The filtrate flow rates obtained during the cross-flow filtration of slurries are dependent on the properties of the slurry particles. Tetraphenylborate is used to precipitate radioactive cesium from supernate salt solutions at the Savannah River Site. These slurries are then processed by a sequence of filtration steps. However, prior to the last filtration step, the slurries are exposed to significant doses of irradiation that appear to dramatically change the properties of these particles. A concomitant decrease in filter performance has been observed. An empirical model has been developed to predict the impact of irradiation on filtration. This model also predicts the dependency of performance on axial velocity and pressure drop.