Abstracts and Available Papers Presented at the
1998 International RERTR Meeting

Design of Gamma-Phase High-Density Uranium Alloys
for LEU Dispersion Fuel Applications

G. L. Hofman, M. K. Meyer
Argonne National Laboratory
Argonne, IL USA

A. Ray
Purdue University
West Lafayette, IN USA

Abstract

Uranium alloys are candidates for the fuel phase in aluminum-matrix dispersion fuels with high uranium loading. These fuels have been tested and shown to have good irradiation performance at intermediate burnup. Previous studies have shown that acceptable fission gas swelling behavior and fuel-aluminum interaction is possible only if the fuel alloy can be maintained in the high-temperature body-centered-cubic gamma-phase during fabrication and irradiation of the fuel. Transition metals in Groups V though VIII are known to allow metastable retention of the gamma phase below the equilibrium isotherm. These metals have varying degrees of effectiveness in stabilizing the gamma phase. Certain alloys are metastable for very long times at the relatively low fuel temperatures seen in research reactor operation. In this paper, we analyze existing data on the gamma stability of binary and ternary uranium alloys. The mechanism and kinetics of decomposition of the gamma phase are assessed with the help of basic metal alloy theory. Alloys with the highest possible uranium content, good gamma-phase stability, and good neutronic performance are identified for metallurgical studies and irradiation tests. Results from theory will be compared with experimentally generated data.