Alternative reference temperature based on master curve approach in Japanese reactor pressure vessel steels

Hirota, Takatoshi*; Hirano, Takashi*; Onizawa, Kunio 

Master Curve approach is the effective method to evaluate the fracture toughness of the ferritic steels accurately and statistically. The Japan Electric Association Code JEAC 4216-2011 was published based on the related standard ASTM E 1921-08 and the results of the investigation of the applicability of the Master Curve approach to Japanese reactor pressure vessel (RPV) steels. The reference temperature To can be determined according to this code in Japan. In this study, using the existing fracture toughness data of Japanese RPV steels, the method for determination of the alternative reference temperature RT based on Master Curve reference temperature To was statistically examined, so that RT has an equivalent safety margin to the conventional RT. Through the statistical treatment, the alternative reference temperature RT was proposed as the following equation; RT = To + C + 2. This method is applicable to the Japan Electric Association Code JEAC 4206 as an option item.