Surveillance program assessment for critical components of next generation nuclear reactors

With the potential worldwide deployment of new nuclear systems it is important to take advantage of the multi–decade experience gained from the surveillance programs of light water reactor (LWR) pressure vessels to address radiation damage monitoring in the critical components. The latter will likely experience conditions that cannot be accurately foreseen because of the current lack of knowledge and experience. Therefore, from the safety assessment and licensing point of view, an appropriate surveillance strategy will be required. This strategy should not be limited in merely monitoring the change of the ductile–to–brittle transition temperature (DBTT) of materials, but should also be extended to other potential degradation phenomena that are associated with the harsher environmental conditions and that are not well understood and/or are difficult to extrapolate in the long run. Limitations can clearly be identified from current surveillance programs, while it is becoming clear that more advanced approaches are needed to ensure the correct evaluation of the effects of irradiation and the other environmental variables on material behavior. This paper reviews some of the pros and cons of the present LWR surveillance programs with an attempt to define an appropriate surveillance program for critical components of the next generation reactors.