An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound (“PYRUC”) shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.

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Radiation shielding materials and containers incorporating same

In a seamless capsule manufacturing apparatus that ejects a droplet (25) from a nozzle (7) into hardening liquid (10) to manufacture a seamless capsule SC, tube passages (6, 9) which are synthetic resin tubes are provided as flexible sections (16) between pumps (5, 8) and the nozzle (7). The vibration caused by the pumps (5, 8) is absorbed in the flexible sections (16) and thus is not transmitted to the nozzle (7), whereby eyes or the like of the seamless capsule caused by vibration noises can be suppressed. Instead of a synthetic resin tube, a vibration absorbing block formed of an elastic member may be attached to the tube passages (6, 9). Alternatively, a vibration absorbing unit, which is provided with a pad formed of an elastic member and for holding the tube passages (6, 9), may be provided.

Apparatus for manufacturing seamless capsules

The main objective of the Depleted UO{sub 2} Kernels Production Task at Oak Ridge National Laboratory (ORNL) was to conduct two small-scale production campaigns to produce 2 kg of UO{sub 2} kernels with diameters of 500 {+-} 20 {micro}m and 3.5 kg of UO{sub 2} kernels with diameters of 350 {+-} 10 {micro}m for the U.S. Department of Energy Advanced Fuel Cycle Initiative Program. The final acceptance requirements for the UO{sub 2} kernels are provided in the first section of this report. The kernels were prepared for use by the ORNL Metals and Ceramics Division in a development study to perfect the triisotropic (TRISO) coating process. It was important that the kernels be strong and near theoretical density, with excellent sphericity, minimal surface roughness, and no cracking. This report gives a detailed description of the production efforts and results as well as an in-depth description of the internal gelation process and its chemistry. It describes the laboratory-scale gel-forming apparatus, optimum broth formulation and operating conditions, preparation of the acid-deficient uranyl nitrate stock solution, the system used to provide uniform broth droplet formation and control, and the process of calcining and sintering UO{sub 3} {center_dot} 2H{sub 2}O microspheres to form densemore » UO{sub 2} kernels. The report also describes improvements and best past practices for uranium kernel formation via the internal gelation process, which utilizes hexamethylenetetramine and urea. Improvements were made in broth formulation and broth droplet formation and control that made it possible in many of the runs in the campaign to produce the desired 350 {+-} 10-{micro}m-diameter kernels, and to obtain very high yields.« less

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Production of Depleted UO2Kernels for the Advanced Gas-Cooled Reactor Program for Use in TRISO Coating Development

A process and apparatus are provided for making solid particles from an ionically cross-linkable material by cross-linking drops of the material with a cross-linking agent in the form of a falling stream. In one embodiment, a stream of the cross-linking agent flows down the inner walls of an enclosure and drops of the material are directed to the stream of cross-linking agent. In another embodiment, a stream of the cross-linking agent is free-falling by gravity in a cascade without contacting any surface and drops of the material are directed to the stream of cross-linking agent. Solid particles are separated from the cross-linking agent at about the bottom of the enclosure or at about the bottom of the cascade. The drops of cross-linkable material are directed at the stream of cross-linking agent preferably at an angle of incidence of less than 90° such as between 5° and 45° and most preferably between 15° and 30°. Particles having a size of 10 μm to 4 mm may be produced. Double layer particles can be produced by using a double nozzle constituted by two concentric orifices. The cross-linkable material may be alginic acid and the cross-linking agent may be a divalent cation such as calcium. Particles containing micro-organism cells may be obtained by combining micro-organism cells with the cross-linkable material before drops are formed. In a preferred embodiment, particles are produced containing Saccharomyces cerivisiae for making sparking wines.

Process and apparatus for forming solid particles by cross-linking drops of a cross-linkable material with a free-falling stream of cross-linking agent

L'invention concerne un procede et un appareil de fabrication de particules solides (16). Cet appareil comprend la generation de gouttes (14) de ce materiau et la solidification de ce materiau par mise en contact avec un agent de solidification (22), caracterise en ce qu'on fait s'ecouler l'agent de solidification (22), sous forme d'un lit fluide (24), on fait s'ecouler en gouttes (14) le materiau solidifiable sur le lit fluide (24) suivant un angle d'incidence inferieur a 90°, en formant ainsi lesdites particules solides (16), et on separe les particules solides (16) formees de l'agent de solidification (en 60). L'invention permet de fabriquer des particules solides pouvant contenir des micro-organismes tels que des levures, a cadence elevee avec un temps de solidification precis, tout en evitant la formation d'agglomerats.

Procede et appareil de fabrication de particules solides a partir d'un materiau solidifiable en presence d'un agent de solidification en de bons rendements.

A simplified internal gelation process for the preparation of gel spheres of nuclear fuels The process utilizes perchloroethylene as a gelation medium Gelation is accomplished by directing droplets of a nuclear fuel broth into a moving volume of hot perchloroethylene (about 85° C) in a trough Gelation takes place as the droplets float on the surface of the perchloroethylene and the resultant gel spheres are carried directly into an ager column which is attached to the trough The aged spheres are disengaged from the perchloroethylene on a moving screen and are deposited in an aqueous wash column

Preparation of nuclear fuel spheres by flotation-internal gelation

Nuclear fuel is made by contacting an aqueous solution containing an actinide salt with an aqueous solution containing ammonium hydroxide, ammonium oxalate, or oxalic acid in an amount that will react with a fraction of the actinide salt to form a precipitate consisting of the hydroxide or oxalate of the actinide. A slurry consisting of the precipitate and solution containing the unreacted actinide salt is formed into drops which are gelled, calcined, and pressed to form pellets.

Paul A. Haas

Papers

Preparation of nuclear fuel spheres by flotation-internal gelation

Method for producing nuclear fuel