When are Main FeedWater Reg Bypass valves typically used?

Main Feedwater Reg Bypass valves are typically used during startup up to 30% power. This is a crucial phase in a power plant operation where maintaining appropriate feedwater flow and pressure is essential for establishing a stable thermal and hydraulic environment in the steam generator. During startup, the feedwater system needs to balance the thermal loads without over-pressurizing the steam generator or causing thermal shock, which could damage the equipment.

The use of bypass valves in this early operational stage allows for better control of the feedwater flow, ensuring that it can be adjusted based on the needs of the system as it ramps up in power. This adaptability is vital for safely transitioning from a shutdown to an operational state. Using bypass valves enables operators to safely manage the constraints of the water system without relying solely on the main feedwater control system until conditions are appropriate for more stable control.

Therefore, their primary function during this startup phase is to prevent potential issues that could arise from rapid changes in feedwater conditions, ensuring a smoother and safer transition to full power.