Which is an example of a closed system in a nuclear plant?

Which is an example of a closed system in a nuclear plant?

• A. Reactor Coolant System
• B. Condenser Circulating Water System Open to Lake
• C. Cooling Tower System
• D. Feedwater Storage Tank

Answer: (A)

A closed system keeps the working fluid inside a sealed loop, with no net mass entering or leaving the loop during normal operation. The Reactor Coolant System fits this because it circulates the primary coolant continuously through the reactor core, pumps, and steam generators in an entirely enclosed loop. The only heat transfer with the environment occurs across heat transfer surfaces, but the coolant itself isn’t discharged or replaced in normal operation, so the mass stays within the system. The condenser circulating water system pulls water from an external source (like a lake) and returns it after cooling, so it exchanges mass with the environment and is not a closed loop. The cooling tower system involves evaporation and interaction with the external atmosphere, which also means mass is exchanged with the surroundings. The feedwater storage tank is part of the secondary side and relies on makeup water and venting, so it isn’t a strictly closed system either.

A closed system keeps the working fluid inside a sealed loop, with no net mass entering or leaving the loop during normal operation. The Reactor Coolant System fits this because it circulates the primary coolant continuously through the reactor core, pumps, and steam generators in an entirely enclosed loop. The only heat transfer with the environment occurs across heat transfer surfaces, but the coolant itself isn’t discharged or replaced in normal operation, so the mass stays within the system.

The condenser circulating water system pulls water from an external source (like a lake) and returns it after cooling, so it exchanges mass with the environment and is not a closed loop. The cooling tower system involves evaporation and interaction with the external atmosphere, which also means mass is exchanged with the surroundings. The feedwater storage tank is part of the secondary side and relies on makeup water and venting, so it isn’t a strictly closed system either.