Summary of activities in 2022

In 2022, the NDC.be reviewed 326 radionuclide particulate spectra to determine the relevance of the detections flagged by the International Data Centre (IDC) of the CTBT Organization. After review, most of these detections were considered as non-relevant for the CTBT verification. For the remaining detections, there was no clear indication that they could be the result of a Nuclear Explosion (NE) event. Their origin is most likely related to releases from civilian nuclear installations. The follow-up of the noble gas samples in the IMS noble gas stations allowed the NDC.be to identify 15 samples where either an abnormally high xenon isotope detection or an abnormal xenon isotopic ratio occurred. The analysis of these 15 samples suggest that the corresponding detections are most likely resulting from the global civilian radioxenon background as no clear indication would support a NE event.

In addition to the continuous follow-up of the radionuclide part of the IMS, technical experts of the NDC.be participated in the two Working Group B sessions of the CTBT. The NDC.be also participated in different CTBT relevant conferences, workshop and meetings.

Apart from the actual verification activities, the NDC.be is performing research to support the CTBT. One pillar of research involves atmospheric transport modelling. It includes (i) uncertainty quantification of atmospheric transport modelling, (ii) inverse modelling using the event analysis and reconstruction code FREAR, (iii) testing the use of deposition measurements for CTBT verification activities and (iv) the use of cosmogenic radionuclides measured by IMS stations to study downward vertical motion in the atmosphere. The second research pillar involves the use of porous materials for adsorption and desorption of noble gases in support of the CTBT verification.

Throughout 2022, technical experts also made use of the information made available by the IMS for other scientific purposes. For instance, the Royal Observatory of Belgium used the IMS seismic and infrasound data for its contribution to a large scale scientific study of the Tonga volcanic eruption of January 2022 (Science, 12 May 2022, Vol 377, Issue 6601).