Atomics International, Inc., North American Aviation, Inc., Canoga Park, Calif.
Pages: 86 Published: Jan 1957
The changes in properties and dimensions that occur in nuclear fuel materials when fissioning takes place are described. The especially pronounced growth and distortion effects that are observed in uranium are discussed as they are affected by grain size and texture, heat treatment, alloy composition, and mechanical treatment. The characteristics included are gross dimensional change, pimpling, orange peeling, and cracking. The various fundamental considerations or theories that rationalize this behavior are presented. The changes in thermal conductivity, ductility, microstructure, and electrical properties are presented as they apply to all fuels, and these data are used to point out those areas of understanding and those of lack of understanding of the controlling variables in radiation damage to fuels. Some of the problems that require examination and additional data for our future development of high-performance reactor fuel elements are suggested. These include the necessary volume increase occurring at high burnup, the modifications of behavior that may be found when the fuel elements are operated at temperatures above our present experience, and improved mechanical and radiation stability that might be achieved by alloy development or composite design.
Paper ID: STP44165S