Calculation and Comparison of Pressure-Temperature Limit Curves Calculation

In order to prevent the brittle fracture,during nuclear power plant（NPP） heatup and cooldown processes,pressure and temperature in the reactor pressure vessel should be kept under the pressure-temperature（P-T） limit curve.In this paper,the P-T limit curve methodologies of ASME code,RCCM code and Chinese Nuclear Industry Standard EJ/T 918 are studied.Calculation and comparison of the P-T curves obtained using methods from different codes are performed.It shows that using static fracture toughness KIC instead of reference fracture toughness KIR to calculate the P-T curves increases acceptable operating region during NPP heatup and cooldown processes significantly.Comparing to the latest versions of ASME and RCCM codes,the Chinese standard is more conservative.