Validation of the MCNP-PoliMi Code for the Simulation of Nuclear Safeguards Experiments on Uranium and Plutonium Metal

This paper presents the validation of the Monte Carlo code MCNP-PoliMi for the simulation of nuclear safeguards experiments with plutonium and uranium metal based on fast time-correlation measurements. A comparison is presented between experimental data acquired with the Nuclear Materials Identification System and the Monte Carlo simulations. The measurements and simulations were performed for assemblies of delta-phase plutonium metal shells of varying inner and outer diameter, in both passive and active mode, and for a highly enriched uranium annular metal casting in active mode. We present the simulation results, generally in good agreement with the measurements, and attempt to give an explanation for the areas of partial disagreement with the measured data.