Validation of 3-Dimensional Neutron-Transport Calculations of CANDU Reactivity Devices

Abstract

It is the stated intent within the nuclear industry in Canada that the WIMS-AECL/RFSP suite of codes be adopted as the industry-standard tools (IST) to be used in CANDU1 reactor-physics analysis. That decision being made, it is therefore essential to represent the reactivity devices in a form that is compatible with the two-group WIMS-AECL-based lattice properties. In a threedimensional reactor-core model, the reactivity devices are usually represented with incremental cross sections derived through supercell calculations. These incremental cross sections are added to the basic lattice-cell properties to evaluate the effect of the device on neutron-flux distributionsand system reactivity. The supercell methodology that has recently been adopted for performing incremental-cross-section calculations for CANDU reactivity devices is based on the DRAGON code. This method uses explicit three-dimensional neutron-transport theory to calculate the macroscopic neutron-flux distribution in and around CANDU reactor fuel channels and reactivity-control devices. The present paper reviews the validation of 3-D DRAGON neutrontransport calculations of CANDU reactivity-device properties against measurements made in two CANDU reactors.