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[en] 'Existing plant flowsheets are insufficient for complete dissolution of unirradiated Mark 42 targets. One option being considered by Nuclear Materials Stabilization and Storage (NMSS) is to dissolve the aluminum components of the Mark 42 targets, allow plutonium solids to settle, transfer some of the aluminum-laden liquid out of the dissolver tank, and recharge the dissolver tank with fresh solution to achieve dissolution of the plutonium solids. The core problem associated with this two-step dissolution procedure is that, after the initial digestion of Mark 42 material, one to two micron-sized PuO2 particles settle from the mixture. Those particles are of concern because they may generate additional nuclear criticality safety requirements, and because they may be transferred out of the dissolver tank and disrupt the efficacy of downstream processes, such as solvent extraction. NMSS asked the Chemical Technology Group (CTG) to evaluate a decanting process in the presence of settled micron-sized particles using a one-fifth-scale mock-up of a canyon tank.'
[en] The centrifuge include a bowl cylindrical at the top and with an inclined internal wall at the bottom the two parts are joined by a conical surface calculated for the particles at the bottom to climb-up in the annular space for a determined rotation speed. Application is made for the separation of residues obtained after dissolution of spent nuclear fuels in the reprocessing
[fr]La centrifugeuse comporte une partie superieure cylindrique et une partie inferieure dont la paroi interne laterale est inclinee. Le raccordement entre les deux parties est assure par une surface conique. L'inclinaison de la partie inferieure du bol et la conicite de la surface de raccordement sont telles qu'a une certaine vitesse de rotation, le liquide et les particules contenus initialement dans la partie inferieure remontent dans l'espace annulaire de ''clarification''. Application au retraitement du combustible nucleaire pour separer les residus de dissolution des elements combustibles
[en] Present article is devoted to flowsheet of processing of carbon-graphite waste. On the base of conducted researches the two stage method of processing of carbon-graphite wastes with pure graphite output has been elaborated. The flowsheet of processing of carbon-graphite waste has been elaborated and proposed.
[en] The design claimed avoid clogging the extractor by solids which are collected in a conical decantation chamber. Application is made to the separation of the aqueous nitric solution, the organic phase of TBP diluted by an aliphatic hydrocarbon and heavy solid particles during spent fuel reprocessing
[fr]Cet extracteur permet l'evacuation des depots solides contenus dans les phases liquides a separer grace a une chambre de decantation conique. Application a la separation des phases aqueuses d'acide nitrique et organique de TBP dilue dans un hydrocarbure, au cours du retraitement des combustibles nucleaires, les depots solides etant elimines
[en] A method of reducing the radioactivity found in naturally occurring kaolins to about 40% below its native value, and the leachable radiogenic components to less than 20% is described. This reduction is achieved by removing from the kaolin particles of a size less than 0.5 microns. This removal may be carried out by gravitational settling, flocculation of non-colloidal particles, or acid leaching
[en] An improved multiple sample handling system, including a fully machine-compatible multiple sample support assembly, sample vortexing apparatus, and sample radioactivity sensing apparatus, is disclosed which enables performance of a complete radioimmunoassay or competitive binding procedure on the samples in the support assembly, generally without the need to remove and handle individual samples, and which greatly increases processing speed and error avoidance. The support assembly includes an apertured tray and sample retainers cooperating therewith and supporting the sample tubes by radially inwardly acting gripping portions. The retainers fit loosely within the tray apertures, but displacement control means are defined on the retainers and tray permitting the retainers together with tubes to smoothly move angularly relative to the tray within a small predetermined solid angle. The assembly with tubes is self-supporting upon the tubes for storage and optionally during sample operation. For mixing sample and reagents, the tubes are simultaneously vortexed in apparatus in which the tray is supported while a surface applying orbital forces contacts the lower tube portions. Mass centrifuging and decanting is readily performed by handling the tray assembly only. The radioactivity of one phase of each sample is sensed by a counting device in which the sample support assembly cooperates with a multiple counting chamber sensing head which accesses the samples from below to enable a plurality of samples to be counted simultaneously, without removing the samples for their support assembly
[en] Determination of the distribution of grain size in a material having dimensious below 325 mesh is presented. Sedimentation technique is used for such determination. The material whose grain size distribution is to be determined is irradiated in a reactor and can be detected by a radiation detector mounted externally to the sedimentation cylinder. The detector counected with a counter and a registerer gives the concentration of particles in function of time
[pt]Apresenta-se uma determinacao da distribuicao de tamanho dos graos de um material de dimensoes abaixo de 325 mesh, utilizando-se o processo da sedimentacao. O material do qual se deseja determinar a distribuicao de granulometria e levado a um reator se tornando radioativo, podendo ser detetado por um detector de radiacao montado externamente ao cilindro de sedimentacao. O detector conectado a um contador e a um registrador fornece a curva da concentracao de particulas em um ponto em funcao de tempo