Which reactor type is fast-neutron and expensive, with no moderator?

Which reactor type is fast-neutron and expensive, with no moderator?

• A. FNR Reactor
• B. Magnox Reactor
• C. Candu Reactor
• D. Light Water Reactors

Answer: (A)

Neutrons in fission can stay fast or be slowed to thermal speeds. A fast-neutron reactor keeps neutrons fast by using little or no moderator, so the fission process relies on fast neutrons rather than slowed, thermal neutrons. This approach, often used for breeding fuel, requires specialized materials and coolants (like liquid metals) and more complex safety and fuel-handling systems, which together drive higher costs. The other reactor types all rely on a moderator to slow neutrons to thermal energies, which makes them thermal-neutron systems rather than fast-neutron ones. That’s why they don’t fit the description of being fast-neutron with no moderator. So the option describing a fast-neutron reactor with no moderator is the correct one.

Neutrons in fission can stay fast or be slowed to thermal speeds. A fast-neutron reactor keeps neutrons fast by using little or no moderator, so the fission process relies on fast neutrons rather than slowed, thermal neutrons. This approach, often used for breeding fuel, requires specialized materials and coolants (like liquid metals) and more complex safety and fuel-handling systems, which together drive higher costs.

The other reactor types all rely on a moderator to slow neutrons to thermal energies, which makes them thermal-neutron systems rather than fast-neutron ones. That’s why they don’t fit the description of being fast-neutron with no moderator.

So the option describing a fast-neutron reactor with no moderator is the correct one.