Boiling Water Reactor (BWR) concept: which statement correctly describes where and how steam is generated in a BWR nuclear power plant?

Introduction / Context:
Commercial light-water reactors are broadly classified into Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs). Understanding their steam cycle configuration is central to power plant engineering and safety systems design.

Given Data / Assumptions:

• Standard BWR arrangement with a single water/steam circuit.
• Turbine receives steam generated directly in the core region.
• No steam generators separating primary and secondary loops.

Concept / Approach:

In a BWR, coolant water enters the reactor core, is heated by fission, and partially boils within the core and upper plenum. The generated steam is separated and dried, then routed to the turbine. This is a single-loop configuration. In contrast, PWRs keep the primary water under high pressure to prevent boiling and transfer heat to a secondary loop via steam generators.

Step-by-Step Solution:

Verification / Alternative check:

Plant schematics and vendor documentation show moisture separators and steam dryers within the BWR vessel, confirming in-vessel steam generation.

Why Other Options Are Wrong:

secondary boiler (two-loop): Describes PWR, not BWR. pressurised water prevented from boiling: Again PWR behavior. homogeneous solution reactor: Different concept; not commercial BWR. helium primary: Gas-cooled reactors, not BWRs.

Common Pitfalls:

Equating all light-water reactors; forgetting that only BWRs intentionally allow boiling in the core.

Final Answer:

Coolant water is allowed to boil directly within the reactor core to produce steam for the turbine