Because the plasmoid rings are self-sustaining, they can actually move through other materials once started until they hit mainly iron, at which point the fusion reaction will consume more energy than it releases.
My notes: If you could induce enough of these in a LENR material simultaneously, you would get a very big explosion. If the explosion produced enough plasmoids, the explosion might continue to propagate through the surrounding materials. Hmmmm.
“Mini-tokamak” is a bit of a misnomer, since it’s not compression by high kinetic energy causing the fusion, but removal of the Coulomb barrier due to quantum effects in the plasmoid which allows the nuclei to hit each other.
There have been several thermal runaway incidents in LENR. The most famous was early in the days of Pons-Fleishmann.