Structural materials for next generation nuclear systems: Challenges and the path forward

•The different Generation IV systems are described.•The materials requirements for Generation IV reactors are presented.•Different innovative cladding materials for fast reactors are discussed.•The corrosion and mechanical behaviour of nickel based high temperature alloys is shown.•The tools needed to achieve fast development of innovative materials are presented.

Next generation nuclear systems will require structural (including cladding) materials capable of withstanding normal operating and accidental conditions drastically more demanding than those typically encountered in current reactors. The main requirements for the structural materials to be used in these reactor systems are dimensional stability under irradiation, acceptable evolution under ageing of the mechanical properties and a good behaviour in corrosive environments. These requirements have to be met not only under normal operating conditions, but also in off normal and accident conditions.These challenging requirements imply that in most cases, the use of nuclear materials used in the current reactors is excluded, therefore a new range of materials has to be developed and qualified for nuclear use. In this paper, an overview of various materials that are essential to establish advanced system feasibility and performance is discussed as well as the various natures of R&D needed to select, optimize, assess and qualify advanced materials.