Which statement identifies the listed isotopes as common fissionable fuels?

Which statement identifies the listed isotopes as common fissionable fuels?

• A. Th-232 and Uranium-238
• B. Naturally occurring
• C. Uranium-235 and Plutonium-239
• D. Common fissionable fuels

Answer: (C)

Fissionable fuels are materials that can sustain a nuclear fission chain reaction by fissioning when struck by neutrons and releasing enough neutrons to keep the process going. Uranium-235 and Plutonium-239 are classic examples because they readily undergo fission with neutrons and release multiple neutrons per fission, allowing the reaction to continue. Uranium-235 is present in natural uranium but is typically enriched to be useful in reactors, while Plutonium-239 is produced in reactors from Uranium-238. In contrast, Thorium-232 and Uranium-238 are fertile: they can absorb neutrons and breed fissile isotopes (like Uranium-233 or Pu-239), but they do not sustain fission as efficiently on their own in standard reactor conditions. Saying something is “naturally occurring” doesn’t specify which fissile isotopes are being used, whereas Uranium-235 and Plutonium-239 directly identify the common fuels.

Fissionable fuels are materials that can sustain a nuclear fission chain reaction by fissioning when struck by neutrons and releasing enough neutrons to keep the process going. Uranium-235 and Plutonium-239 are classic examples because they readily undergo fission with neutrons and release multiple neutrons per fission, allowing the reaction to continue. Uranium-235 is present in natural uranium but is typically enriched to be useful in reactors, while Plutonium-239 is produced in reactors from Uranium-238. In contrast, Thorium-232 and Uranium-238 are fertile: they can absorb neutrons and breed fissile isotopes (like Uranium-233 or Pu-239), but they do not sustain fission as efficiently on their own in standard reactor conditions. Saying something is “naturally occurring” doesn’t specify which fissile isotopes are being used, whereas Uranium-235 and Plutonium-239 directly identify the common fuels.