Materials for Advanced Gas-cooled Nuclear Systems

摘要

The VHTR modular reactor is one of six advanced fission systems of interest for meeting the Generation IV goals of attaining highly economic, safe, reliable, sustainable, proliferation-resistant systems. The VHTR offers significant advantages for long-term development of sustainable energy and in particular for heat applications and hydrogen generation. This system can operate with either a direct or indirect cycle and makes use of the high efficiency brayton cycle. The GCFR system, which features a fast-spectrum helium-cooled reactor and closed fuel cycle is also capable of delivering electricity, hydrogen, or process heat with a high conversion efficiency. Again this system can operate with either a direct or indirect cycle. The reference concept for the GCFR uses a direct-cycle helium turbine. For the VHTR both the pebble bed (e.g. PBMR) and block type (e.g. ANTARES) are under development. For such new Generation IV type reactors it is important to have a good understanding of the limits of the materials used and the behaviour of the main components under the expected operating requirements. Within these system requirements there are also significant synergies with the materials developments for the Fusion Reactor. All three systems use helium as a coolant, joining processes involving the bonding of similar and dissimilar materials developed initially in the Fusion industry are becoming increasingly used in advanced fission heat exchanger design for economy and compactness. The synergies between Fission and Fusion are especially visible in the EXTREMAT-IP which benefits from the close involvement of a wide range of applications (fission, fusion, aerospace, automotive, etc.). For the advanced fission reactors the work within the EXTREMAT-IP addresses the potential of new materials for the reactor control rod (irradiation resistance), for high temperature components such as the heat exchangers, and for protection against corrosion damage (barrier materials). Within the EXTREMAT-IP the main materials addressed for these applications are carbon composites, ODS steels and graphites where a database to store the results of irradiation resistant materials tests is also being developed and implemented.