Which material is closely associated with ore deposits and is used as a fuel feedstock in some nuclear systems?

• A. Smoke Detectors
• B. Natural Uranium
• C. High Level Radiation
• D. Plutonium

Answer: (B)

Natural uranium is the material described. It occurs in uranium ore deposits and is mined as the raw source for nuclear fuel. While most reactors use enriched uranium, some designs—such as heavy-water moderated systems like CANDU reactors—can operate with natural uranium as fuel without enrichment. This makes natural uranium a fuel feedstock closely tied to ore deposits. The other options don’t fit: smoke detectors use americium-241, not a reactor fuel; high level radiation isn’t a material; plutonium is produced from uranium in reactors and isn’t naturally found in ore deposits, though it can be used as fuel in special MOX fuel.