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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Current News from NES

3 October 2017

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Pt nanoparticles: The key to improved stress corrosion cracking mitigation in boiling water reactors

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.

15 September 2017

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Sorption of trivalent lanthanides and actinides onto montmorillonite

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.

19 April 2017

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BKW and PSI agree on partnership for safety analysis services

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.

9 February 2017

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How Switzerland could supply its electric power in 2050

Environment Energy and Environment Renewable Energies ESI Platform

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.

20 December 2016

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The Dynamics of Nuclear Reactors

Nuclear reactor dynamics deals with the transient behaviour of nuclear reactors which mostly refers to time changes of the imbalance between heat production and removal. Since the prediction of the dynamic behaviour is crucial for the safety of a reactor, computational models and methodologies have been developed in the framework of the STARS project, at the Laboratory for Reactor Physics and Systems Behaviour (LRS), with the main goal to simulate the complex behaviours of reactors under various conditions with a high level of fidelity.

29 November 2016

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Simulations for More Efficient Power Stations

Energy and Environment Nuclear Power Plant Safety

In most cases, electricity is generated when water is heated and transformed into vapour. Vapour bubbles in the water play a decisive role in this process. Using computer simulation, researchers at the Paul Scherrer Institute have succeeded in representing the behaviour of vapour bubbles – and in making their performance more calculable.

19 October 2016

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Radioactive targets produced at PSI enable improving the Big Bang Theory

One of the long-lasting unsolved problems in Nuclear Astrophysics is the so-called "Cosmological Li Problem", i.e. the large discrepancy between the primordial 7Li abundance predicted by models of Big Bang Nucleosynthesis and the one inferred from astronomical observation. The study of the production/destruction rates of the radioactive precursor 7Be is one of the clues for solving this problem. Scientists from PSI were able to manufacture two highly radioactive 7Be-targets for the measurement of the 7Be(n,α) cross section at n_TOF CERN. The activity was extracted from the cooling water of the neutron spallation source SINQ. As a result of the experiment, the investigated reaction could be ruled out as responsible for the problem. The innovative work on isotope and target production as well as the new measurement techniques specifically developed for this kind of experiments make further investigations on this "hot topic" feasible. The work has been published in Physical Review Letters and has been selected for the Editor’s Suggestion of the corresponding issue.

10 October 2016

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Molten salt reactors – exploring an alternative

Energy and Environment Nuclear Power Plant Safety

At the Paul Scherrer Institute PSI, a small group of scientists is using theoretical models to explore an alternative for future nuclear reactors: so-called molten salt reactors. This helps to secure Switzerland’s expertise regarding globally relevant questions in the area of nuclear energy and reactor safety, for today and tomorrow.

28 September 2016

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Infrared imaging sheds new light on the condensation/evaporation process

Researcher at PSI (NES/LTH) have brought modern infrared technologies into their large thermal-hydraulic facility, called LINX, to obtain insights into condensation/evaporation process occurring under thermodynamic conditions resembling those of a nuclear power plant containment during a severe accident scenario. In such a scenario, condensation is of prime importance to control the thermodynamic state of the containment. It affects the pressure history, the overall gas (steam, hydrogen) and fission product distribution within this last barrier. Better understanding of these phenomena under accident conditions is essential to properly predict the accident evolution.

14 September 2016

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Post Irradiation Examination of MEGAPIE – How radiochemical analytics helps looking inside a high-power liquid metal spallation target

PSI radiochemists now finished the radiochemical analysis of the residue nuclei production in the Lead-Bismuth Eutectic (LBE) of the MEGAPIE target. Twenty – mostly safety-relevant – radionuclides could be identified and quantified. Comparisons with theoretical predictions show acceptable agreement in most cases, but also considerable discrepancies for some selected radionuclides. Moreover, the scientists learned that noble elements like Gold, Silver, Mercury or Rhodium are homogeneously distributed in the bulk LBE, while others, sensitive to reduction/oxidation (Lanthanides, Iodine, Chlorine), tend to accumulate at exposed positions like vessel walls and free surfaces. These results will help to improve models and codes for predictions and, thus, will improve the safety of existing and future facilities.

26 August 2016

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The chemical state of 79Se in spent nuclear fuel

An interdisciplinary study conducted at different PSI laboratories (LES, AHL, LRS, SYN) in collaboration with Studsvik AB (Sweden) demonstrates that selenium originating from fission in light water reactors is tightly bound in the crystal lattice of UO2. This finding has positive consequences for the safety assessment of high-level radioactive waste repository planned in Switzerland, as it implies (contrary to previous assumptions) that the safety-relevant radionuclide 79Se will be released at extremely low rates during aqueous corrosion of the waste in a deep-seated repository.

26 July 2016

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Designer nuclide for medical applications

Medical Science Human Health Radiopharmacy

Researchers at the PSI have for the first time used a cyclotron to produce the radionuclide scandium-44 in a quantity and concentration as needed for medical treatment. With that, they have achieved the first precondition for scandium-44 to be used one day for medical tests in hospitals.

9 June 2016

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One atom at a time

Matter and Material

At the PSI, the Heavy Elements Research Group explores the exotic, unstable atoms at the end of the periodic table of elements. The dream: to discover one day the island of stability that could exist beyond the elements charted so far on the chemists' map.

22. February 2016

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Decommissioning of the research reactor Proteus

Miscellaneous Energy and Environment Nuclear Power Plant Safety

Start of the public examination period for decommissioning of the nuclear facility Proteus at the Paul Scherrer Institute PSI
The nuclear research facility Proteus is a so-called zero-power reactor. In service, the thermal output of the reactor was limited to a maximum of 1 kW. That means this is an experimental reactor that was run at a power level so low that it did not require cooling. Proteus went into service in 1968. The PSI would like to decommission the facility. The decommissioning project is now being publicly announced in the legally prescribed, official publications.

8. February 2016

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The hotlab research facility

Miscellaneous Energy and Environment Materials Research Nuclear Power Plant Safety

Start of the public examination period for renewed authorization to operate the research facility hotlab at the Paul Scherrer Institute PSI
The hotlab at the Paul Scherrer Institute PSI is a facility, unique in Switzerland, where researchers study highly radioactive materials in specially shielded chambers called hot cells. It serves the needs of applied materials research on highly radioactive samples from core structural components and fuel rods from nuclear power plants, research reactors, and the PSI radiation facilities. Through its operation of the hotlab, the Paul Scherrer Institute also contributes to the safety of the nuclear power plants in Switzerland. Around thirty staff members attend to the hotlab's safety technology and analysis infrastructure.
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