2017 | AFC ACCOMPLISHMENTS 151 Accomplishments: In this study radial power density distributions (Figures 1, 2, and 3) were utilized to evaluate corresponding radial temperature distributions in the cadmium- shrouded irradiation vehicles used for irradiation testing of transmutation fuels and perform comparisons to irradiations in a fast reactor. Formation of the columnar grain region in fast reactor oxide fuels can be easily quantified during postirradiation examination (PIE), allowing determination of the fuel temperature on the outer boundary of the columnar grain region.Therefore, modeling of the MOX fuel restructuring (Figure 4) and comparison of model results to the PIE is an established practice to validate thermal analyses of fast reactor oxide fuel.This is an important step in establishing the relevancy of fuel performance data generated for fast reactor fuels using ATR cadmium- shrouded experiments. Figure 4. Comparison of measured and calculated dimensions of the columnar grain region in MOX fuel.