Neutron irradiation embrittlement modeling in RPV steels--an overview

The degradation of reactor pressure vessel (RPV) steels due to neutron irradiation embrittlement is of particular concern because of its relevance to plant safety and limitation of plant life. In order to ensure structural integrity and safe operation of the nuclear power plant (NPP), it is essential to understand the damage mechanisms in RPV steels and their effect on mechanical behavior of material. To account for the synergistic effects of various embrittlement variables, both microscale and atomic scale models are being successfully used for assessment of structural integrity of RPV. This paper encompasses a brief description of microstructural effects of irradiation in RPV steels resulting in ductile to brittle transition temperature (DBTT) and reduction of fracture toughness, followed by an overview of the existing damage mechanism models. Besides a brief description of the fracture mechanics concept to the irradiation embrittlement, salient features of major damage mechanism models along with the future scope of further developments have been discussed. (authors)