www.epa.gov
April 2014
EPA 402-R14-005
Revision 0
Rapid Radiochemical Method for
Isotopic Uranium in Building Materials
for Environmental Remediation Following
Radiological Incidents
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Radiation and Indoor Air
National Analytical Radiation Environmental Laboratory
Montgomery, AL 36115
Office of Research and Development
National Homeland Security Research Center
Cincinnati, OH 45268
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Isotopic Uranium in Building Materials: Rapid Method for High-Activity Samples
Revision History
Revision 0 | Original release. | 04-16-2014
This report was prepared for the National Analytical Radiation Environmental Laboratory of the Office of
Radiation and Indoor Air and the National Homeland Security Research Center of the Office of Research
and Development, United States Environmental Protection Agency. It was prepared by Environmental
Management Support, Inc., of Silver Spring, Maryland, under contract EP-W-07-037, work assignments B-
41, 1-41, and 2-43, managed by David Carman and Dan Askren. This document has been reviewed in
accordance with U.S. Environmental Protection Agency (EPA) policy and approved for publication. Note
that approval does not signify that the contents necessarily reflect the views of the Agency. Mention of trade
names, products, or services does not convey EPA approval, endorsement, or recommendation.
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RAPID RADIOCHEMICAL METHOD FOR ISOTOPIC URANIUM IN BUILDING MATERIALS
FOR ENVIRONMENTAL REMEDIATION FOLLOWING RADIOLOGICAL INCIDENTS
1. Scope and Application
1.1. The method will be applicable to samples where contamination is either from known
or unknown origins.
OQQ 9^ S 9^/1
1.2. The method is specific for U, U, and U in building materials such as concrete,
brick, etc.
1.3. The method uses rapid radiochemical separation techniques for determining alpha-
emitting uranium isotopes in building material samples following a nuclear or
radiological incident.
OQQ 9^S
1.4. The method is capable of achieving a required method uncertainty for U, U, and
234U of 1.9 pCi/g at an analytical action level of 14.7 pCi/g. To attain the stated
measurement quality objectives (MQOs) (see Steps 9.3 and 9.4), a sample weight of
approximately 1 g and count time of at least 3 to 4 hours are recommended. The
sample turnaround time and throughput may vary based on additional project MQOs,
the time for analysis of the sample test source (STS), and initial sample weight/
volume. The method must be validated prior to use following the protocols provided
in Method Validation Guide for Qualifying Methods Used by Radiological
Laboratories Participating in Incident Response Activities (Reference 16.1).
1.5. The rapid isotopic uranium method was evaluated following the guidance presented
for "Level E Method Validation: Adapted or Newly Developed Methods, Including
Rapid Methods" in Method Validation Guide for Qualifying Methods Used by
Radiological Laboratories Participating in Incident Response Activities (Reference
16.1) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical Protocols
Manual (MARLAP 2004, Reference 16.2).
1.6. Multi-radionuclide analysis using sequential separation may be possible using this
method in conjunction with other rapid methods (see Appendix B). Rapid methods
can also be used for routine analyses with appropriate (typically longer) count times.
1.7. Other solid samples such as soil can be digested using the rapid sodium hydroxide
fusion procedure as an alternative to other digestion techniques, but this procedure
will have to be validated by the laboratory.
2. Summary of Method
2.1. This method is based on the use of extraction chromatography resins to isolate and
purify uranium isotopes by removing interfering radionuclides as well as other
components of the matrix in order to prepare the uranium fraction for counting by
alpha spectrometry. The method utilizes vacuum-assisted flow to improve the speed
of the separations. The sample was fused using Rapid Method for Sodium Hydroxide
Fusion of Concrete and Brick Matrices Prior to Americium, Plutonium, Strontium,
Radium, and Uranium Analyses for Environmental Remediation Following
Radiological Incidents (16.3) and then the uranium isotopes were removed from the
fusion matrix using iron hydroxide and lanthanum fluoride precipitation steps. U-232
tracer, added to the building materials sample, is used as a yield monitor. The STS is
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
prepared by microprecipitation with CeFs. Standard laboratory protocol for the use of
an alpha spectrometer should be used when the sample is ready for counting.
3. Definitions, Abbreviations, and Acronyms
3.1. Analytical Protocol Specifications (APS). The output of a directed planning process
that contains the project's analytical data needs and requirements in an organized,
concise form.
3.2. Analytical Action Level (AAL). The term "analytical action level" is used to denote
the value of a quantity that will cause the decisionmaker to choose one of the
alternative actions.
3.3. Discrete Radioactive Particles (DRPs or "hot particles"). Paniculate matter in a
sample of any matrix where a high concentration of radioactive material is contained
in a tiny particle (|im range).
3.4. Multi-Agency Radiological Analytical Laboratory Protocols Manual (M ARL AP)
provides guidance for the planning, implementation, and assessment phases of those
projects that require the laboratory analysis of radionuclides (Reference 16.2).
3.5. Measurement Quality Objective (MQO). MQOs are the analytical data requirements
of the data quality objectives and are project- or program-specific. They can be
quantitative or qualitative. MQOs serve as measurement performance criteria or
objectives of the analytical process.
3.6. Radiological Dispersal Device (ROD), i.e., a "dirty bomb." This device is an
unconventional weapon constructed to distribute radioactive material(s) into the
environment either by incorporating them into a conventional bomb or by using
sprays, canisters, or manual dispersal.
3.7. Required Method Uncertainty (WMR). The required method uncertainty is a target value
for the individual measurement uncertainties, and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method
uncertainty is applicable below an AAL.
3.8. Relative Required Method Uncertainty (
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
energy resolution characteristics, the quality of the final precipitate that is counted
and the amount of the interfering radionuclide present.
910
4.1.1. Polonium-210 ( Po), in particular, must be effectively removed from the
uranium fraction because it cannot be distinguished from 232U. Its presence
can result in high tracer recoveries and negatively biased U isotopic results.
4.1.2. Thorium (Th) isotopes are removed on TEVA® Resin. Any residual Th that
makes it to TRU Resin is removed with a rinse step. If extremely high levels
of Th isotopes are still present, the 4M HC1-0.2M-0.002M TiCl3 rinse
volume may be increased for difficult samples containing high levels of
interferences.
4.1.3. Nepunium-237 (237Np) (4.78 MeV) can interfere with 234U (4.77 MeV)
analyses due to overlapping alpha energies so 237Np must be effectively
removed.
4.1.4. It may be possible, if very high levels of interferences are present on the
final STS filter, to redissolve the radionuclides in 15 mL of warm 3M
HNO3-0.25M boric acid and perform the column separation again without
digesting another concrete aliquant. This reprocessing step to remove
extremely high levels of Th isotopes, for example, will have to be validated
by the laboratory.
4.1.5. Higher levels of uranium may require more cerium (Ce) to quantitatively
precipitate uranium (150-200 |iL [75-100 |ig] instead of 100 |iL (50 |ig) if
38 U is 10 pCi or more in final purified fraction). There is a slight alpha
peak broadening but complete precipitation is more probable. When very
high activities are suspected, additional Ce should be added and/or aliquant
size reduced.
4.1.6. Fe present in samples and used to preconcentrate samples after the fusion
procedure can interfere slightly with U retention on TRU Resin. The cerium
fluoride (CeFs) precipitation step typically removes iron (Fe) effectively.
4.1.7. Vacuum box lid and holes must be cleaned frequently to prevent cross-
contamination of samples.
4.2. Non-Radiological: Anions such as fluoride and phosphate that complex uranium ions
may cause lower chemical yields. Aluminum that is added in the column load
solution complexes fluoride present as well as any residual phosphate that may be
present. Lanthanum, added to preconcentrate uranium from the sample matrix as
lanthanum fluoride, can have a slight adverse impact on uranium retention on TRU
Resin, but this impact is minimal with the level added. Fe3+ can also have an adverse
impact on uranium retention on TRU Resin, but the residual Fe levels after
preconcentration steps are acceptable.
5. Safety
5.1. General
5.1.1. Refer to your safety manual for concerns of contamination control, personal
exposure monitoring, and radiation dose monitoring.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
5.1.2. Refer to your laboratory's chemical hygiene plan (or equivalent) for general
safety rules regarding chemicals in the workplace.
5.2. Radiological
5.2.1. Hot particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles"
(DRPs), will be small, on the order of 1 mm or less. Typically,
DRPs are not evenly distributed in the media and their radiation
emissions are not uniform in all directions (anisotropic).
5.2.2. For samples with detectable activity concentrations of these radionuclides,
labware should be used only once due to potential for cross contamination.
5.3. Procedure-Specific Non-Radiological Hazards: Particular attention should be paid to
the use of hydrofluoric acid (HF). HF is an extremely dangerous chemical used in the
preparation of some of the reagents and in the microprecipitation procedure.
Appropriate personal protective equipment (PPE) must be used in strict accordance
with the laboratory safety program specification.
6. Equipment and Supplies
6.1. Alpha spectrometer calibrated for use over the range of ~3.5-10 MeV.
6.2. Analytical balance with 10^ g readability, or better.
6.3. Cartridge reservoirs, 10 or 20 mL syringe style with locking device, or reservoir
columns (empty luer tip, CC-10-M) plus 12 mL reservoirs (CC-06-M), Image
Molding, Denver, CO, or equivalent.
6.4. Centrifuge able to accommodate 225 mL tubes.
6.5. Centrifuge tubes, 50 mL and 225 mL capacity.
6.6. Filter manifold apparatus with 25 mm-diameter polysulfone. A single use
(disposable) filter funnel/filter combination may be used to avoid cross-
contamination.
6.7. 25 mm polypropylene filter, 0.1 um pore size, or equivalent.
6.8. Stainless steel planchets or other adhesive sample mounts (Ex. Environmental
Express, Inc., P/N R2200) able to hold the 25 mm filter.
6.9. Tweezers.
6.10. 100 uL, 200 and 500 pipette or equivalent and appropriate plastic tips.
6.11. 1-10 mL electronic pipet or manual equivalent.
6.12. Vacuum pump or laboratory vacuum system.
6.13. Vacuum box tips, white inner, Eichrom part number AC-1000-IT, or PFA 5/32"x 1/4"
heavywall tubing connectors, natural, Ref P/N 00070EE, cut to 1 inch, Cole Farmer
Inc., or equivalent.
6.14. Vacuum box tips, yellow outer, Eichrom part number AC-1000-OT, or equivalent.
6.15. Vacuum box, such as Eichrom part number AC-24-BOX, or equivalent.
6.16. Vortex mixer.
6.17. Miscellaneous laboratory ware of plastic or glass; 250 and 500 mL capacities.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
6.18. Heat lamp.
7. Reagents and Standards
NOTES:
All reagents are American Chemical Society (ACS) reagent grade or equivalent unless otherwise
specified.
Unless otherwise indicated, all references to water should be understood to mean Type I reagent water
(ASTM D1193, Reference 16.4). All solutions used in microprecipitation should be prepared with water
filtered through a 0.45 um (or better) filter.
7.1. Type I reagent water as defined in ASTM Standard Dl 193 (Reference 16.4).
7.2. Aluminum nitrate (A1(NO3)3' 9H2O)
7.2.1. Aluminum nitrate solution (2M): Add 750 g of aluminum nitrate (A1(NO3)3'
9H2O) to -700 mL of water and dilute to 1 L with water. Low-levels of
uranium are typically present in A1(NO3)3 solution.
NOTE: For low-level measurements, trace uranium contamination in the aluminum
nitrate may be removed by passing ~250 mL of 2M A1(NO3)3 through a large column
containing ~7 mL of UTEVA® Resin or TRU Resin (Eichrom Technologies, Lisle, II)
that has been previously preconditioned with ~5 mL of 3M HNO3.
7.3. Ascorbic acid (1.5M): Dissolve 66 g of ascorbic acid (CeHgOe) in 200 mL of water,
warming gently to dissolve, and dilute to 250 mL with water. Shelf life is 30 days or
less.
7.4. Ammonium oxalate ((NH4)2C2O4' H2O)
7.4.1. Ammonium bioxalate solution (0.1M): Dissolve 6.3 g of oxalic acid and 7.1
g of ammonium oxalate in 900 mL of water, filter, and dilute to 1 liter with
water.
7.5. Barium chloride (~0.45%): Dissolve 4.5 grams of barium chloride (BaCl2' H2O) in
500 mL of water and dilute to 1000 mL with water.
7.6. Cerium (III) nitrate hexahydrate (Ce(NO3)3' 6 H2O)
7.6.1. Cerium carrier (0.5 mg Ce/mL): Dissolve 0.155 g cerium (III) nitrate
hexahydrate in 50 mL water, and dilute to 100 mL with water.
7.7. Ethanol, 100%: Anhydrous C2HsOH, available commercially.
7.7.1. Ethanol (-95% v/v): Commercially available or mix 95 mL 100% ethanol
and 5 mL water.
7.8. Ferric nitrate solution (5 mg/mL): Dissolve 18.1-g ferric nitrate in 300 mL water and
dilute to 500 mL with water.
7.9. Hydrochloric acid (12M): Concentrated HC1, available commercially.
7.9.1. Hydrochloric acid (4M): Add 333 mL of concentrated HC1 to 500 mL of
water and dilute with water to 1 L.
7.9.2. Hydrochloric acid (0.25M): Add 20.8 mL of concentrated HC1 to 500 mL of
water and dilute with water to 1 L.
7.10. Hydrofluoric acid (28M): Concentrated HF, available commercially.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
7.10.1. Hydrochloric acid (4M): Hydrofluoric acid (0.2M) solution: Add 7.14 mL
concentrated HF to 1000 mL 4M HC1 and mix well.
7.10.2. Hydrochloric acid (4M): Hydrofluoric acid (0.2M) - 0.002M TiCl3 solution:
Add 0.2 mL of 10 percent by mass (wt%) solution TiCl3 per 100 mL;
prepare fresh daily as needed.
7.11. Hydrogen peroxide, ^262), 30%, available commercially.
7.12. Nitric acid (16M): Concentrated HNO3, available commercially.
7.12.1. Nitric acid (3M): Add 191 mL of concentrated HNO3 to 700 mL of water
and dilute to 1 L with water.
7.12.2. Nitric acid (8M): Add 510 mL of concentrated HNO3 to 300 mL of water
and dilute to 1 L with water.
7.13. Oxalic acid (H2C2O4'2 H2O), available commercially.
7.14. Potassium sulfate (K2SO4), available commercially.
7.15. Sodium nitrite, (NaNO2).
7.15.1. Sodium nitrite solution (3.5M): Dissolve 6.1 g of sodium nitrite (NaNO2) in
25 mL of water. Prepare fresh daily.
7.16. Sulfamic acid (H3NSO3)
7.16.1. Sulfamic acid solution (1.5M): Dissolve 72.7 g of sulfamic acid (H3NSO3)
in 400 mL of water and dilute to 500 mL with water.
7.17. TEVA® Resin - 2 mL cartridge, 50 to 100 |j,m mesh size, Eichrom part number TE-
R50-S and TE-R200-S, or equivalent.
7.18. TRU Resin - 2 mL cartridge, 50 to 100 |j,m mesh size, Eichrom part number TR-R50-
S and TR-R200-S, or equivalent.
7.19. Titanium (III) chloride solution (TiCl3), 10 wt% solution in 20-30 wt% hydrochloric
acid
7.20. Sodium sulfate (Na2SO4), available commercially.
7.21. Sulfuric acid (H2SO4), 18M concentrated, available commercially.
9^9
7.22. Uranium-232 tracer solution: Add 15-25 dpm of U per aliquant, activity known to
at least 5% (combined standard uncertainty of no more than 5%).
NOTE: If count times longer than 1 hour are used, lower levels of tracer activity may be added
instead. Self-cleaning tracer to remove the 228Th daughter from the 232U tracer as described in
Appendix A reduces the chance of 228Th contamination in the purified uranium fraction, which
could overlap with the 232U tracer peak if levels are high enough.
8. Sample Collection, Preservation, and Storage
Not Applicable.
9. Quality Control
9.1. Batch quality control results shall be evaluated and meet applicable Analytical
Protocol Specifications (APS) prior to release of unqualified data. In the absence of
project-defined APS or a project specific quality assurance project plan (QAPP), the
quality control sample acceptance criteria defined in the laboratory quality manual
and procedures shall be used to determine acceptable performance for this method.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
9.1.1. A Laboratory Control Sample (LCS) shall be run with each batch of
samples. The concentration of the LCS should be at or near the action level
or level of interest for the project.
9.1.2. One method blank shall be run with each batch of samples. The laboratory
blank should consist of an acceptable simulant or empty crucible blank
processed through fusion procedure.
9.1.3. One laboratory duplicate shall be run with each batch of samples. The
laboratory duplicate is prepared by removing an aliquant from the original
sample container.
9.1.4. A matrix spike sample may be included as a batch quality control sample if
there is concern that matrix interferences may compromise chemical yield
measurements or overall data quality.
9.2. The source preparation method should produce a sample test source that produces a
spectrum with the full width at half maximum (FWHM) of 0.05-0.1 MeV for each
peak in the spectrum. Precipitate reprocessing should be considered if this range of
FWHM cannot be achieved.
9.3. This method is capable of achieving a 238U WMR of 1.9 pCi/g at or below an action
level of 14.7 pCi/g. This may be adjusted if the event specific MQOs are different.
ryy Q
9.4. This method is capable of achieving a required U (pMR of 13% above 14.7 pCi/g.
This may be adjusted if the event specific MQOs are different.
ryy Q
This method is capable of achieving a required U minimum detectable
concentration (MDC) of-0.5 pCi/g with a counting time of 180 minutes.
10. Calibration and Standardization
10.1. Set up the alpha spectrometry system according to the manufacturer's
recommendations. The energy range of the spectrometry system should at least
include the region between 3.5 and 10 MeV.
10.2. Calibrate each detector used to count samples according to ASTM Standard Practice
D7282, Section 18, "Alpha Spectrometry Instrument Calibrations" (Reference 16.5).
10.3. Continuing Instrument Quality Control Testing shall be performed according to
ASTM Standard Practice D7282, Sections 20, 21, and 24 (Reference 16.5).
11. Procedure
11.1. Initial Sample Preparation for Uranium
11.1.1. U isotopes may be preconcentrated from building material samples using the
procedure Rapid Method for Sodium Hydroxide Fusion of Concrete and
Brick Matrices Prior to Americium, Plutonium, Strontium, Radium, and
Uranium Analyses (Reference 16.3), which fuses the samples using rapid
NaOH fusion followed by iron hydroxide and lanthanum fluoride
precipitation to preconcentrate U isotopes from the hydroxide matrix.1
1 The fusion procedure provides a column load solution for each sample (consisting of 5mL 3M HNO3-0.25M
H3BO3+ 6mL HNO3+7 mL 2M A1(NO3)3 + 3mL 3M HNO3), ready for valence adjustment and column separation on
TEVA Resin.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
11.1.2. This separation can be used with other sample matrices if the initial sample
preparation steps result in a column load solution containing ~3M HNCV
1M A1(NO3)3.
11.1.3. A smaller volume of the total load solution may be taken and analyzed as
needed for very high activity samples, with appropriate dilution factor
calculations applied.
NOTE: It should be noted that the LaF3 matrix removal step in the fusion procedure
(Reference 16.3) following the sodium hydroxide fusion removes Fe to minimal levels
that will not interfere with TRU Resin as Fe3+. If this column method is used on solid
samples (soil, etc.) with high Fe levels without the LaF3 matrix removal, there may be
a significant adverse impact on U retention on TRU Resin.
11.2. Rapid Uranium Separation using TEVA® and TRU Resins
11.2.1. Perform valence adjustment on column load solutions prepared from the
fusion procedure for building materials (Reference 16.3).
NOTE: If a smaller volume was taken instead of the total load solutions, this
smaller volume should be diluted to ~15 mL with 3M HNOs before
proceeding with the valence adjustment.
11.2.1.1. If particles are observed suspended in the solution, centrifuge the
sample, collect the supernatant solution in small beaker and
discard the precipitate.
NOTE: Pu, if present, is valence adjusted to Pu4+ to ensure retention and
removal on TEVA® Resin.
11.2.1.2. Add 0.5 mL of 1.5M sulfamic acid to each solution. Swirl to
mix.
11.2.1.3. Add 0.1 mL of 5 mg/mL ferric nitrate solution.
NOTE: Ferric ions are added and are reduced to ferrous ion s by
ascorbic acid to enhance valence reduction of Pu isotopes and 237Np.
11.2.1.4. Add 1.25 mL of 1.5M ascorbic acid to each solution, swirling to
mix. Wait 3 minutes.
11.2.1.5. Add 1 mL of 3.5MNaNO2 to each sample, swirling to mix.
NOTE: A small amount of brown fumes result from nitrite reaction with
sulfamic acid. The solution should clear with swirling and not remain
dark If the solution does not clear (is still dark) an additional small
volume of sodium nitrite may be added to clear the solution.
11.2.1.6. Add 1.5 mL of concentrated HNCb to each sample, swirling to
mix.
11.2.2. Set up TEVA® and TRU cartridges on the vacuum box system
NOTE: This section deals with a commercially available vacuum box system. Other
vacuum systems developed by individual laboratories may be substituted here as long
as the laboratory has provided guidance to analysts in their use. The cartridges may
be set up and conditioned with nitric acid so that they are ready for column loading
just prior to completion of the valence adjustment steps.
11.2.2.1. Place the inner tube rack (supplied with vacuum box) into the
vacuum box with the centrifuge tubes in the rack. Place the lid
onto the vacuum box system.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
11.2.2.2. Place the yellow outer tips into all 24 openings of the lid of the
vacuum box. Fit in the inner white tip into each yellow tip.
11.2.2.3. Place a TEVA® cartridge above a TRU cartridge and place on
vacuum box.
11.2.2.4. Place reservoirs into top of stacked TEVA®+TRU Resin
cartridges, inserting reservoir into top of TEVA® cartridge.
11.2.2.5. Turn the vacuum on (building vacuum or pump) and ensure
proper fitting of the lid.
IMPORTANT: The unused openings on the vacuum box should be
sealed. Yellow caps (included with the vacuum box) can be used to plug
unused white tips to achieve good seal during the separation. Alternately,
plastic tape can be used to seal the unused lid holes as well.
11.2.2.6. Add 5 mL of 3M HNCb to the column reservoir to precondition
the TEVA® and TRU cartridges.
11.2.2.7. Adjust the vacuum to achieve a flow-rate of ~1 mL/min.
IMPORTANT: Unless otherwise specified in the procedure, use a flow
rate of ~ 1 mL/min for load and strip solutions and ~ 2-4 mL/min for
rinse solutions.
11.2.3. TEVA® and TRU Resin Separation
11.2.3.1. Transfer each solution from Step 11.2.1.5 into the appropriate
reservoir by pouring or by using a plastic transfer pipette.
11.2.3.2. Allow solution to pass through the stacked TEVA® + TRU
cartridges at a flow rate of ~1 mL/min.
11.2.3.3. Add 3 mL of 3M HNO3 to each tube (from Step 11.2.1.5) as a
rinse and transfer each solution into the appropriate reservoir (the
flow rate can be adjusted to ~1 to 2 mL/min).
11.2.3.4. Add 10 mL of 3M HNOs into each reservoir to rinse column
(flow rate ~2 mL/min).
11.2.3.5. Turn off vacuum, discard rinse solutions. Remove and discard
the TEVA® cartridges.
11.2.3.6. To the TRU Resin cartridge only, add 15 mL of 4M HC1-0.2M
HF-0.002M TiCb into each reservoir as second column rinse
(flow rate -1-2 mL/min) to remove Am, Th and Po.
11.2.3.7. Add 5 mL of 8M HNCbinto each reservoir as second column
rinse (flow rate -1-2 mL/min) to reduce bleed-off of organic
extractant.
11.2.3.8. Ensure that clean, labeled plastic 50 mL centrifuge tubes are
placed in the tube rack under each cartridge.
NOTE: For maximum removal of interferences during elution, also
change reservoirs and connector tips prior to U elution.
11.2.3.9. Add 15 mL of 0.1M ammonium bioxalate (NH4HC2O4) to elute
the uranium from each cartridge, reducing the flow rate to -1
mL/min.
11.2.3.10. Set uranium fraction in the plastic centrifuge tube aside for
cerium fluoride coprecipitation, Step 11.3.
11.2.3.11. Discard the TRU cartridge.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
11.3. Preparation of the Sample Test Source
NOTE: Additional Ce (200 uL) is typically needed if the 238U is greater than 10-15 pCi in the
final purified solution to ensure complete precipitation and prevent lower chemical yields. If it
is not known that the 238U is < 10-15 pCi in the final purified solution, 200 uL Ce (100 jig Ce)
should be added instead of 100 uL Ce.
11.3.1. Pipet 100 jiL of the Ce carrier solution into each centrifuge tube.
11.3.2. Pipet 0.5 mL 10 wt% TiCb into each tube to reduce uranium to U4+.
11.3.3. Pipet 1 mL of concentrated HF into each tube.
11.3.4. Cap the tube and mix. Allow solutions sit for -15 minutes before filtering.
11.3.5. Setup a filter apparatus to accommodate aO.l micron, 25 mm membrane
filter on a microprecipitation filtering apparatus.
Caution: There is no visible difference between the two sides of the filter. If the filter is
turned over accidentally, it is recommended that the filter be discarded and a fresh
one removed from the box.
11.3.6. Add a few drops of 95% ethanol to wet each filter and apply vacuum.
Ensure that there are no leaks along the sides before proceeding.
11.3.7. While vacuum applied, add 2-3 mL of filtered Type I water to each filter
and allow the liquid to drain.
11.3.8. Add the sample to the filter reservoir, rinsing the sample tubes with ~3 mL
of water and transfer this rinse to filter apparatus. Allow to drain.
11.3.9. Wash each filter with 2-3 mL of water and allow to drain.
11.3.10. Wash each filter with 1-2 mL of 95% ethanol to displace water.
11.3.11. Allow to drain completely before turning the vacuum off.
11.3.12. Mount the filter on a labeled adhesive mounting disk (or equivalent)
ensuring that the filter is not wrinkled and is centered on mounting disk.
11.3.13. Place the filter under a heat lamp for approximately 5 minutes or more until
it is completely dry.
11.3.14. Count filters for an appropriate period of time by alpha spectrometry.
11.3.15. Discard the filtrate to waste for future disposal. If the filtrate is to be
retained, it should be placed in a plastic container to avoid dissolution of the
glass vessel by dilute HF.
NOTE: Other methods for STS preparation, such or microprecipitation with
neodymium fluoride (NdF3), may be used in lieu of the cerium fluoride
microprecipitation, but any such substitution must be validated as described in
Section 1.5. Nd is typically interchangeable with Ce.
12. Data Analysis and Calculations
12.1. Equation for determination of final result, combined standard uncertainty and
radiochemical yield (if required):
12.1.1. The activity concentration of an analyte and its combined standard
uncertainty are calculated using the following equations:
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
12.1.2. The net count rate of an analyte or tracer and its standard uncertainty are
calculated using the following equations:
r r
n _ ^x "-bx
and
(3)
where:
(4)
Rx = net count rate of analyte or tracer, in counts per second
Cx = sample counts in the analyte or the tracer ROI
4 = sample count time (s)
Cbx = background counts in the same ROI as for x
tb = background count time (s)
u(Rx) = standard uncertainty of the net count rate of tracer or
analyte, in counts per second2
If the radiochemical yield of the tracer is requested, the yield and its
combined standard uncertainty can be calculated using the following
equations:
RY =
0.037x4 x£)t x/t xs
and
where:
(6)
RY = radiochemical yield of the tracer, expressed as a fraction
Rt = net count rate of the tracer, in counts per second
At = activity of the tracer added to the sample (pCi)
Dt = correction factor for decay of the tracer from its reference
date and time to the midpoint of the counting period
/t = probability of a emission in the defined ROI per decay of
the tracer (Table 17.1)
s = detector efficiency, expressed as a fraction
uc(RY) = combined standard uncertainty of the radiochemical yield
2 For methods with very low counts, MARLAP Section 19.5.2.2 recommends adding one count each to the gross
counts and the background counts when estimating the uncertainty of the respective net counts. This minimizes
negative bias in the estimate of uncertainty and protects against calculating zero uncertainty when a total of zero
counts are observed for the sample and background.
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standard uncertainty of the net count rate of the tracer, in
counts per second
standard uncertainty of the activity of the tracer added to
the sample (pCi)
standard uncertainty of the detector efficiency
12.1.3. If the critical level concentration (Lc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations: 3
L =
0.4x -^—1 +0.677x
+1.645
A. x D. x /.
tsxWaxRtxDax!a
(7)
MDC =
2.71x1 + ^
fu
'•11+t
4 x Dt x It
tsxWaxRtxDax!a
(8)
where:
Rbn = background count rate for the analyte in the defined ROI, in counts
per second
12.2. Results Reporting
12.2.1. The following data should be reported for each result: volume of sample
used; yield of tracer and its uncertainty; and FWHM of each peak used in
the analysis.
12.2.2. The following conventions should be used for each result:
12.2.2.1. Result in scientific notation ± combined standard uncertainty.
13. Method Performance
13.1. Method validation results are to be reported.
13.2. Expected turnaround time per batch of 14 samples plus quality control (QC),
assuming microprecipitations for the whole batch are performed simultaneously using
a vacuum box system:
13.2.1. For an analysis of a 1 g sample aliquant, sample preparation and digestion
should take ~3 h.
3 The formulations for the critical level and minimum detectable concentration are based on the Stapleton
Approximation as recommended in MARLAP Section 20A.2.2, Equations 20.54 and 20A.3.2, and Equation 20.74,
respectively. The formulations presented here assume an error rate of a = 0.05, ft = 0.05 (with zi-a = zi-p = 1.645)
and d = 0.4, a constant in equation 20.54 (the z value of 1.645 reflects the 1-a and l-(3 quantiles of the normal
distribution when a=P=0.05). For methods with very low numbers of counts, these expressions provide better
estimates than do the traditional formulas for the critical level and MDC.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
13.2.2. Purification and separation of the uranium fraction using cartridges and
vacuum box system should take -2.5 h.
13.2.3. The sample test source preparation step takes ~1 h.
13.2.4. A 3 to 4 hour counting time should be sufficient to meet the MQOs listed in
9.3, 9.4, and 9.5, assuming detector efficiency of 0.2-0.3, and radiochemical
yield of at least 0.5. A different counting time may be necessary to meet
these MQOs if any of the relevant parameters are significantly different.
13.2.5. Data should be ready for reduction -9.5 to 10.5 hours after beginning of
analysis.
14. Pollution Prevention: The method utilizes small volume (2 mL) extraction chromatographic
resin columns. This approach leads to a significant reduction in the volumes of load, rinse
and strip solutions, as compared to classical methods using ion exchange resins to separate
and purify the uranium fraction.
15. Waste Management
15.1. Types of waste generated per sample analyzed.
15.1.1. Approximately 55 mL of acidic waste from loading and rinsing the two
extraction columns will be generated.
15.1.2. Approximately 25 mL of acidic waste from the microprecipitation method
for source preparation will be generated. The waste contains 1 mL of HF
and - 5 mL of ethanol.
15.1.3. TEVA® cartridge - ready for appropriate disposal. Used resins and columns
should be considered radioactive waste and disposed of in accordance with
restriction provided in the facility's radioactive materials license and any
prevailing local restrictions.
15.1.4. TRU cartridge - ready for appropriate disposal. Used resins and columns
should be considered radioactive waste and disposed of in accordance with
restriction provided in the facility's radioactive materials license and any
prevailing local restrictions.
15.2. Evaluate all waste streams according to disposal requirements by applicable
regulations.
16. References
Cited References
16.1. U.S. Environmental Protection Agency (EPA). 2009. Method Validation Guide for
Radiological Laboratories Participating in Incident Response Activities. Revision 0.
Office of Air and Radiation, Washington, DC. EPA 402-R-09-006, June. Available
at: www.epa.gov/narel.
16.2. Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP).
2004. EPA 402-B-1304 04-001 A, July. Volume I, Chapters 6, 7, 20, Glossary;
Volume II and Volume III, Appendix G. Available at:
www. epa. gov/radiation/marlap.
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
16.3. U.S. Environmental Protection Agency (EPA). 2014. Rapid Method for Sodium
Hydroxide Fusion of Concrete and Brick Matrices Prior to Americium, Plutonium,
Strontium, Radium, and Uranium Analyses. Revision 0, EPA 402-R14-004. Office of
Air and Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.4. ASTM Dl 193, "Standard Specification for Reagent Water," ASTM Book of
Standards 11.02, current version, ASTM International, West Conshohocken, PA.
16.5. ASTM D7282 "Standard Practice for Set-up, Calibration, and Quality Control of
Instruments Used for Radioactivity Measurements," ASTM Book of Standards 11.02,
current version, ASTM International, West Conshohocken, PA.
16.6. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Americium-241 in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R14-007. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.7. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Pu-238 and Pu-239/240 in Building Materials for Environmental Remediation
Following Radiological Incidents. Revision 0, EPA 402-R14-006. Office of Air and
Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.8. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Radium-226 in Building Materials for Environmental Remediation Following
Radiological Incidents. Revision 0, EPA 402-R14-002. Office of Air and Radiation,
Washington, DC. Available at: www.epa.gov/narel.
16.9. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Total Radiostrontium (Sr-90) in Building Materials for Environmental
Remediation Following Radiological Incidents. Revision 0, EPA 402-R14-001.
Office of Air and Radiation, Washington, DC. Available at: www.epa.gov/narel.
16.10. U.S. Environmental Protection Agency (EPA). 2014. Rapid Radiochemical Method
for Isotopic Uranium in Building Materials for Environmental Remediation
Following Radiological Incidents. Revision 0, EPA 402-R14-005. Office of Air and
Radiation, Washington, DC. Available at: www.epa.gov/narel.
Other References
16.11. Maxwell, S., Culligan, B. andNoyes, G. 2010. Rapid method for actinides in
emergency soil samples, Radiochimica Ada. 98(12): 793-800.
16.12. Maxwell, S., Culligan, B., Kelsey-Wall, A. and Shaw, P. 2011. "Rapid Radiochemical
Method for Actinides in Emergency Concrete and Brick Samples," Analytica
ChimicaActa. 701(1): 112-8.
16.13. VBS01, Rev.1.3, "Setup and Operation Instructions for Eichrom's Vacuum Box
System (VBS)," Eichrom Technologies, Inc., Lisle, Illinois (January 2004).
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Rapid Radiochemical Method for Isotopic Uranium in Building Materials
17. Tables, Diagrams, Flow Charts, and Validation Data
17.1. Tables
Table 17.1 - Decay and Radiation Data
Nuclide
238U
235U
234U
232U
Half-Life
(Years)
4.468xl09
7.038xl08
2.457xl05
68.9
>,
(s-1)
4.916xlO~18
3.121xl(T17
8.940xlO~14
3.19xlO~10
Abundance
0.79
0.21
0.050
0.042
0.0170
0.0070
0.0210
0.55
0.170
0.7138
0.2842
0.002
0.6815
0.3155
a Energy
(MeV)
4.198
4.151
4.596
4.556
4.502
4.435
4.414
4.398
4.366
4.775
4.722
4.604
5.320
5.263
17.2. Ingrowth Curves and Ingrowth Factors
This section intentionally left blank
17.3. Spectrum from a Processed Sample
Uranium Spectrum
91
82
73
-. 55
en
£ 46
O 37
B 28
>-
,s
8362 2181 3164
(keV)
48 i2
5234 5659 606S 6522 6988 7400
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17.4. Decay Scheme: Ingrowth is not generally a large concern with this analysis unless
one is running sequential analysis for uranium and plutonium with 236Pu tracer (due to
'TV? OOS
ingrowth of U tracer) or sequential analyses for uranium and thorium (due to Th
232T
tracer ingrowth in the U tracer).
3.3x1 Q4y 7.04x1Q8 y
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17.5. Flowchart
Separation Scheme and Timeline for Determination of
Uranium Isotopes in Building Materials Samples
Elapsed Time
Rapid Fusion (See Separate Procedure)
1. Add 232U tracer and fuse with NaOH
2. Fe/Ti hydroxide then La/Ca fluoride precipitations
3. Dissolve in of 3M HNO3-0.25M H3BO3, 7M HNO3, 2M
AI(NO3)3i andSM HNO3 (column load solution)
Adjust Pu to Pu4+ for removal on TEVA
(Step 11.2.1)
1. Add sulfamic acid, Fe and ascorbic acid
2. Wait 3 minutes
3. Add sodium nitrite
Vacuum Box Setup (Step 11.2.2)
1. Place TEVA + TRU cartridges on
box
2. Condition column with 5 ml 3M
HNO3 @ 1 mL/min
Discard load and
rinse solutions and
TEVA cartridges
(Step 11.2.3.5)
Discard TRU
cartridge
(Step 11.2.3.11)
Discard filtrates
and rinses
(Step 11.3.1.15)
Load Sample to TEVA and TRU Cartridges
(Step 11.2.3.1)
1. Load sample @ 1 mL/min
2. Beaker/tube rinse: 3mL 3M HNO3 @ 1-2 mL/min
3. Column rinse: 10 mL 3M HNO3 @ 2 mL/min
U separation on TRU Resin (Step 11.2.3.6)
1. Column rinse: 15mL4-M HCI-0.2M HF-0.002-M TiCI3
@ 1-2 mL/min
2. Column rinse: 5 mL 8M HNO3 @ 1-2 mL/min
3. Elute U into new tubes with 15 mL 0.1M ammonium
bioxalate@~1 mL/min
Microprecipitation (Step 11.3)
1. Add 50 |jg Ce carrier
2. Add 0.5 mL 10 wt% TiCI3
3. Add 1 mL concentrated HF
4. Wait 15 min and filter
5. Place on mounting disks
6. Warm ~5 min under heat lamp
v
Count sample test source (STS)
by alpha spec for3-4 h or as
needed (Step 11.3.14)
3 hours
31/4 hours
41/2 hours
51/2 hours
61/2 hours
71/2-141/2 hours
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Appendix A:
Preparation of Self-Cleaning 232U Tracer
NOTE: 228Th daughter is removed continually using barium sulfate precipitation to minimize 228Th when using
this tracer.
1. Add 45 g K2SO4, 20 g Na2SO4 and 20 mL cone. H2SO4 to a 1 L Erlenmeyer flask.
2. Pipet the volume prescribed from a 232U stock solution into the flask to prepare the
desired concentration of 232U tracer.
3. Heat solution on a hot plate on medium heat until the tracer solution is evaporated
and fumes of H2SC>4 begins to form.
4. Heat until a thick sulfate solution forms with minimal fumes.
5. Remove flask from the hot plate with tongs and swirl flask until the sulfate fusion
cake forms.
6. Dissolve the fusion cake in 250 mL water and 31.8 mL cone. HNOs, using heat as
needed.
7. Add 3 mL 30% H2O2 to the flask. Swirl to mix.
8. With heating and stirring, add six 10 mL portions 0.45% BaCl2, waiting 1 minute
between each addition.
9. Remove flask from hotplate.
10. Cool flask to room temperature.
11. Transfer solution and solids to 1,000 mL volumetric flask. Rinse initial flask with
water and transfer rinse to the volumetric flask.
12. Dilute volume to 1000 mL with water.
13. Mix standard well.
14. Transfer standard with solids to a 1 L plastic bottle.
15. When volumes of this standard are transferred to smaller containers, make sure that
solids are transferred along with the liquid by swirling prior to transfer.
NOTE: The smaller bottles of 232U tracer used in the lab may be used with or without periodic shaking
and allowing the solids to settle. Tracer volumes should not be taken when volumes are low enough
such that suspended solids (containing 228Th) will also be pipetted. 228Th levels remain low with or
without shaking and either way is acceptable for this method, which contains Th removal steps. For
maximum Th removal, however, shaking and settling should be performed within 1 week of use. Ex. If
the tracer is also used for sequential work where U and Th separations are performed sequentially,
maximum 228Th removal is essential for accurate 228Th assay in samples.
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Appendix B:
Example of Sequential Separation Using Am-241, Pu-238+Pu-239/240, and Isotopic U in
Building Materials
241
238T
, 239/240T
This sequential combination of rapid procedures for Am, Pu+ Pu, and isotopic U in
building materials (References 16.6, 16.7, and 16.10) has been used by some laboratories, but
this sequential approach was not included in this method validation.
TEVA®+ TRU®+DGA®
Add 3 ml_3M HNO3 beaker rinse.
Add 3 ml_3M HNO3 column rinse.
Split cartridges.
v
TEVA®
Rinse w/10 ml_ 3M HNO3
20 ml_ 9 M HCI (remove Th)
5mL3M HNO3
DGA®
Rinse w/ 10ml_0.1M HNO3
(remove U)
v
Elute Pu w/ 20 ml_ 0.1M HCI -
0.05MHF -0.01M TiCI3
Stack TRU® + DGA®
Add 15mL3M HCI
(Move all Am/Cm to DGA)
Add 0.5 mL 30 wt% H2O2 to
oxidize any U
DGA®
Rinse w/ 5 mL 3M HCI,
3mL1M HNO3 + 10ml_0.1M
HN03 + 5mL0.05M HNO3
(remove La)
Elute Am/Cm w/ 10 mL 0.25M
HCI
TRU®
Rinse w/ 15mL4M HCI -
0.2MHF -0.002M TiCI3 +
5mL8M HN03
Elute Uw/15 mLO.IM
Add0.5mL20%TiCI3
V
Add 50 ug Ce to 1 mL 49% HF.
Filter and count by alpha spectrometry.
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