What are the expected advantages of fusion reactors over fission reactors?

Fusion energy comes from the process of combining two light atomic nuclei to form a heavier nucleus. This is the same type of reaction that powers the sun.
A key advantage of fusion energy is its potential to produce significantly more energy compared to traditional fission energy. Fusion reactions can theoretically release about four times more energy than fission reactions. Another important point is that fusion fuels (like isotopes of hydrogen, such as deuterium and tritium) are more abundant and can be extracted from sources such as water. This means that fusion energy can provide a more sustainable and long-lasting energy supply.
The process involves smashing hydrogen nuclei together at extremely high temperatures, causing them to merge and release energy. Because of the amount of energy released, fusion holds the promise of producing large amounts of electricity.

Fission energy is created when a heavy atomic nucleus splits into two lighter nuclei, releasing energy. This process is used in current nuclear reactors and atomic bombs.
Even though fission energy is potent, it has some drawbacks compared to fusion. The fuels used for fission, such as uranium or plutonium, are not as abundant as the fuels for fusion. Additionally, the fission process generates a significant amount of radioactive waste, which poses long-term environmental and health risks.
In a fission reactor, a neutron collides with the nucleus of a heavy atom, typically uranium-235 or plutonium-239, causing it to split into smaller parts. This reaction releases a substantial amount of energy in the form of heat, which is then used to produce electricity.

Radioactive waste is an important consideration when comparing fusion and fission reactors.
Fission reactors produce a significant amount of radioactive waste, including spent fuel and other materials that are contaminated with radionuclides. This waste remains hazardous for thousands of years, requiring secure storage and management to protect human health and the environment.
On the other hand, fusion reactors generate much less radioactive waste. The primary waste product of fusion is helium, which is non-toxic and non-radioactive. Although some radioactive waste is still produced, it has a much shorter half-life and is generally less hazardous than the waste from fission reactors. This makes the management and disposal of fusion waste simpler and safer.

Nuclear safety is a crucial factor when evaluating energy sources.
Fission reactors pose several safety risks, including the possibility of a catastrophic meltdown. If the reactor's cooling system fails, the core can overheat and release large amounts of radiation into the environment, as seen in incidents like Chernobyl and Fukushima.
Fusion reactors, however, have a lower risk of such catastrophic failures. The fusion reaction requires extremely specific conditions to sustain, such as high temperatures and pressures. If these conditions are not maintained, the reaction naturally stops. As a result, fusion reactors are inherently safer and avoid the risk of meltdown. However, maintaining the precise conditions needed for fusion is a significant engineering challenge.

Fuel sources for fusion and fission reactors are quite different, which impacts their sustainability and availability.
Fusion reactors use isotopes of hydrogen, such as deuterium and tritium, which are relatively abundant. Deuterium can be extracted from water, and tritium can be produced from lithium, making fusion fuel more easily accessible and sustainable in the long term.
In contrast, fission reactors rely on heavy elements like uranium and plutonium. These elements are less abundant and must be mined and refined, processes that can be environmentally damaging. Additionally, the availability of uranium is limited, which raises concerns about the long-term sustainability of fission energy.