Advanced research on master curve for safety assessment of reactor pressure vessel

Fracture toughness is the key input for designing, monitoring and residual life assessment of Reactor Pressure Vessel (RPV) components. The value of fracture toughness is influenced by geometry (specimen/component), size (b, a/w), environment (temperature, irradiation, corrosion) and loading (strain rate). One major issue is the transferability of the fracture toughness value obtained experimentally from specimen to real application level and another issue to track the change in the value through the life due to environmental causes. A lot of empirical and theoretical correlations to capture the geometry, size and loading rate dependence of fracture toughness are available and already standardized into code. There are many reasons (low temperature, neutron irradiation and corrosion) for which material loses its ductility and thus degraded. Therefore a key input into the assessment of RPV integrity is the knowledge on variation of the material fracture toughness with temperature and degree of irradiation. In last few decades research has been focused to characterize the temperature dependence of fracture toughness and to extend the methodology to assess the material degradation (embrittlement) by irradiation