Justification of Steam‑Generator Level Setpoints for the V‑392M Reactor Unit during Normal Operation and during Deviations from Normal Operation

The ability to carry load through transients without reaching the actuation conditions of reactor safety systems and emergency shutdown is termed the dynamic stability of an NPP power unit. The water level in steam generators of the VVER‑1200 reactor unit (V‑392M) is regulated to maintain a balance among steam removal, blowdown, and feedwater supply. A change in steam‑generator water level caused by transients can reach technological protection and blocking setpoints, followed by a trip of the main circulation pump and a load reduction. Analysis of commissioning tests at the Novovoronezh, Leningrad, and Belarusian NPP units, together with recorded main‑equipment trips due to steam‑generator level deviations, made it possible to identify ways to enhance the dynamic stability of VVER‑1200 units. Maintaining the nominal water level in the steam generator prevents admission of steam to the turbine with humidity exceeding 1%. There are realistic prospects to improve the dynamic stability of VVER‑1200 units by upgrading the shutoff valves at the steam‑generator feed unit to increase their speed of response and by making corresponding adjustments to steam‑generator water‑level setpoints. Enhancing the dynamic stability of VVER‑1200 units will provide a significant additional contribution to the economic attractiveness of the improved domestically designed NPP project.