Neutron-Induced Fission in Reactors

Steps:

• Recall that nuclear fission involves splitting heavy atomic nuclei like uranium-235.
• Identify the trigger: in reactors, slow neutrons are absorbed by U-235 to form U-236.
• Note that U-236 becomes unstable and splits into lighter nuclei, releasing energy and more neutrons.
• Confirm this chain reaction sustains the reactor process.

Why C is correct:

• Neutrons are absorbed by the U-235 nucleus, forming an excited U-236 isotope that undergoes fission per the nuclear fission process.

Why the others are wrong:

• A: Alpha particles (helium nuclei) are emitted in decay, not used to initiate fission in reactors.
• B: Gamma rays are high-energy photons that ionize but do not induce nuclear splitting in U-235.
• D: Protons cause spallation or other reactions but not the controlled fission chain in reactors.

Final answer: C