We present results of experimental study of nanoporous Si (SiNР) structure formation by using the method of metal-stimulated chemical etching upon irradiation with small doses of γ-radiation directly in the process of production (in situ). It is shown that the radiation leads to an increase of the crystallization of SiNP structures obtained on previously irradiated substrates. Apparently, this can be explained by a decrease in the initial defectiveness of the silicon substrate due to irradiation with small doses of γ-radiation.