b'Separate Effects Testing in TREAT for ATF FuelsPrincipal Investigator: G. Beausoleil & F. Cappia, INLTeam Members/ Collaborators: L.A. Emerson, D. Murray, D. Sell, C. Christensen, A. Winston, D. Wahlquist, M. Bachhav, and B. Miller (INL)Figure 1. Measured radial porosity profile on a polished cross section. Fuel average burnup: 72 GWd/tHM.This work was designed to investigate the causes of fuel fragmentation during accident scenarios by characterizing retained fission gas on the grain boundaries of high burnup UO 2 .T his work performedElectric Power Research Institute examinations on high burnup(EPRI)). The characterization of the UO 2from commercialfuel focused on the differences in power plants with the intentionporosity between the high-burnup of better understanding of fission(rim) zone, the dark (intermediate) gas and fragmentation behavior.zone (DZ), and center zones of the Fuel fragmentation, relocation, andfuel as well as the fission gas content dispersal (FFRD) is a major factorof each region. Work involvedin fuel lifetime limits imposed onthermal treatments to analyzeUO 2by regulators, both domesticfission gas and high resolution and foreign, and is a major area ofmicroscopy techniques tointerest by industry groups (e.g.,investigate pore structure.134 2019|AFC ACCOMPLISHMENTS'