2018 | AFC ACCOMPLISHMENTS 163 Figure 1. Plots of predicted inner clad temperatures as a function of time for three capsules in the Integrated Recycle Test (IRT). The blue band in the plot represents the targeted range of temperatures for the experiment. Accomplishments The first step in the design of the experiment were scoping studies that involved physics calculations (Emily Swain), thermal analyses (Dan Chapman) and fuel fabrication (Randy Fielding) to provide rough estimates of the fuel enrichments required to reach desired burnup rates and temperatures. Once fuel rods were fabricated, a key to this project was to perform analyses based on as-built fuel rod properties that provided best-estimates of heat generation rates (Emily Swain) and temperatures (Dan Chapman) throughout the entire course of the experiment for a variety of gas compositions.These calculations represent first-of-a-kind studies since as-built projections of in-reactor conditions are typically only performed on a cycle-by- cycle basis.The analyses provided a complete picture of the experiments as a function of time and gas-gap composition, which aided in the selection of gas compositions that provided the best balance between accelerating chemical interactions and the risk to the experiment by running a too high a temperature. Selection of gas composition in a timely manner was also essential for fabricating and inserting the experiment into the ATR on schedule. Figure 1 provides but one example of the numerous analyses that were performed in support of these tests.