Simplified P-T limit curve generator for reactor pressure vessels

Although the fracture toughness of reactor pressure vessels decreases over time due to neutron irradiation, the integrity of the vessel must be retained during plant operation under fracture toughness degradation. JEAC 4206-2007 specifies validation test methods for the fracture toughness with the pressure-temperature limit curve (P-T curve) which is one of the standard for the vessel integrity. The P-T curve is obtained by comparing the fracture toughness of the vessel and the stress intensity factors obtained from hoop and thermal stresses. We have developed a numerical analysis program to facilitate the P-T curve evaluation, which includes the thermal conductivity in the vessel wall and P-T curve generation based on JEAC 4206-2007. The numerical simulation of thermal conductivity is carried out using the axial symmetric one-dimensional thermal conductivity equation and the program allows the sensitivity of parameters such as RT_NDT, chemical components and vessel dimensions to be analyzed. Our program has been applied to evaluate the curve for long term operation as an example to showcase its potential. (author)