In the context of nuclear reactors, what is the primary effect of neutron absorption by a nucleus?

• A. It converts the nucleus into a stable isotope without releasing energy.
• B. It can cause the nucleus to undergo fission, releasing energy.
• C. It decreases the number of protons in the nucleus.
• D. It always increases the nuclear binding energy of the nucleus.

Answer: (B)

Verified step by step guidance

1. Understand that neutron absorption by a nucleus means a neutron is captured by the nucleus, increasing its neutron number by one.
2. Recognize that this absorption can make the nucleus unstable, potentially causing it to split into smaller nuclei, a process called fission.
3. Recall that nuclear fission releases a significant amount of energy due to the conversion of mass into energy, as described by Einstein's equation \(E=mc^{2}\).
4. Note that neutron absorption does not necessarily convert the nucleus into a stable isotope; instead, it often leads to instability and fission in fissile materials.
5. Understand that neutron absorption does not decrease the number of protons, nor does it always increase nuclear binding energy; its primary effect in reactors is to induce fission and release energy.