Nuclear Energy and Safety Research Division
Based on this infrastructure and the know-how of its collaborators the Division is involved in three main topics of research: Safety of currently operating light-water reactors, safety characteristics of future reactor concepts and related fuel cycles, and long-term safety of deep geological repositories for nuclear wastes of all kind.
The work is being done on behalf of the Federal Government and in close cooperation with the Swiss nuclear utilities, the national waste management organization, Nagra, and the national regulatory authority, ENSI. It also includes scientific services for the nuclear power plants. Most of the research is connected with international projects on a multi- or bi-national cooperation basis.
Recent News from NES
Assessment of stress corrosion cracking incidents in Alloy 182 – reactor pressure vessel dissimilar metal welds
Several stress corrosion cracking (SCC) incidents recently occurred in Alloy 182 - reactor pressure vessel (RPV) dissimilar metal welds in boiling water reactors (BWR). These SCC cracks tend to grow towards the RPV due to weld microstructure and residual stress profiles and might grow into the RPV. They thus represent a serious potential safety concern. PSI has evaluated under which conditions such cracks could grow into the RPV and also developed SCC crack growth disposition curves for the RPV steels that can be used for safety assessments of such cracks. With these curves that were recently accepted as a new Code Case N-896 in the ASME Boiler and Pressure Vessel Code, sufficient safety margins could be demonstrated for such crack configurations with the current inspection intervals of the periodic in-service inspection.
PSI researchers simulate and model large-scale research facilities as well as experiments, for example, in the materials and biological sciences. Andreas Adelmann, head of PSI's Laboratory for Scientific Computing and Modelling, explains how they do it.
Researchers in PSI's Laboratory for Scientific Computing and Modelling solve the most complex problems through a combination of theory, modelling, and high-performance computing. With powerful computers, they simulate the smallest molecules or large-scale research facilities.
At the neutron source SINQ, PSI researchers are producing special radionuclides that aid in the development of new and more effectively targeted cancer therapies. In this they collaborate closely with the clinics in the surrounding area.
The Energy Economics Group quantified the new World Energy Scenarios 2019 in collaboration with the World Energy Council and Accenture Strategy. The three scenarios (named "Modern Jazz", "Unfinished Symphony", and "Hard Rock") depict possible future developments of the global energy systems until 2040 and were presented at the World Energy Congress 2019 in Dubai.
Nuclear reactors are complex systems with inherent stochastic behaviour. In simple words, the behaviour of various reactor processes are continuously fluctuating over their mean values, even under normal operation and steady-state conditions. The detailed and systematic analysis of this noisy behaviour can reveal valuable information about the operating status of the studied nuclear reactor. More importantly, designed modifications of the reactor’s operation or even unexpected deviations from the normal performance can be identified using advanced signal analysis techniques. The STARS program, at the Laboratory for Reactor Physics and Thermal-Hydraulics (LRT) in PSI, based on a tight collaboration with the Swiss nuclear industry, has developed a well-established signal analysis methodology, being continuously improved since more than two decades. The latest enhancements of the PSI signal analysis methodology allow a deeper understanding of the underlying mechanisms that drive the reactor’s operation, and can provide better insight on the root-cause of possible disturbances or malfunctions. Recently, the latest STARS activities in advanced signal analysis techniques were culminated by an international recognition through a special distinction from the AIP Chaos Journal.
PSI researchers have developed a material whose shape memory is activated through magnetism. Application areas for this new kind of composite material include, for example, medicine, space flight, electronics, and robotics.
In the Nuclear Energy and Safety Research Division at PSI, Johannes Bertsch focuses on the so-called cladding tubes that are used in nuclear power plants.
The EU Horizon 2020 program granted 3.5 million Euros to the research and innovation project SAMOSAFER, where PSI is one of the 14 project partners. The total budget of the project, inclusive own and in-kind contributions, is 4.5 million Euros. The aim of SAMOSAFER project is to develop and demonstrate new safety barriers and a more controlled behaviour in severe accidents of the Molten Salt Reactor (MSR). Three groups at PSI will be involved in the project: the LSM groups for Advanced Nuclear Systems (ANS) and Multiscale Materials Modelling (MMM) and the Severe Accidents Research group (Sacre) of LRT, focusing on redistribution of the source term in the fuel treatment unit of MSR and assessment and reduction of radionuclide mobility during accidental conditions.