Studies in the Zed-2 critical facility of reactivity coefficients for Candu cores fueled with plutonium fuels

Measurements and calculations relevant to the understanding of coolant-void and coolant/fuel-temperature reactivity coefficients of Pu-containing fuel in CANDU reactor lattices have been made. The measurements used few-rod substitution techniques in cores fuelled mainly with natural uranium. Calculations were made with the lattice-code WIMS-AECL (using a data library based on ENDF/B-5) and a reactor core code (CONIFERS). Conclusions drawn are that the calculations overestimate the reactivity effect of voiding the coolant and underestimate a positive reactivity contribution to the fuel/coolant temperature coefficient