Artavazd M. Sujyan

National Research Center “Kurchatov Institute”

Abstract. This article presents the results of computational work on the study of the dynamics of the VVER-SKD reactor installation, performed using the capabilities of the RELAP5/MOD3.3 program. A characteristic feature of this reactor is a rather noticeable change in the density of the coolant in the core. In combination with neutron-physical feedback, it creates risks of thermal-hydraulic and neutron-thermal-hydraulic instability, especially during transients. In this regard, it is necessary to be able to predict the occurrence of instabilities, to assess the limits of the stability of the system. For these purposes, a design model of the reactor plant was developed. The choice of the RELAP5 code for this work is due to the extensive experience of its use in justifying the safety of existing water-cooled reactors. To obtain the possibility of calculations of VVER-SKD by the RELAP5 code, the properties of water were expanded and detailed in the field of supercritical pressures and temperatures. For the developed model of the VVER-SKD reactor plant, calculations of the conditional start-up of the reactor to the nominal operating mode were per-formed. The influence of deviations of the feed water temperature and flow rate on the dynamics of the reactor plant was also considered. Based on the results of calculations, conclusions are made about the stability of the reactor plant in the nominal mode.

reactor plant, VVER-SKD, dynamics, stability, feedwater, feedbacks