How does fission differ from fusion in nuclear reactions?

Fission involves splitting a heavy nucleus into two lighter ones, while fusion combines two light nuclei to form a heavier one.

In nuclear reactions, fission and fusion represent two distinct processes. Nuclear fission is a process where a heavy nucleus, such as uranium or plutonium, is split into two or more smaller nuclei along with the release of a large amount of energy. This process is typically initiated by the absorption of a neutron by the heavy nucleus, which makes it unstable and causes it to split. The resulting fragments are typically radioactive, leading to a chain reaction that can be controlled in a nuclear reactor or uncontrolled in a nuclear weapon.

On the other hand, nuclear fusion is a process where two light nuclei, typically isotopes of hydrogen like deuterium and tritium, combine to form a heavier nucleus, such as helium. This process also releases a large amount of energy, but unlike fission, it requires extremely high temperatures and pressures to overcome the electrostatic repulsion between the positively charged nuclei. This is why fusion reactions are the primary energy source in stars, including our sun, where such extreme conditions exist.

While both processes release energy, the energy per nucleon released in fusion reactions is much greater than in fission reactions. This is because fusion reactions involve light elements, which have a lower binding energy per nucleon, meaning it takes less energy to break them apart. When these light elements combine to form a heavier element, the difference in binding energy is released as a large amount of energy.

However, despite the greater energy potential of fusion, it is much more difficult to achieve and control on Earth due to the extreme conditions required. Fission, while less energy-dense, is easier to initiate and control, which is why it is currently the primary method used in nuclear power plants. Both processes, however, have significant implications for energy production and the environment, with ongoing research aimed at making fusion a viable and sustainable energy source.