Application of Master Curve Approach to WWER-1000 RPV Materials

Part of the IRLA (International Residual Life Assessment) project was concentrated on a detailed analysis of existing and available fracture toughness data of WWER-1000 (Water-Water-Energetical-Reactor) reactor pressure vessel materials – steel 15Kh2NMFA (Ni-Cr-Mo-V) type and its welding metals. A wide database of standard fracture toughness data from testing specimens with thicknesses between 10 and 150 mm were collected. Together, 34 different materials were tested – 20 base metals of 15Kh2NMFA(A) grade and 14 weld metals — 11 of SAW (submerged arc weld) type welds (4 welds with 08KhGNMTA grade wire, 4 welds with 10KhGNMAA grade wire and 3 welds with 12Kh2NMAA grade wire; weld with narrow gap, U-groove as well as V-groove technologies were prepared), 1 of EAW (electroslag automatic weld) with 16KhNMFA type wire and finally 2 SMAW welds (manual arc weld) with RT-45A and RT-45B electrodes, respectively. Altogether, this database contains 398 static fracture toughness data from base metals and 121 from weld metals – K_IC or K_JC types in accordance on testing conditions. This database was primarily analysed with respect to design fracture toughness curves given in WWER standards. Then, data were re-calculated in accordance with the “Master Curve” approach and results were compared with these requirements. Comparison of standard “design fracture toughness” and “Master” curves are presented.