Fuel choice for a Boiling Water Reactor (BWR): which nuclear fuel is typically loaded in the core?

Introduction / Context:
Commercial BWRs are thermal reactors using light water as both moderator and coolant. The neutron economy of light water requires fuel with higher fissile content than naturally occurring uranium to achieve practical core sizes and cycle lengths.

Given Data / Assumptions:

• Moderator and coolant: ordinary light water.
• Standard commercial fuel form: UO2 pellets in zirconium alloy cladding.
• Typical enrichment: a few weight percent U-235.

Concept / Approach:
Because hydrogen in light water captures neutrons and moderates strongly, natural uranium (0.711% U-235) is usually insufficient for steady criticality with practical core geometry. Therefore, BWRs, like PWRs, use enriched uranium—commonly in the 2–5% U-235 range—fabricated as ceramic oxide fuel.

Step-by-Step Solution:
1) Identify reactor type: thermal, light-water moderated.2) Evaluate neutronic requirements: light water absorptivity demands higher fissile content.3) Conclude that enriched uranium fuel is standard for BWR cores.

Verification / Alternative check:
Vendor data sheets and generic BWR core design descriptions specify low-enriched uranium fuel assemblies; MOX loading is possible in some programmes but is not the baseline.

Why Other Options Are Wrong:
Plutonium metal is not the typical commercial BWR fuel form.Natural uranium is used in heavy-water-moderated reactors, not standard BWRs.Thorium requires a breeding strategy (e.g., Th-U fuel cycle) and is not the default BWR fuel.

Common Pitfalls:
Assuming “natural uranium” works in all thermal reactors; overlooking the role of moderator absorption in fuel enrichment needs.

Final Answer:
Enriched uranium