Groundwater monitoring and modelling of the “Vector” site for near-surface radioactive waste disposal in the Chornobyl exclusion zone

Abstract

Results of purposeful groundwater monitoring and modelling studies are presented, which were carried out in order to better understand groundwater flow patterns from the "Vector" site for near-surface radioactive waste disposal and storage in the Chornobyl exclusion zone towards river network. Both data of observations at local-scale monitoring well network at "Vector" site carried out in 2015 -2016 and modelling analyses using the regional groundwater flow model of Chornobyl exclusion zone suggest that the groundwater discharge contour for water originating from "Vector" site is Sakhan River, which is the tributary to Pripyat River. The respective groundwater travel time is estimated at 210 -340 years. The travel times in subsurface for 90 Sr, 137 Cs, and transuranium radionuclides (Pu isotopes, 241 Am) are estimated respectively at thousands, tenths of thousands, hundreds of thousandsmillion of years. These results, as well as presented data of analyses of lithological properties of the geological deposits of the unsaturated zone at "Vector" site, provide evidence for good protection of surface water resources from radioactivity sources (e.g., radioactive wastes) to be disposed in the near-surface facilities at "Vector" site.

Solid-liquid distribution coefficients (Kd-s) of geological deposits at the Chernobyl Nuclear Power Plant site with respect to Sr, Cs and Pu radionuclides: A short review

“…2) are composed of predominantly sands with inter-layers of silt and clayey moraine deposits. The thickness of these layers vary from tenths of centimeters to 3-4 m or more (Shehtman et al, 1996;Bugai et al, 2017).…”

“…Bulk density of sandy deposits usually ranges from 1.6 to 1.8 g/cm 3 , while porosity usually ranges from 33 to 42% (Matoshko et al, 2004;Bugai et al, 2017). The eolian deposits have low cation-exchange capacity (CEC) values, which are usually less than 1 meq/100 g, while the alluvial and fluvio-glacial deposits have CEC values in the range from 2 to 10 meq/100 g (depending on content and mineralogy of the clay fraction) (Matoshko et al, 2004;Bugai et al, 2017). Based on data of (Kuznetvov, 1973;Olkhovik et al, 1992;Matoshko et al, 2004) Quaternary alluvial sandy deposits of the study area are predominantly composed of quartz with admixtures of the feldspar (up to ~10 %).…”

“…During the last decade, the 'Vector' complex for disposal of radioactive waste originating from decommissioning of ChNPP and remedial works in Chernobyl Exclusion Zone was created in the elevated area dividing the watersheds of the Uzh and Pripyat Rivers at about 14 km distance from the ChNPP (Bugai et al, 2017) (Fig. 1).…”

“…During the more than 30-year period that has passed since the Chernobyl accident a number of studies were carried out in order to predict radionuclide transport in the geosphere from the radioactivity sources of accidental origin situated at ChNPP site (waste dump sites, cooling pond, Sarcophagus etc.) (e.g., Bugai et al, 1996Bugai et al, , 2005Kivva et al, 1996;Onishi et al, 2007;Molitor et al, 2017), as well as to carry out performance assessment analyses for the planned radioactive waste disposal and storage facilities of the Vector Complex (Shehtman et al, 1996;Bugai et al, 2017). In some instances, the studies mentioned above included experimental determination of site-specific parameters for radionuclide transport in the subsurface environment.…”