Simulation of Main Pump Two-Speed Start-Up Strategy of Advanced Small Reactor Based on Stable operation of Once-Through Steam Generator

Once-through Steam Generator (OTSG) is widely used in advanced small reactors because of its high heat transfer efficiency and compact structure. Aiming at the start-up of OTSG, a main pump two-speed start-up scheme is proposed. In this scheme, main pumps maintain low speed running before OTSG reach the stable operation power stage, and switch to high speed running after OTSG reach the stable operation power stage, and the secondary side of OTSG maintains constant pressure. The response of flow rate and the average temperature of primary side and flow rate and pressure of secondary side of OTSG during start-up are analyzed by modeling based on the system analysis program, choosing the appropriate OTSG heat transfer and resistance relationship. The results show that the scheme can quickly pass through the unstable flow period during the start-up of OTSG, and the constant pressure control of secondary side avoids the pressure fluctuation and impact of secondary side system and equipment during operation. Moreover, the main pumps in start-up stage consumes less power and has high economy, which has engineering practice value.