When the nucleus of an atom in a crystalline solid undergoes radiative neutron capture there is disruption of the crystal in the vicinity of the event due to energetic processes accompanying the nuclear transformation. This local disruption has been termed a "hot-zone" or "displacement spike". The chemical state of a transformed recoil atom immediately following transformation is unknown. Within a microsecond the "hot zone" has cooled sufficiently to "freeze" the recoil atom into a stable (or metastable) chemical state. A fraction of the metastable recoil atoms can undergo thermal annealing reactions, and the chemical nature of the metastable state can sometimes be inferred from annealing data. It is characteristic of these reactions that the recoil atoms tend to be reincorporated into the parent chemical form.