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Don CarpenterGeochemist ARCADIS U.S., Inc.Brighton, MI
LEVERAGING THE AGE DATING OF NORM TO AID IN ENVIRONMENTAL CHALLENGES
2 May 2, 2023 © 2013 ARCADIS
The Age of a Radioactive Waste is Often Unimportant, Up to the Time it Becomes Important
“Owner A” “Owner B” “Owner C”
Ris
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Time
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Ra-228Th-228
Radioactive Age Dating of NORM may be the solution
3 May 2, 2023 © 2013 ARCADIS
This Presentation Will Discuss a Comparatively Unique Age Dating Approach
Ra+2 Ba+2 SO4-2
Ra226 Pb210
0 5 10 15 20 25 30 35 40 45 500%
10%20%30%40%50%60%70%80%
NORM is 20 years old
4 May 2, 2023 © 2013 ARCADIS
Nuclear Instability
Rate of Nuclear Decay
Features of an “Ideal Age Dating” Material
Discussion of Radium-Enriched Barite NORM
Applications of Age Dating of NORM
THIS PRESENTATION WILL SYSTEMATICALLY ADDRESS THE
FOLLOWING ITEMS:
5 May 2, 2023 © 2013 ARCADIS
It is Important to Address a Misconception that Radioactive Instability is Uncommon
H
U
La
Ba
Pb
6 May 2, 2023 © 2013 ARCADIS
260
1440
Stable IsotopesRadioactive Isotopes
Radioactive Instability is Actually Far More Common Than are “Stable” Isotopes
85% of all known isotopes are radioactive
7 May 2, 2023 © 2013 ARCADIS
Radioactivity is Due to Nuclear Instability Rather than Reactions Between Orbital Electrons
Alpha radiation results in the ejection of two protons and two neutrons
Beta decay results in either the loss (and commensurate gain) of a proton or a neutron
Rate is fixed and is measure of the degree of instability of isotope
8 May 2, 2023 © 2013 ARCADIS
Mathematics of Radioactive Decay are Related by a few Comparatively Simple Equations
-dN/dt = λN0
Rate of decrease in decaying isotope is a function of the decay constant and the number of atoms at any timet½ = ln(2)/ λ
“Half-life” is a function of the decay rate
9 May 2, 2023 © 2013 ARCADIS
Characteristics of a “Good” Age Dating Candidate Consist of a Few Specific Criteria
Absence of prior progeny
Geochemical retention of parent radionuclides
Geochemical retention of progeny
Half Life duration consistent with the age dating challenge• Years or Tens of Years, not minutes or
billions of years
10 May 2, 2023 © 2013 ARCADIS
Decay of Naturally Occurring Uranium and Thorium Generates Radioactive Progeny and NORM
10
Radium isotopes are produced within each decay chain
Comparatively short half-life of Radium-228 results in rapid natural attenuation
Lead-210’s 22 year half life allows it to
potentially accumulate
11 May 2, 2023 © 2013 ARCADIS
Predictable Manner of Nuclear Decay Provides Insight as to Radionuclide Composition with Time
Rate of formation of Radium from known activity of Uranium
Rate of formation of Lead-210 from known activity of Radium
Rates of formation of other radionuclides of interest
© 2013 ARCADISMay 2, 202312
Precipitation of Alkaline Earth Sulfates can Co-Precipitate Radium Sulfate forming a NORM
Ba+2 + SO4-2 → BaSO4
Ba+2 + (Ra+2) + SO4-2 → Ba(Ra)SO4
Acid insoluble
Low (“insolubility”) of Barite causes Radium and decay products to be largely retained within crystalline structure
13 May 2, 2023 © 2013 ARCADIS
Lead-210 Will Accumulate at a Fixed Rate in the Barite Scale Due to the Decay of Radium-226
Time of Formation
Time of Formation Plus
20 Years
Time of Formation Plus
40 Years
Lead-210
14 May 2, 2023 © 2013 ARCADIS
Radium-Enriched Barite has all of the “Ideal” Age Dating Characteristics
Geochemically “inert”
Rapidly formedAbsence of any progeny due to geochemical-induced separationRetains Radium parent(s) and progenyRadium-226 has decay rate commensurate with needsRadium-228 and Po-210 may also be employed for “recent” NORM
15 May 2, 2023 © 2013 ARCADIS
0 10 20 30 40 50 60 70 80 90 1000%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
The Predicable Rate of Lead-210 Accumulation Allows an Age Estimate to be Calculated
Ratio of Lead-210 to Radium-226 allows an “age of NORM formation” to be calculated
Percent of Lead-210 “In-growth” with Time (in years)
16 May 2, 2023 © 2013 ARCADIS
Lead-210 Data may also Aid in Identifying Possible Different Sample Populations of NORM
Relationship Between Radium-226 Activity and Estimated Lead-210-Based Age
0.0 5.0 10.0 15.0 20.0 25.0 30.00
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Rad
ium
-226
Act
ivity
(pC
i/g)
Estimated Lead-210-Based Age (Years)
17 May 2, 2023 © 2013 ARCADIS
“Young” NORM Might Allow for “Independent” Age Estimates to be Made
Pb-210/Po-210 and Ra-228/Th-228
Ra-228/Th-228 and Ra-226/Pb-210
Up to 2 years
2 to 6 years
18 May 2, 2023 © 2013 ARCADIS
Age Estimates Need to Comport with “Other” Information
Age estimates of NORM pre-dating operational activities
“Known” date of NORM formation
Help establish accuracy of “anecdotal” information
19 May 2, 2023 © 2013 ARCADIS
Age Dating Information May Provide Critical Data for Specific Environmental Needs
Help identify responsible parties for NORM
Provide an upper limit for the time of exposure to potential receptors; a possibly critical element in lawsuits
Develop an age estimate for NORM or the ages of NORM produced by different processes over time.
Provide insight into the mass and location of NORM related to a specific operational change or processing of different solutions.
State-based regulations may exempt “old” NORM that predates regulations