UMB1A Particle Sources

  • μ-XAS-tomography of an oxidised fuel particle released during the fire in the Chernobyl reactor (Salbu et al., 2000). (Left) 3-D rendering of tomographic slices showing the surface of the particle. (Right) Computerised slicing of the 3-D image of the oxidised fuel particle.
    Photo
    Salbu et al., 2000

Models for predicting the environmental impact of radioactive contamination are mostly based on the assumption that radionuclides are present as ions, whereas particles show marked differences in behaviour. This may result in significant errors in assessment and modelling of impact. UMB1A has addressed this.

UMB1A

  • The research in umbrella 1A has focused on particle characteristics, transformation rates, remobilization and prediction of ecosystem transfer. We have studied particles containing U and/or Pu and originating from sources such as nuclear weapon tests (Semipalatinsk, Kazakhstan), safety tests (Maralinga, Taranaki, Australia), nuclear reactor accidents (Chernobyl, Fukushima) and NORM (Fen, Søve, Norway; Former Soviet Union uranium mining sites in central Asia). NMBUs unique archive of nano- and micrometer-sized radioactive particles from different sources was utilized. New state-of-the-art methods for particle characterization have been developed, involving advanced micro- and nano-analytical techniques. These have enabled the quantification of particle transformation as a consequence of exposure to leaching media. The results from leaching experiments show that particle weathering and leaching depend on the oxidation state of the carrying matrix and that retention in soils and sediments delay the ecosystem transfer. These results are important for improving the impact prediction models for radioactive contamination in the environment.
  • We developed new state-of-the-art methods to detect and localize low-level radioactive particles within organisms. The results show that uptake of particles in snails and mussels occurs, and that particles retained in tissues then act as point sources. This retention phenomenon was demonstrated in samples from contaminated ecosystems as well as from laboratory experiments. When retention occurs, the use of concentration ratios (CR) in environmental impact modelling will give rise to large uncertainties.
  • Thanks to Umb1A research, particle characteristics can now be linked to specific sources, to ecosystem transfers (RA2) and biological effects (RA3). The new insights in particle deposition and time-dependent remobilization of associated radionuclides have enabled us to improve the accuracy of impact and risk assessment models by replacing constants with time-functions.
Published 7. April 2017 - 10:10 - Updated 24. November 2020 - 14:28