Measurements of heavy metals in the environment surrounding the European Spallation Source

Sammanfattning

The European Spallation Source (ESS) is a neutron source in the final stages of construction in Lund. Over 800 radionuclide species are expected to be produced in the tungsten target as a by-product of spallation, and in the case of an unplanned release, these nuclides risk being spread in the environment. This study provides a baseline assessment of elemental and heavy metal concentrations in soils, plants, and seed crops surrounding the ESS, and methods of detection of radionuclides produced in the ESS target were investigated. A multi-method approach was used, combining X-ray fluorescence, time-of-flight elastic recoil detection analysis, and particle induced X-ray emission, and the results from these methods were compared. These results were complemented by existing data from gamma-ray spectroscopy and ICP-MS measurements. The elemental analysis show that the baselines are mostly consistent with expected concentrations in the region, and deviations were attributed to local disturbances, such as construction sites. Spatial distribution in the seed samples showed accumulation of potassium, calcium, and iron in the husk and aleurone layer of the seeds, which could be used as chemical analogues for other nuclides in the same group in the periodic table. Quantitative XRF analysis was made available with the XRF setup at the Tandem Laboratory, Uppsala University, by the configuration of PyMca and the use of a standard flux calibration procedure. A model of the transfer of radionuclides from a release from the ESS into the food chain was created using Afry Intelligent Scenario Modelling. The model predicted activity levels in crops higher than allowed according to the regulation EURATOM only in a highly localised deposition scenario.