ANALYSIS OF THERMOHYDRAULIC CHARACTERISTICS OF STEAM GENERATOR CASSETTES OF THE RITM-200 REACTOR PLANTS OF THE UNIVERSAL NUCLEAR ICEBREAKERS

Currently, a new icebreaking fleet including universal nuclear icebreakers of the new generation of project 22220 is being intensively built in Russia. The nuclear icebreakers of this project such as “Arctic” and “Siberia” are already in operation. The “Ural” “nuclear icebreaker is almost ready for commissioning. “Yakutia” and “Chukotka” icebreakers as well as the icebreaker-leader of project 10510 are under construction. The integrated layout of the main equipment of the reactor plant had been used for the first time on the nuclear icebreakers of the new generation of these projects. The application of the new principle of equipment layout required switching to a fundamentally new method of forming the heat exchange surface of steam generators. As a result, straight-tube modular structures assembled into cassettes of steam generators were used. The approach to providing feed water supply and steam removal from steam generators has also changed, which significantly affects the thermohydraulic processes in the cassettes and leads to a decrease in the temperature of steam at the outlet of steam generators. In addition, the heat exchange surface of the modules in the longitudinal section forms annular channels with two-way heating by a coolant, which also affects the steam generators characteristics formation. In particular, the coefficients of heat transfer and heat transfer over the phase sections of heat exchange, the average logarithmic heat heads and the distribution of the heat exchange surfaces of the sections have changed compared to the previously used coil steam generators. At the same time, the hydraulic resistance of the flows through the working fluid and the coolant has decreased which reduces energy costs for pumping media and creates favorable conditions for improving natural circulation. In this paper, the task is to analyze the features of the thermohydraulic characteristics of steam generator cassettes, to compare them with similar characteristics of coil steam generators in operation.