Nuclear Energy and Safety Research DivisionThe 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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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.
Noise appears in many areas of science, and commonly has an unwanted and disturbing nature by deteriorating signals’ quality. Therefore, various techniques have been developed over the years for separating noise from pure signals. However, noise has a key role in signal analysis of nuclear reactors as its’ appropriate assessment can be used not only for exploring the normal and dynamic behaviour of nuclear cores, but also for identifying and detecting possible anomalies of reactor systems. State of the art methods have been recently implemented within the well-established signal analysis methodology of the STARS program, at the Laboratory for Reactor Physics and Systems Behaviour (LRS), for investigating nuclear reactor noise and getting a better insight on analysing reactors’ operation.
Pt nanoparticles: The key to improved stress corrosion cracking mitigation in boiling water reactorsMaterials Research Energy and Environment Nuclear Power Plant Safety
The formation and growth of cracks by stress corrosion cracking (SCC)in reactor internals and recirculation pipes due to the highly oxidising environment is a serious issue in boiling water reactors. At first, SCC mitigation was attempted by injecting H2 into the feed water, where the injected H2 recombines with the H2O2 and O2 to water and reduces the electrochemical corrosion potential, and consequently the SCC susceptibility. Several disadvantages of the injection of high amounts of H2, have led to the development of noble metal additions to the reactor feed water. With injection of a much smaller amount of H2, the noble metal particles of a few nanometres in size, formed in-situ, work as catalysts for the efficient reduction of the oxidizing species formed by radiolysis, and thus lower the ECP and SCC susceptibility.
The credibility of long-term safety assessments of radioactive waste repositories may be greatly enhanced by a molecular level understanding of the sorption processes onto individual minerals present in the near- and far-fields. A study conducted at LES in collaboration with the Helmholtz Zentrum Dresden Rossendorf used extended X-ray absorption fine structure (EXAFS) and time-resolved laser fluorescence spectroscopies (TRLFS) to elucidate the uptake mechanism of trivalent lanthanides and actinides (Ln/AnIII) by the clay mineral montmorillonite.The excellent agreement between the thermodynamic model parameters obtained by fitting the macroscopic data, and the spectroscopically identified mechanisms, demonstrates the mature state of the 2SPNE SC/CE sorption model developed at LES for predicting and quantifying the retention of Ln/AnIII elements by montmorillonite-rich clay rocks.
BKW’s Engineering Division and the Paul Scherrer Institute (PSI) joined forces to provide risk and safety analysis services in the nuclear sector. By combining their expertise, the two companies are able to solve highly complex problems in the field of nuclear safety. The range of joint services is aimed at customers from the power plant sector and supply industry, as well as public and state institutions. The collaboration will focus exclusively on the international (non-Swiss) market.
The Laboratory for Energy Systems Analysis at the Paul Scherrer Institute PSI is investigating how Switzerland’s electricity supply might look, up to the year 2050, under a variety of boundary conditions. On the basis of their calculations, the lab’s researchers are able to generate insights on possible future developments of the energy sector, for example, determine how an ambitious reduction in CO2 emissions could be achieved at the lowest possible cost.