One of the factors responsible for the reliable operation of wet steam turbines is the safe operation of the moisture separator steam reheaters (MSR). Based on the analysis of existing designs and operational experience of domestic and foreign MSRs, the main disadvantages of MSR constructions were identified. Recommendations on modernizing the existing models and creating advanced MSR constructions are proposed. The project of the modernized constructions SPP-220M and SPP-1000, used at operating NPP units with the VVER-440 and VVER-1000 reactors, is presented. A distinctive feature of the proposed project is that it can be implemented in the «old» or new case, which is identical to the original. Thermal-hydraulic calculations and the comparison of technical characteristics of constructions before and after the upgrade were carried out to justify the project. The positive experience of MSR modernization in the Loviisa NPP (Finland) also confirms the effectiveness and feasibility of the proposed modernization project. MSR modernization was made by the German firm Balcke Durr. The main provisions of the modernization are identical to the proposed project.