Nuclear reactor physics is the study of how nuclear reactors operate, focusing on the processes of nuclear fission and neutron interactions. In a reactor, heavy atomic nuclei, such as those of uranium or plutonium, split into smaller nuclei when struck by neutrons, releasing energy. This energy is harnessed to produce steam, which drives turbines to generate electricity. Key concepts in nuclear reactor physics include neutron moderation, which slows down fast neutrons to increase the likelihood of fission, and control rods, which absorb excess neutrons to regulate the reaction rate. Understanding these principles is essential for safe and efficient reactor design and operation.