During which operations are the Main FeedWater pumps bypassed?

The Main FeedWater pumps are typically bypassed during startup and shutdown operations. This is primarily due to the fact that during these phases, the system needs to manage fluid flow and pressure differently compared to steady-state operations.

During startup, the system is not yet operating at full capacity, and any excess feedwater being supplied by the Main FeedWater pumps can lead to undesired fluctuations in pressure and flow. By bypassing the pumps, operators can control the infusion of water into the system more effectively and ensure that the initial conditions are stable for safe startup.

Similarly, during shutdown, the focus is on safely reducing the system pressure and temperature. Bypassing the pumps allows for a gradual decrease in flow and helps in managing the shutdown process without introducing unnecessary stress or flow into the system which could complicate pressure stabilization.

In normal operations and at full power, the pumps are actively working to maintain the required feedwater supply to the system. During maintenance checks, while the pumps may be temporarily deactivated, they aren’t necessarily bypassed in the same systematic manner as during startup and shutdown procedures, where specific guidelines are in place to ensure safety and efficiency.