Scientific Highlights NES

Datum

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.

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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.

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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.

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How Switzerland could supply its electric power in 2050

Energy and Climate Renewable Energies Environment ESI Platform Energy transition

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.

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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 Thermal-Hydraulics (LRT), with the main goal to simulate the complex behaviours of reactors under various conditions with a high level of fidelity.

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Simulations for More Efficient Power Stations

Energy and Climate Nuclear energy Energy transition

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.

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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.

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Molten salt reactors – exploring an alternative

Energy and Climate Nuclear energy

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.

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Infrared imaging sheds new light on the condensation/evaporation process

Researcher at PSI (NES/LRT) 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.

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