b'Accelerating IrradiatedAdvanced manufacturing techniques enable researchers to explore new Fuel Studies by Advancedapproaches to accelerate and reduce the cost of nuclear fuel development.SurrogateSamples Q ualification of new nuclear fuel and the safe operation of conventional fuels require a deep understanding of fuel performance up to high burnup. Current fuel performance testing is mainly achieved by long and expensive irradiation campaigns, which are nearly impossible to accelerate in reactor. This research explored a new approach to accelerate and reduce the cost of fuel development through the fabrication of surrogate samples that mimic TOTAL APPROVED AMOUNT:irradiated fuel. The realistic simulated irradiated fuel microstructure is possible by $152,000 over 3 years leveraging in-house fabrication capabilities, such as spark plasma sintering. These surrogates simulated both the high burnup structure and the chemical composition PROJECT NUMBER:of irradiated fuel. These samples represent a unique opportunity to perform separate 18A40-014 and combined effects studies, providing valuable validation data for the MARMOT PRINCIPAL INVESTIGATOR:microstructure evolution modeling suite.Fidelma Di Lemma The first proof-of-concept for these surrogates was obtained by producing uranium dioxide CO-INVESTIGATORS: surrogate samples that simulated high burn up microstructure. Parameters of the powder Nathan Jerred, INL preparation and spark plasma sintering method were optimized to reproduce grain size, Patrick Moo, INL reaching the desired 200 nm dimension. Porous formers were tested for the reproduction Robert OBrien, INL of the porosities observed in the high burnup structure. While the density, distribution, and Tsvetoslav Pavlov, INL volumetric concentration were in line with the ones found in irradiated fuel, the porosities Tiankai Yao, INL seemed to be much smaller than the desired ones and required the use of much larger porous former. The final task was the introduction of surrogate fission products. This was successful as all the products were retained in the pellet. However, the distribution and size of the fission product precipitates was not in line with that reported in the literature. Further powder processing could be successful in producing smaller and better distributed precipitates. The reaction of fission products to form intermetallic and gray phase precipitates was also analyzed and was observed to be limited. Further annealing may be necessary to promote such reactions. Finally, thermal properties of these surrogates were measured to be compared to irradiated data.TALENT PIPELINE:Patrick Moo, student at University of FloridaNathan Jerred, student at University of IdahoTsvetoslav Pavlov, INLRussell L. Heath Distinguished PostdocTiankai Yao, Postdoc from Rensselaer Polytechnic Institute(a) Grain size obtained via spark plasma sintering, leading to desired grain structure. (b) Comparison with real irradiated high-burnup structure microstructure from Spino et al. (2012).68'