solution sursaturee a un pH compris entre 6,6 et 7,2Original Title
Uranate d'ammonium sous forme de particules spheriques ayant une bonne coulabilite et son procede d'obtention
Primary Subject
Source
19 Dec 1980; 10 p; FR PATENT DOCUMENT 2457257/A/; Available from Institut National de la Propriete Industrielle, Paris (France)
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Patent
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Fuller, R.R.
Westinghouse Electric Corp., Pittsburgh, Pa. (USA)1974
Westinghouse Electric Corp., Pittsburgh, Pa. (USA)1974
AbstractAbstract
[en] The invention discloses a method for the continuous manufacture of ammonium diuranate (ADU) from ammonium hexafluoride (UF6) and its conversion to uranium dioxide (UO2) through calcination. The method is characterized by the following steps: dissolving UF6 in water with the formation of UO2F2 and HF; partially neutralizing the aqueous solution by concentrated NH4OH; transferring the partially neutralized solution into a precipitation vessel; adding concentratred NH4OH for precipitating ADU (by injecting a suspension of the precipitate, large-area ADU-particles are obtained); continuously drawing off about 10% of the suspension for preparing, by eliminating water, a slurry comprising at least 35% of ADU, by weight; ADU is used for manufacturing UO2 fuel pellets
[fr]
Cette invention decrit un procede pour la fabrication en continu du diuranate d'ammonium (ADU) a partir de l'hexafluorure d'ammonium (UF6) et sa conversion par calcination en UO2. Le procede est caracterise par les etapes suivantes: dissolution d'UF6 dans l'eau avec formation de UO2F2 et HF; neutralisation partielle de la solution aqueuse par NH4OH concentre; transfert de la solution partiellement neutralisee dans un recipient de precipitation; adjonction de NH4OH concentre provoquant la precipitation de l'ADU; par l'injection d'une suspension du precipite on obtient la formation de particules d'ADU de grande surface; soutirage en continu d'environ 10% de la suspension pour preparer par elimination d'eau, une boue comprenant au moins 35% en poids d'ADU. L'ADU est utilise pour la fabrication de pastille de combustible UO2Original Title
Ameliorations de ou relatives a la production de diuranate d'ammonium pour conversion an dioxyde d'uranium; manufacture of uranium dioxide pellets
Primary Subject
Source
21 Jun 1974; 15 p; FR PATENT DOCUMENT 2234230/A/; Available from Institut National de la Propriete Industrielle, Paris (France); priority claim: 22 Jun 1973, USA.
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Patent
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Kraikaew, J.; Srinyawach, C.; Suparith, N.
Proceedings of the 6th nuclear science and technology conference1996
Proceedings of the 6th nuclear science and technology conference1996
AbstractAbstract
[en] One of the products from Monazite ore processing is yellow cake which is Ammonium diuranate with thorium impurity. Continuous liquid-liquid extraction in laboratory scale was simulated to purify uranium by scrubbing thorium using various scrub solutions and flow ratios. The results indicated that the uranium extraction efficiency at flow ratio (solvent : feed) of 3:2 and 6 stage numbers is higher than 99.8 percents. The thorium scrub efficiency is higher than 80 percents when 52,950 ppm uranyl nitrate is used as scrub solution at flow ratio (feed : scrub solution) of 7:1 and 4 stage numbers
Primary Subject
Source
Office of Atomic Energy for Peace, Bangkok (Thailand); 761 p; Dec 1996; [14 p.]; 6. Conference on Nuclear Science and Technology; Bangkok (Thailand); 2-4 Dec 1996; ALSO AVAILABLE FROM OFFICE OF ATOMIC ENERGY FOR PEACE, BANGKOK (THAILAND)
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Miscellaneous
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Conference; Numerical Data
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Paik, Shrishma; Bhattacharya, S.; Biswas, S.; Roy, S.B., E-mail: shrishma@barc.gov.in
Proceedings of DAE-BRNS biennial symposium on emerging trends in separation science and technology2012
Proceedings of DAE-BRNS biennial symposium on emerging trends in separation science and technology2012
AbstractAbstract
[en] The ammonium nitrate bearing effluent after ADU precipitation can be recycled as strippant in the stripping process of solvent extraction during uranium refining process. The nature of stripping of uranium with various concentration of ammonium nitrate as strippant was studied experimentally and a suitable theoretical model developed for the estimation of Distribution coefficient. The theoretical values of equilibrium constant distribution coefficient was estimated after employing the correction factors due to the activity coefficients each species at higher ionic strength. The activity coefficients of salts in aqueous solution were estimated the correlations developed by 'Bromley' for activity coefficients of multiple salt solutions. The model equations were developed by the mass balance of uranium at equilibrium for biphasic system. Solubility of TBP in water is not considered in the equation so developed. Also the model does not take into account for the ideality of organic phase
Primary Subject
Source
Pathak, P.N.; Mohapatra, P.K.; Goswami, A. (Radiochemistry Div., Bhabha Atomic Research Centre, Mumbai (India)) (eds.); Sawant, R.M.; Ramakumar, K.L. (Radioanalytical Chemistry Div., Bhabha Atomic Research Centre, Mumbai (India)) (eds.); Board of Research in Nuclear Sciences, Department of Atomic Energy, Mumbai (India); S.V.K.M. Mithibai College, Mumbai (India); 274 p; 2012; p. 124; SESTEC-2012: 5. DAE-BRNS biennial symposium on emerging trends in separation science and technology; Mumbai (India); 27 Feb - 1 Mar 2012; 3 refs.
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Book
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Conference
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AbstractAbstract
[en] The final quality of a sintered ceramic depends on starting powder characteristics, forming and firing conditions. The powder characteristics are, in turn, dependent on the characteristics of the precursor from which the powder is obtained by thermal decomposition. The precursor precipitate ammonium diuranate is dried, calcined and reduced at specific temperatures and heating rates to yield UO2 powder. The final acceptance of sintered UO2 has been found to be high with a combination of a low precipitation temperature, intermediate precipitate aging, precipitate washing and controlled thermal decomposition that would not only preserve precursor morphology, but also develop sufficient porosity. These conditions yield agglomerate-free soft powders that do not require milling or binder addition before compaction. The powders, after granulation, pack well in compaction and yield homogeneous high density microstructures on sintering. (UK)
Primary Subject
Source
British Nuclear Energy Society, London (United Kingdom); British Nuclear Industry Forum, London (United Kingdom); Institution of Civil Engineers, London (United Kingdom); Institution of Mechanical Engineers, London (United Kingdom); Institution of Chemical Engineers, London (United Kingdom); Institution of Electrical Engineers, London (United Kingdom); 292 p; ISBN 0 7277 2619 6;
; 1997; p. 5.284-5.292; Thomas Telford Publishing; London (United Kingdom); TopFuel '97 conference; Manchester (United Kingdom); 9-11 Jun 1997

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Book
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AbstractAbstract
No abstract available
Original Title
Recuperacao de uranio de lixivias cloridricas do fosforito do Nordeste
Primary Subject
Source
Associacao Brasileira de Quimica, Rio de Janeiro; 178 p; 1985; p. 161; 26. Brazilian Congress on Chemistry; Fortaleza, CE (Brazil); 6-11 Oct 1985; Published in summary form only.
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Miscellaneous
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Conference
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AbstractAbstract
[en] Published in summary form only
Original Title
Precipitacao seletiva de uranio com hidroxido de amonio e em presenca do EDTA
Primary Subject
Source
Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil); 279 p; 1984; p. 170
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Miscellaneous
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Kraikaew, J.; Yacumpai, O.; Pruantonsai, P.
Proceedings of the 5th nuclear science and technology conference1994
Proceedings of the 5th nuclear science and technology conference1994
AbstractAbstract
[en] This study was carried out in order to select the optimum conditions for ammonium diuranate (ADU) precipitation to obtain high density uranium dioxide. The data were collected for ADU precipitation reactor design. The precipitation temperature was controlled at 500C. The stirrer speeds are 5.9 and 7.1 Hz. The properties namely : specific filtration resistance, initial settling rate and agglomerate size of ADU precipitates obtained at various pH were investigated. The results indicated that when the pH of precipitation increases, specific filtration resistance increases but ADU agglomerate size decreases and causing difficulty in filtration
Primary Subject
Source
Office of Atomic Energy for Peace, Bangkok (Thailand); 514 p; ISBN 974-7400-06-5;
; Nov 1994; p. B110-B124; 5. conference on nuclear science and technology; Bangkok (Thailand); 21-23 Nov 1994

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Miscellaneous
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Conference; Numerical Data
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Ramana Rao, S.V.; Pramanik, D.; Mistry, R.K.; Ramana Rao, A.V., E-mail: svrr@nfc.gov.in
Proceedings of the third international conference on characterization and quality control of nuclear fuels2009
Proceedings of the third international conference on characterization and quality control of nuclear fuels2009
AbstractAbstract
[en] The quality of sintered UO_2 fuel pellets, in terms of density and pore size distribution is influenced to a large extent by the method of powder preparation and associated thermal treatment. The microstructure of a Uranium dioxide pellet is directly the result of the different transport mechanisms, some of which are efficient at lower temperatures while others need high temperatures. In addition uniformity and homogeneity of particle packing in the green body has an enormous impact on how well the green body will densify during sintering. Nuclear grade uranium dioxide powders are prepared, pressed and sintered to yield pellets of high density and homogeneous microstructure. UO_2 powder used in this study is produced by ADU route. The green pellets are sintered at various temperatures starting from,1173 °K to 1973°K. All the sintering tests were performed in reducing atmosphere in high temperature dilatometer. Temp vs. dimensional shrinkage plots were obtained from dilatometric studies for all the pellets. Data obtained thus were analysed using different methods to find out the kinetics and microstructural changes occurring during the sintering process. Microstructural observations helped in correlating reasons for some of the low density pellets in the production lots
Primary Subject
Source
Nuclear Fuel Complex, Hyderabad (India); International Atomic Energy Agency, Vienna (International Atomic Energy Agency (IAEA)); Board of Research in Nuclear Sciences, Mumbai (India); 186 p; 2009; 2 p; CQCNF-2009: 3. international conference on characterization and quality control of nuclear fuels; Hyderabad (India); 18-20 Feb 2009
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Book
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Conference
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Neto, R.M.L.
Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)1989
Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)1989
AbstractAbstract
[en] Three preparation methods of high-density U3O8 powder have been studied: grinding of sintered U3O8 pellets, sintering of calcined U3O8 granules; and sintering of ammonium diuranate (ADU) granules. Experiments have been carried out varying ADU calcination time and temperature as well as sintering time, yielding ten U3O8 batches. Powder characteristics, granulometric yield, and number of process steps have been taken into account for comparison purposes. Impurity content, specific surface area, stoichiometry, morphology, density, porosity distribution and phase identification have been considered as parameters for powder characterization. The main conclusions show that the second method (following a 6000C/3h ADU calcination) gives the best results. Moreover, the third method gives also good results, but there were some difficulties with ADU handling. (author)
[pt]
Tres metodos de obtencao de po de U3O8 de alta densidade foram estudados: trituracao de pastilhas sinterizadas de U3O8; sinterizacao de granulos de U3O8 calcinado; e sinterizacao de granulos de diuranato de amonio (DUA). Testes foram conduzidos variando-se a temperatura e o tempo de calcinacao do DUA, bem como o tempo de sinterizacao, resultando em dez lotes de U3O8. Os processos foram comparados em termos de caracteristicas dos pos obtidos, rendimento granulometrico e numero de etapas. O teor de impurezas, a area de superficie especifica, a estequiometria, a morfologia, a densidade, a distribuicao de porosidade e a identificacao de fases foram considerados como parametros de caracterizacao dos pos. As principais conclusoes mostraram que o segundo metodo (no qual o DUA foi calcinado a 6000C por 3h) forneceu os melhores resultados. Alem disso, o terceiro metodo tambem produziu bons resultados, porem com dificuldades de manuseio da DUA. (autor)Original Title
Estudo de processos de obtencao de po de U3O8 empregado em elementos combustiveis do tipo MTR
Primary Subject
Source
1989; 151 p; Tese (M.Sc.).
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Miscellaneous
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Thesis/Dissertation
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