A high-resolution β - γ coincidence spectrometry system has been set-up and calibrated at the UK CTBT Radionuclide Laboratory (known as GBL15) at AWE. The system has been configured specifically to measure the signatures of radioxenon isotopes that can be indicative of a nuclear explosion. The high purity germanium (HPGe) and PIPSBox detectors have been placed in an ultra-low-background lead shield to reduce the background count-rate and new software allows the combination of signals from four detectors (two HPGe detectors and two silicon-based detectors) to cover a larger solid angle. Measurements of samples of radioxenon isotopes are used to realise an improved detection efficiency and background acquisitions have demonstrated the achievable detection limits to reach 1.3 mBq for Xe and ≤0.3 mBq for the metastable isomers Xe and Xe. Due to the improved energy resolution in both photon and electron detectors, the detection sensitivity remains high in the presence of interfering signals from other radioxenon isotopes, such as those that may be present due to the significant levels of atmospheric radioxenon in parts of the world. This paper summarises the detector setup, efficiency calibration measurements and determination of the limits of detection. This work demonstrates the benefits of high-resolution coincidence detector systems for re-measurement of samples from the CTBT International Monitoring System (IMS) - improved detectability of metastable isomers Xe and Xe in the presence of Xe, compared to the current laboratory system.
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http://dx.doi.org/10.1016/j.jenvrad.2022.106915 | DOI Listing |
J Environ Radioact
December 2024
AWE Aldermaston, Reading, RG7 4PR, UK.
The prevalence of isotopes of radioxenon in the atmosphere poses a problem for the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The atmospheric radioxenon background has accumulated due to emissions from civil nuclear facilities and as a result, the IMS frequently detects isotopes that might be considered a signal of a nuclear explosion. The UK National Data Centre (NDC) at the Atomic Weapons Establishment (AWE) analyses all data from the IMS radionuclide network and through a new 'event analysis' pipeline, works to determine the source of each detection of interest.
View Article and Find Full Text PDFJ Environ Radioact
March 2024
A global network of monitoring stations is set up that can measure tiny concentrations of airborne radioactivity as part of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. If Treaty-relevant detections are made, inverse atmospheric transport modelling is one of the methods that can be used to determine the source of the radioactivity. In order to facilitate the testing of novel developments in inverse modelling, two sets of test cases are constructed using real-world Xe detections associated with routine releases from a medical isotope production facility.
View Article and Find Full Text PDFJ Environ Radioact
March 2024
Pacific Northwest National Laboratory, 902 Battelle Blvd., Richland, WA, 99354, USA. Electronic address:
Many countries are considering nuclear power as a means of reducing greenhouse gas emissions, and the IAEA (IAEA, 2022) has forecasted nuclear power growth rates up to 224% of the 2021 level by 2050. Nuclear power plants release trace quantities of radioxenon, an inert gas that is also monitored because it is released during nuclear explosive tests. To better understand how nuclear energy growth (and resulting Xe emissions) could affect a global nonproliferation architecture, we modeled daily releases of radioxenon isotopes used for nuclear explosion detection in the International Monitoring System (IMS) that is part of the Comprehensive Nuclear Test-Ban Treaty: Xe, Xe, Xe, and Xe to examine the change in the number of potential radioxenon detections as compared to the 2021 detection levels.
View Article and Find Full Text PDFJ Environ Radioact
February 2024
Pacific Northwest National Laboratory, Richland, WA, 99354, USA. Electronic address:
The purpose of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is to establish a legally binding ban on nuclear weapon test explosions or any other nuclear explosions. The Preparatory Commission for the CTBT Organization (CTBTO PrepCom) is developing the International Monitoring System (IMS) that includes a global network of 80 stations to monitor for airborne radionuclides upon entry into force of the CTBT. All 80 radionuclide stations will monitor for particulate radionuclides and at least half of the stations will monitor for radioxenon.
View Article and Find Full Text PDFJ Environ Radioact
December 2023
Comprehensive Nuclear-Test-Ban Treaty Organization, International Data Centre, Vienna, Austria.
For the enhancement of the International Data Centre's products, specifically the Standard Screened Radionuclide Event Bulletin, an important step is to establish methods to associate the detections of the Comprehensive Nuclear-Test-Ban Treaty-relevant nuclides in different atmospheric radioactivity samples with the same radionuclide release to characterize its source for the purpose of nuclear explosion monitoring. Episodes of anomalously high activity concentrations in samples at the International Monitoring System radionuclide stations are used as the primary assumption for being related to the same release. For multiple isotope observations, the consistency of their isotopic ratios in subsequent samples with radioactive decay is another plausible hint for one unique release.
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