Radionuclide transport and dose calculations for Zapadnoe uranium mill tailings test case using NORMALYSA tool. Daria Koliabina. 1. , Dmitry Grygorenko. 1.
Facilia International
Technical note
Radionuclide transport and dose calculations for Zapadnoe uranium mill tailings test case using NORMALYSA tool
Daria Koliabina1, Dmitry Grygorenko1, Dmitri Bugai2, Rodolfo Avila3 1 – Facilia International, Kiev, Ukraine 2 – Institute of Geological Sciences, Kiev, Ukraine 3 – Facilia AB, Bromma, Sweden
Draft - 14.01.2016
Kiev – Stockholm - 2016 1
Summary This technical note documents application of NORMALYSA tool to radionuclide transport and dose calculations test case. Test calculations are presented for two scenarios for Zapadnoe uranium mill tailings situated at the Pridneprovsky Chemical Plant, Ukraine. The input parameter data set was prepared in the frame of the IAEA MODARIA project WG3 model inter-comparison exercise. Annual committed effective doses (total and for each specific exposure pathway) to the worker of the Baryer company, who is visiting regularly the site for work purposes (monitoring, surveillance etc.) were calculated in the Scenario 1. This Scenario includes the following exposure pathways: external exposure from material on the ground, radon and radioactive dust inhalation. Annual committed effective doses (total and for each exposure pathway) to the resident of a dwelling 800 m downstream from the site were calculated in the Scenario 2. This hypothetical resident establishes his garden after the end of the active institutional control period of the site. This Scenario includes the following exposure pathways: ingestion of vegetables from the garden irrigated by contaminated ground water, ingestion of fish from Konoplyanka River and agricultural activities in the contaminated garden. Results of calculations showed that, the main exposure pathway for Scenario 1 is external exposure from material on the ground. Dose from external exposure is estimated at 3.15E-3 Sv/year. Dose from inhalation of radon and radioactive aerosols is estimated at 2.67E-4 Sv/year.The main contribution to inhalation dose comes from Rn-222. Total dose from all pathways is 3.42E-3 Sv/year. Hydrologic transport calculations and dose analyses in Scenario 2 were carried out for the following radionuclides of U-238 decay series: U-238, U-234, Th-230, Ra-226, Po-210 and Pb-210. The time frame of the assessment was 1000 years. According to the modeling results for Scenario 2 uranium concentration in well water progressively increases during the simulation period and reaches maximum (6.97 E+04 Bq/m3) at time t=1000 years for U-234 and U-238. The same picture is observed for river water, however concentration of U-234 and U-238 in the river is quite low as a result of dilution of contaminated groundwater discharge from the aquifer by upstream river flow. In this case radionuclides concentration in fish is also relatively low. The main exposure pathway is ingestion of vegetables from garden irrigated by contaminated groundwater. Maximum dose is reached at t=1000 years and constitutes 1.76E-3 Sv/year (Dose from ingestion of vegetables constitutes 99.94% from the overall dose).
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Contents
Introduction........................................................................................................................................................5 PART 1. Calculations for Scenario 1 ....................................................................................................................6 1.1
Scenario description .........................................................................................................................6
1.2
Schematization of calculations ...........................................................................................................6
1.3
Realization of model in Normalysa.....................................................................................................6
1.4
Input parameters................................................................................................................................7
1.5
Results ................................................................................................................................................8
1.6
Conclusions for Scenario 1 .................................................................................................................8
PART 2. Calculations for Scenario 2 ....................................................................................................................9 2.1
Scenario description .........................................................................................................................9
2.2
Schematization of calculations ...........................................................................................................9
2.2.1
Short descriptions of sub-models and data exchanges ..............................................................9
2.2.2
Geometry and main compartments of geomigration model ...................................................10
2.2.3
Cropland and Dose models ......................................................................................................12
2.3
Realization of models in Normalysa .................................................................................................12
2.3.1
Geomigration model ................................................................................................................13
2.3.2
Cropland and Dose models ......................................................................................................13
2.4
Input parameters..............................................................................................................................14
2.5
Results ..............................................................................................................................................19
2.5.1
Radionuclides concentration in well water ..............................................................................19
2.5.2
Radionuclides concentration in river water and freshwater food ...........................................20
2.5.3
Dose results ..............................................................................................................................21
2.6
Conclusions for Scenario 2 ...............................................................................................................24
References ....................................................................................................................................................25
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List of figures Figure 1. 1. Schematization of calculations for Scenario 1. ...............................................................................6 Figure 1. 2. Realization of the model for Scenario 1 in Normalysa. ...................................................................7
Figure 2. 1. Schematic representation of the contaminated site and relevant exposure pathways for Scenario 2 ...........................................................................................................................................................9 Figure 2. 2.Calculation sequence in model for Scenario 2. ..............................................................................10 Figure 2.3. Geometry and main compartments of Geomigration model for Scenario 2 .................................11 Figure 2. 4. Scheme of the river channel for Scenario 2 ..................................................................................11 Figure 2. 5. Dose model for Scenario 2 ............................................................................................................12 Figure 2. 6. Normalysa modules used to develop computer model for Scenario 2 .........................................12 Figure 2. 7. Geomigration model realization for Scenario 2 ............................................................................13 Figure 2. 8. Cropland and dose models realization in Normalysa for Scenario 2 ............................................14 Figure 2. 9. Dynamic of RN concentration in well water for Scenario 2 ..........................................................19 Figure 2. 10 RN concentrations in water food for Scenario 2 ..........................................................................21 Figure 2. 11. Dose calculation result for different pathways for Scenario 2 ....................................................23
List of tables Table 1. 1. Input parameters of Block “Constants” (Scenario 1) ........................................................................7 Table 1. 2.Input parameters of sub-system “Dose from occupancy outdoors” (Scenario 1) ............................8 Table 1. 3. Doses from different pathways for Scenario 1 ................................................................................8 Table 1. 4 .Dose from aerosols and radon inhalation for Scenario 1 .................................................................8
Table 2. 1. Input parameters for Sub-system Tailing without cover for Scenario 2.........................................14 Table 2. 2. Input parameters for Sub-system Unsaturated Zone for Scenario 2 .............................................15 Table 2. 3. Input parameters for Sub-system Aquifer Mixing for Scenario 2 ...................................................15 Table 2. 4. Input parameters for Sub-system Aquifer 1- Aquifer 3 for Scenario 2...........................................15 Table 2. 5. Input parameters for Sub-system Well for Scenario 2 ...................................................................16 Table 2. 6. Input parameters for Sub-system Fresh Water Body for Scenario 2..............................................16 Table 2. 7 Input parameters for Sub-system Cropland for Scenario 2 .............................................................16 Table 2. 8. Input parameters “Constants” for Scenario 2 ................................................................................17 Table 2. 9. Input parameters for Dose models sub-systems for Scenario 2 ....................................................17 Table 2. 10. Calculated RN concentrations in well water for Scenario 2 .........................................................19 Table 2. 11.Calculated RN concentrations in river water for Scenario 2 .........................................................20 Table 2. 12. Calculated RN concentration in water food for Scenario 2 ..........................................................20 Table 2. 13. Doses from ingestion of food ( Crops and aquatic food) for Scenario 2 ......................................21 Table 2. 14. Doses from ingestion of soil for Scenario 2 (garden works) .........................................................22 Table 2. 15. Doses from occupancy in the garden and inhalation for Scenario 2 ...........................................22 Table 2. 16. Сomparison of different pathways for Scenario 2 ........................................................................22
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Introduction Calculations for two scenarios for Zapadnoe uranium mill tailings site situated at the Pridneprovsky Chemical Plant (Ukraine) are presented. Calculations are carried out using NORMALYSA tool in the context of IAEA MODARIA project WG3 model inter-comparison exercise [1]. NORMALYSA modeling platform represents the set of models and databases for radiological assessment of sources incorporating Naturally Occurring Radioactive Materials (NORM) and radioactive legacy sites. NORMALYSA includes models for potentially important transport pathways (e.g., groundwater, atmospheric, surface run-off) and contaminated receptor environments (e.g., freshwater bodies, groundwater wells, crop lands, pasture lands, etc.) [2]. The NORMALYSA modeling tool is based on Ecolego 6.0 compartmental radiological modeling software, developed by Facilia AB [3]. NORMALYSA was initially developed by IAEA, and is currently tested and improved in the frame of IAEA MODARIA Project WG 3 activities. This technical note describes configuring and application of NORMSLYSA to Zapadnoe tailings modeling case. The technical note consists of two individual parts devoted to two simulated exposure scenarios for Zapadnoe. Each part includes the following information: Scenario description; Presentation of schematization of calculations; Description of implementation of transport and exposure models in NORMALYSA; Throughout list of input parameters; Discussion of results, and Conclusions.
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PART 1. Calculations for Scenario 1 1.1
Scenario description
Source: Zapadnoe tailings. Exposure pathways:
For the personnel working at the PChP (Pridneprovsky Chemical Plant ) site: External exposure from material on the ground; Inhalation of radioactive aerosols and Rn-222. Receptor environment: Industrial area. Exposed person: Worker of the Baryer company (adult) visiting regularly the site for work purposes (monitoring, surveillance etc.). It is assumed that during these works the worker visits all locations within the site with the same frequency. Occupancy:
Fraction of time spent on site: Outdoors=50%. Description of calculation endpoints : Annual committed effective dose (total and for each exposure pathway) to the worker described. More details on contaminated site and Scenario description can be found in [1].
1.2
Schematization of calculations
Dose from inhalation was calculated from monitoring data on radon and radionuclides (RN) concentration in outdoor air. Dose from occupancy outdoors was calculated from measured dose-rate at the surface of Zapadnoe tailing (Figure 1.1.).
Dose from inhalation of aerosols and Rn-222 Total Dose Dose from external exposure
Figure 1. 1. Schematization of calculations for Scenario 1.
1.3
Realization of model in Normalysa
In this Scenario exposure doses were calculated using two Normalysa models –“Dose from occupancy outdoors” and “Total dose”. Realization of model in Normalysa is shown in the Figure 1.2.
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Figure 1. 2. Realization of the model for Scenario 1 in Normalysa.
1.4
Input parameters
Input parameters are listed in tables 1.1 – 1.2. Parameters listed in table 1.1 represent default values used in NORMALYSA. Table 1. 1. Input parameters of Block “Constants” (Scenario 1) Parameter Value Conversion factor from ambient to effective dose Adults 0.6 Dose coefficient for effective dose by inhalation (Adults) Pb-210 5.6E-6 Ra-226 9.5E-6 Th-230 1.0E-4 U-238 8.0E-6 Dose coefficient for effective dose by 6.1E-9 Radon inhalation (Adults) Equilibrium factor outdoors (Adults) 0.4 Inhalation rate (Adults) 0.92
Unit
Sv/Bq
(Sv*m3)/(Bq*h)
m3/h
Site-specific and scenario specific parameter values are shown in Table 1.2. According to Radiation Safety Norms of Ukraine [3] referent duration of staff exposure at working place is 1700 hours/year. In our case worker spends 50% of his working time on contaminated area that is 850 hours/year. This means that parameter “fractional time exposed outdoors” equals 10% of “number of hours per year” (850 hours/year= 0.1*365 days/year*24 hours/day).
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Table 1. 2.Input parameters of sub-system “Dose from occupancy outdoors” (Scenario 1)
1.5
Parameter Fraction of time exposed outdoors RN concentration in outdoor air
Value 0.1
Pb-210 Ra-226 Rn-222 Th-230 U-238 Measured ambient dose rate outdoors
4.6E-7 8.0E-8 125.0 0.0 6.0E-8 6.0Е-6
Unit Bq/m3
Sv/h
Results
Doses from different pathways are shown in table 1.3. Table 1. 3. Doses from different pathways for Scenario 1 Exposure pathway External irradiation Inhalation Total
Dose, Sv/year 3.15E-3 2.67E-4 3.42E-3
Contributions to inhalation exposure from different radionuclides are shown in table 1.4. Table 1. 4 .Dose from aerosols and radon inhalation for Scenario 1
1.6
Radionuclide Aerosols Pb-210 Ra-226 Th-230 U-238
Dose, Sv/year
Rn-222
2.67E-4
2.08E-9 6.12E-10 0.0 3.87E-10
Conclusions for Scenario 1
The main exposure pathway for Scenario 1 is external exposure from material on the ground. Dose from external exposure is estimated at 3.15E-3 Sv/year. Dose from inhalation of radon and radioactive aerosols is estimated at 2.67E-4 Sv/year. The main contribution to inhalation dose comes from Rn-222. Total dose from all pathways is 3.42E-3 Sv/year.
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PART 2. Calculations for Scenario 2 2.1
Scenario description
The long-term potential exposure from Zapadnoe tailings can be caused by: - Using contaminated groundwater for irrigation in agricultural activities (growing vegetables in a garden); - Exposure to external irradiation from material on the ground and inhalation of radioactive aerosols during the work in the garden irrigated by contaminated groundwater; - contaminated groundwater discharge to surface water body (Konoplyanka River) resulting in contamination of fish. Receptor environment Residential area where local groundwater is used for irrigation (800 m downstream from the site); fishing from Konoplyanka River. Exposed person Resident of a dwelling 800 m downstream from the site. The resident establishes his garden after the end of the active institutional control period of the site (300 years). Occupancy Resident (adult) establishes vegetable garden irrigated by contaminated groundwater from the production well to alluvial aquifer. It is assumed that the vegetable garden provides to resident 100% of potato and 50% of other vegetable (all types) diet. Resident spent 1000 hours/year in the garden carrying out agricultural works. Resident also consumes contaminated fish from Konoplyanka River (100% of fish diet). Description of calculation endpoints Annual committed effective dose (total and for each exposure pathway) to the exposed person described in the previous paragraph (timescale: from end of institutional control period (300 years) to 1000 years from now). More details on contaminated site and Scenario 2 description can be found in [1].
2.2
Schematization of calculations
2.2.1
Short descriptions of sub-models and data exchanges
Schematic representation of the contaminated site and relevant exposure pathways is shown in Figure 2.1. Dose from ingestion of vegetables
Tailing
Well
Garden Dose via inhalation, soil ingestion and external exposure from agriculture activity
Aquifer
River
Dose from ingestion of fish
Unsaturated Zone
Geomigration model
Cropland and Dose models
Figure 2. 1. Schematic representation of the contaminated site and relevant exposure pathways for Scenario 2 9
The overall model for Scenario 2 includes two sub-models : Geomigration model and Cropland & Dose model. Output parameters from Geomigration model are input parameters for Cropland and Dose models. Geomigration model includes tailing facility (source), unsaturated zone and aquifer (transport environment) and receptor points (well and river). Radionuclide concentration in well is input parameter for cropland model. Outflow concentration from the aquifer is input for river model. Radionuclide concentration in fish is calculated in river module and is input for dose model. The calculations proceed as follows (Figure 2.2): 1) Geomigration model is run for t=1000 years. 2) Dose calculations start at time point t=300y, which corresponds to the end of institutional control period. 3) Concentrations in well water and river water / fish were calculated for a period of 1000 years with a step of 100 y. 4) Then RN concertation in well water and fish were taken at points in time 300, 400, 500, 600, 700, 800, 900, 1000 y and used as input data in cropland and dose models. Each time the cropland model was run with the described above input concentrations for a period of 70 years. Then average yearly dose to resident was estimated. RN concentration in water t=300 ….. t=1000 years
=
Well
RN concentration in irrigation water
RN concentration in fish t=300 ….. t=1000 years
=
Cropland
Initial RN concentration in fish
Dose from ingestion of fish River
Figure 2. 2.Calculation sequence in model for Scenario 2.
2.2.2
Geometry and main compartments of geomigration model
This part of model describes uranium tailing site with subsurface radionuclide migration pathway. The groundwater pathway includes the unsaturated zone and several aquifer compartments. We separated aquifer into 3 aquifer compartments in accordance with the different initial RN concentrations in groundwater. Well and river compartments are included to the Geomigration model as receptor points. Geometry and main compartments of Geomigration model are shown in Figure 2.3.
10
10m
550m
250m м
Tailing
14m
Unsaturaited Zone
10m
Aquifer Mixing
200m м R I V E R
W E L L Aquifer 1
150m
Aquifer 2
800m
Aquifer 3
300m
1000m
Figure 2.3. Geometry and main compartments of Geomigration model for Scenario 2
The assumed scheme of the river channel, which receives the contaminated GW discharge from the tailing, is shown in Figure 2.4.
300 m 10 m Inflow of contaminated GW
RIVER 1m 5 cm 50 cm
Flow rate 1.1 E8 m3/y
Sediments Top c layer(sand) Bottom layer(sand)
Figure 2. 4. Scheme of the river channel for Scenario 2
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2.2.3
Cropland and Dose models
This part of overall model includes Dose models: dose from ingestion of vegetables and fish, and Dose from inhalation and external exposure from agriculture activity outdoor in the vegetable garden (Figure 2.5) . Dose from ingestion of vegetables
Total Dose
Dose via inhalation, soil ingestion and external exposure from staying outdoors during work in the garden
Dose from ingestion of fish
Figure 2. 5. Dose model for Scenario 2
2.3
Realization of models in Normalysa
To implement the described above conceptual model we use the following Normalysa models: Tailing without cover, Unsaturated zone, Aquifer Mixing, Aquifer (Three blocks with different parameters), Well, Fresh Water Body, Cropland, Dose from ingestion of crops, Dose from occupancy outdoors, Dose from ingestion of freshwater fish, Total Dose (Figure 2.6). Tailing Tailing without cover
GW System
Well
River
Unsaturated Zone Aquifer Mixing Aquifer
Well
Fresh Water Body
Normalysa moduls
Dose Models
Dose from ingestion of freshwater fish Dose from occupancy outdoors Dose from ingestion of crops
Vegetable Garden Cropland
Figure 2. 6. Normalysa modules used to develop computer model for Scenario 2
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2.3.1
Geomigration model
Geomigration model is realized in Normalysa using the following modules: Source (Tailing without cover), Transport (Unsaturated zone, Aquifer Mixing, Aquifer), Receptors(Well, Fresh Water Body). The River (Fresh Water Body) model accounted for groundwater discharge dilution by upstream surface water flux, and for RN exchange between water column and bottom sediments (top and bottom layers). Runoff from subcatchment, sedimentation processes and RN deposition on water body were not taken into account. For the Geomigration model it was assumed that all aquifer compartments have the same material properties. Realization of model in Normalysa is shown in Figure 2.7.
Figure 2. 7. Geomigration model realization for Scenario 2
2.3.2
Cropland and Dose models
Cropland module is used for prediction of RN concentration in garden soil and vegetables. At the next step doses from ingestion of contaminated materials (soil and vegetables) and agricultural activity on contaminated area were calculated; dose from fish ingestion was added. RN concentration in irrigation water and initial RN concentration in fish were taken from the Geomigration model. Cropland and Dose model realization in Normalysa is shown below in Figure 2.8.
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Figure 2. 8. Cropland and dose models realization in Normalysa for Scenario 2
2.4
Input parameters
The most important parameters for the overall model according to Normalysa sub-systems (or modules) are presented below in tables 2.1 – 2.9. Values for some parameters were assigned using data of the report [5] and/or expert judgment of authors. Table 2. 1. Input parameters for Sub-system Tailing without cover for Scenario 2 Parameter Infiltration recharge rate through waste layer RN concentration in infiltration recharge water to the waste layer Thickness of contaminated soil (waste) layer Waste site (contaminated soil) area Contaminated soil (waste) moisture content Waste (contaminated soil) bulk density Specific activity of RN in waste (initial) Po-210 Pb-210 Ra-226 Th-230 U-238/ U-2348 Waste Kd Po-210 Pb-210 Ra-226 Th-230 U-238/ U-234 Default values of NORMALYSA are marked by this color
Value 0.3 0 10 40200 0.15 1730
Unit m/year Bq/m3 m m2 kg/m3 Bq/kg
21000 5800 5900 12700 1600 m3.kg-1 2.5 3.5 6.3 10 0.003
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Table 2. 2. Input parameters for Sub-system Unsaturated Zone for Scenario 2 Parameter Moisture content in the UZ Thickness of the UZ Soil bulk density in UZ Initial specific activity of soil in UZ Po-210 Pb-210 Ra-226 Th-230 U-238/ U-2348 Unsaturated zone Kd Po-210 Pb-210 Ra-226 Th-230 U-238/ U-234
Value
Unit
0.15 14 1700
m kg/m3 Bq/kg
920 2200 435 510 510 m3.kg-1 0.1 0.5 0.2 3 0.003
Table 2. 3. Input parameters for Sub-system Aquifer Mixing for Scenario 2 Parameter Aquifer porosity Groundwater flow Darcy velocity Aquifer material bulk density Initial radionuclide concentrations in the groundwater / aquifer Po-210 Pb-210 Ra-226 Th-230 U-238/ U-234
Value 0.3 10 1600
Unit m/year kg/m3 Bq/m3*103
0.015 0.033 0.048 0 0.35
Table 2. 4. Input parameters for Sub-system Aquifer 1- Aquifer 3 for Scenario 2 Parameter Aquifer material bulk density Aquifer material porosity Length of the flow tube Initial Concentration of RN in the groundwater / aquifer Po-210 Pb-210 Ra-226 Th-230 U-238/ U-234 Aquifer Kd U-238/ U-234 Po-210 Th-230 Ra-226 Pb-210
Aquifer 1 1600 0.3 250
Value Aquifer 2 1600 0.3 550
Aquifer 3 1600 0.3 200
Unit
-------------------------------
5 20 0 0 2030
5 20 0 0 2030
kg/m3 m Bq/m3
m3.kg-1 0.005 0.1 3 0.2 0.5
0.005 0.1 3 0.2 0.5
0.005 0.1 3 0.2 0.5
3 0.2 0.5
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Table 2. 5. Input parameters for Sub-system Well for Scenario 2 Parameter Fraction of groundwater coming to the well from the flow tube
Value
Unit
1
Table 2. 6. Input parameters for Sub-system Fresh Water Body for Scenario 2 Parameter Average lake(water body) depth, Concentration ratio for freshwater food Pb-210 Ra-226 Th-230 U-238/ U-234 Po-210 Density of the deep sediment layer Density of the top sediment layer Deposition rate of radionuclides on the FWB Height of the deep sediment layer Height of the top sediment layer Lake (Water body) area Porosity of soil in subcathment area Radionuclide distribution coefficient U-238/ U-234 Th-230 Ra-226 Po-210 Pb-210 Runoff Upstream water flux
Value 1 0.1 0.014 0.311 2.7E-4 0.144 1200 600 0.5 0.05 3000 0.21 0.003 3 0.2 0.1 0.5 0 1.10E8
Unit m kgDW/m3
kgDW/m3 kgDW/m3 Bq year-1 m m m2 m3/m3 m3/kgDW
m/year m3/year
Table 2. 7 Input parameters for Sub-system Cropland for Scenario 2 Parameter Area of considered object Biomass of crops Potato Vegetables Bioturbation Concentration of dust in atmospheric air Crop exposure period Potato Vegetables Density of the deep zone soil Density of the rooting zone soil Distribution coefficient for the deep soil zone, U-238/ U-234 Distribution coefficient for the soil rooting zone U-238/ U-234 Erosion rate Evapotranspiration rate vegetables potato
Value 10000 1.11 1.02 5.858 5.0E-8 100 100 2115 1626
Unit m2 kgDW/m2 kgDW/(m2*year) gDW/m3 d
kgDW/m3 kgDW/m3 m3/kgDW
0.021 m3/kgDW 3,81E-01 0.05
kgDW/(m2*year) m3/(m2*year)
0.4 0.5 16
Height of the deep soil zone Height of the soil rooting zone Initial deposition on the cropland U-238/ U-234 Irrigation rate for crops vegetables potato Mass interception factor vegetables potato Porosity of the deep soil zone Porosity of the soil rooting zone RN concentration in irrigation water
Time period of irrigation of crops vegetables potato Weathering half time
0.5 0.25
m m Bq
0 m3/(m2*year) 0.16 0.16 m2/kgFW 0.3 0.3 0.21 0.36 CALCULATED in Table 12 for each time point
m3/m3 m3/m3 Bq/m3
d 15 15 22.4
d
Table 2. 8. Input parameters “Constants” for Scenario 2 Parameter Value Conversion factor from ambient to effective dose 0,6 Dose coefficient for effective dose by ingestion U-234 4.9E-8 U-238 4.5E-8 Dose coefficient for effective dose by inhalation, U-234 9.4E-6 U-238 8.0E-6 Dose coefficient for effective dose from total deposit U-234 6.6E-18 U-238 1.5E-18 Fractional water content of the crops vegetables 0.87 potato 0.92 Ingestion rate of crops, vegetables 122.4 potato 91.2 Ingestion rate of freshwater food fish 20.4 Ingestion rate of soil 5.0E-6 Inhalation rate 0.92 Precipitation rate 0.39
Unit Sv/Bq
Sv/Bq
(Sv*m3)/(Bq*h)
kgFW/year
kgFW/year kgDW/h m3/h m3/(m2*year)
Table 2. 9. Input parameters for Dose models sub-systems for Scenario 2 Parameter Value Dose model from ingestion of crops Fractional contribution to the ingestion of crops from specific cropland Adult 1 Fractional contribution to the ingestion of crops vegetables 0.5 potato 1.0
Unit
17
Dose from ingestion of freshwater food Fractional contribution to the ingestion of aquatic food Initial RN concentration in freshwater food Dose from occupancy outdoors Fraction of time exposed outdoors
1 CALCULATED Bq/kgFW in Table 2. 13 for each point of time 0.11
18
2.5
Results
2.5.1
Radionuclides concentration in well water
Predicted RN concentrations in well water are shown below in Table 2.10 and Figure 2.9. Concentrations of Pb-210, Po-210, Ra-226 and Th-230 in well water are 5-6 orders of magnitude lower compared to uranium, therefore we neglect these RN in our subsequent dose calculations. Table 2. 10. Calculated RN concentrations in well water for Scenario 2 Time (Years)
U-234 Bq/m3
U-238 Bq/m3
Pb-210 Bq/m3
Po-210 Bq/m3
Ra-226 Bq/m3
Th-230 Bq/m3
300
1,81E+03
1,81E+03
4,67E-03
2,35E-02
8,91E-03
9,34E-03
400 500 600 700 800 900 1000
3,31E+03 9,42E+03 2,16E+04 3,81E+04 5,45E+04 6,58E+04 6,97E+04
3,31E+03 9,42E+03 2,16E+04 3,81E+04 5,45E+04 6,58E+04 6,97E+04
5,39E-03 8,81E-03 1,53E-02 2,89E-02 5,56E-02 1,01E-01 1,71E-01
2,68E-02 4,39E-02 7,62E-02 1,44E-01 2,77E-01 5,05E-01 8,52E-01
1,55E-02 2,56E-02 4,56E-02 8,75E-02 1,67E-01 2,99E-01 4,93E-01
1,30E-02 2,23E-02 4,62E-02 9,34E-02 1,67E-01 2,64E-01 3,73E-01
1.00E+05 1.00E+04 1.00E+03 1.00E+02 1.00E+01 1.00E+00 1.00E-01 1.00E-02 1.00E-03 300 Pb-210
400
500 Po-210
600 Ra-226
700 Th-230
800 U-234
900
1000 U-238
Figure 2. 9. Dynamic of RN concentration in well water for Scenario 2
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2.5.2
Radionuclides concentration in river water and freshwater food
Estimated RN concentrations in river water and shown below in Table 2.11. Concentrations of Pb210, Po-210, Ra-226 and Th-230 are much lower compared to uranium and therefore were neglected in dose calculations. Table 2. 11.Calculated RN concentrations in river water for Scenario 2 Time RN (Years) concentration in water Pb-210 Bq/m3 300 1,22E-06 400 500 600 700 800 900
1,42E-06 2,22E-06 3,26E-06 4,79E-06 7,55E-06 1,28E-05
1000
2,19E-05
RN concentration in water Po-210 Bq/m3 6,14E-06 7,09E-06 1,11E-05 1,62E-05 2,39E-05 3,76E-05 6,34E-05 1,09E-04
RN concentration in water Ra-226 Bq/m3 2,35E-06
RN concentration in water Th-230 Bq/m3 2,51E-06
RN concentration in water U-234 Bq/m3 5,18E-01
RN concentration in water U-238 Bq/m3 5,18E-01
4,10E-06 6,29E-06 9,12E-06 1,36E-05 2,19E-05 3,74E-05
3,31E-06 4,17E-06 5,80E-06 9,88E-06 1,85E-05 3,34E-05
4,94E-01 6,62E-01 1,58E+00 3,79E+00 7,30E+00 1,14E+01
4,94E-01 6,62E-01 1,58E+00 3,79E+00 7,30E+00 1,14E+01
6,41E-05
5,45E-05
1,50E+01
1,50E+01
RN concentrations in freshwater food are shown below in Table 2.12 and Figure 2.10. In this case we have the same situation as with RN concentrations in water. Table 2. 12. Calculated RN concentration in water food for Scenario 2 Time (Years)
300 400
RN concentration in fish Pb-210 Bq/m3 2,69E-08 3,13E-08
RN concentration in fish Po-210 Bq/m3 1,94E-07 2,25E-07
RN concentration in fish Ra-226 Bq/m3 7,38E-09 1,29E-08
RN concentration in fish Th-230 Bq/m3 1,72E-07 2,26E-07
RN concentration in fish U-234 Bq/m3 3,08E-05 2,93E-05
RN concentration in fish U-238 Bq/m3 3,08E-05 2,93E-05
500 600 700 800
4,89E-08 7,17E-08 1,05E-07 1,66E-07
3,51E-07 5,14E-07 7,56E-07 1,19E-06
1,98E-08 2,87E-08 4,27E-08 6,88E-08
2,85E-07 3,97E-07 6,76E-07 1,27E-06
3,93E-05 9,39E-05 2,25E-04 4,34E-04
3,93E-05 9,39E-05 2,25E-04 4,34E-04
900 1000
2,81E-07 4,82E-07
2,01E-06 3,45E-06
1,18E-07 2,01E-07
2,29E-06 3,73E-06
6,78E-04 8,92E-04
6,78E-04 8,92E-04
20
1.00E+00 1.00E-01 1.00E-02 1.00E-03 1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08 1.00E-09 300
400
Pb-210
500 Po-210
600 Ra-226
700 Th-230
800
900
U-234
1000 U-238
Figure 2. 10 RN concentrations in water food for Scenario 2
2.5.3
Dose results
Doses from ingestion of crops, of freshwater food, outdoor exposure and inhalation and soil ingestion (garden works), and total dose at time points 300,400, 500, 600, 700, 800, 900, 1000 years are shown in Tables 2.15-2.18 and Figure 2.11. Table 2. 13. Doses from ingestion of food ( Crops and aquatic food) for Scenario 2 Time 300 400 500 600 700 800 900 1000
Ingestion of Crops U-234 [Sv/year] U-238 [Sv/year] 2,38E-05 2,19E-05 4,34E-05 3,99E-05 1,24E-04 1,14E-04 2,84E-04 2,60E-04 5,00E-04 4,60E-04 7,15E-04 6,57E-04 8,64E-04 7,94E-04 9,15E-04 8,41E-04
Total 4,57E-05 8,33E-05 2,37E-04 5,44E-04 9,60E-04 1,37E-03 1,66E-03 1,76E-03
Ingestion of aquatic food U-234 [Sv/year] U-238 [Sv/year] 3,08E-11 2,83E-11 2,93E-11 2,69E-11 3,93E-11 3,61E-11 9,38E-11 3,61E-11 2,25E-10 3,61E-11 4,33E-10 2,07E-10 6,78E-10 6,22E-10 8,92E-10 8,19E-10
Total 5,90E-11 5,62E-11 7,54E-11 1,30E-10 2,61E-10 6,40E-10 1,30E-09 1,71E-09
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Table 2. 14. Doses from ingestion of soil for Scenario 2 (garden works) Time 300 400 500 600 700 800 900 1000
Ingestion of soil U-234 [Sv/year] U-238 [Sv/year] 1,78E-08 1,64E-08 3,25E-08 2,98E-08 9,26E-08 8,50E-08 2,12E-07 1,95E-07 3,75E-07 3,44E-07 5,35E-07 4,92E-07 6,47E-07 5,94E-07 6,85E-07 6,29E-07
Total 3,42E-08 6,23E-08 1,78E-07 4,07E-07 7,19E-07 1,03E-06 1,24E-06 1,31E-06
Table 2. 15. Doses from occupancy in the garden and inhalation for Scenario 2 Time 300 400 500 600 700 800 900 1000
Inhalation U-234 [Sv/year] U-238 [Sv/year] 1,38E-08 1,18E-08 2,52E-08 2,15E-08 7,19E-08 6,12E-08 1,65E-07 1,40E-07 2,91E-07 2,48E-07 4,16E-07 3,54E-07 5,03E-07 4,28E-07 5,32E-07 4,53E-07
Total 2,56E-08 4,67E-08 1,33E-07 3,05E-07 5,39E-07 7,70E-07 9,30E-07 9,85E-07
Outdoor exposure U-234 [Sv/year] U-238 [Sv/year] 3,45E-10 1,56E-07 6,29E-10 2,85E-07 1,79E-09 8,11E-07 4,11E-09 1,86E-06 7,25E-09 3,28E-06 1,04E-08 4,69E-06 1,25E-08 5,67E-06 1,33E-08 6,00E-06
Total 1,57E-07 2,85E-07 8,13E-07 1,86E-06 3,29E-06 4,70E-06 5,68E-06 6,02E-06
Table 2. 16. Сomparison of different pathways for Scenario 2 Time Total dose from aquatic food ingestion 300 5,90E-11 400 5,62E-11 500 7,54E-11 600 1,30E-10 700 2,61E-10 800 6,40E-10 900 1,30E-09 1000 1,71E-09
Total dose from inhalation 2,56E-08 4,67E-08 1,33E-07 3,05E-07 5,39E-07 7,70E-07 9,30E-07 9,85E-07
Total dose from outdoor exposure 1,57E-07 2,85E-07 8,13E-07 1,86E-06 3,29E-06 4,70E-06 5,68E-06 6,02E-06
Total DOSE for all pathways
Ing. of Crops,%
Ing. of Fish,%
Inh,%
4,57E-05 8,33E-05 2,37E-04 5,44E-04 9,61E-04 1,37E-03 1,66E-03 1,76E-03
9,96E+01 9,96E+01 9,96E+01 9,96E+01 9,96E+01 9,96E+01 9,96E+01 9,96E+01
1,29E-04 6,73E-05 3,17E-05 2,38E-05 2,71E-05 4,65E-05 7,81E-05 9,70E-05
5,59E-02 5,59E-02 5,59E-02 5,59E-02 5,59E-02 5,59E-02 5,59E-02 5,59E-02
Outdoor,% 3,41E-01 3,41E-01 3,41E-01 3,41E-01 3,41E-01 3,41E-01 3,41E-01 3,41E-01
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Dose, Sv/Year
1.00E+00
Total DOSE Ingestion of aquatic food Outdoor exposure
Ingestion of Crops Inhalation Ingestion of Soil
1.00E-01 1.00E-02 1.00E-03 1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08 1.00E-09 1.00E-10 1.00E-11
300
t, years
400
500
600
700
800
900
1000
Figure 2. 11. Dose calculation result for different pathways for Scenario 2
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2.6
Conclusions for Scenario 2
Calculations of concentrations for following radionuclides: Pb-210, Po-210, Ra-226, Th-230, U-234 U-238 in well, river water and fish at time points 300, 400, 500, 600, 700, 800, 900, 1000 show that the highest mobility in groundwater - surface water pathway is observed for U-234 and U-238. Uranium concentrations in well water are 5-6 orders of magnitude higher compared to other radionuclides. Respectively contributions of RN of U decay chain to the total dose for hydrologic pathway can be neglected. U-234 and U-238 basically form the dose for all pathways. Uranium concentration in well water progressively increases during the simulation period and reaches maximum at time t=1000 year ( 6.97 E+04 Bq/m3 for U-234 and U-238). Therefore, estimated doses caused by using contaminates groundwater for irrigation purposes increase throughout the simulation period. The same picture is observed for river water, however concentration of U-234 and U-238 radionuclides in the river at time points 300, 400, 500, 600, 700, 800, 900, 1000 years, is quite low as a result of dilution of contaminated GW discharge from the aquifer by upstream river flow. In this case concentration in fish is also relative low. This pathway has minor contribution to total dose. The main exposure pathway is ingestion of vegetables from garden irrigated by contaminated groundwater. Maximum dose is reached at t=1000 years and constitutes 1.76E-3 Sv/year (Dose from ingestion of vegetables constitutes 99.94% from the overall dose).
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References 1. 2. 3. 4.
Input data set – Zapadnoe test case (IAEA MODARIA WG3 working materials) http://project.facilia.se/normalysa/software.html http://home.facilia.se/products/ http://www.insc.gov.ua/docs/nrbu97.pdf // p.27 table 3.4
5. Bugai D., M.Kozak, J.van Blerk, R. Avila, I.Kovalets. Remediation of the Zapadnoe Uranium Tailings Facility: Radiological Safety Assessment. Report on ENSURE-II project, Sweden SSM – Ukrainian Ministry of Energy and Coal Industry, 2014, DOI: 10.13140/RG.2.1.1188.7444
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