Regulations the Netherlands for regular discharges of radioactivity (aquatic environment)

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Regulations the Netherlands for regular
discharges of radioactivity (aquatic environment)

• R. Heling
• NRG-Arnhem
• The Netherlands

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Hydrological ModelsRelevance

• Application
• Nuclear accidents
• Regular discharges
• Relevance
• dosisbelasting niet verwaarloosbaar maar niet
  cruciaal in reguliere situaties, in
  ongevalssituaties perceptie van het risico een
  probleem

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Type of modelling

• Runoff, Transport land-to-water
• Transport in rivers
• Transport in estuaries en coastal regions
• Transport in reservoirs en lakes
• Transport in groundwater

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Different kind of models (1)

• Hydrodynamics
• Transport of radionuclides
• Near- field to far field modelling
• Modelling of short, middle, and long-term

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Aquatic model and type (2)

• Runoff 2D (grens 1000 km2) algoritme
• Rivers 2D, 1D, box, multi-box
• Lakes 3D, 2D, box
• Estuaries 3D, 2D, box
• Coast Box, 2D, 3D
• Groundwater 1D, 2D, 3D

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Modelberekeningen

• Oplossen van de advectie/diffusie vergelijking
  (numeriek)
• Verzamelen inputgegevens
• bijv meteo, bathymetry, lozingen, water afvoer,
  salinity, getijdengegevens
• Klant krijgt eindresultaat toegesneden op de
  vraagstelling

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Tsjernobyl koelvijver Dnjepr
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3D model Estuarium (Dniepr Boeg) Sr-90
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Groundwater model (beneath the Chernobyl)
Sr-90
90Sr (Bq/L) in groundwater - 2045
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North Sea THREETOX
Cs-137 in Seawater
Cs-137 Bottom sediments
Hypothetical Discharge Borssele PP (NL)
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POSEIDON Coastal regions
Local compartments can be added by user
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Besluit Stralingsbescherming 2001 Article 35 (and
108)
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Necessary to model or not?

• Radiotoxicity-equivalence
• Activity leading to 1Sv effective dose by
  ingestion
• Modelling not needed if
• Surface waters A 0.1 RE
• On the sewer system A 10 RE

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Derived criteria
Wsn secondary level test assuming dilution
108, leading to 1 uSv/ yr, (unit f RE) so Wsn
100 RE, leading to this dose. Wmax
A/RE Criteria (max) - 100 uS / yr (max per
location, above no permit) Criteria (low) 1 uS
/ yr (SN secondary level) under this no
modelling needed External irradiation 10 us/yr
(SN), under this no modelling needed Wmax/Wsn lt1
dose lt 1 uSv, no modelling needed
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Discharge per year, under which no permit needed,
otherwise acquiring permit obliged (dose less
than 10 uSv/yr).
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Model Concept DOVISDosisberekening voor de
Omgeving bij Vergunningverlening Ioniserende
Straling

• To model objects
• Rivers
• Lakes
• Coastal region
• Estuaries
• Waste Water Treatment Installations

• Important Note IF the system is connected to the
  coastal region, the these should be included as
  well

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Model conceptDOVIS

• Processes
• sedimentation
• resuspension
• Transport between compartments
• Daughter - nuclides
• Standard Kd- values
• Not obliged Sediment - water interaction

• These processes have to taken account in the
  model, more processes are of course allowed in
  more complex models

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Model concept DOVIS

• Exposure pathways
• Consumption fishery products
• Consumption drinking water
• Consumption agricultural products
• (irrigation)
• External irradiation

• Secondary pathways
• Usage of harbour sludge and sewer sludge in
  agriculture
• Irrigation
• Effect of flooding
• Residence at the coast (sea)

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Source to Dose
Sewage sludge
Meat/Dairy products
Floodplains
Water
Fish
Dose Calculations (input consumption Behaviour
Population)
Drinking water
Sediment
Irrigation
Agricultural Pr.
Sand
External Irridation (Inhalation)
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Choice Dispersion modelCriteria

• Grid resolution (homogeneous mixing)
• Dynamic or Steady-State
• Conservative or non-conservative behaviour
  radionuclide

• Reference Group (gt5 of the population)
• Available input data (very restrictive)
• Drinking water inlet location (lakes, rivers)
• Fish migration

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Company Consultant

• Company
• Discharge data
• Discharge scenario
• Discharge rates
• Radionuclides in discharge

• Consultant
• Collects model input
• Calculation concentrations radionuclides
• Calculation doses

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Case Study (1) North Sea

• Discharges NORM on the continental shelf
  (continuous)
• Discharges of radioactivity in the Westerscheldt
  estuary. (semi-continuous)
• Question Does it matter which compartments are
  chosen, and which model has been applied

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Case Study (2) Noordzee

• Scenario 1 Coast at Rotterdam (min)
• Scenario 2 Coast at Rotterdam (max)
• Scenario 3 Continental Shelf
• Scenario 4 Westerschelde estuary

• Comparison between NRG models for the coastal
  waters with PC CREAM (commercial dose assessment
  tool, HPA (formerly NRPB, UK)

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Case Study (3) North Sea Model configuration PC
CREAM - NRG models
Model configurations
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NRG model 10 compartiments
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Case Study (4) Noordzee Model input

• Exposure pathways
• inhalation (particles, sea spray)
• consumption (fish, mussels, shrimps)
• External irradiation (beach)

• Dose
• After a year (Scen. 4. Westerscheldt)
• Yearly Dose (other scenario's)
• Discharge
• scenario 4 real estimated release into the
  environment
• Other scenario's Unit Discharge

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Case Study (5) NoordzeeReferentiegroepen
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Case Study (6) NoordzeeTabel resultaat NRG-1
model
10 compartimenten Rotterdam-Den Helder 1GBq/yr
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Case Study (7) Noordzee Resultatenvergelijking
PC-CREAM en NRG modellen (-)
Dominant belastingspad
1 TBq /jaar Ra-226 (2.8 105 RE)
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Discharge Westerscheldt (1E5 MBq/y)
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Case Study (8) North SeaConclusies

• Choice of compartment size affects the results.
• Commercial software not straight-forwarded
  applicable (be careful for wrong usage).
• Inhalation negligible exposure pathway
• Dosis below the legal upper limit of 100 ?Sv

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Huidige Beschikbaarheid Modellen NRG

• Alle lozingssituaties zijn te modelleren m.b.v
  RIVTOX, COASTOX, SUSTOX, WATOX, THREETOX,
  LAKECO-B, en POSEIDON
• Meestal voldoet 1D model of compartiment model
  voor reguliere lozing
• Aanpassing voor RWZIs en baggerslib noodzakelijk

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Tot slot Praktische punten

• Binnen NRG expertise aanwezig
• Projecten kunnen worden geformuleerd
• Voor toxische stoffen expertise binnen KEMA/NRG
• Alle modellen betrouwbaar uitgebreid getest en
  gevalideerd in internationale projecten (EC,
  IAEA) in de afgelopen 15 jaar