Air fast-cooling technology for 1000 MW nuclear steam turbines and its application

The large-scale integration of renewable energy requires increased flexibility from nuclear power units in modern power systems. Steam turbines in nuclear units have low natural cooling efficiency and slow cooling rates due to their large size and intricate structure. This study investigates the application of air fast-cooling technology to enhance the shutdown speed and flexibility of a 1000 MW nuclear steam turbine, marking its first application to Hua-long Pressurized Reactor (HPR1000). The finite element method was utilized to simulate the evolution of temperature and stress fields during the air fast-cooling process. The results demonstrate that the proposed air fast-cooling scheme effectively reduces rotor temperatures. Specifically, a 40 hrs cooling period decreases temperatures across rotor surfaces to below 100°C, thereby confirming its high cooling efficiency. Moreover, the maximum thermal stress during air fast-cooling is 85.2 MPa, significantly below the material’s fatigue stress limit, validating the safety of the scheme. This technology has been implemented in the fast cooling of the HPR1000, with measured cooling times showing high consistency with simulation results, confirming its safety and reliability.