SOurce CHAracterizatiOn accounting for meTeorologIcal unCertainties (SOCHAOTIC) – first-year report

Jens Havskov Sørensen, Henrik Feddersen, Kasper Skjold Tølløse, Rostislav Kouznetsov, Mikhail Sofiev, Andreas Uppstu, Heiko Klein, Magnus Ulimoen, Lennart Robertson, Jan Pehrsson, Bent Lauritzen, Dan Bohr, Agnieszka Hac-Heimburg, Carsten Israelson, Einar Améen, Anna Maria Blixt Buhr, Jonas Lindgren, Tuomas Peltonen

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In recent years, events have occurred in which radionuclides were detected by filter stations in European countries without knowledge on the origin of those radionuclides. In such cases, there is a need to locate potential release sites. However, if the release site is actually known, or if a potential release site has been localized by inverse methods, then there is an additional need to estimate the release rates from this location as a function of time for the various radionuclides detected.
While in the SLIM NKS project, methodologies were developed to localize an unknown source of radionuclides dispersed in the atmosphere, the SOCHAOTIC project develops methodologies, suited for operational use, by which characterization of the source, whose location is known, can be derived, i.e. to estimate the temporal release profiles of the radionuclides detected. For operational use, nuclear decision-support systems should be extended with modules handling and analysing such monitoring data automatically, and conveying the data together with the geographical coordinates of the release point to the national meteorological centre accompanied by a request to estimate the temporal evolution of the release rates.
In the first year of SOCHAOTIC, the following results are obtained:
• Case studies identified and selected, viz. the ETEX-1 and the October 2017
case of Ru-106 in Europe. In addition, an artificial case is produced by running a dispersion model forward and calculating average concentrations at filter stations and gamma dose rates at nearby gamma stations.
• Methods for estimation of the temporal release profiles are developed, implemented and described.
• Deterministic numerical weather prediction model data are derived.
• Quality-controlled measurement data of ground-level concentration are obtained.
• The methods for source term characterization are applied by using the DERMA, MATCH, SILAM and SNAP atmospheric dispersion models.
Results are intercompared.
Original languageEnglish
PublisherNordic Nuclear Safety Research
Number of pages59
ISBN (Print) 978-87-7893-551-9
Publication statusPublished - 2022

Bibliographical note



  • Nuclear emergency preparedness
  • Atmospheric dispersion modelling
  • Source characterization
  • Inverse modelling
  • Concentration measurements
  • Gamma dose measurements
  • Uncertainty


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