Microstructural investigation of hydride reorientation in zirconium based spent nuclear fuel cladding

Hydride embrittlement and the impact of hydride reorientation are failure phenomena of particular interest during the transportation process of spent nuclear fuel from wet storage to dry storage. This process exposes the cladding to elevated temperatures and high pressure-induced hoop stresses that can release the hydride platelets back into solution and cause them to radially precipitate upon cooling. Though the impact of high temperature and high-pressure conditions on hydride reorientation have been investigated for many nonirradiated specimens, a data gap remains for the coupling effects of irradiation at these conditions in high burnup spent nuclear fuel rods. To simulate this behavior, high burnup spent nuclear fuel rods from H.B. Robinson and North Anna reactors have been exposed to hydride reorientation tests performed in the Irradiation Fuel Examination Laboratory at Oak Ridge National Laboratory. Microstructural characterization of the hydrides before and after hydride reorientation tests have been analyzed using TEM, STEM, EELS, and TKD.