Why is nuclear fusion considered a safer alternative to nuclear fission?

Nuclear fusion is considered a safer alternative to nuclear fission primarily because it cannot launch chain reactions. In nuclear fission, the splitting of heavy atomic nuclei can lead to a chain reaction that, if uncontrolled, can result in catastrophic outcomes, such as nuclear meltdowns. This dangerous characteristic is not present in nuclear fusion, where two light atomic nuclei combine to form a heavier nucleus, releasing energy in the process.

Because fusion reactions require extremely high temperatures and pressures to occur, achieving and maintaining these conditions is challenging. This makes it inherently self-limiting; if any disruption occurs, such as a drop in temperature or pressure, the fusion reaction stops, reducing the risk of uncontrolled reactions. Therefore, the ability for fusion to not sustain chain reactions significantly enhances its safety profile compared to fission.

While other aspects of fusion, such as fuel requirements and byproducts, may offer advantages, the primary safety attribute lies in its inability to create chain reactions, thus avoiding the risks associated with fission.