Which statement best differentiates PWRs and BWRs in terms of the coolant loop?

Which statement best differentiates PWRs and BWRs in terms of the coolant loop?

• A. CANDU
• B. PWR
• C. BWR
• D. PHWR

Answer: (B)

The statement being tested is how the coolant loop differs between PWRs and BWRs. In a PWR, the reactor coolant stays in a closed primary loop inside the reactor vessel and transfers heat to a separate secondary loop through steam generators. The turbine is powered by steam from that secondary loop, so the primary loop never becomes steam. In a BWR, the coolant boils directly in the reactor vessel and the generated steam goes straight to the turbine, meaning there’s a single loop handling both cooling and steam production. This difference—the separation of the primary and secondary cooling/steam loops in a PWR versus the single loop in a BWR—is the clearest way to differentiate the two designs. The other options refer to different reactor types and don’t address the coolant loop arrangement, so they don’t fit as well.

The statement being tested is how the coolant loop differs between PWRs and BWRs. In a PWR, the reactor coolant stays in a closed primary loop inside the reactor vessel and transfers heat to a separate secondary loop through steam generators. The turbine is powered by steam from that secondary loop, so the primary loop never becomes steam. In a BWR, the coolant boils directly in the reactor vessel and the generated steam goes straight to the turbine, meaning there’s a single loop handling both cooling and steam production. This difference—the separation of the primary and secondary cooling/steam loops in a PWR versus the single loop in a BWR—is the clearest way to differentiate the two designs. The other options refer to different reactor types and don’t address the coolant loop arrangement, so they don’t fit as well.