How does nuclear fission generate energy in a reactor?

Understanding Nuclear Fission: How Energy is Generated in a Reactor

Nuclear fission is a powerful process that generates energy in nuclear reactors, providing a significant portion of the world’s electricity. This process involves splitting the nucleus of a heavy atom, such as uranium-235 or plutonium-239, into smaller fragments, releasing a tremendous amount of energy in the form of heat.

Inside a nuclear reactor, fuel rods containing fissile material are arranged in a core submerged in water, which acts as both a coolant and a neutron moderator. When a neutron collides with the nucleus of a fissile atom, it causes the nucleus to become unstable and split into two smaller nuclei, known as fission fragments. This splitting releases additional neutrons and a large quantity of energy—approximately 200 million electron volts (MeV) per fission event.

The released neutrons can then collide with other fissile nuclei, sustaining a controlled chain reaction. Control rods made of materials like boron or cadmium are inserted or withdrawn from the reactor core to absorb excess neutrons, regulating the rate of fission and ensuring the reaction remains stable and safe.

The heat generated from fission raises the temperature of the reactor coolant, typically water, to about 550°F (288°C). This heated water or steam drives turbines connected to generators, converting thermal energy into electrical energy. The efficiency and safety of this process depend on precise engineering and rigorous safety protocols.

Nuclear fission offers a low-carbon energy source, producing no direct greenhouse gas emissions during operation. However, it requires careful management of radioactive waste and stringent safety measures to prevent accidents. Understanding the science behind nuclear fission helps appreciate its role in the global energy landscape and the ongoing efforts to harness this powerful reaction responsibly.