Using the concept of the neutron Bloch wave presented previously, the possibility of an effective nuclear reaction of a thermal neutron and a nucleus in a boundary region of crystals is determined. Many experimental data of nuclear transmutations in the surface layer or surface region of solid materials loaded with deuterium supposedly induced by nuclear reactions with a thermal neutron are investigated using the nature of the neutron Bloch wave in solids. The physics of the nuclear reaction phenomena is discussed in the trapped neutron catalyzed fusion model.