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Cagniant A.,CEA DAM Ile-de-France | Le Petit G.,CEA DAM Ile-de-France | Nadalut B.,Preparatory Commission for the Comprehensive Nuclear Test Ban Treaty Organization | Gross P.,CEA DAM Ile-de-France | And 3 more authors.
Applied Radiation and Isotopes | Year: 2014

127Xe has a longer half-life than 131mXe, it can be easily purely produced and it is present in the environment at very low level. For these reasons, 127Xe is supposed to be a convenient quality control radionuclide for remote noble gas stations of the International Monitoring System (IMS) network. As CEA/DAM has recently developed two new photon/electron setups for low-level detection of 131mXe, 133mXe, 133Xe and 135Xe, we took the opportunity to test these setups for the measurement of a 127Xe standard. The results and a detailed description of these measurements are presented in this paper. They illustrate the complexity of 127Xe decay, emitting simultaneously several γ, X-rays, conversion electrons and Auger electrons; this results in highly summated coincidence spectra. The measurements performed provide precise electron energy calibration of the setups. The count rate of electrons in coincidence with iodine Kα X-rays was found to be surprisingly low, leading to the study of electron-gated photon spectrum. Finally, a comparison of three photon/electron coincidence spectra obtained with three different setups is given. The use of 127Xe as a standard for energy calibration of IMS noble gas station is possible, but it appears to be quite complicated for efficiency check of noble gas station equipped with β/γ detectors. © 2014 Elsevier Ltd. Source

Ringbom A.,Swedish Defence Research Agency | Axelsson A.,Swedish Defence Research Agency | Aldener M.,Swedish Defence Research Agency | Auer M.,Preparatory Commission for the Comprehensive Nuclear Test Ban Treaty Organization | And 9 more authors.
Journal of Environmental Radioactivity | Year: 2014

Observations made in April 2013 of the radioxenon isotopes 133Xe and 131mXe at measurement stations in Japan and Russia, belonging to the International Monitoring System for verification of the Comprehensive Nuclear-Test-Ban Treaty, are unique with respect to the measurement history of these stations. Comparison of measured data with calculated isotopic ratios as well as analysis using atmospheric transport modeling indicate that it is likely that the xenon measured was created in the underground nuclear test conducted by North Korea on February 12, 2013, and released 7-8 weeks later. More than one release is required to explain all observations. The 131mXe source terms for each release were calculated to 0.7TBq, corresponding to about 1-10% of the total xenon inventory for a 10kt explosion, depending on fractionation and release scenario. The observed ratios could not be used to obtain any information regarding the fissile material that was used in the test. © 2013 The Authors. Source

Wotawa G.,Central Institute for Meteorology and Geodynamics | Becker A.,Preparatory Commission for the Comprehensive Nuclear Test Ban Treaty Organization | Kalinowski M.,University of Hamburg | Saey P.,Preparatory Commission for the Comprehensive Nuclear Test Ban Treaty Organization | And 2 more authors.
Pure and Applied Geophysics | Year: 2010

Monitoring of radioactive noble gases, in particular xenon isotopes, is a crucial element of the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The capability of the noble gas network, which is currently under construction, to detect signals from a nuclear explosion critically depends on the background created by other sources. Therefore, the global distribution of these isotopes based on emissions and transport patterns needs to be understood. A significant xenon background exists in the reactor regions of North America, Europe and Asia. An emission inventory of the four relevant xenon isotopes has recently been created, which specifies source terms for each power plant. As the major emitters of xenon isotopes worldwide, a few medical radioisotope production facilities have been recently identified, in particular the facilities in Chalk River (Canada), Fleurus (Belgium), Pelindaba (South Africa) and Petten (Netherlands). Emissions from these sites are expected to exceed those of the other sources by orders of magnitude. In this study, emphasis is put on 133Xe, which is the most prevalent xenon isotope. First, based on the emissions known, the resulting 133Xe concentration levels at all noble gas stations of the final CTBT verification network were calculated and found to be consistent with observations. Second, it turned out that emissions from the radioisotope facilities can explain a number of observed peaks, meaning that atmospheric transport modelling is an important tool for the categorization of measurements. Third, it became evident that Nuclear Power Plant emissions are more difficult to treat in the models, since their temporal variation is high and not generally reported. Fourth, there are indications that the assumed annual emissions may be underestimated by factors of two to ten, while the general emission patterns seem to be well understood. Finally, it became evident that 133Xe sources mainly influence the sensitivity of the monitoring system in the mid-latitudes, where the network coverage is particularly good. © 2009 Birkhäuser Verlag Basel/Switzerland. Source

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