What are neutron-induced reactions in a reactor?

Neutron-induced reactions in a reactor are reactions triggered by the absorption of neutrons by atomic nuclei.

In a nuclear reactor, neutron-induced reactions are fundamental processes that drive the production of energy. These reactions occur when atomic nuclei absorb neutrons, leading to a series of transformations and emissions. The most common type of neutron-induced reaction in a reactor is nuclear fission, where the absorption of a neutron by a heavy nucleus (like uranium-235 or plutonium-239) causes the nucleus to become unstable and split into two smaller nuclei, releasing a large amount of energy in the process.

Another type of neutron-induced reaction is radiative capture, where a neutron is absorbed by a nucleus, leading to the emission of gamma radiation. This process does not result in the splitting of the nucleus, but it does lead to the formation of a different isotope of the same element. For example, when a uranium-238 nucleus absorbs a neutron, it transforms into uranium-239, which eventually decays into plutonium-239, a fuel used in some types of reactors.

Neutron-induced reactions are also responsible for the creation of nuclear waste. Some of the products of fission are radioactive isotopes with long half-lives, which remain hazardous for a long time. The management of this waste is a significant challenge in the operation of nuclear reactors.

The rate of neutron-induced reactions in a reactor is controlled by adjusting the number of neutrons in the reactor core. This is typically done by using control rods, which absorb neutrons and thus reduce the number of neutrons available to induce reactions. By carefully managing the position of these control rods, operators can control the rate of fission reactions and thus the power output of the reactor.

In summary, neutron-induced reactions are key processes in the operation of a nuclear reactor. They drive the production of energy, the creation of new isotopes, and the generation of nuclear waste. Understanding these reactions is crucial for the safe and efficient operation of nuclear power plants.