DIFFERENCES IN EXIT BURNUP, DEPLETION, AND FUEL REACTIVITY CALCULATIONS ARISING FROM THE CHOICE OF MODELLING CODE FOR BUNDLES WITH THORIUM AND URANIUM

Abstract

A computational benchmark, using the deterministic codes WIMS-AECL and WOBI, and the stochastic code SERPENT, is made for burnup calculations of advanced thorium fuels in heavy water moderated reactors. Exit burnups and the concentration of the longer-lived actinides from the deterministic code set of WIMS-AECL and WOBI, which are 2-D, were compared to those from a full 3-D calculation in SERPENT. Results for reactivity vs. time are in general agreement to within a few mk (<1% in overall neutron multiplication) and appear to be systematic. Results for exit burnup were larger, in the 3%–6% range, because small reactivity effects can be amplified here.