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.
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.
Structure of concrete disease
solved
When bridges, dam walls and other structures made of concrete are streaked with dark cracks after a few decades, the culprit is the so-called the concrete disease. Researchers from the Paul Scherrer Institute PSI and Empa have now solved the structure of the material produced in these cracks at atomic level - and have thereby discovered a previously unknown crystalline arrangement of the atoms.