Which reactor type is most popular in the U.S., uses ordinary water as coolant and moderator, and requires enriched uranium?

Which reactor type is most popular in the U.S., uses ordinary water as coolant and moderator, and requires enriched uranium?

• A. Light Water Reactors
• B. Candu Reactor
• C. AGR Reactor
• D. Heavy Water Reactors

Answer: (A)

Light water reactors are the dominant type in the United States. They use ordinary water (H2O) as both coolant and moderator, which slows neutrons to energies favorable for fission. To sustain the chain reaction in this setup, the fuel must be enriched uranium—increasing the fraction of fissile U-235 from natural levels of about 0.7% to a few percent—because natural uranium would not maintain the reaction efficiently with a light-water moderator. The other options involve different moderators or coolants (heavy water, or CO2 gas with graphite) and are not the common US choice, so they don’t match the given criteria.

Light water reactors are the dominant type in the United States. They use ordinary water (H2O) as both coolant and moderator, which slows neutrons to energies favorable for fission. To sustain the chain reaction in this setup, the fuel must be enriched uranium—increasing the fraction of fissile U-235 from natural levels of about 0.7% to a few percent—because natural uranium would not maintain the reaction efficiently with a light-water moderator. The other options involve different moderators or coolants (heavy water, or CO2 gas with graphite) and are not the common US choice, so they don’t match the given criteria.