Application of Master Curve Approach for Rector Pressure Vessel Integrity Assessment

The state-of-the-art of structural integrity assessment of reactor pressure vessels (RPV) uses universal and experimentally verified reference fracture toughness curves. These curves are constructed as the lower boundary to an available plain strain fracture toughness, KIC, database.
Recent industry attention has been focussed on the direct use of measured fracture toughness properties in the RPV integrity assessment. The Master Curve Concept (MC)is a new methodology to characterise the fracture toughness in the transition region. The MC methodology provides a reference temperature, T0, that directly relates the reference toughness curve to the measured fracture toughness values.
The utilities and licensing authorities establish short and long-range objectives in implementing MC technology. The short range objective is to develop an alternative method of indexing the universal plain strain fracture toughness curves using measured fracture toughness T0 instead of the existing drop weight and Charpy-based methodology. The long range objective is to implement a statistically defined MC as an alternative fracture toughness curve in place of the KIC lower bound curves.
The paper introduces the state-of-the-art and future trend of the RPV integrity assessment in Germany. In the second part the MC approach is demonstrated for Russian WWER-type RPV steels.