Study on control strategies of the MW-scale supercritical CO₂ recompression Brayton cycle for lead-cooled fast reactor

The supercritical CO₂ (sCO₂) Brayton cycle for the lead-cooled fast reactor (LFR) is an ideal power generation system for the distributed energy supply in remote islands. To figure out the optimal operating modes of the MW-scale sCO₂ LFR unit in different load demands, this work performs a dynamic simulation based on the developed control modules. A parametric analysis is conducted about the effects of rotational speed, split ratio, and main gas temperature on the dynamic characteristics. Control strategies are further studied based on the thermodynamic performance and safety under four variable temperature load regulation modes and three fixed temperature rapid load regulation modes. Results show that the tracking α_opt mode has the highest average net efficiency (η_netav) of 19.13 %. The tracking α_safe mode allows compressors to operate in the safest range by sacrificing a little η_netav. Excellent load change rates are revealed by using the main circuit regulating valve control mode and the turbine bypass control mode, with −12.48 %Pe/min & 11.92 %Pe/min, and −8.25 %Pe/min & 9.70 %Pe/min, respectively. Though the load change rate of the RS control mode is −3.96 %Pe/min & 3.47 %Pe/min, its η_netav is higher. Our work guides the efficient, flexible, and safe operation of the sCO₂ LFR unit.