What is the role of steam generators in PWRs?

• A. To generate steam directly.
• B. To cool the reactor core.
• C. To keep primary water separate from secondary water while generating steam.
• D. To filter contaminants.

Answer: (C)

Steam generators in pressurized water reactors act as heat exchangers that transfer heat from the hot, high-pressure primary coolant to a separate secondary water loop while keeping the two fluids physically separated. This separation is crucial because the primary coolant, which is in contact with the reactor core, stays in a closed loop at high pressure to prevent boiling and to contain any radioactivity. The secondary loop, which is non-radioactive, receives that heat and boils to produce steam that drives the turbine.

The steam is generated on the secondary side, not in the primary loop, and the heat transfer happens through the tube walls that separate the two fluids. This arrangement provides the necessary heat transfer boundary between the radioactive primary circuit and the non-radioactive secondary circuit, enabling efficient power generation without mixing the waters. It isn’t where steam is produced directly in the primary circuit, nor is it a cooling device for the core or a filter for contaminants.