Scientific Highlights from Research Division Nuclear Energy and Safety
(NES)
Scientific Highlights
New element and speciation specific analytical options at AHL
The Hot Laboratory division (AHL) within PSI’s Nuclear Energy and Safety (NES) division continually upgrades and advances its analytical infrastructure to provide cutting-edge scientific service to PSI’s researchers and industrial customers. A new, fully automatable and highly flexible Ion Chromatograph (IC) furthers AHL’s efforts in sample miniaturization and extends the spectrum of destructive analytical capabilities to element and speciation specific analyses. With the new IC and its modern ICP-MS (Inductively Coupled Plasma Mass Spectrometry) facilities, AHL offers innovative scientific options for nuclear and general research. Moreover, speciation analyses by IC-ICP-MS for polyvalent inorganic water pollutants such as Cr or As and the acquisition of a new ICP-OES system (Inductively Coupled Plasma Optical Emission Spectrometry) enable future autonomy in wastewater management.
Deep geological disposal of radioactive waste in clay rocks
Geological waste disposal, cement clay interaction
• A considerable reduction of HTO and 36Cl− was observed after 6 years interaction.
• The chloride flux showed a much stronger reduction compared to HTO.
• For HTO the relation between the De and the porosity in the clay part can be described using Archie's law.
• No complete clogging of the porosity was observed after 6 years interaction.
Used Nuclear Fuel: from Better Characterization to Better Optimization
A safe, economical and environmental friendly disposal of used nuclear fuel represents an essential objective of relevance for all. This guides the approach under development at the laboratory for reactor physics and thermal-hydraulics. Establish higher resolution simulation methods to gain more detailed knowledge on the content of each single nuclear fuel rod ever irradiated in a reactor. Thereafter, use this knowledge to explore optimization approaches that could potentially enlarge the range of disposal options allowing to fulfill the highest level of safety standards while reducing economical costs and geological footprints at the same time.
Hydrogen uptake into Zr-based fuel claddings
At the hot surface of a fuel rod cladding in the reactor water, the water is partially dissociated in hydrogen and oxygen, leading to corrosion of the cladding and to the uptake of a part of the created hydrogen. Hydrogen in solid solution and in precipitated form changes the mechanical properties of the cladding tube. The uptake of the hydrogen through the dense oxide layer is unclear. The structure and physical properties of the oxide near the metal-interface is critical The resistivity of the oxide increases with distance from the interface. Nb-containing alloys show lower resistivity in the oxide close to the metal interface, and exhibit a lower hydrogen pick-up. The time in the reactor is an important factor, leading to increasing resistivity in the oxide close to the metal interface, and a higher hydrogen uptake late in life.
Relevance of the findings: considering resistivity, the model of hydrogen uptake is better understood, revealing hints for further cladding development.
Life cycle assessment of cars – new web tool helps consumers and researchers
Decision support for car buyers: Researchers at the Paul Scherrer Institute have developed a web tool called the Carculator that can be used to compare the environmental performance of passenger cars in detail.
Long-term developments of energy pricing and consumption in industry
Researchers from the Paul Scherrer Institute PSI, on behalf of a research project funded by the Swiss Federal Office of Energy (SFOE), have studied how energy consumption by Swiss industry develops depending on energy prices. One result: Price increases for energy usually affect energy consumption only over the long term.
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.
Nuclear Data – Towards a Stronger Link between Nuclear Physics and Nuclear Simulations
All matter in the universe is made of atoms and all atoms are made of particles. Spontaneous changes within atoms as well as collisions between atoms and surrounding particles are nuclear reaction processes guided by nuclear physics laws. To simulate these processes using computer models, probabilities for the various involved nuclear reactions are required. This is precisely the role of nuclear data: supply the computational models with evaluated quantities representing these nuclear reaction probabilities.
Through this, nuclear data can effectively be seen as the fundamental link between nature and any computer simulation involving nuclear reactions. It is thus of primary importance to continuously improve knowledge on nuclear data. In that context, researchers at the laboratory for reactor physics and thermal-hydraulics have recently focused on the development and application of Bayesian frameworks combining both differential and integral experiments for the improvement of nuclear data. By considering the different experiments together, the aim is to achieve enhancements of the nuclear data evaluations while preserving the basic nuclear physics sum rules.
World Energy Scenarios 2019
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.