What describes a fast breeder reactor?

What describes a fast breeder reactor?

• A. Produces more Pu-239 than it consumes and uses no moderator
• B. Runs on standard light water moderator
• C. Produces energy by fusion
• D. Is a low-temperature reactor

Answer: (A)

Fast breeder reactors rely on fast neutrons to both keep fission going and to convert fertile material into new fissile fuel. Because the neutrons stay fast, these reactors run with little or no neutron moderator. The keeper idea is that U-238 can capture a neutron and become Pu-239, which can then fission to produce energy, and over time more Pu-239 is created than is consumed. That net production of Pu-239 is what “breeds” fuel. Other descriptions describe a thermal (moderated) reactor, energy from fusion, or a low-temperature reactor, which don’t match how fast breeders operate.

Fast breeder reactors rely on fast neutrons to both keep fission going and to convert fertile material into new fissile fuel. Because the neutrons stay fast, these reactors run with little or no neutron moderator. The keeper idea is that U-238 can capture a neutron and become Pu-239, which can then fission to produce energy, and over time more Pu-239 is created than is consumed. That net production of Pu-239 is what “breeds” fuel. Other descriptions describe a thermal (moderated) reactor, energy from fusion, or a low-temperature reactor, which don’t match how fast breeders operate.