Which reactor type boils water directly in the reactor vessel to produce steam?

• A. PWR
• B. Small modular reactor
• C. CANDU
• D. BWR

Answer: (D)

Boiling water reactors generate steam directly in the reactor vessel by letting the coolant reach its boiling point inside the core. The steam that forms is sent straight to the turbine, so there’s no separate steam generator or secondary loop. This direct boiling setup distinguishes it from other designs where the reactor coolant is kept under high pressure to avoid boiling and heat transfer to a secondary water loop via a steam generator. CANDU and many small modular reactors use a separate steam-raising system rather than boiling inside the vessel. So the design that boils water in the reactor vessel to produce steam is the boiling water reactor.