The observed by Dr. D. Alexandrov energy release in solids occurs in interactions of nuclei of hydrogen isotopes incorporated in the solid crystal lattice. These hydrogen isotopes could be hydrogen, or deuterium or tritium or gas mixture between them. The incorporation of these nuclei in the crystal structure occurs due to absorption of the corresponding hydrogen isotopes.

The incorporated nuclei interact with each other as localized electrons in solids provide the necessary electrical screening needed for overcoming the electrical repulsion between these nuclei, which have positive electrical charges. It is the physical difference between the observed reactions by Dr. D. Alexandrov in solids and the thermonuclear reactions – localized electrons in solids overcome the electrical repulsion between the interacting nuclei alloying them to join each other and nuclear fusion to occur, while very high temperatures are required in thermonuclear reactions in order for the overcoming of the electrical repulsion between the interacting nuclei to occur and they to join each other. The physical difference between both types of nuclear reactions provides that both energy release and helium release are observed in reactions carried out by Dr. D. Alexandrov and in thermonuclear reactions, however, radiation release is a typical outcome in thermonuclear reactions, while no radiation or negligible radiation release can take place in the reactions observed by Dr. D. Alexandrov.