Nuclear fusion power plants produce electricity without incurring the dangers associated with nuclear fission.
No risk of meltdown or explosion
Fusion systems cannot melt down or explode since the fusion reaction only acts on a small amount of nuclear fuel at a time and can only occur if suitable conditions can be created and maintained for a sufficient time. If any part of the process does not work perfectly, fusion will not occur. In contrast, in a fission reactor, fuel is added in bulk and the reactor controls the rate at which a chain reaction occurs; if the control mechanism fails, the reaction can run away and a meltdown can occur.
No highly active, long-lived radioactive wastes
Fusion systems do not use or produce highly active, long-lived radioactive waste. In contrast, fission reactors create reaction products that are unstable and more highly radioactive than the parent fuel material. Some of these fission products have half-lives of tens of thousands of years, creating long-term radioactive waste storage problems.
Fusion power plants that use tritium need to breed very small quantities of it for fuel, but this tritium is consumed almost immediately after creation. Tritium is commonly used inside glow-in-the-dark EXIT signs, and is only weakly radioactive. It has a short 12-year half-life, and is only dangerous to humans if ingested. By comparison, coal power plants disperse concentrations of uranium, thorium, and other naturally-occurring radioactive isotopes in fly ash.
Unattractive terrorist targets
Fusion power plants are unattractive terrorist targets since their destruction cannot cause widespread environmental damage or human injury, and they do not produce or contain any materials that could be used for making bombs.
In contrast, fission reactors can disperse long-lived radioactive materials if destroyed, and their fuel can sometimes be used in nuclear weapons.