Reactors for propulsion applications use

A. Natural uranium

B. Molten lead

C. Any form of uranium

D. Thorium

Answer: Option B

Solution(By Examveda Team)

Molten lead can be used as the primary coolant because lead and bismuth have low neutron absorption and relatively low melting points.
Neutrons are slowed less by interaction with these heavy nuclei and therefore help make this type of reactor a fast-neutron reactor.