Evaluation of Nuclear Grade SiC/SiC Composites for Control Rod Sheaths

78702S Some Generation IV nuclear reactor designs call for employing high reactor core temeratures to improve the thermodynamic efficiency of the power generation and to efficiently produce process heat. Materials are required that are capable of sustaining temperatures approaching 1000¿C and also are stable in a high radiation environment. One such application is the outer containment of the control rod material, where the sheath material is subjected to large thermal gradients and thermal cycling in addition to the high temperature, high radiative flux environment. This project will develop a silicon-carbide-fiber/reinforced-silicon-carbide matrix composite that is stable under these high neutron fluxes and addresses the requirements for control rod sheaths. In Phase I, full-scale diameter tubes of silicon carbide/silicon carbide composite will be fabricated and their thermal and mechanical properties will be evaluated, from ambient temperatures to 1000¿C. The validity of the test techniques for determining the mechanical properties of the tube will also be determined and compared with test results of smaller diameter tubes. A finite element model will be developed to determine thermal stresses in these tubes. Commercial Applications and Other Benefits as described by the awardee: The new materials technology should provide a needed advancement in high temperature materials for irradiated environments.