Validation of $RTT0$ for German Reactor Pressure Vessel Steels

For the introduction of the new reference temperature $RTT0$ of the ASME Code Cases N-629 and N-631 into the German Standard KTA 3201.2, the applicability of $RTT0$ was validated by the reevaluation of the existing fracture toughness database of German reactor pressure vessel. (RPV) steels including unirradiated and irradiated base materials and weld metal data. The test temperatures of the database were standardized to the reference temperature $T0$ of the master curve of the data sets and the database was compared with the ASME $KIC$-curve as adjusted by $RTT0$⁠. The $KIC$-curve adjusted by $RTT0$ enveloped both the $1T$-size adjusted database and also the as-measured database, corresponding to the definition of $RTT0$⁠. Thus, the results also prove the validity of the $KIC(RTT0)$-curve for allowable flaw sizes and up to the crack length spectrum of the ASME $KIC$-database without size adjustment of $T0$⁠. The results of both investigations confirmed the validity of $RTT0$ for German RPV steels. The majority of existing fracture toughness data are based on $KIC$-values. More recent data are $(KJC)$ related to the issuing of ASTM E 1921 in 1997 and to the success of the master curve-based $T0$ approach. Therefore, the possible difference between $T0$ determined from $KJC$ and from $KIC$ was investigated with available databases for RPV steels. The comparison of $T0(KJC)$ and $T0(KIC)$ showed a 1:1 correlation proving the equivalence of $KJC$ and $KIC$ in the determination of $T0$⁠.