A radiation heat transfer model has been developed for severe fuel damage analysis that accounts for anisotropic effects of reflected radiation. The model simplifies the view factor calculation, which results in significant savings in computational cost with little loss of accuracy. Radiation heat transfer rates calculated by the isotropic and anisotropic models compare reasonably well with those calculated by other models. The model is applied to an experimental nuclear rod bundle during a slow boil-off of the coolant liquid, a situation encountered during a loss-of-coolant accident with severe fuel damage. At lower temperatures and also lower temperature gradients in the core, the anisotropic effect was not found to be significant.