In nuclear fusion facilities, the nuclear reaction virtually takes place in a vacuum.

Damage of the plasma vessel (Figure: segment for Stellarator Wendelstein 7-X) causes extinction of the reaction.

A catastrophic accident is impossible besides since there are always only a few milligrams of 'fuel' within the facility.

There is virtually no radioactive waste during operation, but it ensues with the disassembly of worn out reactors (neutron-activated material constructions).

Deactivation of this waste lasts for 100 to 500 years; within a few decades it reduces to weakly radioactive waste.

As long as one cannot dispense with the radioactive tritium as fuel, however, an exacting safety regime is indispensable.