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Yamba K.,University of Ouagadougou | Sanogo O.,Center National Of Recherche Scientifique Et Technologique Cnrst | Kalinowski M.B.,Comprehensive nuclear Test Ban Treaty Organization CTBTO | Nikkinen M.,Comprehensive nuclear Test Ban Treaty Organization CTBTO | Koulidiati J.,University of Ouagadougou
Applied Radiation and Isotopes | Year: 2016

This study reports on a fast and accurate assessment of zero time of certain nuclear events using La-140/Ba-140 isotopic activity ratio. For a non-steady nuclear fission reaction, the dating is not possible. For the hypothesis of a nuclear explosion and for a release from a steady state nuclear fission reaction the zero-times will differ. This assessment is fast, because we propose some constants that can be used directly for the calculation of zero time and its upper and lower age limits. The assessment is accurate because of the calculation of zero time using a mathematical method, namely the weighted least-squares method, to evaluate an average value of the age of a nuclear event. This was done using two databases that exhibit differences between the values of some nuclear parameters. As an example, the calculation method is applied for the detection of radionuclides La-140 and Ba-140 in May 2010 at the radionuclides station JPP37 (Okinawa Island, Japan). © 2016 Elsevier Ltd.

Krysta M.,Comprehensive nuclear Test Ban Treaty Organization CTBTO | Becker A.,Comprehensive nuclear Test Ban Treaty Organization CTBTO | Brachet N.,Comprehensive nuclear Test Ban Treaty Organization CTBTO
HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes | Year: 2010

Inverse modelling for the phenomenon of atmospheric dispersion is often hindered by a limited number of measurements which makes the problem severely underdetermined. Superimposed are inaccuracies in the meteorological fields which drive the atmospheric transport models, simplifications in the models themselves and the errors intrinsic to the measurement procedures. Consequently, obtaining informative and reliable results of inverse modelling requires additional information which needs to be provided to an inversion algorithm. Mathematical techniques could be employed in order to constrain the underdetermined inverse problem, or, in case of a simple source characterised by a small number of parameters, the estimation could be limited to those parameters. In the context of monitoring compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) yet other pieces of information are taken advantage of. Large regions indicating a possible presence of a source of radionuclides can be overlaid with an accurate location of the phenomena emitting seismic, infrasound or hydroacoustic signals. Ultimately, under the hypothesis that the source of radioactivity coincides in space and time with one of the detected phenomena, the atmospheric transport modelling (ATM) aids to discriminate between those which could have been and could not have been at the origin of a detected release.

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