What are the benefits of using fusion over fission as a source of nuclear energy? Why have fusion reactors not been developed yet?

Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus, releasing a significant amount of energy. This reaction powers stars, including the sun, and has the potential to provide a nearly limitless and clean energy source on Earth. The primary fuels for fusion are isotopes of hydrogen, such as deuterium and tritium, which can produce energy without the long-lived radioactive waste associated with fission.

Nuclear fission is the splitting of a heavy atomic nucleus into smaller nuclei, accompanied by the release of energy and neutrons. This process is utilized in current nuclear power plants, where uranium or plutonium isotopes are commonly used as fuel. While fission can generate substantial energy, it produces radioactive waste and poses risks of nuclear accidents, making fusion an attractive alternative.

Despite the advantages of fusion, developing practical fusion reactors has proven challenging due to the extreme conditions required for the reaction to occur, such as high temperatures and pressures. Containing the hot plasma necessary for fusion without it cooling or escaping is a significant hurdle. Current experimental reactors, like ITER, are working towards achieving sustained fusion, but technological and engineering challenges remain, delaying commercial viability.