Replicable experimental results about low‐energy nuclear fusion reactions based on initially reacting deuterium nuclei giving cold nuclear fusion synthesis of helium (both isotopes ³He and ⁴He) and energy release as final products are reported in this article. These final products are results of interaction of deuterium with the solids in experimental system including two specimens: molybdenum metal and palladium nanowires. Experimental proofs about cold nuclear fusion synthesis of both ³He and ⁴He are provided. It reported a correlation between concentration of the generated helium and the measured temperature of the sample holder. It is found that the concentrations of both ³He and ⁴He increase with increase of the kinetic energies of the interacting deuterium nuclei and also with increase of the temperature of the sample holder.

A significant energy release over a short time is achieved in replicable experiments involving the interaction of deuterium gas with constantan specimens. The experiments were carried out in a gas chamber where the injected deuterium interacted with heated specimens: (i) Many replicable experiments were performed at initial temperatures in the range of 666–681 °C. The temperatures of the specimens began to increase ~8 s after the beginning of deuterium injection as additional increases of 358–382 °C reached after ~30 s. The released excess power was in the range of 183–209 W, its density ranged from ~114–130 W/g, and the ratio of (output power)/(input power) was ≈ 3.76–3.91. (ii) Several replicable experiments were performed at initial temperatures of 950 °C. In all these experiments, explosive evaporation of the wires occurred immediately after the beginning of deuterium injection. The released excess momentary power was greater than 3400 W, its density was 2280 W/g, and the ratio of (output power)/(input power) was ≈ 16 and greater. The outcomes found were as follows: (a) the released excess power was not of electrical origin; (b) the released excess power of chemical origin was less than ~0.18% of the total released excess power; (c) the significant density of the released excess power; and (d) helium release, correlating with the energy release, was observed. The conclusion that the released energy is of nuclear origin was drawn.