Enhancing grid stability with renewable energy sources by integrating thermal energy storage into nuclear power plants for load balancing

This study evaluates the feasibility of integrating steam accumulator-based thermal energy storage into the nuclear power plant secondary circuit to enable intraday grid stabilization, addressing renewable energy source intermittency using Poland's projected 2040 energy system as a representative case study. The proposed system demonstrates capacity to prevent 3.1 GWh of renewables curtailment during a 72-h analysed period while maintaining stable nuclear reactor thermal power and preserving existing steam turbine designs, avoiding costly retrofits. In the tested configuration, thermal energy storage enables reducing the nuclear unit's electrical output by >40% and increasing it by ∼5% of nominal power. Results validate thermal energy storage as a technically viable alternative to battery storage for stabilising reactor load, proving cost-advantageous over the plant's 60-year lifespan. The solution aligns with decarbonization goals by enhancing grid flexibility through carbon-free stabilization, offering a replicable model for hybrid nuclear-renewable systems.