Abstract: Uniform spherical fuel and/or fertile particles are formed by conversion of an oscillating liquid stream of a uranium and/or thorium compound solution flowing from at least one nozzle in an amount of more than 3,000 drops per minute by allowing these drops to fall into an ammonia solution and subsequently drying and sintering the particles thus formed.

Abstract: Graphite or carbon molded articles of high isotropy and high heat conductivity, especially useful for high temperature reactor fuel elements are prepared by pressing a mixture of a binder and a powdery carbon filler which consists partially or wholly of pyrolytically produced isotropic carbon with subsequent heat treatment of the pressed article. There is used as the filler an isotropic pyrolytic carbon made by depositing a hydrocarbon on a carbon granulate and then grinding to a particle size of less than 100 .mu.m.

Abstract: Fuel, fertile material or absorber material containing particles for high temperature fuel elements are coated in a fluidized bed by heating the particles and fluidizing through carrier gas preheated to the desired temperature. The coating gas, having a higher velocity than the carrier gas causing fluidizing, is blown into the fluidized particle bed from one or more nozzles from above counter to the flow of the carrier gas. The nozzles end above the fluidized layer.

Abstract: Fuel particles in a fluidized bed are provided with a coating of pyrolytic carbon having substantially no property gradients by holding the speed of growth constant during the entire coating time and insuring the same speed of growth in all particles of the particle bed.

Abstract: There are provided pressed spherical fuel elements for high temperature reactors made of a graphite matrix with separate embedded coated fuel and fertile material particles wherein the fuel elements comprise 3 concentric layers including a graphite nucleus or core (1) which only contains fertile material particles (4), this graphite nucleus (1) is surrounded by a graphite zone (2) which only contains the fuel particles (5) and this is encased in a shell (3) of pure graphite, the same graphite material being present in all three layers.

Abstract: Graphite or carbon molded articles of high isotropy and high heat conductivity, especially useful for high temperature reactor fuel elements are prepared by pressing a mixture of a binder and a powdery carbon filler which consists partially or wholly of pyrolytically produced isotropic carbon with subsequent heat treatment of the pressed article. There is used as the filler an isotropic pyrolytic carbon made by depositing a hydrocarbon on a carbon granulate and then grinding to a particle size of less than 100 .mu.m.

Abstract: There are prepared fuel elements for high temperature reactors from which the fuel zone can be removed from the structural graphite after the burnup of the fissile material has taken place so that the fuel element can be filled with new fuel and again placed in the reactor by having the strength of the matrix in the fuel zone sufficient for binding the embedded coated fuel particles but substantially less than the strength of the structural graphite whereby by the action of force it can be easily split up without destroying the particles.

Abstract: Prismatic graphite molded objects for high temperature fuel elements are prepared by producing the outer geometry and the holes for cooling channels and for receiving fuel and fertile materials in the formation of the carbon object.

Abstract: Graphite molding powders are prepared which contain phenol-formaledehyde as a binder and which are intended for use in the manufacture of graphite molded articles, especially fuel inserts, fuel elements and absorber elements for high temperature reactors by mixing a graphite powder with a phenol formaldehyde binder and subsequent heat treatment, in a given case in admixture of coated fuel, fertile or absorber particles. The invention resides in not adding to phenol-formaldehyde as such to the graphite powder but as the starting components namely phenol and formaldehyde or source of formaldehyde and heating the mixture to the resin condensation temperature.