Methodology for determination of critical crack depth in a class-I component

In this study, a methodology for the determination of critical crack depth in a class-I component using the failure assessment diagram has been proposed and implemented through the finite element method. Overviewing the literature in the field of fracture mechanics, the need for the development of such methodology was felt, as such straightforward methodologies are difficult to find in contemporary literature. As a case study, the proposed methodology was then successfully applied to a pressurized water reactor’s pressure vessel closure head (class-I component). Subsequently, the critical crack depth was determined through a failure assessment diagram under pressurized thermals shock induced during the small break loss of coolant accidental and Rancho-Seco transient accidental conditions of the reactor. •Methodology for determination of critical crack depth.•Stress analysis of the RPV closure head to determine the critical locations.•Development of high-quality hexahedral mesh around the crack fronts.•Evaluation of fracture ratio and load ratio.•Determination of the critical crack depth through failure assessment diagram.