Nuclear Energy and Safety Research Division

The Paul Scherrer Institute has a long tradition in energy research. With respect to nuclear energy, PSI has a unique position in Switzerland. This is due to its heavy infrastructure, namely the Hot Laboratory with so-called hot cells, well equipped and shielded zones for work and research on radioactive material. In addition, the nuclear energy division takes advantage of PSI's large facilities like the Swiss Light Source (SLS) and the Swiss Spallation Neutron Source (SINQ).

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.

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Recent News from NES

13 March 2018

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BSAF-2: Analysis of Unit 3 accident and fission product transport



The Accident at the Fukushima Daiichi Nuclear Power Station, which occurred in March 2011, had a very strong impact on the nuclear community. Three reactors suffered core damage and fission products were released to the environment. Paul Scherrer Institute (PSI) has participated in an Organisation for Economic Cooperation and Development (OECD) project, Benchmark Study of the Accident at the Fukushima (BSAF). The project aimed to evaluate and analyse the accident progression, likely end-state of the reactor core after the accidents, and the release of radioactivity to the environment. PSI has concentrated on the analysis of unit 3 using MELCOR 2.1. Hundreds of calculations have been performed and a plausible scenario which predicted remarkably well the main signatures has been selected.

24 January 2018

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Neutron radiography of detrimental hydrogen in nuclear fuel claddings

Materials Research Energy and Environment Nuclear Power Plant Safety

Hydrogen is at the source of degradation mechanisms affecting mechanical properties of many structural metal materials. In nuclear power plants, zirconium alloy fuel cladding tubes take up a part of the hydrogen from coolant water due to oxidation. Because of the high mobility of hydrogen interstitial atoms down temperature and concentration gradients and up stress gradients, hydrogen distribution in fuel claddings can often be non-uniform, arising the risk for the integrity of spent fuel rods under mechanical load. At the Laboratory of Nuclear Materials (LNM) in collaboration with the Laboratory of Neutron Scattering and Imaging (LNS), hydrogen redistribution in zirconium alloys was quantified by neutron radiography using the state-of-the-art detector of PSI Neutron Microscope, and the concentration was computed based on thermodynamics, to predict hydrogen diffusion and precipitation for used nuclear fuel.

5 January 2018

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UO2 fuel behavior at very high burnup

The investigation of the nuclear fuel at very high burnup is critical for evaluating the safety margin for the evaluated fuel in normal as well as in accidental conditions. PSI is one of the very few hot laboratories which possess access to irradiated UO2 fuel with very high burnup from commercial reactors. The application of relevant tools for the investigation, handling and analysis of those highly irradiated materials emphasize the necessary expertise.

5 January 2018

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New Focused Ion Beam (FIB) in the Hot Laboratory

The implementation of Focused Ion Beam instruments in material research laboratories during the last decade has not only strongly improved the preparation of very thin specimens for the Transmission Electron Microscope (TEM), in particular at interfaces, but also led to the development of new analysis methods inside the instrument itself. It became a powerful instrument for the analyses of highly radioactive materials, because it allows for the production and analysis of very small specimens that can be then analyzed with very sensitive detectors without strong interference from the radiation field of the specimen itself.
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