[Geezer (OP)]

There is on-going research into hybrid fusion/fission reactors. If I have it right, the general idea is that fission only takes place in response to bombardment from particles that result from fusion. I believe it's still a long way from being practical of course, but the thing that struck me about this approach is that it could possibly be made intrinsically fail-safe.

Conventional fission reactors operate because of a chain reaction, and, as we have seen several times now, when things go wrong, that chain reaction can be difficult to control.

Would I be right in thinking that as soon as the power is removed from the lasers that initiate the fusion process, the whole thing will start to cool down?