Progress in the RERTR fuel development program

Initial irradiation testing of U-Mo dispersions beginning in the late 1990's established the promising irradiation behavior of these fuels. Subsequent experiments abroad and in the U.S. established shortcomings in fuel behavior at high power and temperature. Detailed postirradiation examinations indicate that fuel performance issues arise not from the poor performance of the U-Mo fuel particles, but from the swelling behavior of the reaction layer that forms between the fuel and the aluminum matrix during irradiation. The continued development of very-high-density, low-enrichment fuels requires a detailed program of fuel fabrication development, out-of-pile characterization, irradiation testing, postirradiation examination, and fuel performance evaluation and modeling. Several potential remedies are available to correct the known fuel performance problems; these range from relatively minor changes to the fuel and matrix chemistry, to replacement of the aluminum matrix with another material, or to eliminate the matrix altogether. All of these variations are currently being investigated as part of a fuel development collaboration involving six nations (Argentina, Canada, France, Republic of Korea, Russia, and the United States). Current test results from the RERTR-6 irradiation test and supporting experiments will be reviewed, and the path forward for qualification of low-enrichment, high-density fuel(s) by the end of 2010 will be discussed. (author)