Abstract— <p>The influence of corrosion products of metal structures of a repository on the sorption behavior of long-lived radionuclides in the environment of the host crystalline rocks should be taken into account during modeling aimed at confirming the safety of deep disposal of radioactive waste (RW). This study focuses on the influence of iron(II/III) on the sorption and spatial distribution of ²³⁷Np, ²³⁹Pu, and ²⁴¹Am on the minerals of a fractured gneiss sample from the Yeniseisky site of the Nizhnekansky massif (Krasnoyarsk krai). Kinetic dependencies and quantitative parameters were obtained for actinide sorption in the presence of iron in model solutions, including solution affected by contact with steel ST3. It was shown that the presence of iron (oxy)hydroxide increases the rate of actinide sorption by the rock, whereas ionic iron species have practically no effect on this process. Digital radiography demonstrated that the preferential actinide retention phase was formed by iron(III) precipitation on the calcite surface. The Raman spectrum of this phase corresponds to the iron-bearing mineral lepidocrocite.</p>