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| Titel |
Geostatistics: a decision-support tool for the decontamination and the recovery of radiocontaminated territories. Study at the scale of the T22 trench in the Chernobyl exclusion zone |
| VerfasserIn |
Huong Lien Nguyen, Chantal de Fouquet, Christelle Courbet, Caroline Simonucci |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102966
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| Publikation (Nr.) |
 EGU/EGU2015-2366.pdf |
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| Zusammenfassung |
| The explosion of Chernobyl reactor n°4 released nearly 13.1019 Bq of radionuclides in the
atmosphere and led to the delineation of a 30 km radius exclusion zone. The following year,
about 800 shallow trenches were dug and the low to medium activity nuclear wastes
were buried in order to prevent their dispersal. However, those trenches are dug in
permeable aeolian sand and do not prevent the migration of radionuclides in the
superficial aquifer. As the Ukrainian authorities would like to recover part of the
exclusion zone territory, it is necessary to quickly assess the radionuclide stock, which
could still possibly contaminate the groundwater, by reliable means. The study of
the T22 trench shows the effectiveness and the relevance of geostatistics in this
issue.
The stock of cesium-137 available in 1999 in the T22 trench and its uncertainties related to
the spatial variability are assessed. To do so, the limits of the trench basement are first
interpolated using the results of ground penetrating radar profiles, undertaken to characterize
the subsoil, and using the results of the in situ gamma spectrometry carried on boreholes
drilled in the trench. Different geostatistical approaches are examined. Then, the
raw data characterizing the intensity of gamma radiation in the soil are analyzed
according to their localization in the trench to reassess the limits of the trench, the
volume of radiocontaminated soil, the stock of cesium-137 in 1999 and the associated
uncertainties. The results of the current and previous analysis of the radionuclide
stock and its limits are discussed and the different results of the trench limits are
compared.
Finally, a hydrogeological model is constructed. The hydraulic parameters are estimated and
compared using different methodologies of inverse modeling. Several geostatistical
simulations based on the variogram model of the radionuclide stock are introduced
in the hydrogeological model in order to evaluate the impact of the radionuclide
stock spatial variability on the groundwater pollution plume underneath the T22
trench.
The aim of this work is to integrate geostatistics as a tool that quantifies the uncertainties
related to the spatial variability of certain parameters leading to a reasoned approach to land
decontamination. |
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