The Reactor Building is the most important part of the nuclear power plant. That’s why the protection of the Reactor Building and its accurate modelling is the basis of safe operation of the nuclear power plant. The most common type of reactor building structures is a double shell of monolithic reinforced concrete. The inner protective shell is performed prestressed. There are no specialized Russian standards for the calculation of prestressed inner protective shell. The formulas proposed by SP 63.13330.2012 in the calculation of long-term losses do not take into account the nonlinearity of deformations taking into account time, as well as many other factors. In the course of the work, various foreign standards were analyzed, and a compilation of theoretical and measured values was performed.