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Contribution of U-235 family to dose rates received by aquatic wildlife EMRAS II BMG Vienna January 2011 K. Beaugelin-Seiller Photo provided by Richard R. Goulet CNSC Context Beaverlodge scenario Incremental risk assessment

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Contribution of U-235 family to dose rates received by aquatic wildlife

EMRAS II BMG Vienna January 2011

  • K. Beaugelin-Seiller

Photo provided by Richard R. Goulet CNSC

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U-235 family contribution – January 2011 – IAEA, Vienna

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Context

▌Incremental risk assessment

  • Exposure concentration (added) = measurement – background
  • For each exposure media (water, sediment and biota)

▌Additive risk

  • three isotopes of uranium: 234, 235 and 238
  • decay chains

▌Data gaps

  • assumptions

 Beaverlodge scenario  an ERE as realist and exhaustive as possible

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Data set

▌Priority to measurements ▌When gaps

  • If data in sediment at the same site, back calculation applying a Kd
  • If no data :
  • Equilibrium with mother
  • For Rn, outgassing taken into consideration
  • For U-235, natural U-235/U-238 applied

 Water concentration  A value for each RN

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Data set

 Water concentration

Radionuclide Data origin

238U

Measured/back calculated from sediment

234Th to 234U

In equilibrium with 238U

230Th

Measured/back calculated from sediment/equilibrium with mother

226Ra

Measured/back calculated from sediment/equilibrium with mother

222Rn

In equilibrium with 226Ra after devolatilisation

218Po to 214Po

In equilibrium with 222Rn

210Pb

Measured/back calculated from sediment/equilibrium with mother

210Bi

In equilibrium with 210Pb

210Pb

Measured/back calculated from sediment/equilibrium with mother

235U

Equilibrium with 238U after application of the isotopic ratio

231Th to 223Ra

Equilibrium with 235U

219Rn

In equilibrium with 223Ra after devolatilisation

215Po to 207Tl

In equilibrium with 219Rn

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Data set

▌Sediment

  • Priority to measurements, background (reference site) considered
  • When no data, use of Kd from site (Pb214 as Pb210) else from literature

(ERICA + extrapolation methods) ▌Biota

  • Priority to measurements, background (reference site) considered
  • When no data, use of CF from site (U-235 as U-238) else from literature

(ERICA data + extrapolation methods)

 other concentrations  Again a value for each RN

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Data set

 other concentrations  A value for each RN

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Results

▌Beaverlodge and Key lakes ▌Benchmarks : 2 µGy.h-1 vertebrates, 200 µGy.h-1 invertebrates

(PROTECT)

 Study on 2 lakes  Organisms at risk for each site

Fish Chironomus Pisidium Caddisfly pelagic benthic large small Beaverlodge Lake Dubyna Lake

21.8 57.7 55.8 10.3 4.25 4.04

Hanson Bay

13.6 12.4 7.71 7.16 1.87 1.43

Beaverlodge

5.67 13.4 16.7 9.97 1.63 1.40

Keddy Bay

6.01 16.0 7.82 9.17 1.06 1.08

Key Lake Delta Lake

122 12.7 10.3 12.2 1.41 1.44

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Interpretation

▌CF and Kd from sites or literature ▌All « significant » daughter products included

  • Most of the other approaches neglect U-235 and its daughter products

▌Measures + equilibrium assumption for radioactive decay

 Levels of conservatism?  Contribution of the U-235 family ?

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Wildlife exposure to U-235 family

Theoretical approach

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The U-235 decay chain

235U 231Th 231Pa 227Ac 223Fr 227Th 223Ra 219Rn 215Po 211Pb 215At 1 1 1 0,0138 0,9862 1 1 1 0,999996 4,0 10-5 1 210Pb 210Bi 210Po 206Pb 1 1 219At 211Bi 207Tl 207Pb 1 1 211Po 0,997 0,00276 6,0 10-5 0,99994 0,03 1 8 10-12 8 10-12 206Hg 206Tl 1,9 10-8 1 1,32 10-7 1,34 10-11 209Pb 209Bi 208Pb 10-14 227Ra 10-10 1 1 1 1 215Bi 0,97 1 6,4 10-10 1

7 108 ans 1,06 jour 3.3 104ans 21.79 ans 18.72 jours 11.44 jours 3.96 s 1.78 ms 36.1 mn 2.14 mn 4.77 mn

235U 231Th 231Pa 227Ac 223Fr 227Th 223Ra 219Rn 215Po 211Pb 215At 1 1 1 0,0138 0,9862 1 1 1 0,999996 4,0 10-5 1 210Pb 210Bi 210Po 206Pb 1 1 219At 211Bi 207Tl 207Pb 1 1 211Po 0,997 0,00276 6,0 10-5 0,99994 0,03 1 8 10-12 8 10-12 206Hg 206Tl 1,9 10-8 1 1,32 10-7 1,34 10-11 209Pb 209Bi 208Pb 10-14 227Ra 10-10 1 1 1 1 215Bi 0,97 1 6,4 10-10 1

7 108 ans 1,06 jour 3.3 104ans 21.79 ans 18.72 jours 11.44 jours 3.96 s 1.78 ms 36.1 mn 2.14 mn 4.77 mn

Additional element to take on board/ U-238 chain Additional element to take on board/ U-238 chain + 11 new isotopes

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Water concentrations

0.01 0.1 1

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Ref: U-238 =1

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Water concentrations

0.01 0.1 1

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Ref: U-238 =1

Equilibrium with U-238

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Water concentrations

0.01 0.1 1

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Ref: U-238 =1

Outgassing Equilibrium with Rn-222

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Water concentrations

0.01 0.1 1

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Ref: U-238 =1

Natural U-235/U-238 Equilibrium with U-235

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Water concentrations

0.01 0.1 1

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Ref: U-238 =1

Outgassing Equilibrium with Rn-219

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Transfer parameters

Kd (l/kg dry)

1.00E-04 1.00E-03 1.00E-02 1.00E-01 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

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

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Media concentrations

0.01 0.1 1

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

1.00E-06 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 1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Ref: U-238 =1 water sediment

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Organims concentrations

fish

1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

pisidium

1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

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DCCs

Pisidium internal DCCs

1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Pisidium external (water) DCCs

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

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Total dose rates

Pisidium total dose rate (µGy/h)

1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

93% 7% 91% 9%

pisidium fish

U-235 family contribution

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Wildlife exposure to U-235 family

Case study

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Beaverlodge Lake

▌U-235 family contribution

Chironomus Pisidium Caddisfly pelagic large small Dubyna Lake 33.47 20.07 14.94 45.00 73.66 66.93 Hanson Bay 10.52 20.02 21.78 38.55 48.40 54.56 Beaverlodge 23.72 21.64 11.20 14.65 60.72 61.23 Keddy Bay 38.22 21.88 30.85 18.72 83.62 70.64 Fish benthic

 Results  A higher contribution that the theoretical one

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Explanation

▌ Water concentration

 Keddy Bay

Theoretical added water concentration (Bq/l)

1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

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1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Explanation

▌ Water concentration

 Keddy Bay

measurements

 decay chain not at equilibrium or/and metrology bias?

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Explanation

▌ Water concentration

 Keddy Bay

Used added water concentration (Bq/l)

1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

Application of equilibrium/outgassing/natural isotope ratio to measurements

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Explanation

▌ Pisidium concentration (Water concentration x CF)

 Keddy Bay

Pisidium concentration (Bq/kg)

1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

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Explanation

▌ Pisidium total dose rate

 Keddy Bay

20 40 60 80 100 120 140

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

dose rate (µGy/h)

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Explanation

▌ Pisidium total dose rate

 Keddy Bay  Heavy weight of hypothesis about daughters

20 40 60 80 100 120 140

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

dose rate (µGy/h)

2 RNS explain the U-235 family high contribution

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Explanation

▌ Pisidium total dose rate

 Keddy Bay  Heavy weight of hypothesis about daughters

20 40 60 80 100 120 140

U238 Th234 Pa234m U234 Th230 Ra226 Rn222 Po218 Pb214 Bi214 Po214 Pb210 Bi210 Po210 U235 Th231 Pa231 Ac227 Th227 Ra223 Rn219 Po215 Pb211 Bi211 Tl207

dose rate (µGy/h)

2 RNS explain the U-235 family high contribution

Realistic assessment = need for more information regarding

  • daughter products
  • measurement methods
  • measurement results validity