Deformation of unirradiated CANDU fuel elements under bending loads

Nuclear fuel rods offer a simple multi-body structure with an interesting and complex mechanical behaviour. Fuel pellets within the Zircaloy cladding are free to move for low cladding deformations. The complexity of such interactions complicates the successful modelling of fuel pencils. Mechanical tests using non-axial loads were performed on typical unirradiated CANDU fuel elements by applying a load at the fuel element mid-point and measuring the resulting element deformation along the fuel element axis. An ANSYS finite element model of the fuel elements containing cladding, endcaps, and individual pellets was developed and used to predict the single fuel element deformation observed in the tests. The model provides excellent predictions of the experimentally measured fuel element deformation using known geometrical dimensions and mechanical properties for CANDU fuel. (author)