Simulating the Operation of the Jet-Vortex Condenser Used in the VVER-440 Reactor Plant’s Confinement System

A jet-vortex condenser (JVC) used as part of the confinement system (CS) serves for limiting the pressure in sealed rooms to the maximum admissible value for which the civil structures of NPPs equipped with VVER-440 reactors made according to the V-230 and V-179 projects are designed under the loss of coolant accidents' conditions. Fitting the Kola NPP’s first stage equipped with the VVER-440 reactor (made according to the V-230 project) in combination with taking certain other measures opened the possibility to extend the NPP service life. To substantiate the possibility of extending the service life of NPP power units, their safety will be assessed using an analysis model. The article presents the results from such modeling aimed at analyzing the performance of the jet-vortex condenser that is used as part of the confinement system for limiting the pressure in the sealed rooms down to the maximum admissible value for which the VVER-440 reactor-based NPP civil structures are designed with due regard to loss of coolant accidents (LOCA). The jet-vortex condenser operation model incorporated into the KUPOL-M computer code was verified against the experimental data obtained on the test facility installed at the All-Russian Research Institute for Nuclear Power Plants Operation (VNIIAES). A comparative analysis has shown that the calculated and experimental data are in fairly good agreement with each other. The KUPOL-M code with the jet-vortex condenser model integrated into it was used for calculating the parameters of medium in the system of sealed rooms in modeling the large break LOCA and small break LOCA conditions for the Kola NPP’s first stage, the distinctive feature of which is that it contains a JVC in the confinement area. The calculation results have confirmed the JVC efficiency under the conditions of a wide range of loss of coolant accidents. At present, the JVC has been put into use in the Kola NPP units 1 and 2, in the Novovoronezh NPP units 3 and 4, and in the Kozloduy NPP units 3 and 4 in Bulgaria.