Determination of Natural Radionuclides in Austrian Drinking Water

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Determination of Natural Radionuclides in
Austrian Drinking Water

• Claudia Landstetter

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• Council Directive 98/83/EC (1998) on the quality
  of water intended for human consumption
• Drinking water ordinance BGBl. II Nr. 304/2001
• indicator parametric value
• Tritium 100 Bq/L
• Total Indicative Dose (TID) 0,1 mSv/a

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• Codex Alimentarius Austriacus section B1
• TID can be determined by Austrian Standards for
  determination and evaluation of the total dose
  due to radionuclides in drinking water (OE-NORM,
  ON-S 5251, 2005)
• TID
• 226Ra and 228Ra are taken into account
• 238U, 234U minor contribution to the effective
  dose 232Th and 234Th with low solubility in water
• Artificial radionuclides and other natural
  radionuclides (with the exception of Tritium,
  40K, 222Rn and its progenies) are taken into
  account if dose-relevant concentrations can be
  suspected

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• EU-Recommendation 2001/928/Euratom reference
  values for 222Rn, 210Pb and 210Po are proposed
• 210Pb and 210Po determined if considerable
  concentrations can be assumed
• Recommended in Austria if 222Rn gt 100 Bq/L

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222Rn, 226Ra determination via LSC

• gastight bottle with appropriate size
• pre-filled with 8 ml of concentrated HNO3
• 10 ml of the water 10 ml of Perkin Elmer high
  efficiency mineral oil scintillator?
• 222Rn in equilibrium with 218Po and 214Po
• 226Ra after in equilibrium with 222Rn

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210Pb, 210Po separation and determination by LSC

• ingrowth of 210Pb from 222Rn
• 100 Bq 222Rn 1 week of storage will result in 34
  mBq 210Pb
• 222Rn should be measured shortly after the
  sampling
• storage time until the further analyses for 210Pb
  and 210Po should be as short as possible

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210Pb, 210Po , 228Ra separation and determination
by LSC

• little difference of the energy of beta radiation
  
• 228Ra 0.046 MeV
• 210Pb 0.064 MeV
• for separation two already existing methods are
  combined

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228Ra separation and determination via LSC

• Figure 3 Spectrum of a mixed standard solution
  with 0.3 ml of a 210Pb standard solution with
  1.74 Bq/ml and 0.5 ml of a 232Th standard
  solution of 1.06 Bq/ml. (dark upper curve). The
  lower curve shows the spectrum of 228Ra after
  separation. The two bars define the selected
  range for the analysis

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Methods
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Determination of 228Ra by LSC

• Spectra of 228Ra the two bars define the selected
  range for the analysis

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210Pb, 210Po separation and determination by LSC

• Figure 1 Spectrum of 210Bi, extracted with
  Polex? after reaching radioactive equilibrium
  with 210Pb. The two bars define the selected
  range for the analysis.

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210Pb, 210Po separation and determination by LSC

• Figure 2 Spectrum of 210Po extracted with
  Polex?. The two bars define the selected range
  for the analysis.

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228Ra separation and determination via LSC

• all Ra isotopes are coprecipitated
• ingrowth of the decay products
• 226Ra 214Pb 1.024 MeV
• 214Bi 3.272 MeV
• measured shortly after the separation
• ingrowth of 234Th with 24.1 d half life time
  (0.273 MeV) from 238U
• Th is coprecipitated with Pb

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chemical recovery

• 210Pb 208Pb is measured by ICP-MS
• 228Ra 137Ba and 138Ba measured by ICP-MS

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Limits of detection
For routine screening For a new water source
for which it is plausible that 228Ra exceeds 20
of the reference concentration, which is 0.2 Bq/L
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228Ra determination by LSC

• Distribution of the 228Ra activity-concentration
  in Austrian drinking water. The point upon the
  curve represents the median value of the samples

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210Po determination by LSC

• Distribution of the 210Po activity-concentration
  in Upper Austrian drinking water.

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210Pb determination by LSC

• Distribution of the 210Pb activity-concentration
  in Upper Austrian drinking water.

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committed effective dose per unit intake via
ingestion 1 y and gt17 y

• 226Ra 4.7 10-6 2.8 10-7 Sv/Bq
• 228Ra 3 10-5 6.9 10-7 Sv/Bq
• 210Po 2.6 10-5 1.2 10-6 Sv/Bq
• 210Pb 8.4 10-6 6.9 10-7 Sv/Bq
• annual intake 250 730 L/y

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Sample 1
Sample 3
Sample 2
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indicator parametric value TID 0.1 mSv/a
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• For most water samples the TID can be determined
  by Austrian Standards but for special regions
  210Pb, 210Po and Uranium have to be taken into
  account.
• With our drinking water project we are trying to
  identify regions with high activity
  concentrations
• And we are trying to identify regions with
  activity concentrations below the lower limit of
  detection to reduce the amount of samples which
  have to be analysed.

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238U determination by ICP-MS

• direct introduction of the acidified samples
• no chemical pre-treatment
• Rh as internal standard