Qualification of coupled 3D neutron kinetic/thermal hydraulic code systems by the calculation of a VVER-440 benchmark – re-connection of an isolated loop

The 7th AER dynamic benchmark is a continuation of the efforts to validate the codes systematically for the estimation of the transient behavior of VVER type nuclear power plants. The main part of the benchmark is the simulation of the reconnection of an isolated circulation loop with low temperature in a VVER-440 plant. This benchmark was calculated by the National Research Centre "Kurchatov Institute" (with the code ATHLET/BIPR-VVER), UJV Rez (with the code RELAP5-3D (c)) and HZDR (with the code DYN3D/ATHLET). The paper gives an overview of the behavior of the main thermal hydraulic and neutron kinetic parameters in the provided solutions.