2017 | AFC ACCOMPLISHMENTS 56 2.2 HIGH-PERFORMANCE LWR FUEL DEVELOPMENT Fundamental elastic and mechanical properties of high density fuels Principal Investigators: U. Carvajal Nunez (LANL) Collaborators:T.Saleh, N.A. Mara, A.T. Nelson (LANL) Figure 1. Experimental set up of a RUS cylinder sample sandwiched between hemispherical Al2O3 wear plates, glued to the transducers (left). Measured frequency response of a U3Si2 sample from 200 to 500kHz (right). The mechanical properties of nuclear fuels are historically far less studied than thermo- dynamic or transport properties, but nonetheless play an important role in fuel behavior. For new or little under- stood fuel forms such as many pres- ently considered as accident tolerant candidates, even basic mechanical properties are absent from the litera- ture. Evaluation of mechanical proper- ties is therefore necessary to support fuel performance modeling.Two methods have been deployed to meet this need and demonstrated on a series of U-Si compounds. Nanoindentation was used for measurement of hardness andYoung’s modulus, and Resonant Ultrasound Spectroscopy (RUS) was used to determine elastic constants C11, C44 and the bulk modulus; these can then be used to calculateYoung’s modulus and Poisson’s ratio.These data have been determined for a U3Si, U3Si2, USi.