b'Figure 2. Neutronic Model Rendering of the ARCTIC Concept.The AFC irradiation team alsoThese efforts were designed to be performed design and modelingsynergistic with the first Fission to finalize a test matrix and beganAccelerated Steady-state Test (FAST-1) tooling up for fabrication of theirradiation. FAST rodlets use an previously planned AFC-4F and -Ginnovative approach where radial tests. This matrix included irradia- dimension reduction and enrichment tion of U-Zr and U-Pu-Zr alloys withincrease are used to manage thermal promising FCCI-mitigating liners,conditions with boosted fission rates. strategic inclusion of rare earthAccordingly, the AFC-4F and -4G were elements to help accelerate FCCIdesigned to focus on geometry and effects (a form of accelerated testingscale phenomena at representative to help hasten liner type selection),radial dimensions for comparable and the use of annular extruded anddesigns. Unfortunately, congressional slotted fuel designs to help enableapproval of the overall program direct disposal sodium-free designs.budget in winter of 2020 brought 140 2020|AFC ACCOMPLISHMENTS'