Controlled nuclear fission refers to the process of splitting the nucleus of an atom into smaller parts in a controlled manner. In this context, neutrons play a crucial role.
In a controlled nuclear fission reaction, a large nucleus, typically that of a uranium-235 or plutonium-239 atom, is bombarded with a neutron. This collision causes the large nucleus to become unstable and split into two or more smaller nuclei, releasing a significant amount of energy in the form of heat.
Importantly, during controlled fission, additional neutrons are also released along with the smaller nuclei. These neutrons can go on to collide with other fissile nuclei, causing them to undergo fission as well. This creates a chain reaction, where each fission event releases more neutrons that induce further fission reactions.
To control this process and harness the energy released, various measures are taken. Control rods made of materials that absorb neutrons, such as boron or cadmium, are inserted into the reactor. These control rods can be adjusted to regulate the number of neutrons available to sustain the chain reaction. By carefully managing the neutron population, the rate of fission reactions can be controlled, allowing for the steady release of energy without the risk of an uncontrolled or runaway reaction.
Controlled nuclear fission is the principle behind nuclear power plants, where the heat generated by the controlled fission reactions is used to produce steam, which, in turn, drives turbines to generate electricity. This process provides a reliable and efficient source of power with lower greenhouse gas emissions compared to traditional fossil fuels.