What Rossi did was to weld the nano-powder to the stainless steel hot walls of the reaction vessel to get excellent phonon conduction to the active nuclear sites on the surface of the nano-powder.
In the Rossi reactor, the surface boundaries of this welded Nano-powder are where phonons are reflected. These grain boundaries and defects reflect and concentrate phonon energy at the points of constructive photonic interference. The intersection of enough of these reflections supplements the “Heisenberg confinement energy" to the point where nuclear reactions can start. With this gross photonic loading mediated by the transmission provided by the stainless steel substrate, the first bonding events gives off more phonons, causing more reactions in the immediate grain or boundary area which tends to perpetuate the chain reaction.
