Numerical and experimental studies of the natural circulation mode during commissioning of Unit-1 Novovoronezh NPP-2

Abstract

Abstract Natural circulation (NC) of the coolant is an important component of ensuring safety and core cooling in conditions when forced flowrate has been lost. Unit 1 of Novovoronezh NPP-2 is the leading unit of the new NPP-2006 design with VVER- 1200. When commissioning this power unit, tests were conducted for the first time to verify the natural circulation mode, confirming both the development of this mode while simultaneously shutting down all the main coolant pumps (MCP), and as the design value of the permissible reactor power level in this mode. Due to the significance of the obtained experimental data during the commissioning tests and the need for validation of the calculation model for NPP-2006 design, numerical and experimental studies of the natural circulation mode were carried out jointly by the filial \Novovoronezhatomtechenergo" of the JSC \Atomtechenergo" and the National Research Center \Kurchatov Institute", taking into account their specializations. The analysis of experimental data demonstrates the ability of the plant to work in this mode. Calculation results obtained by ATHLET/BIPRVVER software package showed good agreement with the measured data, but a further improvement of the calculations of the NC mode is needed.