Out-of-pile Tests of Simulated Rock-like Oxide (ROX) Fuels

Abstract

A new type of fuel, that is, ROX (rock-like oxide) fuel originally being composed of PuO2-SZR (stabilized zirconia)-MgAl2 O4 is under development by JAERI. In order to increase data base, the simulated ROX fuel replaced PuO2 by UO2 was fabricated and out-of-pile tests were performed. The following results were obtained: (1) The densities of simulated ROX fuels ranged from 4.9 to 5.4g/cc, which were of order of about 47–52% of that in UO2. (2) The melting points (MPs) of simulated ROX fuel ranged from 2,206 to 2,139 K, which was lower of order of about 30% to that of UO2. (3) There was no marked difference in linear thermal expansion coefficient (LTEC) between simulated ROX fuels and UO2 ones. Linear thermal expansion coefficient was increased with increasing SZR. (4) The creep propensity compared by the stress index (the ratio of deformation rate (h−1) to log (stress)) of simulated ROX fuel to UO2 was similar. (5) The magnitude of hardness (Hv) was changed by MgAl2O4. The Hv of simulated ROX fuel is significantly large than that of UO2. (6) The difference in thermal diffusivity between simulated ROX fuels and UO2 ones was insignificant. Similarly, the difference in thermal conductivity between the two was also little.