The article discusses a model of the interaction between a liquid−metal coolant (Pb, Pb55Bi(e)) and a heat exchanger material (316L steel) in an SVBR-type nuclear reactor cooling device for the case in which the effect of liquid-metal embrittlement cannot be ignored. It is assumed that a crack propagates due to the penetration of the liquid-metal coolant into intergrain boundaries. The free energy of a wetted surface is calculated using the mean-field theory within the formalism of finite element analysis. Tensile stress S (MPa) is determined for the propagation of a crack 50 µm long from a defect in the form of a 0.15-mm scratch on the surface of the heat exchanger. The calculation is carried out for an operation temperature range of 900–1100 K, when the melt wets the steel. The values of and have been obtained for the interaction of Pb55Bi melts and Pb with 316L steel, respectively. The calculation results mean that a heat exchanger with surface defects can be damaged due to the effect of liquid-metal embrittlement.