This paper deals with the investigation of crack strength of nuclear reactor cooling system wedge valve body. The main fracture mechanics expressions linking stress intensity factor with cracklike defect length are presented in the introduction. Analytical equations for reliability function evaluation are obtained, fracture toughness and stress intensity factor are viewed as Gaussian random values in the second part of the paper. The statistical linearization method is used to determine the distribution parameters (mean value, dispersion). The stress intensity was estimated by the finite element method with the use of SolidWorks Simulation system. Calculations are done for different types of cracks: throughwall, edge and semielliptic. It is shown that the presence of cracklike defects, even of small length, rather reduces the level of reliability function.

Keywords: fracture toughness, stress intensity factor, survival function