Validation of DYN3D pin-power calculation against experimental VVER-full-core benchmark

The EU NURESIM V1000-VALCO-STAT benchmark is focused on three-dimensional VVER-1000 steady-states with assembly-averaged and fine-mesh power distributions. Calculation results are compared with measurements from the Moscow zero-power critical facility V-1000, which was used as a full-scale mock-up of the Russian VVER-1000 reactor core. A very low moderator temperature and radial-reflector asymmetries were significant for this core. The calculations are performed with the reactor dynamic nodal code DYN3D. The usual node-averaged approach is applied in the first step. Then, an intra-nodal pin-wise power reconstruction method and its combination with the pin-powers from the lattice code HELIOS zero-net-current fuel-assembly calculations are applied. The power distributions calculated by pin-wise reconstruction show better agreement with the measurement than the node-averaged values, which is particularly obvious for fuel assemblies with inserted control clusters.