2018 | AFC ACCOMPLISHMENTS 18 A new, flexible irradiation vehicle has been deployed to perform highly accelerated irradiation testing of miniature fuel specimens to facilitate high throughput nuclear fuels science. Screening of new fuel concepts for disqualifying behaviors (e.g., signifi- cant swelling) can be accomplished in far shorter times.This may enable exploration of a broader range of fuel concepts and conditions than would otherwise be possible given the significant investment needed for test irradiations. In addition to the benefits afforded by the irradiation conditions, samples do not need to be fabricated using enriched uranium. Depleted or natural uranium is adequate to achieve the burnup rates cited above. Despite the lower enrichment, very high powers can be achieved due to the extremely high neutron flux in the HFIR. Neutron absorption in 238U results in rapid breeding of 239Pu. Eventu- ally, an equilibrium between 239Pu production and fission is achieved.At this point, the fuel fission rate remains nearly constant for the remainder of the irradiation. Accomplishments: The initial insertion of MiniFuel samples was achieved in FY18.This first irradiation is focused on baseline performance of particle fuels.The objective of this irradiation is to demonstrate the basic capsule build, gain familiarity with assembly and handling of fuel materials smaller than are standard, establish the basic ability of the MiniFuel capsule to achieve the desired irradiation conditions, and provide initial samples for develop- ment of postirradiation examination (PIE) techniques. Successful demon- stration of PIE for small fuel samples is the major challenge of MiniFuel. While the small volume provides numerous advantages as detailed above, the reduced fuel volume does strain conventional methods for determination of critical fuel proper- ties such as swelling and fission gas behavior. Modern tomography and automated software analysis have been developed to calculate sample volume