Typically, in a PWR Nuclear Power Plant it is necessary to postulate a crack to demonstrate that brittle fracture will not happen in equipment whose rupture could cause loss of lives or severe consequences for the plant or the environment. Also, in some situations or locations is almost impossible to guarantee that the material is free from manufacturing, construction defects or, even, defects that initiates after years of operation. The presented application considers an axial and semi-elliptical flaw on the inside surface of the pressurizer shell under circumferential stresses, the ones that tend to open the crack, due to a pressure and temperature transients. The analysis is conduct for two different scenarios of operation, during heatup and at 100% power. The procedure analysis follows the Appendix G from the ASME Code Section III. The results show that brittle fracture is not a concern for any of the studied cases.