Fission Processes

Introduction

The nucleus of an atom splits into two lighter nuclei during nuclear fission. In some cases, the process occurs spontaneously, while in others, it is induced by excitation of the nucleus with a variety of particles (e.g., neutrons, protons, deuterons, or alpha particles) or electromagnetic radiation in the form of gamma rays. A large amount of energy is released during the fission process, radioactive products are formed, and several neutrons are emitted. These neutrons can cause fission in a nearby nucleus of fissionable material, releasing more neutrons that can repeat the sequence, resulting in a chain reaction in which a large number of nuclei fission and a massive amount of energy is released.

Nuclear Fission

Fission occurs when a big, relatively unstable isotope (atoms with the same number of protons but a different number of neutrons) is bombarded with high-speed particles, often neutrons. These neutrons are accelerated before colliding with the unstable isotope, causing it to fission, or break up into smaller particles. 

During the process, a neutron is accelerated and impacts the target nucleus, which is Uranium-235 in the majority of nuclear power reactors today. This divides the target nucleus into two smaller isotopes (the fission products), three high-speed neutrons, and a massive amount of energy. This generated energy is subsequently utilised to heat water in nuclear reactors, resulting in the generation of electricity.

Example

Most nuclear reactors use uranium-235 as the target nucleus into which a neutron is carried, splitting the atom into two smaller isotopes (called “fission products”) and three additional neutrons, releasing a huge quantity of energy.

Nuclear Fusion

Nuclear fusion is the process of producing energy by combining atomic nuclei rather than dividing them (as with fission). This process happens naturally in the center of stars, such as the Sun, and produces no long-term radioactive waste or greenhouse gases.

Fusion power plants function similarly to fission plants, using the heat created by the atomic reaction to heat water, make steam, drive turbines, and generate electricity, but creating the essential conditions in a fusion reactor without spending more energy than produced has proven difficult.

Example

When two low-mass isotopes join under great heat and pressure, fusion occurs. This is most common with the hydrogen isotopes tritium (hydrogen-3) and deuterium (hydrogen-2) combining to form helium and a single additional neutron.

Fission Processes 

Albert Einstein’s famous equation relating mass and energy is as follows: 

E=MC2

This means that any reaction generates or consumes energy as a result of mass loss or gain. Energy and mass are the same thing.

The energy is released when nucleons, or particles that form an atomic nucleus, combine to form an atom. The mass of the nucleus is always less than that of the sum of the masses of the individual protons and neutrons that comprise it, corresponding to the mass defect.

Nuclear binding energy is the amount of energy required to break one mole of nuclei into individual nucleons. The greater the binding energy per nucleon, the more tightly the nucleons are held together and more stable the nucleus will be. 

Binding energies per nucleon are lower in less stable atoms. In other words, a nucleus with a high binding energy is more difficult to break apart than a nucleus with a low binding energy. The binding energy per nucleon differs with mass number. 

By undergoing nuclear fusion, light nuclei gain stability. But Nuclear fission makes heavy nuclei more stable.

Conclusion

Fission and fusion are both nuclear reactions that generate energy, but the processes are very different. Fission is the process by which a heavy, unstable nucleus splits into two lighter nuclei, whereas fusion is the process by which two light nuclei combine and release massive amounts of energy. Despite their differences, the two processes play an important role in the creation of energy in the past, present, and future.

However, research into better harnessing the power of fusion continues, but research is still in the experimental stage, as scientists continue to work on controlling nuclear fusion in an effort to create a fusion reactor that can produce electricity.