Describe the fission process in general?

• A. When a heavy nucleus is hit with a neutron at the right energy, it may split into two lighter nuclei and release neutrons, heat, and radiation.
• B. When a light nucleus collides with a proton to form heavier nucleus only releasing photons.
• C. Fission occurs only in hydrogen and releases only neutrons.
• D. Fission requires no energy input and produces no new particles.

Answer: (A)

Fission is the splitting of a heavy nucleus after it absorbs a neutron, becoming highly excited and breaking into two lighter nuclei. This process also releases several prompt neutrons, as well as energy in multiple forms. In a reactor, fissile materials like U-235 or Pu-239 capture a thermal neutron, and the resulting system fissions. Most of the energy appears as the kinetic energy of the fission fragments, which shows up as heat in the reactor coolant. The emitted neutrons can initiate further fissions in nearby nuclei, enabling a chain reaction; some gamma radiation is also produced during the event. This description captures the essential features: neutron-induced fission of a heavy nucleus yielding lighter fragments, additional neutrons, energy, and radiation. The other statements describe phenomena like fusion or incorrect energy requirements, which do not describe fission.