Introduction
The Advanced Nuclear Materials program covers long-term and basic research oriented R&D activities. The current focus is put to target and structural materials for Spallation Neutron Sources (SNS) and fuel elements for fast reactors and accelerator-driven systems (ADS) and to the unique SINQ Target Irradiation Program (STIP). The ANM program is essential for the safe operation and performance of SINQ at PSI and construction of the European Spallation Source (ESS) in Europe as well as for the improvement of the sustainability of nuclear energy production within the International Generation IV Forum (GIF). The latter two are international obligations of Switzerland with PSI as major implementing agency. These activities are important for nuclear education and attraction of young gifted people. With a limited financial effort, they allow to directly follow the international development in this field (technology watch) and to preserve sufficient judging competence.
Main activities
Core materials for advanced fission reactors
The main motivation for future nuclear systems are an increased efficiency, a better usage of the uranium recourses, plus the minimization of high level waste. The efficiency addresses the electricity production, direct production of Hydrogen with chemical processes and process heat. All of these require high temperature materials and understanding of phenomena, such as creep, phase changes and dissociations or formation of precipitates. The uranium usage plus waste conditioning calls for a fast spectrum, and therefore requires especially irradiation resistant materials. The scientific questions here are also the creep, phase and precipitate changes and additionally the poisoning of the material with products from nuclear reactions such as He and H. Here especially the He effects and the temperature plus irradiation induced creep are addressed for the structural core materials Concerning the fuels the main emphasis is put on an innovative concept where the fuel is composed of microspheres which can directly be filled into pins. The concept promises simpler production and a feasible fabrication of minor actinide containing fuel for implementing the closed fuel cycle.
Materials for spallation targets
Spallation targets gain great interest, as large spallation sources are projected (ESS) and the concept of producing neutrons is also used in the subcritical reactor concepts for burning minor actinides. Therefore a large emphasis is also put on the research of target and structural materials applied to spallation targets. The scientific interests here are mainly the synergistic effects of radiation displacement damage and transmutation products, especially He and H, on the change in microstructure and degradation of mechanical properties. At PSI this research is closely linked to the safe operation of SINQ where structural materials suffer high neutron and proton exposures at elevated temperatures. Whereas the STIP irradiation experiments continuously provide materials data for the R&D of high power spallation targets.