Comparison of MCNP Calculations Against Measurements in Moderator Temperature Experiments With CANFLEX-LEU in Zed-2

Abstract

This paper summarizes sample calculations of MCNP5 compared against measurements of moderator temperature coefficient experiments in the ZED-2 critical facility with CANFLEX®-LEU fuel. MCNP5 is tested for key parameters associated with various reactor physics phenomena of interest for CANDU®/ ACR-1000® reactors, including reactivity changes with coolant density, moderator density, and moderator temperature, and also normalized flux distributions. The experimental data for these comparisons were obtained from critical experiments in AECL’s ZED-2 critical facility using CANFLEX-LEU fuel in a 24-cm square lattice pitch. These comparisons establish biases/uncertainties in the calculation of k-eff, coolant void reactivity, and moderator temperature coefficient of reactivity. Results show very little bias in the moderator temperature coefficient of reactivity, and very good agreement in the calculation of normalized flux distributions.