EN07.03.01 : Thermal Conductivity of UO2+x

5:00 PM–7:00 PM Apr 3, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Daniel Antonio1

1, Idaho National Laboratory, Idaho Falls, Idaho, United States

Uranium dioxide is an important material which is the primary fuel used in commercial nuclear reactors. It has been extensively studied, but newer and improved techniques allow us to further explore and expand our understanding of its behavior at extreme conditions, which can be applied to optimize simulation and manufacturing techniques. It has a magnetic transition 30.8 K, corresponding to unusual physical behavior, indicating strong mangeto-structural coupling. Below TN, UO2 orders antiferomagnetically and shows a small volume collapse due to a lattice distortion, as well as a rarely seen piezomagnetic behavior. UO2 crystalizes in the calcium fluoride structure, but the binary uranium-oxygen system (UO2+x) stablizes in a wide range of stoichiometries with similar crystal structure, having both deficiencies and interstitial inclusions in the oxygen site. The structural, electronic, and magnetic properties of the material can be highly dependent on x. Previous studies on powder uranium dioxide have been done over the last several decades, but the samples used in them often had mixed stoichiometries due to manufacturing techniques and oxidation. Using high quality and uniform single crystals of UO_2+x with known stoichiometries, we have systematically examined the change in thermal properties. <div id="UMS_TOOLTIP" style="position: absolute; cursor: pointer; z-index: 2147483647; background-color: transparent; top: -100000px; left: -100000px; background-position: initial initial; background-repeat: initial initial;"> </div>