A model for inspection, and its application to a reprocessing plant of the Nuclear Fuel Services type, have been developed. Two possible means of diverting material are (a) diverting material within the uncertainty of the material balance and (b) falsifying data. Statistical tests are performed by the inspecting authority: In the first case, the inspector compares material unaccounted for (MUF) with a significance threshold, while in the second case, a sample of the reported data is compared with his own remeasurements. Both methods are combined, and the optimal control and diversion strategies are computed (for an assumed probability of a false alarm and the amount to be diverted).