Determination of the source location of anthropogenic radionuclides collected in Finland and Sweden in June 2020 using a multi-technology analysis.

In June 2020, observations of anthropogenic radionuclides in Estonia, Finland, and Sweden that were not related to any acknowledged environmental release led to a comprehensive investigation on the source and cause of the unusual emissions. Several of the observed radionuclides were on the list of Comprehensive Nuclear-Test-Ban Treaty (CTBT) relevant radionuclides as an indicator of a potential nuclear test, and warranted detailed investigation. While analysis of aerosol samples coupled with Atmospheric Transport and Dispersion Modelling (ATDM) is a standard approach for environmental particulate releases, several new techniques were employed to better characterize the samples that allowed for useful inferences to be made.

SAUNA III - The next generation noble gas system for verification of nuclear explosions.

The SAUNA III represent the next generation of the SAUNA systems designed for detection of low levels of radioactive xenon in the atmosphere, with the main purpose of detecting underground nuclear explosions. The system automatically collects, processes and measures 40 m atmospheric samples every 6 h, increasing both the sensitivity and time resolution as compared the systems currently in use. The higher sensitive increases the number of detections, especially for samples were more than one isotope of xenon are detected.

SAUNA Q - Array: The realization of a new concept in radioxenon detection.

We introduce a new concept in radioxenon detection - the radioxenon Array, defined as a system where air sampling and activity measurement is performed at multiple locations, using measurement units that are less sensitive, but on the other hand less costly, and easier to install and operate, compared to current state-of-the-art radioxenon systems. The inter-unit distance in the Array is typically hundreds of kilometres. Using synthetic nuclear explosions together with a parametrized measurement system model, we argue that, when such measurement units are combined into an Array, the aggregated verification performance (detection, location, and characterization) can be high.

SAUNA field - A sensitive system for analysis of radioxenon in soil gas samples.

A high throughput system for processing and detection of low levels of radioxenon in soil gas samples has been developed. Processing and analysis of sub-soil noble gas samples puts high demands on the gas separation part of the system since the samples might contain high levels of Rn, CO as well as other gases. The gas process is optimized to remove all CO, HO and Rn with a high recovery yield of the xenon in the sample to ensure a high sensitivity even for small samples.

Europe-Wide Atmospheric Radionuclide Dispersion by Unprecedented Wildfires in the Chernobyl Exclusion Zone, April 2020.

From early April 2020, wildfires raged in the highly contaminated areas around the Chernobyl nuclear power plant (CNPP), Ukraine. For about 4 weeks, the fires spread around and into the Chernobyl exclusion zone (CEZ) and came within a few kilometers of both the CNPP and radioactive waste storage facilities. Wildfires occurred on several occasions throughout the month of April.