Young's modulus evaluation of high burnup structure in UO2 with nanometer resolution

Kurt A. Terrani, Mehdi Balooch, Joseph R. Burns, Quinlan B. Smith

Index: 10.1016/j.jnucmat.2018.04.004

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Abstract

The mechanical properties of a well-characterized irradiated light water reactor fuel pin with an average burnup of 72 MWd/kgU were investigated by utilizing nano-indentation technique. Young's modulus and hardness are reported as functions of radial positions covering from mid radial position in the urania pellet to high burnup structure, fuel-cladding chemical interaction zone and zirconium-based cladding. By probing microstructure of the high burnup zone, the mechanical properties of sub-grains and the interaction between them were examined at the nanometer scale. Force-displacement curves from each of these individual sub-grains suggest they resemble single crystal UO2. However, these restructured grains are weakly bonded to their neighbors.