[dogma1138]

Depending on the scale and reactor design, we have really good examples of run away fusion reactions. Run away reactions are easy, controlled ones are hard.

And whilst I won’t doubt that if fusion ever becomes commercially viable the reactors would be walk away safe it doesn’t mean that you don’t need to account for that in your design.

[willis936]

What is an example of a run away fusion reaction?

[dogma1138]

The US strategic arsenal.

[blamestross]

A Hydrogen Bomb. It is basically using a nuke (fission) to trigger fusion instead of lasers.

[willis936]

That is a run away fission reaction that ignites a short lived fusion reaction. We don't even talk about neutron populations or k factors in fusion because there is no avalanche effect possible.