Sedimentological study of the Chernobyl NPP site to schematise radionuclide migration conditions

Matoshko, Andrei V.; Bugai, D.; Dewiére, L.; Skalskyy, A.

doi:10.1007/s00254-004-1067-3

Cited by 13 publications

(13 citation statements)

References 9 publications

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“…The upper part of geological strata at ChNPP site that hosts the unconfined aquifer is composed of Quaternary Pliocene and Pleistocene-Holocene sandy deposits (Matoshko et al 2002(Matoshko et al , 2004) (Fig. 2).…”

Section: Geological Structurementioning

confidence: 99%

“…With regard to geomorphology, the following elements can be distinguished at the ChNPP site (see The Quaternary alluvial deposits are most often represented by strata of relatively homogeneous finemedium sands, with inter-bedded layers of loam and silt materials. Thickness of lenses of finer deposits vary from several centimeters to 1-2 m and more (Matoshko et al, 2004).…”

Section: Geomorphology and Lithologymentioning

confidence: 99%

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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

2020

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A review is presented of data on solid-liquid distribution coefficients (Kd-s) of the main radiologically important radionuclides of the Chernobyl release within geological deposits at the Chernobyl Nuclear Power Plant (ChNPP) Site. The Kd values for Sr, Cs and Pu for Quaternary sandy deposits that form sedimentary cover at Chernobyl fall within the range of parameters reported in international sorption databases. In agreement with general knowledge on radionuclide geochemical behavior and affinity to soils, Kd-s increase in the sequence: Sr < Cs < Pu. Alluvial and fluvioglacial sandy deposits are characterized by larger Kd values then deposits of eolian genesis due to higher content of clay minerals in fine fractions. For Sr, laboratory batch tests have given Kd values that are in a reasonable agreement with in situ measurements. At the same time, the 90 Sr Kd-s obtained from groundwater transport model calibrations were noticeably lower than experimentally determined values, thus showing potential limitations of the Kd-approach. Monitoring data on mobility of 90 Sr, 137 Cs and 239,240 Pu in groundwater in the Chernobyl zone on a whole are consistent with the radionuclide Kd-s summarized in this article. The highest concentrations in groundwater (based on data for 2012-2014) were observed for 90 Sr, while orders of magnitude lower concentrations were observed for 137 Cs and 239,240 Pu. At the same time, detection of 137 Cs and 239,240 Pu in groundwater at sites with a relatively deep groundwater table suggests the possibility of facilitated transport of small amounts of these radionuclides in the form of nonretarded colloids or complexes.

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Section: Geological Structurementioning

confidence: 99%

Section: Geomorphology and Lithologymentioning

confidence: 99%

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

2020

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“…The catchment is largely covered by grassy meadow and wetlands. The forest area is occupied by coniferous and mixed forests 33 . The geological strata are composed of sandy quaternary deposits 33 .…”

Section: Methodsmentioning

confidence: 99%

Simulating dissolved 90Sr concentrations within a small catchment in the Chernobyl Exclusion Zone using a parametric hydrochemical model

Igarashi

Onda

Smith

et al. 2020

Sci Rep

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Strontium-90 (90 Sr) is the major long-lived radionuclide derived from the chernobyl accident, and is still being detected in the heavily contaminated catchments of the chernobyl exclusion Zone. this study examines the long-term decrease in the dissolved-phase 90 Sr concentration and the concentrationdischarge (90 Sr-Q) relationship in stream water since the accident. We show that the slow decline in 90 Sr follows a double-exponential function, and that there is a clear relationship between 90 Sr and Q. This study is the first to reveal that the log(90 Sr)-log(Q) slope has been gradually decreasing since the accident. this trend persists after decay correction. thus, it is not caused by the physical decay of 90 Sr and environmental diffusion, but implies that the concentration formation processes in stream water have been changing over a long period. We propose a hydrochemical model to explain the timedependency of the 90 Sr-Q relationship. this paper presents a mathematical implementation of the new concept and describes the model assumptions. our model accurately represents both the long-term 90 Sr trend in stream water and the time-dependency of the 90 Sr-Q relationship. Although this paper considers a small catchment in chernobyl, the conceptual model is shown to be applicable to other accidental releases of radionuclides. It has been 34 years since the Chernobyl nuclear power plant (CNPP) accident in Ukraine (Fig. 1), when large amounts of radionuclides were released into the environment. At present, high levels of dissolved-phase strontium-90 (90 Sr) are still being detected in the small catchment streams inside the Chernobyl Exclusion Zone (CEZ) (Fig. 2b). The main long-term source of exchangeable and available 90 Sr in the CEZ soils is micron-sized "fuel particles" (FP) that are gradually dissolving. These are derived from the accidental release from CNPP Unit 4 on 26 April, 1986, and were formed by the mechanical destruction of nuclear fuel. The dissolution rate of FP in CEZ soils varies from several percent to several tens of percent of the activity inventory per year, depending on the degree of oxidation of the particle UO 2 matrix and the ambient geochemical conditions (e.g. soil solution pH and oxygen availability) 1-6. The 90 Sr from small streams in the CEZ is discharged into the main Pripyat river, which is a critical component of the Dnieper river-reservoir system, one of the largest surface water systems in Europe 7. Through this river system, 90 Sr is also transported to the Kiev metropolitan area in Ukraine. Therefore, predicting and evaluating the radionuclide flux within the water system, and using models to evaluate the potential radiological consequences to the downstream population, remain important tasks.

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“…Water exchange through this low permeability Turonian aquitard layer can be neglected for modelling purposes [4]. Details on the ChNPP site geology and hydrogeology can be found in [6,7].…”

Section: Groundwater Modelling Studiesmentioning

confidence: 99%

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

Bugai¹,

Skalskyy²,

Haneke³

et al. 2017

Nucl. Phys. At. Energy

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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.

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Sedimentological study of the Chernobyl NPP site to schematise radionuclide migration conditions

Cited by 13 publications

References 9 publications

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

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

Simulating dissolved 90Sr concentrations within a small catchment in the Chernobyl Exclusion Zone using a parametric hydrochemical model

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

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