Neutronic calculations for the VVER-1000 LEU and MOX assembly computational benchmark using the GETERA code

Abstract

Disassembling nuclear warheads require the deployment of mixed oxide fuel (UO2+PuO2) for the utilization of Plutonium from warheads. For this purpose, the Nuclear Energy Agency has proposed a computational benchmark consisting of two VVER-1000 assemblies: LEU and MOX; to study their physics and the main differences between them. GETERA code which is based on the collision probability method was used to study the neutronic characteristics of these assemblies at different reactor states. The aim of this work is to test the accuracy of the GETERA code and its nuclear data library BNAB-93 against previously obtained solutions. Burnup calculations were conducted up to 40 MWd/kgHM. Calculations of the infinite multiplication factor, average isotopic composition, several reactivity effects and the radial variation of isotopic composition in Uranium-Gadolinium (UGD) pins were performed. Comparison of our results with the benchmark mean results was performed and was shown to give a very good agreement.