Analysis of irradiated U-7wt%Mo dispersion fuel microstructures using automated image processing

Abstract

The High Performance Research Reactor Fuel Development (HPPRFD) program is responsible for developing low enriched uranium (LEU) fuel substitutes for high performance reactors fueled with highly enriched uranium (HEU) that have not yet been converted to LEU. The uranium-molybdenum (U-Mo) fuel system was selected for this effort. In this study, fission gas pore segmentation was performed on U-7wt%Mo dispersion fuel samples at three separate fission densities using an automated image processing interface developed in MATLAB. Pore size distributions were attained that showed both expected and unexpected fission gas behavior. In general, it proved challenging to identify any dominant trends when comparing fission bubble data across samples from different fuel plates due to varying compositions and fabrication techniques. The results exhibited fair agreement with the fission density vs. porosity correlation developed by the Russian reactor conversion program.

Determination of the degree of grain refinement in irradiated U-Mo fuels

“…As was the case when characterizing fission gas bubbles, it is noted that the mechanical preparation relative to preparation with a focused ion beam relieves the necessity for filters to remove curtaining artifacts [5, 6, 7, 8]. The major difference between the characterization of fission gas bubbles and the determination of the degree of grain refinement is the optimal image magnification to be acquired from the microscope leading to ideal results.…”

“…Certain analyses of the data and images generated from post-irradiation examination can be quite complex. Thus, development of easily-repeatable baseline methods of analysis that can be directly compared by various researchers to calibrate results for relative comparison is of interest [5, 6, 7, 8]. Development of such baseline approaches not only allows for easier comparison of results from various efforts, but also allows for easier communication of more complex analytical methods that can be presented as deviations from baseline methods.…”

Microstructural Changes and Chemical Analysis of Fission Products in Irradiated Uranium-7 wt.% Molybdenum Metallic Fuel Using Atom Probe Tomography

“…Alloying U with molybdenum (Mo) results in a metastable body-centered cubic structure that exhibits stable swelling behavior and eliminates anisotropic growth. In particular, U-7 wt.% Mo [8][9][10] has been selected as a candidate alloy for dispersion fuel particles. The fuel particles studied here also incorporate a ZrN coating to limit the detrimental effect of the U-Mo interaction with the Al dispersion fuel matrix [11][12][13][14][15].…”