Electron probe microanalysis of irradiated FUTURIX-FTA U-Pu-Zr alloy with added minor actinides

[摘要] Electron microprobe examinations were performed to characterize the chemical features of a full cross section of irradiated nuclear fuel from the FUTURIX-FTA experiment. This experiment investigated the nuclear fuel performance of a candidate fuel alloy intended for the transmutation of long-lived minor actinides in a fast neutron spectrum. The irradiated fuel, designated FUTURIX-FTA DOE1, was composed of 34.1U-28.3Pu-3.8Am-2.1Np-31.7Zr (where the preceding numbers indicate concentrations in weight %). The fuel was irradiated in the Phenix sodium fast reactor in France to a measured burnup of 9.5% fissions per initial heavy metal atom (FIMA), and experienced a peak cladding temperature of 550 degrees C. Microprobe analysis showed elemental redistribution of Zr and U where Zr has increased in concentration in the fuel center from an initially fabricated content of 31.7 wt % to 41.5 wt%, and U decreased from 34.1 wt% to 24.8 wt%. From the center of the fuel extending out radially approximately 1 mm, the fuel represented dominantly a single phase. Beyond this region to the fuel periphery, the fuel separated into two major phases, descibed by their composition as a (U, Np, Pu) Zr-2-like phase and a high uranium content-low zirconium content phase. From the outer radius of the fuel extending approximately 1.7 mm radially into the fuel, americium, lanthanide elements, and actinide elements precipitated in a phase whose chemical analysis resembles Nd-7(Pd, Rh)(3). In addition, americium occurred as a dissolved species in the major fuel phases. Sm and Am penetrated up to 15 mu m into the cladding along presumed grain boundaries, while major cladding elements Fe, Ni, and Cr penetrated at least 30 mu m into the fuel. No phase formation between cladding elements and fuel elements was observed as the result of cladding element diffusion into the fuel. (C) 2019 Elsevier B.V. All rights reserved.

[发布日期] 2019-12-01