Stress intensity factors of corner cracks at set-in nozzle–cylinder intersection of a PWR reactor pressure vessel

Fracture analysis of the set-in nozzle of a PWR reactor pressure vessel – Part 1: Determination of critical crack

“…The engineering drawing of a typical double loop cylindrical RPV [1,3] of a 300 MW pressurized water reactor is shown in Fig. 1.…”

“…Fig. 2 presents the typical design of the set-in nozzle [1,4]. The thickness of the vessel's wall at the nozzle-cylinder intersection is denoted by parameter 't' which has the value 't = 400 mm' as shown in Fig.…”

“…The orientation of the cracks, as shown in Fig. 10, is such that the cracks are perpendicular to the maximum principal stress which is the hoop stress [1]. In this orientation, the cracks are in mode-I (opening mode) in reference to the hoop stress which is the most detrimental stress for the RPV.…”

“…The fracture mechanics analysis of different parts of the RPV under normal operating conditions [1][2][3] is quite straight forward; however the analysis becomes critical under accidental conditions of the plant. In this paper, the fracture analysis of the set-in nozzle of an RPV is being presented under accidental conditions of the plant [4].…”

“…For the fracture analysis the highest stress concentration point (HSCP) of the nozzle, under normal operating conditions of the plant [1,4] is selected: the nozzle-cylinder intersection. A wide range of corner surface cracks has been analyzed at the nozzle-cylinder intersection under the accidental conditions.…”