Reactivity control in typical unit operation activities of third-generation nuclear power plants

Effective reactivity management, as an important means to ensure the safe operation of nuclear power plants, is a policy requirement proposed by the World Association of Nuclear Power Operators (WANO) for various nuclear power plants and has gradually become a factor that designers need to consider in the design of reactivity control systems. In recent years, there has been an urgent need for domestic operational facilities to enhance their reactivity management capabilities, and at the same time, advanced operational design for third-generation nuclear power also urgently needs to understand relevant information. However, due to various reasons, there are few research discussions on reactivity control and management in the operation of nuclear power plants both domestically and internationally. The AP1000 power plant adopts the latest designs such as Mechanical Shimming (MSHIM) and Rapid Power Reduction System (RPR). The operating range of its units is wide and diverse, and the corresponding reactive management measures are highly representative. Based on the above issues, the core monitoring software was used to simulate and summarize three typical operational activities of the AP1000 power plant, including start-up, unit peak shaving, and rapid power reduction system triggering. The reactivity change characteristics and control elements were analyzed in detail, and corresponding key monitoring parameters were proposed. A detailed reactivity management strategy was provided. This has significant reference significance for improving the reactivity management capability of domestic nuclear power plants and strengthening operational safety, especially for the operational design of reactivity control for third-generation nuclear power units in China.