Validation of RT_To for German Reactor Pressure Vessel Steels

For the introduction of the new reference temperature RT_To of the ASME Code Cases N-629 and N-631 into the German KTA rules the equation RT_To = T₀ + 19,4 °C (35 °F) was validated by the re-evaluation of the existing fracture toughness data base of German RPV steels, including unirradiated and irradiated base material and weld metal data. The test temperatures of the data base were standardized to the reference temperature T₀ of the Master Curve of the data sets and the data base was compared with the ASME K_Ic-curve as adjusted by RT_To. The K_Ic-curve adjusted by RT_To enveloped both, the 1T-size adjusted data base and also the as measured data base, corresponding with the definition of RT_To. Thus the results also prove the validity of the K_Ic(RT_To)-curve for allowable flaw sizes and up to the crack length spectrum of the ASME K_IC-data base without size adjustment of T₀. The results of both investigations confirmed the validity of RT_To for German RPV steels.