b'Figure 5. MiniFuel irradiationthose HGRs into a finite-elementreceived at ORNL, each of the fueled vehicle assembly thermal model of the experiment.subcapsules was assembled. Each Adjustments to the subcapsulesubcapsule assembly comprised ODs and the target fill-gas werea fuel specimen, cup, heater tube, made iteratively until the desiredSiC thermometry, grafoil insula-TAVA temperatures were met intors, and a subcapsule holder and each subcapsule. Fuel temperaturesendcap. The cup, tube, holder, and during a single HFIR cycle areholder endcap were all comprised of expected to vary by 150200C,low-carbon arc-cast Mo. An example although approximately 100-125Cof the subcapsule components laid of that variation occurs over theout prior to subcapsule assembly is first two days of each cycle asshown in Figure 3. Once assembled, HFIRs control drives are adjusted.each subcapsule underwent an elec-An example of the time-dependenttron beam welding process followed temperature predicted for one of theby a tungsten inert gas seal welding fuel specimens is shown in Figure 2. process in a helium back-filled Fuel specimens for the experimentchamber. The bottom target endcap were provided by Los Alamoswas orbital welded to the main National Laboratory (LANL). Oncehousing tube, and then the stack 48 2023|AFC ACCOMPLISHMENTS'