Time-dependent transport analysis calculations have been carried out, using experimentally determined plasma parameters to obtain the variation of electron and ion thermal diffusivities following pellet injection into moderate density Alcator C discharges. The ion thermal diffusivity, which is typically higher than neoclassical predictions by a factor of three to five in the gas-fuelled target plasma, is found to decrease after pellet injection to approximately the neoclassical value. The electron thermal conductivity is not reduced after pellet injection.