The RPV is the critical component for plant life management, due to the unacceptable consequences of its failure and to the difficulty of its replacement. It is subjected to neutron irradiation which results in irradiation-induced embrittlement.
The classical approaches are based on empirical formula that are obtained from fitting the results issued from testing specimens out of the surveillance capsules inserted in each reactor. The resulted empirical formula cannot be used to predict the behaviour of the material especially if the lifetime of the reactors is to be extended. The stainless steel Internal Structures of the vessels are closer to the core and are thus subjected to more intense neutron irradiation.
So far, the monitoring and the mitigation of these degradation phenomena rely on long-term irradiation programs in test reactors. Therefore, predictions of irradiation induced changes in these materials coupled with their in service inspections and safety analysis are necessary to ensure safe and reliable plant operation.
Continuous progress in the physical understanding of the underlying mechanisms and in computer sciences encroach the development of multi-scale numerical tools able to simulate the materials behaviour in nuclear environment. A Users' Group and a training scheme have been adopted is order to allow representatives of constructors, utilities, research organisations from Europe, USA and Japan to participate actively in the process of appraising the limits and potentialities of the developed tools as well as their validation against qualified experimental data.
Furthermore, an important effort will be deployed to teach young researchers in the field of materials' degradation in nuclear field and to disseminate the results among different partners, in international conferences, peer reviewed journals and in a dedicated website.