CONFORMAL MAPPING AND HEXAGONAL NODAL METHODS .2. IMPLEMENTATION IN THE ANC-H CODE

The ANC-H code is the hexagonal geometry version of the Westinghouse t hree-dimensional advanced nodal code ANC. Together with PHOENIX-H, the hexagonal geometry version of the Westinghouse pressurized water reac tor (PWR) lattice code PHOENIX-P, they provide the Westinghouse code p ackage for designing VVER-type PWR cores of hexagonal geometry. The no dal theory of ANC-H is the net current nodal expansion method implemen ted with the technique of conformal mapping, which maps a hexagon to a rectangle while preserving the diffusion operator. The use of conform al mapping eliminates the root cause of singularities resulting from t he conventional transverse integration. The intranode burnup gradient is accounted for by allowing spatially dependent nodal cross sections. The theory of ANC-H is qualified by benchmarking ANC-H against fine-m esh finite difference code solutions for a variety of benchmark proble ms. In all cases, the agreement has been excellent. The accuracy of AN C-H for hexagonal geometry cores is as good as ANC for Cartesian geome try cores.