Studies were conducted to establish the mechanical properties of uranium 10 wt.% molybdenum (U-10Mo) in both the un-irradiated condition and after neutron irradiation. In the un-irradiated condition, mechanical properties were obtained for various temperatures and after the alloy had been wrought processed by rolling into four different rolling conditions. The irradiated mechanical properties were obtained at various fission densities and then the degradation of the mechanical properties from the un-irradiated to irradiated condition evaluated and a correlation with porosity developed. The mechanical properties obtained of the un-irradiated material differed from that previously published in the literature, which was expected due to the differences in thermomechanical processing conditions between the materials evaluated. The mechanical properties degraded as fission density increased as expected, and correlate to the increase of porosity that develops with increasing fission density.

The stress-strain properties of the APDA reference alloy of uranium- 10 wt.% molybdenum at various burnups up to 2.1 total at. % are described. Data were ob tained on both irradiated and unirradiated specimens of the alloy by the use of a remotely operated bend-testing machine. Tensile properties of unirradiated material are also reported for comparison with data obtained from the bend tests. The mathematical procedure used in obtainirg equivalent uniaxial stress-strain properties from the bend-test data is described in the Appendix. The results of the bend tests indicate that the physical properties of the reference alloy were severely affected by irradiation to burnups as high as 2.1 total at.%. At a test temperature of 500 deg C, the modulus of elasticity, ultimate strength, and strain at fracture decreased rapidly up to a burnup of about 0.5 to 1.0 total at.% with the rate of change decreasing thereafter. No important differences were noted between coextruded and hot-rolled material. An indication was obtained that the ultimate strength of the alloy was improved with increasing irradiation temperatures up to about 500 deg C. Data obainined on unirradiated material indicated that ductility of the reference alloy was lower at 500 deg C than at room temperature. Stress-strain curves for the irradiated specimens are included. The value of these data is limited because of the large number of variables encountered in the specimen histories and the small number of tests involved in this program. (auth).

This publication presents the material properties of all unirradiated Uranium-Molybdenum (U-Mo) fuel constituents that are essential for fuel designers and reactor operators to evaluate the fuel's performance and safety for research reactors. Many significant advances in the understanding and development of low enriched uranium U-Mo fuels have been made since 2004, stimulated by the need to understand irradiation behavior and early fuel failures during testing. The publication presents a comprehensive overview of mechanical and physical property data from U-Mo fuel research

Contributing Authors Include H. Etherington, R. C. Dalzell, D. W. Lillie And Others.