ASTM C1474-19

Standard Test Method for Analysis of Isotopic Composition of Uranium in Nuclear-Grade Fuel Material by Quadrupole Inductively Coupled Plasma-Mass Spectrometry

SIGNIFICANCE AND USE
5.1 Nuclear-grade reactor fuel material must meet certain criteria, such as those described in Specifications C753, C776, C778, and C833. Included in these criteria is the uranium isotopic composition. This test method is designed to demonstrate whether or not a given material meets an isotopic requirement and whether the effective fissile content is in compliance with the purchaser's specifications.
SCOPE
1.1 This test method is applicable to the determination of the isotopic composition of uranium (U) in nuclear-grade fuel material. The following isotopic weight percentages are determined using a quadrupole inductively coupled plasma-mass spectrometer (Q-ICP-MS):  233U,  234U,  235U,  236U, and  238U. The analysis can be performed on various material matrices after acid dissolution and sample dilution into water or dilute nitric (HNO3) acid. These materials include: fuel product, uranium oxide, uranium oxide alloys, uranyl nitrate (UNH) crystals, and solutions. The sample preparation discussed in this test method focuses on fuel product material but may be used for uranium oxide or a uranium oxide alloy. Other preparation techniques may be used and some references are given. Purification of the uranium by anion-exchange extraction is not required for this test method, as it is required by other test methods such as radiochemistry and thermal ionization mass spectroscopy (TIMS). This test method is also described in ASTM STP 13442.  
1.2 The  233U isotope is primarily measured as a qualitative measure of its presence by comparing the  233U peak intensity to a background point since it is not normally found present in materials. The example data presented in this test method do not contain any  233U data. A  233U enriched standard is given in Section 8, and it may be used as a quantitative spike addition to the other standard materials listed.  
1.3 A single standard calibration technique is used. Optimal accuracy (or a low bias) is achieved through the use of a single standard that is closely matched to the enrichment of the samples. The intensity or concentration is also adjusted to within a certain tolerance range to provide good statistical counting precision for the low-abundance isotopes while maintaining a low bias for the high-abundance isotopes, resulting from high-intensity dead time effects. No blank subtraction or background correction is utilized. Depending upon the standards chosen, enrichments between depleted and 97 % can be quantified. The calibration and measurements are made by measuring the intensity ratios of each low-abundance isotope to the intensity sum of  233U,  234U,  235U,  236U, and  238U. The high-abundance isotope is obtained by difference.  
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. The instrument is calibrated and the samples measured in units of isotopic weight percent (Wt %). For example, the  235U enrichment may be stated as Wt %  235U or as g  235U/100 g of U. Statements regarding dilutions, particularly for μg/g concentrations or lower, are given assuming a solution density of 1.0 since the uranium concentration of a solution is not important when making isotopic ratio measurements other than to maintain a reasonably consistent intensity within a tolerance range.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 9.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by ...

General Information

• Status: Published
• Publication Date: 31-Jan-2019
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: C26 - Nuclear Fuel Cycle
• Drafting Committee: C26.05 - Methods of Test

Relations

• Replaces: ASTM C1474-00(2011) - Standard Test Method for Analysis of Isotopic Composition of Uranium in Nuclear-Grade Fuel Material by Quadrupole Inductively Coupled Plasma-Mass Spectrometry
• Effective Date: 01-Feb-2019
• Refers: ASTM C859-24 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E135-20 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 01-Jan-2020
• Refers: ASTM E135-19 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-May-2019
• Refers: ASTM E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E882-10(2016)e1 - Standard Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
• Effective Date: 01-Dec-2016
• Refers: ASTM E882-10(2016) - Standard Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
• Effective Date: 01-Dec-2016
• Refers: ASTM E135-16 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-May-2016
• Refers: ASTM C753-16 - Standard Specification for Nuclear-Grade, Sinterable Uranium Dioxide Powder
• Effective Date: 01-Feb-2016
• Refers: ASTM E135-15a - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 01-Jul-2015
• Refers: ASTM E135-15 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-May-2015
• Refers: ASTM E135-14b - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-Aug-2014
• Refers: ASTM C859-14a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Jun-2014

Overview

ASTM C1474-19 specifies a standardized test method for the determination of the isotopic composition of uranium in nuclear-grade fuel materials using quadrupole inductively coupled plasma-mass spectrometry (Q-ICP-MS). Uranium isotope ratios-specifically of ^233U, ^234U, ^235U, ^236U, and ^238U-are critical parameters for compliance with reactor fuel specifications. The method is applicable to a variety of uranium-containing matrices, including uranium oxide, uranium oxide alloys, uranyl nitrate crystals, and nuclear fuel solutions, following appropriate sample preparation and dissolution protocols. This standard is essential for quality assurance in the nuclear fuel cycle, aiding in verifying compliance with criticality and regulatory requirements.

Key Topics

• Isotopic Analysis by Q-ICP-MS
  This method uses quadrupole ICP-MS to measure weight percentages of uranium isotopes with high precision. The analysis relies on acid dissolution and dilution of fuel material, followed by introduction into the Q-ICP-MS system.

• Calibration and Quality Control
  A single calibration standard, closely matched to the target uranium isotopic enrichment, is used for optimal accuracy. The system utilizes intensity ratios for minor isotopes relative to the sum of all uranium isotope counts, helping ensure precision in isotopic ratio measurement.

• Sample Preparation
  Procedures focus on complete dissolution using nitric and hydrofluoric acids as needed, with subsequent dilution to achieve suitable concentrations for Q-ICP-MS analysis. The standard emphasizes minimizing contamination and maintaining consistent sample intensity for accurate results.

• Interferences and Instrument Optimization
  The document addresses potential interferences from adjacent isotopic peaks, molecular ion formation, and memory effects due to sample carryover. It recommends instrument settings and rinsing protocols to minimize these issues.

• Data Calculation and Interpretation
  The isotopic abundances for low-level uranium isotopes are directly measured, while the major isotope is calculated by difference. Calibration, bias corrections, and quality control checks are integral to ensuring reliable data.

• Safety Considerations
  Handling uranium compounds and acids, especially hydrofluoric acid, demands adherence to strict laboratory and regulatory safety protocols.

Applications

• Nuclear Fuel Quality Control:
  Verifies that uranium isotopic composition in fuel pellets, oxides, and uranyl nitrate solutions meets reactor specifications such as those defined in ASTM C753, C776, and C833.

• Process Monitoring:
  Supports enrichment process monitoring by accurately quantifying uranium isotope distributions, ensuring consistent fuel performance and regulatory compliance.

• Non-Proliferation and Safeguards:
  Enables precise assessment of fissile material content, aiding in nuclear material accounting and non-proliferation efforts by delivering reliable uranium isotopic data.

• Research and Development:
  Facilitates advanced studies in nuclear material science, supporting method development, validation, and comparative analysis with established techniques like TIMS (thermal ionization mass spectrometry).

• Regulatory Compliance:
  Ensures documentation and verification of isotopic content for licensing and international trade, critical for safety, transport, and storage of nuclear-grade materials.

Related Standards

• ASTM C753 - Specification for Nuclear-Grade, Sinterable Uranium Dioxide Powder
• ASTM C776 - Specification for Sintered Uranium Dioxide Pellets for Light Water Reactors
• ASTM C778 - Specification for Standard Sand
• ASTM C833 - Specification for Sintered (Uranium-Plutonium) Dioxide Pellets for Light Water Reactors
• ASTM C1347 - Practice for Preparation and Dissolution of Uranium Materials for Analysis
• ASTM D1193 - Specification for Reagent Water
• ASTM E135/E456/E882 - Related standards on analytical chemistry, terminology, and laboratory quality control

Practical Value

ASTM C1474-19 provides a robust and efficient approach to uranium isotope analysis for the nuclear industry. By offering a rapid, precise, and standardized method, this test protocol enables nuclear facilities and laboratories to consistently achieve compliance with fuel specifications, regulatory mandates, and safety standards for handling fissionable materials in the nuclear fuel cycle. The method supports the operational needs of reactor operators, fuel manufacturers, and regulatory agencies and upholds international confidence in the safe use and trade of nuclear-grade materials.

Keywords: uranium isotopic analysis, nuclear fuel, Q-ICP-MS, ASTM C1474-19, uranium isotopic composition, nuclear material quality control, nuclear-grade uranium testing, reactor fuel specifications, uranium isotope ratio, mass spectrometry, nuclear industry standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1474 − 19
Standard Test Method for
Analysis of Isotopic Composition of Uranium in Nuclear-
Grade Fuel Material by Quadrupole Inductively Coupled
Plasma-Mass Spectrometry
This standard is issued under the fixed designation C1474; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope countingprecisionforthelow-abundanceisotopeswhilemain-
taining a low bias for the high-abundance isotopes, resulting
1.1 This test method is applicable to the determination of
from high-intensity dead time effects. No blank subtraction or
the isotopic composition of uranium (U) in nuclear-grade fuel
background correction is utilized. Depending upon the stan-
material. The following isotopic weight percentages are deter-
dards chosen, enrichments between depleted and 97% can be
mined using a quadrupole inductively coupled plasma-mass
233 234 235 236 238 quantified. The calibration and measurements are made by
spectrometer (Q-ICP-MS): U, U, U, U, and U.
measuring the intensity ratios of each low-abundance isotope
The analysis can be performed on various material matrices
233 234 235 236 238
to the intensity sum of U, U, U, U, and U. The
after acid dissolution and sample dilution into water or dilute
high-abundance isotope is obtained by difference.
nitric (HNO ) acid. These materials include: fuel product,
uranium oxide, uranium oxide alloys, uranyl nitrate (UNH) 1.4 The values stated in SI units are to be regarded as the
crystals, and solutions. The sample preparation discussed in standard. The values given in parentheses are for information
this test method focuses on fuel product material but may be only.Theinstrumentiscalibratedandthesamplesmeasuredin
used for uranium oxide or a uranium oxide alloy. Other unitsofisotopicweightpercent(Wt%).Forexample,the U
235 235
preparation techniques may be used and some references are enrichment may be stated as Wt% Uorasg U/100 g of
given. Purification of the uranium by anion-exchange extrac- U. Statements regarding dilutions, particularly for µg/g con-
tion is not required for this test method, as it is required by centrations or lower, are given assuming a solution density of
other test methods such as radiochemistry and thermal ioniza- 1.0 since the uranium concentration of a solution is not
tion mass spectroscopy (TIMS). This test method is also importantwhenmakingisotopicratiomeasurementsotherthan
described in ASTM STP 1344 . tomaintainareasonablyconsistentintensitywithinatolerance
233 range.
1.2 The U isotope is primarily measured as a qualitative
1.5 This standard does not purport to address all of the
measure of its presence by comparing the U peak intensity
safety concerns, if any, associated with its use. It is the
to a background point since it is not normally found present in
responsibility of the user of this standard to establish appro-
materials. The example data presented in this test method do
233 233
priate safety, health, and environmental practices and deter-
notcontainany Udata.A Uenrichedstandardisgivenin
mine the applicability of regulatory limitations prior to use.
Section 8, and it may be used as a quantitative spike addition
Specific precautionary statements are given in Section 9.
to the other standard materials listed.
1.6 This international standard was developed in accor-
1.3 Asingle standard calibration technique is used. Optimal
dance with internationally recognized principles on standard-
accuracy(oralowbias)isachievedthroughtheuseofasingle
ization established in the Decision on Principles for the
standard that is closely matched to the enrichment of the
Development of International Standards, Guides and Recom-
samples. The intensity or concentration is also adjusted to
mendations issued by the World Trade Organization Technical
within a certain tolerance range to provide good statistical
Barriers to Trade (TBT) Committee.
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear
2. Referenced Documents
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
2.1 ASTM Standards:
Test.
Current edition approved Feb. 1, 2019. Published February 2019. Originally
approved in 2000. Last previous edition approved in 2011 as C1474–00(2011).
DOI: 10.1520/C1474-19.
2 3
Policke,T.A.,Bolin,R.N.,andHarris,T.L.,“UraniumIsotopeMeasurements For referenced ASTM standards, visit the ASTM website, www.astm.org, or
by Quqdrupole ICP-MS for Process Monitoring of Enrichment,” Symposium on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Applications of Inductively Coupled Plasma-Mass Spectrometry to Radionuclide Standards volume information, refer to the standard’s Document Summary page on
Determinations: Second Volume, ASTM STP 1344, ASTM, 1998, p. 3. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1474 − 19
C753Specification for Nuclear-Grade, Sinterable Uranium series to a concentration of approximately 0.10 µg of uranium
Dioxide Powder per gram of solution (µg U/g solution or ppm of U). Other
C776SpecificationforSinteredUraniumDioxidePelletsfor dissolution methods may be used.Astandard peristaltic pump
Light Water Reactors is used as the means of sample introduction into the plasma.
C778Specification for Standard Sand The uranium intensity (that is, concentration), as initially
C833Specification for Sintered (Uranium-Plutonium) Diox- indicatedbyaratemeterreading,isadjustedtowithinacertain
ide Pellets for Light Water Reactors tolerance range to provide good precision and a reduced bias
C859Terminology Relating to Nuclear Materials for all sample, standard, and control measurements.Acalibra-
C1347Practice for Preparation and Dissolution of Uranium tion standard is run and all sample analyses are bracketed by
Materials for Analysis theanalysisofcontrols.Calculationsareperformedtomeasure
D1193Specification for Reagent Water the intensity ratios of each low-abundance isotope to the
233 234 235 236 238
E135Terminology Relating to Analytical Chemistry for intensity sum of U, U, U, U, and U. Mass bias
Metals, Ores, and Related Materials correction factors, which are established using the instrument
E456Terminology Relating to Quality and Statistics software and the calibration standard data, are then applied to
E882Guide for Accountability and Quality Control in the the sample and control data. The corrected ratio measurement
Chemical Analysis Laboratory for a low abundance isotope is equal to the abundance of that
isotope(forexamplethe Uintensity/Uisotopeintensitysum
3. Terminology
equals the U abundance). The high abundance isotope is
determined by subtracting the low-abundance isotopes from
3.1 Definitions:
100%.
3.1.1 For definitions of terms relating to analytical atomic
spectroscopy, refer to Terminology E135.
5. Significance and Use
3.1.2 For definitions of terms relating to statistics, refer to
5.1 Nuclear-grade reactor fuel material must meet certain
Terminology E456.
criteria, such as those described in Specifications C753, C776,
3.1.3 For definitions of terms relating to nuclear materials,
C778, and C833. Included in these criteria is the uranium
refer to Terminology C859.
isotopic composition. This test method is designed to demon-
3.1.4 For definitions of terms specifically related to
strate whether or not a given material meets an isotopic
Q-ICP-MS in addition to those found in 3.2, refer toAppendix
requirement and whether the effective fissile content is in
3 of Jarvis et al.
compliance with the purchaser’s specifications.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 dead time, n—the interval during which the detector
6. Interferences
and its associated counting electronics are unable to record
6.1 Adjacent Isotopic Peak Effects—Interferences can occur
another event or resolve successive pulses. The instrument
from adjacent isotopes of high concentration, such as an
signal response becomes nonlinear above a certain count rate
235 234
intense U peak interfering with the measurement of U
due to dead time effects.
and U. This is particularly the case for instruments that
3.2.2 mass bias or fractionation, n—the deviation of the
provide only nominal unit mass resolution at 10% of the peak
observed or measured isotope ratio from the true ratio as a
height. For this test method, the Q-ICP-MS peak resolution
function of the difference in mass between the two isotopes.
for U was set to within 0.70 6 0.15 daltons (Atomic Mass
Thisdeviationistheresultofseveraldifferentprocesses.Ithas
Units-AMU) full-width-tenth-maximum (FWTM) peak height
been suggested that the Q-ICP-MS ion transmission and
to reduce adjacent peak interference effects.
focusing device create a dense space charge effect, which can
6.2 Isobaric Molecular Ion Interferences— U could inter-
cause a preferential loss of lighter isotopes. The result is an
236 +
fere with U determinations by forming a UH ion. Follow
under estimation of the lighter isotopes which can be signifi-
5 the instrument manufacturer’s instructions to minimize these
cant. “Rayleigh fractionation associated with sample evapo-
molecular ion formations, for example by optimizing the
rationinwhichlighterisotopesarecarriedawaypreferentially”
nebulizer gas flow rate. The use of a calibration standard that
is insignificant with solution nebulization, but with other
is similar in isotopic composition and intensity to the samples
methods of introduction such as electrothermal vaporization,
reducesthepotentialbiasfromthisinterferenceeffect.Thebias
can be more significant.
+
from the UH interference only becomes significant for the
integrated peak intensity of U when the sample intensity
4. Summary of Test Method
deviates from the calibration standard intensity and it is very
4.1 A sample of the nuclear-grade material (nominally 0.2
low, that is, near the background intensity contribution. A
g) is digested in HNO or a HNO /HF mixture and diluted in
3 3
naturally enriched standard, which contains no U, can be
used to test the significance of this interference.
6.3 Memory Interference Effects—Memory effects or
Jarvis, K. E., Gray, A. L., and Houk, R. S., Handbook of Inductively Coupled
Plasma Mass Spectrometry, Blackie and Son Ltd., Glasgow and London, or
sample carryover can occur from previously run samples.
Chapman and Hall, New York, 1992.
Theseeffectscanbedetectedinseveralways.Firstofall,ifthe
Date,A.R.,andGray,A.L., Applications of Inductively Coupled Plasma Mass
bias factors from the calibration standard are outside of a
Spectrometry, Blackie and Son Ltd., Glasgow and London, or Chapman and Hall,
NewYork, 1989. normaltendedrange,itcanshowthattheglasswareanduptake
C1474 − 19
system is contaminated with another enrichment. Secondly, it standard secondary stock solution (see 8.7) to a 125-mL
can be detected by looking at the standard deviation of the polypropylene sample bottle, and dilute to approximately 84.7
repeat trials from a sample analysis and whether the peak g with water.
intensitymeasurementsarerandombetweentherepeattrialsor
NOTE 1—The concentration of the calibration and control standard
whether they drift toward increasing or decreasing intensity.
solutions are adjusted or remade for a given sample batch analysis to
Also, the percent standard deviation (% SD) of the intensity
achieve a maximum established uranium intensity measurement. Refer to
ratios should be less than or on the same order of the % SD of 13.1.5 for directions on how this intensity level of the uranium isotope
sumisdetermined.Theintensitysumwasestablishedat2.0 60.2million
the peak intensities. If the peak intensity measurements are
counts per second (cps) for the data presented. The sensitivity, and
higher, then it may be an indication of a memory effect from a
therefore this concentration, is dependent upon the user’s own instrumen-
sample of a different enrichment level. It could also be
tation.The2.0-millioncpsintensitylevelisestablishedbasedonanupper
indicative of general instrument instability or problems with
intensity level at which the instrument continues to operate in a linear
intensity versus concentration range, and is therefore also instrument
sample uptake and delivery to the plasma.
dependent. Intensity levels above this range can become nonlinear as a
function of concentration due to dead time effects.
7. Apparatus
8.6 Isotopic Enrichment Standard Primary Stock Solutions,
7.1 Balance, with precision of 0.0001 g.
5000 µg of U O per g of solution (4235 µg of U per g of
3 8
7.2 Polytetrafluoroethylene (PTFE) Oak Ridge Tubes,30
solution)—0.250 g of the appropriate NBL U O isotopic
3 8
mL, or equivalent.
standard heated to dissolve with 5 mL of water and 10 mL of
7.3 Drying Oven, controlled at 108 6 5°C. concentrated HNO , then diluted to 50.0 g of water in a
125-mL polypropylene sample bottle.
7.4 Polypropylene Sample Bottle, 125 mL, or equivalent.
8.7 Isotopic Enrichment Standard Secondary Stock
7.5 Disposable Polypropylene Tubes With Snap-on Caps ,
Solutions, 84.7 µg of U per g of solution—Add 2.0 mL of the
14 mL, or equivalent.
appropriate isotopic enrichment standard primary stock solu-
7.6 Q-ICP-MS Instrument, controlled by computer and
tion (see 8.6) to a 125-mLpolypropylene sample bottle, add 5
fitted with the associated software and peripherals.
mL of concentrated HNO , then dilute to 100.0 g with water.
7.7 Peristaltic Pump.
NOTE 2—The isotopic calibration standard and analysis control mate-
rials should be within 1.0 Wt % of the U enrichment to be analyzed in
8. Reagents and Materials 234
unknown sample materials. Likewise, the low-abundance isotopes ( U
and U)shouldbeincloseagreementbetweenstandardsandsamples.It
8.1 Purity of Reagents—Reagent grade chemicals shall be
is recommended that separate primary and secondary stock solutions be
used in all tests. Unless otherwise indicated, it is intended that
made from a separate and preferably an independent source of isotopic
all reagents conform to the specifications of the Committee on
enrichment standard (to serve as standard and control stock solutions) if
Analytical Reagents of theAmerican Chemical Society where
such a source can be found. However, given the limited availability of
such standards, the primary and secondary stock solutions may be made
Other grades may be used
such specifications are available.
from the same enrichment CRM, with separate dissolutions and bottles
provided it is first ascertained that the reagent is of sufficiently
being designated as standard and control stock solutions.
high purity to permit its use without lessening the accuracy of
8.8 Isotopic Enrichment U O Standards—New Brunswick
the determination. 3 8
Laboratory (NBL) Certified Reference Materials (CRMs),
8.2 Purity of Water—Unless otherwise indicated, references
dependingontheenrichmentleveltobeanalyzed:forexample,
to water shall be understood to mean reagent water, as defined
CRM U-010, CRM U-030, CRM U-030A, CRM U-050, CRM
by Type I of Specification D1193.
U-200, CRM U-350, CRM U-500, CRM U-750, CRM U-850,
8.3 Hydrofluoric Acid (sp gr 1.18)—49% w/w concentrated
CRM U-900, CRM U-930, and CRM U-970.
hydrofluoric acid (HF).
8.9 Nitric Acid (sp gr 1.42)—70% w/w concentrated nitric
8.4 Isotopic Calibration Standard, 0.10 µg of U per g of
acid (HNO ).
solution—Add 100 uL of the appropriate isotopic calibration
8.10 U Isotopic Enrichment Spike Standard—New
standard secondary stock solution (see 8.7) to a 125-mL
Brunswick Laboratory (NBL) CRM 111A, used as a spike
polypropylene sample bottle, and dilute to approximately 84.7
addition. This standard is listed for optional use by the user as
g with water.
aspikeadditiontotheotherstandardspreviouslygiven,if U
8.5 Isotopic Control Standard, 0.10 µg of U per g of
is found to be present in measurable quantities for the sample
solution—Add 100 uL of the appropriate isotopic control
materials (see 1.2)
8.11 Nitric/Hydrofluoric Acid Rinse Solution (4% HNO
6 v/v and 0.5% HF v/v)—Add approximately 6.0 mL of con-
PTFE Oak Ridge Tubes (30 mL) and 14-mL disposable polypropylene tubes
with snap-on caps are available from Fisher Scientific or other major laboratory
centratedHNO and1.0mLofconcentratedHFtowater,dilute
supply house.
to 100 mL, and mix.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory 9. Hazards
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopoeia
9.1 The plasma or ICP of the instrument is at a very high
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. temperature and emits ozone and intense ultraviolet light.
C1474 − 19
Protection from such radiation and emissions are provided by 11.5 Remove the tube from the oven and allow it to cool to
the instrument shields and covers along with adequate venti- or below room temperature. The sample may be placed under
lation of the chamber exhaust. a cool water flow or in a refrigerator for 5 min to aid in the
cooling.
9.2 Since uranium-bearing materials are radioactive and
11.6 Open the sample tube and add about 10 mL of water.
toxic,adequatelaboratoryfacilitiesandfumehoodsalongwith
Replacethecaptoshakeorswirlthetubeandthen,afterletting
safehandlingtechniquesmustbeused.Adetaileddiscussionof
any solids settle to the bottom, decant off the liquid into a tare
all safety precautions needed is beyond the scope of this test
weighed 125-mLsample bottle. Repeat the water addition and
method. Follow site- and facility-specific radiation protection
decanting a second time.
and chemical hygiene plans.
11.7 With about 0.5 mL of water placed in the tube or
9.3 Hydrofluoric acid is a highly corrosive acid that can
remaining from the decanting process, add 1.0 mL of concen-
severely burn skin, eyes, and mucous membranes. Hydroflu-
trated HNO to the tube and replace the cap.
oric acid differs from other acids because the fluoride ion
readily penetrates the skin, causing destruction of deep tissue 11.8 Placethetubebackintheovensetat108 65°Cfor20
to 60 min. If all of the undissolved material goes into solution,
layers. Unlike other acids that are rapidly neutralized, hydro-
fluoric acid reactions with tissue may continue for days if left thetubemayberemovedfromtheovenbeforethe60-mintime
period, otherwise remove it after 60 min.
untreated.FamiliarizationandcompliancewiththeSafetyData
Sheet is essential.
11.9 Allowthetubetocooltoorbelowroomtemperatureas
described in 11.5.
10. Sampling, Test Specimens, and Test Units
11.10 Open the sample tube and add about 10 mLof water.
10.1 Criteria for material sampling are given in Specifica-
Replacethecaptoshakeorswirlthetube.Ifanysolidsremain
tions C753 and C776 for the material types that they address
in the tube, let them settle to the bottom, then decant off the
and can also be used as a guidance for other material types.
liquidintothe125-mLsamplebottle.Repeatthewateraddition
Generally, only about 0.2 g of material is used during sample
and decant a second time.
digestion and it is then diluted to a proper concentration level.
11.11 Ifsolidsremaininthetube,returnto11.3torepeatthe
Because so little material is actually used (about 2 µg), often
acid dissolution. Once the sample is completely dissolved,
times the remainder portion of the sample from some other
thoroughly rinse the tube into the sample bottle.
analysis, such as uranium titration, is taken and diluted
11.12 Dilute the sample in the bottle to approximately 100
appropriately. Since the analysis is performed at a very low
g or a dilution factor of about 500:100-g solution/0.20-g
concentration level, the dilutions are easily subject to
sample = 500.
contamination,therefore,disposableplasticwareisusedwhen-
ever possible.
11.13 Dilute the sample into a labelled 14-mL disposable
polypropylene tube by taking 200 µL of sample from the
11. Sample Preparation
sample bottle and diluting to 10 mL with water.
NOTE 3—The sample preparation discussed as follows is designed for
thedissolutionoffuelproductmaterialorothermaterialtypesthatrequire
12. Preparation of Apparatus
a HNO /HF acid dissolution. It provides a complete dissolution of the
12.1 Set up the necessary instrument software files for data
material that may then be used for other analyses. A simple acid leach
followed by dilution may be adequate for the user’s needs. The initial
acquisition, calculation, archival, and so forth. The instrument
stage of the dissolution (using H O/HNO /HF) may be omitted for
2 3
software of many instruments can establish and apply the
material that can be dissolved using only HNO , such as U O . Other
3 3 8
appropriateequationsdiscussedasfollowswhichrepresentthe
sample preparation methods may be used which result in a HNO matrix
235 238
sum of the uranium isotopes as either Uor U. If the
(about 1 to 2% w/v) which may have a trace presence of HF (less than
1%w/v)afterdilutiontoaconcentrationofabout0.10µgofuraniumper
instrumentdoesnothavethisability,thedatamanipulationcan
gram of solution for analysis. Refer to Practice C1347.The UNH crystals
be performed using an external software program.
are prepared in water and diluted to the appropriate concentration.
12.1.1 Two separate equations are set up for use in the data
manipulation, one for high-enriched uranium (HEU) isotopic
11.1 Weigh out approximately 0.20 g of material into a
30-mL PTFE Oak Ridge tube. measurements and one for low-enriched uranium (LEU) iso-
topic analyses. In each case, the high-abundance isotope
11.2 If the material type is known to be digested using
intensity is set to equal the sum of all of the uranium isotope
HNO alone,thenadd0.5mLofwatertothetubeandproceed
235 238
intensities, then redefined as either U* or U*, for high-
to 11.7.
enrichment and low-enrichment analyses, respectively. The
equations are given as follows:
11.3 Add 100 µL of water and 100 µL of concentrated
The HEU analysis equation:
HNO to the tube.Add 100 µLof concentrated HF to the tube
and immediately cap the tube tightly to avoid sample loss 235 233 234 235 236 238
U*5 Uint 1 Uint 1 Uint 1 Uint 1 Uint (1)
beforeanyreactionfullydevelops.Shakeorswirlittomixthe
The LEU analysis equation:
material thoroughly.
238 233 234 235 236 238
U*5 Uint 1 Uint 1 Uint 1 Uint 1 Uint (2)
11.4 Place the tube in a small beaker or container to hold it
upright and place it in the oven set at 108 6 5°C for 45 min. where:
C1474 − 19
233 233
The establishment of a calibration in which the measured
Uint = measured U peak intensity,
234 234
intensity ratio (low-abundance isotope-to-intensity sum) is set
Uint = measured U peak intensity,
235 235
to equal the weight percent of t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C1474 − 00 (Reapproved 2011) C1474 − 19
Standard Test Method for
Analysis of Isotopic Composition of Uranium in Nuclear-
Grade Fuel Material by Quadrupole Inductively Coupled
Plasma-Mass Spectrometry
This standard is issued under the fixed designation C1474; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method is applicable to the determination of the isotopic composition of uranium (U) in nuclear-grade fuel
material. The following isotopic weight percentages are determined using a quadrupole inductively coupled plasma-mass
233 234 235 236 238
spectrometer (Q-ICP-MS): U, U, U, U, and U. The analysis can be performed on various material matrices after acid
dissolution and sample dilution into water or dilute nitric (HNO ) acid. These materials include: fuel product, uranium oxide,
uranium oxide alloys, uranyl nitrate (UNH) crystals, and solutions. The sample preparation discussed in this test method focuses
on fuel product material but may be used for uranium oxide or a uranium oxide alloy. Other preparation techniques may be used
and some references are given. Purification of the uranium by anion-exchange extraction is not required for this test method, as
it is required by other test methods such as radiochemistry and thermal ionization mass spectroscopy (TIMS). This test method
is also described in ASTM STP 1344 .
233 233
1.2 The U isotope is primarily measured as a qualitative measure of its presence by comparing the U peak intensity to a
background point since it is not normally found present in materials. The example data presented in this test method do not contain
233 233
any U data. A U enriched standard is given in Section 8, and it may be used as a quantitative spike addition to the other
standard materials listed.
1.3 A single standard calibration technique is used. Optimal accuracy (or a low bias) is achieved through the use of a single
standard that is closely matched to the enrichment of the samples. The intensity or concentration is also adjusted to within a certain
tolerance range to provide good statistical counting precision for the low-abundance isotopes while maintaining a low bias for the
high-abundance isotopes, resulting from high-intensity dead time effects. No blank subtraction or background correction is utilized.
Depending upon the standards chosen, enrichments between depleted and 97 % can be quantified. The calibration and
233 234 235
measurements are made by measuring the intensity ratios of each low-abundance isotope to the intensity sum of U, U, U,
236 238
U, and U. The high-abundance isotope is obtained by difference.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
The instrument is calibrated and the samples measured in units of isotopic weight percent (Wt %). For example, the U
235 235
enrichment may be stated as Wt % U or as g U/100 g of U. Statements regarding dilutions, particularly for ug/gμg/g
concentrations or lower, are given assuming a solution density of 1.0 since the uranium concentration of a solution is not important
when making isotopic ratio measurements other than to maintain a reasonably consistent intensity within a tolerance range.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 9.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.
Current edition approved June 1, 2011Feb. 1, 2019. Published June 2011February 2019. Originally approved in 2000. Last previous edition approved in 20062011 as
ε1
C1474 – 00 (2006)(2011). . DOI: 10.1520/C1474-00R11.10.1520/C1474-19.
Policke, T. A., Bolin, R. N., and Harris, T. L., “Uranium Isotope Measurements by Quqdrupole ICP-MS for Process Monitoring of Enrichment,” Symposium on
Applications of Inductively Coupled Plasma-Mass Spectrometry to Radionuclide Determinations: Second Volume, ASTM STP 1344, ASTM, 1998, p. 3.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1474 − 19
2. Referenced Documents
2.1 ASTM Standards:
C753 Specification for Nuclear-Grade, Sinterable Uranium Dioxide Powder
C776 Specification for Sintered Uranium Dioxide Pellets for Light Water Reactors
C778 Specification for Standard Sand
C833 Specification for Sintered (Uranium-Plutonium) Dioxide Pellets for Light Water Reactors
C859 Terminology Relating to Nuclear Materials
C1347 Practice for Preparation and Dissolution of Uranium Materials for Analysis
D1193 Specification for Reagent Water
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E456 Terminology Relating to Quality and Statistics
E882 Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms relating to analytical atomic spectroscopy, refer to Terminology E135.
3.1.2 For definitions of terms relating to statistics, refer to Terminology E456.
3.1.3 For definitions of terms relating to nuclear materials, refer to Terminology C859.
3.1.4 For definitions of terms specifically related to Q-ICP-MS in addition to those found in 3.2, refer to Appendix 3 of Jarvis
et al.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 dead time, n—the interval during which the detector and its associated counting electronics are unable to record another
event or resolve successive pulses. The instrument signal response becomes nonlinear above a certain count rate due to dead time
effects.
3.2.2 mass bias or fractionation, n—the deviation of the observed or measured isotope ratio from the true ratio as a function
of the difference in mass between the two isotopes. This deviation is the result of several different processes. It has been suggested
that the Q-ICP-MS ion transmission and focusing device create a dense space charge effect, which can cause a preferential loss
of lighter isotopes. The result is an under estimation of the lighter isotopes which can be significant. “Rayleigh fractionation
associated with sample evaporation in which lighter isotopes are carried away preferentially” is insignificant with solution
nebulization, but with other methods of introduction such as electrothermal vaporization, can be more significant.
4. Summary of Test Method
4.1 A sample of the nuclear-grade material (nominally 0.2 g) is digested in HNO or a HNO /HF mixture and diluted in series
3 3
to a concentration of approximately 0.10 ugμg of uranium per gram of solution (ug(μg U/g solution or ppm of U). Other dissolution
methods may be used. A standard peristaltic pump is used as the means of sample introduction into the plasma. The uranium
intensity (that is, concentration), as initially indicated by a ratemeter reading, is adjusted to within a certain tolerance range to
provide good precision and a reduced bias for all sample, standard, and control measurements. A calibration standard is run and
all sample analyses are bracketed by the analysis of controls. Calculations are performed to measure the intensity ratios of each
233 234 235 236 238
low-abundance isotope to the intensity sum of U, U, U, U, and U. Mass bias correction factors, which are established
using the instrument software and the calibration standard data, are then applied to the sample and control data. The corrected ratio
measurement for a low abundance isotope is equal to the abundance of that isotope (for example the U intensity/U isotope
intensity sum equals the U abundance). The high abundance isotope is determined by subtracting the low-abundance isotopes
from 100 %.
5. Significance and Use
5.1 Nuclear-grade reactor fuel material must meet certain criteria, such as those described in Specifications C753, C776, C778,
and C833. Included in these criteria is the uranium isotopic composition. This test method is designed to demonstrate whether or
not a given material meets an isotopic requirement and whether the effective fissile content is in compliance with the purchaser’s
specifications.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Jarvis, K.E., Gray, A.L., K. E., Gray, A. L., and Houk, R.S., R. S., Handbook of Inductively Coupled Plasma Mass Spectrometry, Blackie and Son Ltd., Glasgow and
London, or Chapman and Hall, New York, 1992.
Date, A. R., and Gray, A.L., A. L., Applications of Inductively Coupled Plasma Mass Spectrometry, Blackie and Son Ltd., Glasgow and London, or Chapman and Hall,
New York, 1989.
C1474 − 19
6. Interferences
6.1 Adjacent Isotopic Peak Effects—Interferences can occur from adjacent isotopes of high concentration, such as an intense
235 234
U peak interfering with the measurement of U
and U. This is particularly the case for instruments that provide only nominal unit mass resolution at 10 % of the peak height.
For this test method, the Q-ICP-MS peak resolution
for U was set to within 0.70 6 0.15 daltons (Atomic Mass Units-AMU) full-width-tenth-maximum (FWTM) peak height to
reduce adjacent peak interference effects.
235 236 +
6.2 Isobaric Molecular Ion Interferences— U could interfere with U determinations by forming a UH ion. Follow the
instrument manufacturer’s instructions to minimize these molecular ion formations, for example by optimizing the nebulizer gas
flow rate. The use of a calibration standard that is similar in isotopic composition and intensity to the samples reduces the potential
+
bias from this interference effect. The bias from the UH interference only becomes significant for the integrated peak intensity
of U when the sample intensity deviates from the calibration standard intensity and it is very low, that is, near the background
intensity contribution. A naturally enriched standard, which contains no U, can be used to test the significance of this
interference.
6.3 Memory Interference Effects—Memory effects or sample carryover can occur from previously run samples. These effects can
be detected in several ways. First of all, if the bias factors from the calibration standard are outside of a normal tended range, it
can show that the glassware and uptake system is contaminated with another enrichment. Secondly, it can be detected by looking
at the standard deviation of the repeat trials from a sample analysis and whether the peak intensity measurements are random
between the repeat trials or whether they drift toward increasing or decreasing intensity. Also, the percent standard deviation (%
SD) of the intensity ratios should be less than or on the same order of the % SD of the peak intensities. If the peak intensity
measurements are higher, then it may be an indication of a memory effect from a sample of a different enrichment level. It could
also be indicative of general instrument instability or problems with sample uptake and delivery to the plasma.
7. Apparatus
7.1 Balance, with precision of 0.000010.0001 g.
7.2 Polytetrafluoroethylene (PTFE) Oak Ridge Tubes , 30 mL, or equivalent.
7.3 Drying Oven, controlled at 108 6 5°C.
7.4 Polypropylene Sample Bottle, 125 mL, or equivalent.
7.5 Disposable Polypropylene Tubes With Snap-on Caps , 14 mL, or equivalent.
7.6 Q-ICP-MS Instrument, controlled by computer and fitted with the associated software and peripherals.
7.7 Peristaltic Pump.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such
specifications are available. Other grades may be used provided it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
8.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water, as defined by
Type I of Specification D1193.
8.3 Hydrofluoric Acid (sp gr 1.18)—49 % w/w concentrated hydrofluoric acid (HF).
8.4 Isotopic Calibration Standard, 0.10 ugμg of U per g of solution—Add 100 uL of the appropriate isotopic calibration standard
secondary stock solution (see 8.7) to a 125-mL polypropylene sample bottle, and dilute to approximately 84.7 g with water.
8.5 Isotopic Control Standard, 0.10 ugμg of U per g of solution—Add 100 uL of the appropriate isotopic control standard
secondary stock solution (see 8.7) to a 125-mL polypropylene sample bottle, and dilute to approximately 84.7 g with water.
NOTE 1—The concentration of the calibration and control standard solutions are adjusted or remade for a given sample batch analysis to achieve a
maximum established uranium intensity measurement. Refer to 13.1.5 for directions on how this intensity level of the uranium isotope sum is determined.
The intensity sum was established at 2.0 6 0.2 million counts per second (cps) for the data presented. The sensitivity, and therefore this concentration,
is dependent upon the user’s own instrumentation. The 2.0-million cps intensity level is established based on an upper intensity level at which the
instrument continues to operate in a linear intensity versus concentration range, and is therefore also instrument dependent. Intensity levels above this
PTFE Oak Ridge Tubes (30 mL) and 14-mL disposable polypropylene tubes with snap-on caps are available from Fisher Scientific or other major laboratory supply house.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopoeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
C1474 − 19
range can become nonlinear as a function of concentration due to dead time effects.
8.6 Isotopic Enrichment Standard Primary Stock Solutions, 5000 ugμg of U O per g of solution (4235 ugμg of U per g of
3 8
solution)—0.250 g of the appropriate NBL U O isotopic standard heated to dissolve with 5 mL of water and 10 mL of
3 8
concentrated HNO , then diluted to 50.0 g of water in a 125-mL polypropylene sample bottle.
8.7 Isotopic Enrichment Standard Secondary Stock Solutions, 84.7 ugμg of U per g of solution—Add 2.0 mL of the appropriate
isotopic enrichment standard primary stock solution (see 8.6) to a 125-mL polypropylene sample bottle, add 5 mL of concentrated
HNO , then dilute to 100.0 g with water.
NOTE 2—The isotopic calibration standard and analysis control materials should be within 1.0 Wt % of the U enrichment to be analyzed in unknown
234 236
sample materials. Likewise, the low-abundance isotopes ( U and U) should be in close agreement between standards and samples. It is recommended
that separate primary and secondary stock solutions be made from a separate and preferably an independent source of isotopic enrichment standard (to
serve as standard and control stock solutions) if such a source can be found. However, given the limited availability of such standards, the primary and
secondary stock solutions may be made from the same enrichment CRM, with separate dissolutions and bottles being designated as standard and control
stock solutions.
8.8 Isotopic Enrichment U O Standards—New Brunswick Laboratory (NBL) Certified Reference Materials (CRMs),
3 8
depending on the enrichment level to be analyzed: for example, CRM U-010, CRM U-030, CRM U-030A, CRM U-050, CRM
U-200, CRM U-350, CRM U-500, CRM U-750, CRM U-850, CRM U-900, CRM U-930, and CRM U-970.
8.9 Nitric Acid (sp gr 1.42)—70 % w/w concentrated nitric acid (HNO ).
8.10 U Isotopic Enrichment Spike Standard—New Brunswick Laboratory (NBL) CRM 111A, used as a spike addition. This
standard is listed for optional use by the user as a spike addition to the other standards previously given, if U is found to be
present in measurable quantities for the sample materials (see 1.2)
8.11 Nitric/Hydrofluoric Acid Rinse Solution (4 % HNO v/v and 0.5 % HF v/v)—Add approximately 6.0 mL of concentrated
HNO and 1.0 mL of concentrated HF to water, dilute to 100 mL, and mix.
9. Hazards
9.1 The plasma or ICP of the instrument is at a very high temperature and emits ozone and intense ultraviolet light. Protection
from such radiation and emissions are provided by the instrument shields and covers along with adequate ventilation of the
chamber exhaust.
9.2 Since uranium-bearing materials are radioactive and toxic, adequate laboratory facilities and fume hoods along with safe
handling techniques must be used. A detailed discussion of all safety precautions needed is beyond the scope of this test method.
Follow site- and facility-specific radiation protection and chemical hygiene plans.
9.3 Acute exposure to HF can cause painful and severe burns upon skin contact that require special medical attention. Chronic
or prolonged exposure to low levels on the skin may cause fluorosis.Hydrofluoric acid is a highly corrosive acid that can severely
burn skin, eyes, and mucous membranes. Hydrofluoric acid differs from other acids because the fluoride ion readily penetrates the
skin, causing destruction of deep tissue layers. Unlike other acids that are rapidly neutralized, hydrofluoric acid reactions with
tissue may continue for days if left untreated. Familiarization and compliance with the Safety Data Sheet is essential.
10. Sampling, Test Specimens, and Test Units
10.1 Criteria for material sampling are given in Specifications C753 and C776 for the material types that they address and can
also be used as a guidance for other material types. Generally, only about 0.2 g of material is used during sample digestion and
it is then diluted to a proper concentration level. Because so little material is actually used (about 2 ug),μg), often times the
remainder portion of the sample from some other analysis, such as uranium titration, is taken and diluted appropriately. Since the
analysis is performed at a very low concentration level, the dilutions are easily subject to contamination, therefore, disposable
plastic ware is used whenever possible.
11. Sample Preparation
NOTE 3—The sample preparation discussed as follows is designed for the dissolution of fuel product material or other material types that require a
HNO /HF acid dissolution. It provides a complete dissolution of the material that may then be used for other analyses. A simple acid leach followed by
dilution may be adequate for the user’s needs. The initial stage of the dissolution (using H O/HNO /HF) may be omitted for material that can be dissolved
2 3
using only HNO , such as U O . Other sample preparation methods may be used which result in a HNO matrix (about 1 to 2 % w/v) which may have
3 3 8 3
a trace presence of HF (less than 1 % w/v) after dilution to a concentration of about 0.10 ugμg of uranium per gram of solution for analysis. Refer to
Practice C1347. The UNH crystals are prepared in water and diluted to the appropriate concentration.
11.1 Weigh out approximately 0.18 6 0.02 0.20 g of material into a 30-mL PTFE Oak Ridge tube.
11.2 If the material type is known to be digested using HNO alone, then add 0.5 mL of water to the tube and proceed to 11.7.
11.3 Add 100 uLμL of water and 100 uLμL of concentrated HNO to the tube. Add 100 uLμL of concentrated HF to the tube
and immediately cap the tube tightly to avoid sample loss before any reaction fully develops. Shake or swirl it to mix the material
thoroughly.
C1474 − 19
11.4 Place the tube in a small beaker or container to hold it upright and place it in the oven set at 108 6 3°C5°C for 45 min.
11.5 Remove the tube from the oven and allow it to cool to or below room temperature. The sample may be placed under a cool
water flow or in a refrigerator for 5 min to aid in the cooling.
11.6 Open the sample tube and add about 10 mL of water. Replace the cap to shake or swirl the tube and then, after letting any
solids settle to the bottom, decant off the liquid into a tare weighed 125-mL sample bottle. Repeat the water addition and decanting
a second time.
11.7 With about 0.5 mL of water placed in the tube or remaining from the decanting process, add 1.0 mL of concentrated HNO
to the tube and replace the cap.
11.8 Place the tube back in the oven set at 108 6 3°C5°C for 20 to 60 min. If all of the undissolved material goes into solution,
the tube may be removed from the oven before the 60-min time period, otherwise remove it after 60 min.
11.9 Allow the tube to cool to or below room temperature as described in 11.5.
11.10 Open the sample tube and add about 10 mL of water. Replace the cap to shake or swirl the tube. If any solids remain in
the tube, let them settle to the bottom, then decant off the liquid into the 125-mL sample bottle. Repeat the water addition and
decant a second time.
11.11 If solids remain in the tube, return to 11.3 to repeat the acid dissolution. Once the sample is completely dissolved,
thoroughly rinse the tube into the sample bottle.
11.12 Dilute the sample in the bottle to approximately 100 g or a dilution factor of about 500:100-g solution/0.20-g sample =
500.
11.13 Dilute the sample into a labelled 14-mL disposable polypropylene tube by taking 200 uLμL of sample from the sample
bottle and diluting to 10 mL with water.
12. Preparation of Apparatus
12.1 Set up the necessary instrument software files for data acquisition, calculation, archival, and so forth. The instrument
software of many instruments can establish and apply the appropriate equations discussed as follows which represent the sum of
235 238
the uranium isotopes as either U or U. If the instrument does not have this ability, the data manipulation can be performed
using an external software program.
12.1.1 Two separate equations are set up for use in the data manipulation, one for high-enriched uranium (HEU) isotopic
measurements and one for low-enriched uranium (LEU) isotopic analyses. In each case, the high-abundance isotope intensity is
235 238
set to equal the sum of all of the uranium isotope intensities, then redefined as either U* or U*, for high-enrichment and
low-enrichment analyses, respectively. The equations are given as follows:
The HEU analysis equation:
235 233 234 235 236 238
U*5 Uint 1 Uint 1 Uint 1 Uint 1 Uint (1)
The LEU analysis equation:
238 233 234 235 236 238
U*5 Uint 1 Uint 1 Uint 1 Uint 1 Uint (2)
where:
233 233
Uint = measured U peak intensity,
234 234
Uint = measured U peak intensity,
235 235
U
...