What process is used in nuclear reactors to generate power?

• A. Nuclear fusion
• B. Ionization
• C. Chemical oxidation
• D. Nuclear fission

Answer: (D)

Energy in nuclear reactors comes from splitting heavy atomic nuclei in a process called fission. When a heavy nucleus such as uranium-235 absorbs a neutron, it becomes unstable and splits into lighter fragments, releasing more neutrons and a large amount of heat. That heat is transferred to a coolant, used to make steam, and that steam turns a turbine to generate electricity. The reaction is carefully controlled with neutron-absorbing control rods and a moderator to prevent it from running away.

Fusion would join light nuclei to release energy, which is not how current reactors operate. Ionization is just removing electrons, which doesn’t produce the massive energy needed for power. Chemical oxidation releases energy through chemical bonds, far less energy per mass than nuclear reactions, and isn’t capable of the sustained power output of a nuclear plant.