[en] The aim of the performed study is to find a reliable correlation between the measured thermocouples values at core outlet of reactor VVER-1000 with the coolant temperatures at the assemblies outlets at these positions. Studies have been performed with the system coupled code ATHLET/BIPR-VVER, which allows to model the thermal-hydraulics and kinetics processes in VVER reactors in a 3D manner. The analysis is based on local in-core measurements data collected during the commissioning phase of VVER-1000 NPP Kalinin. The studied transient is a switch off of one main circulation pump at nominal power while the other there pumps remain in operation