In a PWR shutdown, the heat sink for steam is typically either the condenser or the atmosphere.

• A. Turbine and condenser
• B. Condenser and atmosphere
• C. Boiler and condenser
• D. Cooling tower and atmosphere

Answer: (B)

When a PWR is shut down, the remaining heat in the plant still has to be removed from the steam cycle. The steam that must be rejected can be handled in two practical ways: condensing it in the condenser, or dumping it to the atmosphere through an atmospheric dump system.

The condenser is the primary heat sink because it uses cooling water to remove the latent heat of the steam, returning condensate to the feedwater system and letting cooldown proceed efficiently. This path is suited for long-term cooldown and steady heat removal.

If the condenser isn’t available or during certain cooldown scenarios, steam can be released directly to the atmosphere through steam dumps or relief paths. This provides an alternate heat sink, albeit less efficient and with direct steam release to the environment, ensuring the plant can continue removing heat without relying on the condenser.

The other options don’t fit as heat sinks for the steam themselves: the turbine isn’t used as a heat sink for steam when the plant is shut down, there isn’t a boiler in the PWR secondary system acting as a sink, and while the cooling tower supports the condenser’s cooling water, it isn’t a direct sink for the steam itself.