Atmospheric Transport Modelling for potential releases and detections of radioxenon possibly connected with nuclear test explosions conducted in North Korea

Various techniques of Atmospheric Transport Modelling were applied after the announced nuclear tests conducted by the DPRK in order to support the analysis of potentially connected radionuclide detections. Forward dispersion forecasts from the test-site predicted potentially affected IMS stations; forward ATM for known background sources assessed their potential contribution to measured concentrations.

In case of detections, backward ATM has shown consistency with certain emitter locations and identified coincident source regions for multiple detections.

The presentation gives a comprehensive overview how ATM supported the analysis within the German NDC for all six nuclear test explosions announced by the DPRK.  It is particularly in focus how potential interference with known background sources had an impact on the assessment. In several cases, measurements of releases from nuclear facilities caused ambiguous radioxenon detections in the aftermath of DPRK tests.    

Finally, for two DPRK tests (2009 and 2016-Sep) it was not possible to identify potentially related radioxenon detections, for two tests there were consistent but not conclusive detections of Xe-133 only  (2016-Jan, 2017) and for two tests there were matching isotopic ratios and fitting atmospheric conditions (2006, 2013) indicating strong evidence for the actual nuclear fission event.