Characterization of U-Nb-Zr dispersion fuel prepared by centrifugal atomization process

The dispersions of U-Nb-Zr alloy particles in aluminum were characterized i n order to assess the applicability of this dispersion as research reactor fuel. Heat treatment revealed that the 9 wt% Nb alloy powder had, as expect ed, higher gamma-phase stability that the 5 wt% Nb alloy powder. A lamellar structure consisting of an alpha-U phase and gamma-phase was observed to s tart at the grain boundaries during heat treatment. The U-Nb-Zr alloy dispe rsion exhibited large volume increases during annealing when compared with similar experimental results for U3Si, U3Si2 and U-Mo dispersion fuel syste ms. The reaction product (U,Nb,Zr)Al-3 forms preferentially by diffusion of aluminum in the alpha-U phase which, in turn, forms during the diffusion p rocess as the metastable gamma-phase decomposes. (C) 1999 Elsevier Science B.V. All rights reserved.