An improved model for cladding strain intensification over radial cracks in nuclear fuel pellets

The opening of radial cracks in fuel pellets can cause strains in adjacent cladding to be large, as frictional forces inhibit relative movement between the pellet and the cladding. An analytical model of this strain intensification process is presented. This model, more rigorous than previously published approaches, explicitly accounts for strain concentration only over part of the cladding perimeter. The azimuthal extent of slipping at the fuel-cladding interface is calculated and the effect of external pressure and any prior uniform clad strain is included. Numerical results are presented for sample cases and the coupling of the model to fuel performance codes is described