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Preparation of Ceramic-Grade Thorium-Uranium Oxide; Preparation d'un melange d'oxydes de thorium et d'uranium propre a la fabrication de combustible ceramique; Izgotovlenie keramicheskogo torievo-uranovogo okisla; Preparacion de mezclas de oxidos de uranio y torio, de tipo ceramico

Conference:

Abstract

A method for the preparation of sintered bodies of thorium-uranium mixed oxide starting from a solution of thorium nitrate and uranyl nitrate was investigated. This method can be useful both in the fabrication of fuel elements and in the reprocessing of such type of materials. In the first step of the method, uranyl nitrate is reduced to uranium (IV) nitrate. As reducing agent, both gaseous hydrogen and formic acid are employed; urea is added to prevent the formation of nitrous acid, which catalyses the reoxidation of uranium (IV). As catalyst, both platinum and palladium can be employed. Data are given for a continuous process, in which formic acid and urea are added to the solution, which is then pre-heated and passed in a column packed with 1/8 in x 1/8 in alumina pellets, carrying 0.5 wt.% of platinum. The influence of flow rate, temperature, formic acid and urea concentration, as well as catalyst life and poisoning are studied. The second step in the method is the precipitation of an oxalate of thorium and uranium (IV). The influence of oxalic acid to thorium-uranium ratio, temperature, aging time on settling and filtering characteristics of the precipitate and on the ceramic properties of  More>>
Authors:
Cogliati, G.; De Leone, R.; Ferrari, S.; Gabaglio, M.; Liscia, A. [1] 
  1. Centro Studi Nucleari della Casaccia, Rome (Italy)
Publication Date:
Nov 15, 1963
Product Type:
Conference
Resource Relation:
Conference: Conference on New Nuclear Materials Technology, Including Non Metallic Fuel Elements, Prague (Czech Republic), 1-5 Jul 1963; Other Information: 17 figs., 2 tabs., 6 refs.; Related Information: In: New Nuclear Materials Including Non Metallic Fuel Elements. Vol. I. Proceedings of the Conference on New Nuclear Materials Technology, Including Non Metallic Fuel Elements| 582 p.
Subject:
36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; AGING; ALUMINIUM OXIDES; CATALYSTS; COLD PRESSING; DENSITY; FLOW RATE; FUEL ELEMENTS; ISOTOPE RATIO; NITROUS ACID; PALLADIUM; PLATINUM; POWDERS; SINTERING; TEMPERATURE DEPENDENCE; THORIUM; THORIUM NITRATES; THORIUM OXIDES; URANIUM OXIDES; URANYL NITRATES; UREA
OSTI ID:
22117378
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA13R0429073999
Submitting Site:
INIS
Size:
page(s) 37-53
Announcement Date:
Aug 01, 2013

Conference:

Citation Formats

Cogliati, G., De Leone, R., Ferrari, S., Gabaglio, M., and Liscia, A. Preparation of Ceramic-Grade Thorium-Uranium Oxide; Preparation d'un melange d'oxydes de thorium et d'uranium propre a la fabrication de combustible ceramique; Izgotovlenie keramicheskogo torievo-uranovogo okisla; Preparacion de mezclas de oxidos de uranio y torio, de tipo ceramico. IAEA: N. p., 1963. Web.
Cogliati, G., De Leone, R., Ferrari, S., Gabaglio, M., & Liscia, A. Preparation of Ceramic-Grade Thorium-Uranium Oxide; Preparation d'un melange d'oxydes de thorium et d'uranium propre a la fabrication de combustible ceramique; Izgotovlenie keramicheskogo torievo-uranovogo okisla; Preparacion de mezclas de oxidos de uranio y torio, de tipo ceramico. IAEA.
Cogliati, G., De Leone, R., Ferrari, S., Gabaglio, M., and Liscia, A. 1963. "Preparation of Ceramic-Grade Thorium-Uranium Oxide; Preparation d'un melange d'oxydes de thorium et d'uranium propre a la fabrication de combustible ceramique; Izgotovlenie keramicheskogo torievo-uranovogo okisla; Preparacion de mezclas de oxidos de uranio y torio, de tipo ceramico." IAEA.
@misc{etde_22117378,
title = {Preparation of Ceramic-Grade Thorium-Uranium Oxide; Preparation d'un melange d'oxydes de thorium et d'uranium propre a la fabrication de combustible ceramique; Izgotovlenie keramicheskogo torievo-uranovogo okisla; Preparacion de mezclas de oxidos de uranio y torio, de tipo ceramico}
author = {Cogliati, G., De Leone, R., Ferrari, S., Gabaglio, M., and Liscia, A.}
abstractNote = {A method for the preparation of sintered bodies of thorium-uranium mixed oxide starting from a solution of thorium nitrate and uranyl nitrate was investigated. This method can be useful both in the fabrication of fuel elements and in the reprocessing of such type of materials. In the first step of the method, uranyl nitrate is reduced to uranium (IV) nitrate. As reducing agent, both gaseous hydrogen and formic acid are employed; urea is added to prevent the formation of nitrous acid, which catalyses the reoxidation of uranium (IV). As catalyst, both platinum and palladium can be employed. Data are given for a continuous process, in which formic acid and urea are added to the solution, which is then pre-heated and passed in a column packed with 1/8 in x 1/8 in alumina pellets, carrying 0.5 wt.% of platinum. The influence of flow rate, temperature, formic acid and urea concentration, as well as catalyst life and poisoning are studied. The second step in the method is the precipitation of an oxalate of thorium and uranium (IV). The influence of oxalic acid to thorium-uranium ratio, temperature, aging time on settling and filtering characteristics of the precipitate and on the ceramic properties of the obtained powders is reported. Firing was carried out both in reducing and oxidizing atmosphere. After preliminary tests, two standard procedures were set up for the fabrication of ceramic bodies, namely by cold pressing and sintering and by extrusion and sintering. The ability of the different powders to sinter was tested by both of the two standard methods. With some of the powders, densities higher than 95% of theoretical density were obtained; reproducibility tests were successfully carried out. (author) [French] Les auteurs etudient une methode de preparation de melanges frittes d'oxydes de thorium et d'uranium a partir d'une solution de nitrate de thorium et de nitrate d'uranyle. Cette methode peut etre utile auessi bien pour la fabrication d'elements combustibles que pour le recyclage de matieres de ce genre. Le procede consiste tout d'abord a reduire le nitrate d'uranyle en nitrate d'uranium (IV). On utilise comme agents reducteurs de l'hydrogene gazeux et de l'acide formique; on ajoute de l'uree pour prevenir la formation d'acide nitreux qui catalyse la reoxydation de l'uranium (IV). On peut employer comme catalyseurs le platine et le palladium. Les auteurs donnent des indications sur un processus continu au cours duquel on ajoute de l'acide formique et de l'uree a la solution qui est ensuite rechauffee avant d' etre passee dans une colonne remplie de.pastilles d'a lumine de 3,17 x 3,17 mm contenant 0,5% en poids de platine. Ils fournissent egalement des renseignements sur l'influence du debit, de la temperature et de la concentration de l'acide formique et de l'uree, ainsi que sur la duree de vie du catalyseur et l'empoisonnement. La precipitation d'un oxalate de thorium et d'uranium(IV) constitue la deuxieme phase. Les auteurs mentionnent l'influence de l'acide oxalique sur le rapport thorium/uranium, ainsi que ce l le de la temperature et du vieillissement surtles caracteristiques de la precipitation et du filtrage et sur les proprietes ceramiques des poudres obtenues. La mise a feu a ete faite dans une atmosphere reductrice et dans une atmosphere oxydante. Ces essais preliminaires ont abouti a la mise au point de deux methodes normalisees pour la fabrication d'elements ceramiques, a savoir la methode du pressage a froid puis frittage et la methode par extrusion et frittage. L'aptitude au frittage des differentes poudres a fait l'objet d'essais selon les deux methodes susmentionnees. Avec certaines des poudres, on a obtenu des densites depassant 95% de la valeur theorique; des essais de reproductibilite ont ete concluants. (author) [Spanish] Los autores han estudiado un metodo para preparar cuerpos sinterizados, compuestos por una mezcla de oxido de torio y uranio, a partir de una solucion de nitrato de torio y de nitrato de uranilo. Este metodo puede ser de utilidad para la elaboracion de elementos combustibles y para la regeneracion de los mismos. En la primera fase del metodo, el nitrato de uranilo se reduce a nitrato de uranio (IV). Como agente reductor se emplea acido formico e hidrogeno gaseoso; se anade urea para impedir la formacion de acido nitroso, que cataliza la reoxidacion del uranio (IV). En calidad de catalizadores pueden emplearse platino y paladio. Se facilitan datos relativos a un proceso continuo, en el que el acido formico y la urea se afladan a la solucion, que seguidamente se precalienta y se hace pasar a traves de una columna rellena de pastillas de alumina de 3,17 x 3,17 mm, que contienen 0,5% en peso de platino. Se estudia la influencia de la velocidad de circulacion, temperatura, concentraciones de acido formico y de urea, asi como la duracion y el envenenamiento del catalizador. La segunda fase del metodo consiste en la precipitacion de oxalato de torio y uranio (IV). Se estudia la influencia de la razon acido oxalico torio-uranio, de la temperatura y del tiempo de envejecimiento sobre las caracteristicas de sedimentacion y de filtracion del precipitado y sobre las propiedades ceramicas de los polvos obtenidos. El calentamiento se ha efectuado tanto en atmosfera reductora como oxidante. Luego de ensayos preliminares, se han establecido dos procedimientos normales para la elaboracion de cuerpos ceramicos, a saber, por prensado en frio y sinterizacion y por extrusion y sinterizacion. Las propiedades de sinterizacion de los diferentes polvos se han ensayado por los dos procedimientos normales. Con algunos de los polvos se han obtenido densidades superiores al 95% del valor teorico; se han realizado con exito ensayos de reproductibilidad. (author) [Russian] Issledovan protsess izgotovleniya spechennykh izdelij iz smesi torievo-uranovykh okislov, nachinayushchijsya s rastvoreniya nitrata toriya i nitrata uranila. Ehtot protsess mozhet okazat'sya poleznym kak dlya izgotovleniya toplivnykh ehlementov, tak i dlya regeneratsii materialov takogo roda. Na pervoj stadii protsessa nitrat uranila vosstanavlivaetsya do nitrata urana (IV). V kachestve vosstanovitelya ispol'zuyutsya kak gazoobraznyj vodorod, tak i murav'inaya kislota; mochevina dobavlyaetsya dlya predotvrashcheniya obrazovaniya azotistoj kisloty, kotoraya uskoryaet povtornoe okislenie urana (IV). V kachestve katalizatora mogut primenyat'sya platina i palladij. Privodyatsya dannye dlya nepreryvnogo protsessa, v kotorom murav'inaya kislota i mochevina dobavlyayutsya k rastvoru, poslednij zatem podogrevaetsya i podaetsya v kolonku, zapolnennuyu alyuminievymi tabletkami razmerom 3,87 x 3,17 mm, 0,5% kotorykh sostavlyaet platina. Izucheny vliyaniya skorosti potoka, temperatury, kontsentratsii murav'inoj kisloty i mocheviny, a takzhe prodolzhitel'nost' sluzhby i otravlenie katalizatora. Vtoraya stadiya protsessa zaklyuchaetsya v osazhdenii oksalato'v toriya i urana (IV). Opisyvaetsya vliyanie shchavelevoj kisloty na otnoshenie torij/uran, temperatury i vremeni stareniya na otstaivanie i fil'tratsionnye kharakteristiki osadka i na keramicheskie svojstva poluchennykh poroshkov. Prokalka proizvodilas' kak v vosstanovitel'noj, tak i v okislitel'noj atmosferakh. Posle predvaritel'nykh ispytanij byli prinyaty dva standartnykh metoda izgotovleniya keramicheskikh izdelij, a imenno: kholodnaya pressovka i spekanie, ehkstruziya i spekanie. Spekaemost' razlichnykh poroshkov byla ispytana s pomoshch'yu ehtikh oboikh standartnykh metodov. S nekotorymi poroshkami byli polucheny plotnosti svyshe 95% teoreticheski dopustimoj. Uspeshno byli provedeny ispytaniya na vosproizvodimost'. (author)}
place = {IAEA}
year = {1963}
month = {Nov}
}