ASTM C1267-17(2022)
(Test Method)Standard Test Method for Uranium by Iron (II) Reduction in Phosphoric Acid Followed by Chromium (VI) Titration in the Presence of Vanadium
Standard Test Method for Uranium by Iron (II) Reduction in Phosphoric Acid Followed by Chromium (VI) Titration in the Presence of Vanadium
SIGNIFICANCE AND USE
5.1 Factors governing selection of a method for the determination of uranium include available quantity of sample, homogeneity of material sampled, sample purity, desired level of reliability, and facility available equipment.
5.2 This uranium assay method is referenced in the Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Uranium Dioxide Powders and Pellets (Test Methods C696) and in the Test Methods for Chemical, Mass Spectrometric, and Spectrochemical, Nuclear, and Radiochemical Analysis of Nuclear-Grade Uranyl Nitrate Solutions (Test Methods C799). This uranium assay method may also be used for uranium hexafluoride and uranium ore concentrate. This test method determines 20 mg to 200 mg of uranium; is applicable to product, fuel, and scrap material after the material is dissolved; is tolerant towards most metallic impurity elements usually specified in product and fuel; and uses no special equipment.
5.3 The ruggedness of the titration method has been studied for both the volumetric (6) and the weight (7) titration of uranium with dichromate.
5.4 Fitness for Purpose of Safeguards and Nuclear Safety Application—Methods intended for use in safeguards and nuclear safety applications shall meet the requirements specified by Guide C1068 for use in such applications.
5.4.1 When used in conjunction with the appropriate certified reference materials (SRM6 or CRM), this procedure can demonstrate traceability to the national measurement base. However, use of the test method does not automatically guarantee regulatory acceptance of the resulting safeguards measurements. It remains the sole responsibility of the user of this test method to assure that its application to safeguards has the approval of the proper regulatory authorities.
SCOPE
1.1 This test method, commonly referred to as the Modified Davies and Gray technique, covers the titration of uranium in product, fuel, and scrap materials after the material is dissolved. The test method is versatile and has been ruggedness tested. With appropriate sample preparation, this test method can give precise and unbiased uranium assays over a wide variety of material types (1, 2).2 Details of the titration procedure in the presence of plutonium with appropriate modifications are given in Test Method C1204.
1.2 Uranium levels titrated are usually 20 mg to 50 mg, but up to 200 mg uranium can be titrated using the reagent volumes stated in this test method.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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. For specific safeguard and safety precaution statements, see Section 5.
1.5 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.
General Information
Relations
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: C1267 − 17 (Reapproved 2022)
Standard Test Method for
Uranium by Iron (II) Reduction in Phosphoric Acid Followed
by Chromium (VI) Titration in the Presence of Vanadium
This standard is issued under the fixed designation C1267; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method, commonly referred to as the Modified
C696Test Methods for Chemical, Mass Spectrometric, and
Davies and Gray technique, covers the titration of uranium in
SpectrochemicalAnalysis of Nuclear-Grade Uranium Di-
product, fuel, and scrap materials after the material is dis-
oxide Powders and Pellets
solved. The test method is versatile and has been ruggedness
C799Test Methods for Chemical, Mass Spectrometric,
tested. With appropriate sample preparation, this test method
Spectrochemical,Nuclear,andRadiochemicalAnalysisof
can give precise and unbiased uranium assays over a wide
Nuclear-Grade Uranyl Nitrate Solutions
variety of material types (1, 2). Details of the titration
C859Terminology Relating to Nuclear Materials
procedure in the presence of plutonium with appropriate
C1068Guide for Qualification of Measurement Methods by
modifications are given in Test Method C1204.
a Laboratory Within the Nuclear Industry
1.2 Uranium levels titrated are usually 20mg to 50mg, but
C1128Guide for Preparation of Working Reference Materi-
up to 200mg uranium can be titrated using the reagent
als for Use in Analysis of Nuclear Fuel Cycle Materials
volumes stated in this test method.
C1204Test Method for Uranium in Presence of Plutonium
by Iron(II) Reduction in Phosphoric Acid Followed by
1.3 The values stated in SI units are to be regarded as
Chromium(VI) Titration
standard. No other units of measurement are included in this
C1346Practice for Dissolution of UF from P-10 Tubes
standard.
C1347Practice for Preparation and Dissolution of Uranium
1.4 This standard does not purport to address all of the
Materials for Analysis
safety concerns, if any, associated with its use. It is the
2.2 NIST Standard:
responsibility of the user of this standard to establish appro-
SRM 136ePotassium Dichromate (Oxidimetric Standard)
priate safety, health, and environmental practices and deter-
2.3 NBL Standard:
mine the applicability of regulatory limitations prior to use.
CRM 112AUranium Metal Standard
For specific safeguard and safety precaution statements, see
3. Terminology
Section 5.
1.5 This international standard was developed in accor- 3.1 Except as otherwise defined herein, definitions of terms
dance with internationally recognized principles on standard-
are as given in Terminology C859.
ization established in the Decision on Principles for the
4. Summary of Test Method
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4.1 Samplesarepreparedbydissolutiontechniquesdetailed
Barriers to Trade (TBT) Committee.
in Practices C1346, C1347, or Refs (2), (3), and (4). Appro-
priate uncertainties for sampling and weight determination
1 3
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Test. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJuly1,2022.PublishedJuly2022.Originallyapproved the ASTM website.
in 1994. Last previous edition approved in 2017 as C1267–17. DOI: 10.1520/ Available from National Institute of Standards and Technology (NIST), 100
C1267-17R22. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
2 5
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof NewBrunswickLaboratory(NBL)CertifiedReferenceMaterialsCatalog(U.S.
this standard. Department of Energy), http://science.energy.gov/nbl.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1267 − 17 (2022)
should be applied to the overall precision and bias calculations 5.4.1 When used in conjunction with the appropriate certi-
for the final result. Aliquants containing 20mg to 200 mg of fied reference materials (SRM or CRM), this procedure can
uranium are prepared by weight. The sample is fumed to demonstrate traceability to the national measurement base.
dryness after the appropriate acid treatment. The sample is However, use of the test method does not automatically
guarantee regulatory acceptance of the resulting safeguards
dissolved in dilute nitric acid or water prior to titration.
measurements. It remains the sole responsibility of the user of
4.2 Uraniumisreducedtouranium(IV)byexcessiron(II)in
this test method to assure that its application to safeguards has
concentrated phosphoric acid (H PO ) containing sulfamic
3 4
the approval of the proper regulatory authorities.
acid. The excess iron(II) is selectively oxidized by nitric acid
(HNO ) in the presence of a molybdenum(VI) catalyst. After
6. Interferences
the addition of a vanadium(IV) solution, the uranium(IV) is
6.1 Interferingelementsarenotgenerallypresentinproduct
titrated with chromium(VI) to a potentiometric end point.
and fuel material in quantities which cause interference in the
4.3 Thechromium(VI)titrantmaybedeliveredmanuallyon
titration.
a weight or on a volumetric basis as specified by the facility
6.1.1 Of the metallic impurity elements usually included in
titration procedure.
specifications for product and fuel, silver, manganese, and
4.3.1 If the titrant is delivered on a volumetric basis, vanadium (in the V oxidation state) interfere when present in
correctionstothevolumeoftitrantmaybeneededtoadjustfor amounts of 10 mg or greater of impurity per 100 mg of
the difference between the temperature of preparation and the uranium (2, 8).
ambient temperature. 6.1.2 Silver and vanadium (in the V oxidation state) cause
positive bias when present in milligram quantities in the
4.3.2 Automated titrators are facility specific and are not
sample. The aliquant treatment adjusts the oxidation state of
explicitly addressed in this test method. However, automated
any vanadium(V) present in the sample (2). To remove silver,
titrators which have comparable bias and precision may be
the sample must be treated prior to titration (8).
used.
6.1.3 Manganese was originally found to cause a negative
4.3.3 There is an alternate, high precision (;0.005% RSD)
bias (2), but this bias is eliminated when the titration aliquant
modified Davies and Gray titration, which is similar to the
preparation procedure is followed as given (9, 10) in this
method covered in this procedure. In the high precision
titrimetric method.
method, the amount of uranium titrated is increased and about
90%ofthetitrantisdeliveredonasolidweightbasisfollowed 6.2 Interferences with the Modified Davies and Gray
titration, which may be present in some uranium materials,
by titration to the end point with a dilute titrant. Details of this
alternate method are available in Ref (5). have been systematically studied.
6.2.1 The non-interference of copper, titanium, cobalt,
nickel, cerium, and samarium was demonstrated (11) at the
5. Significance and Use
50mg impurity level for 100 mg of uranium.
5.1 Factors governing selection of a method for the deter-
6.2.2 The effects of the following elements in milligram
mination of uranium include available quantity of sample,
quantities were studied: silver, gold, lead, iodine, arsenic,
homogeneity of material sampled, sample purity, desired level
antimony, and bismuth (8).
of reliability, and facility available equipment.
6.2.2.1 Gold, lead, arsenic(V), antimony(V), and bismuth
do not interfere when present in amounts of 10 mg for 100 mg
5.2 This uranium assay method is referenced in the Test
of uranium.
Methods for Chemical, Mass Spectrometric, and Spectro-
6.2.2.2 Silver, iodine, arsenic(III), and antimony(III) inter-
chemical Analysis of Nuclear-Grade Uranium Dioxide Pow-
fere seriously in the determination of uranium and must be
ders and Pellets (Test Methods C696) and in the Test Methods
eliminated prior to titration.
for Chemical, Mass Spectrometric, and Spectrochemical,
6.2.3 The effects of impurities on the titration of uranium
Nuclear,andRadiochemicalAnalysisofNuclear-GradeUranyl
continued with the platinum metals (ruthenium, rhodium,
Nitrate Solutions (Test Methods C799). This uranium assay
palladium, osmium, iridium, and platinum), chloride, bromide
method may also be used for uranium hexafluoride and
(12), fluoride (13), and technetium (14).
uraniumoreconcentrate.Thistestmethoddetermines20mgto
6.2.3.1 Ruthenium, palladium, osmium, iridium, and plati-
200 mg of uranium; is applicable to product, fuel, and scrap
num cause serious positive errors in the determination of
materialafterthematerialisdissolved;istoleranttowardsmost
uranium. Rhodium alone among the platinum metals does not
metallic impurity elements usually specified in product and
cause any significant error.
fuel; and uses no special equipment.
6.2.3.2 Chloride and bromide interfere with the assay
5.3 The ruggedness of the titration method has been studied
through their effect on the platinum indicator electrode.
for both the volumetric (6) and the weight (7) titration of
6.2.3.3 Small amounts of fluoride, less than 400 mg as
uranium with dichromate.
hydrofluoric acid (HF) or 600 mg if HNO is present, can be
tolerated by the titration.
5.4 Fitness for Purpose of Safeguards and Nuclear Safety
Application—Methods intended for use in safeguards and
nuclear safety applications shall meet the requirements speci-
fied by Guide C1068 for use in such applications. SRM is a registered trademark.
C1267 − 17 (2022)
6.2.3.4 Technicium,foundinhightemperaturereactorgrade of sufficiently high purity to permit its use without lessening
recycle (htgr) fuel, interferes with the titration and must be the accuracy of the determination.
removed before titration.
8.2 Purity of Water—Unless otherwise indicated, references
6.3 The removal of certain interferences in the modified
to water shall be understood to mean laboratory accepted
Davies and Gray titration has also been studied.
demineralized or deionized water.
6.3.1 The initial fuming of titration aliquants with sulfuric
8.3 Ferrous Sulfate Heptahydrate (FeSO ·7 H O, 1.0 M)—
4 2
acidremovesimpurityelementssuchasthehalidesandvolatile
Add 100 mLof sulfuric acid (H SO , sp gr 1.84) to 750 mLof
2 4
metallic elements (2, 12, 13).
waterasthesolutionisstirred.Add280gofFeSO ·7H O,and
4 2
6.3.2 Arsenic(III) and antimony(III) can be eliminated in
dilute the solution to 1Lwith water. Prepare the FeSO ·7 H O
4 2
theH PO bypotassiumdichromate(K Cr O )oxidationprior
3 4 2 2 7
reagentfresh,weekly.SeetheNote5in11.8oncombinationof
to its addition to the titration medium (8).
this reagent with the H PO .
3 4
6.3.3 Elimination of interferences in the titration by
mercury, platinum, and palladium by means of a copper
8.4 Nitric Acid(HNO ,8M)—Add500mLofHNO (spgr
3 3
column was evaluated (15).
1.42) to <500 mL of water, and dilute to 1L.
6.3.4 Elimination of interferences by solvent extraction of
8.5 HNO , 1 M—Add 64 mL of HNO (sp gr 1.42) to
3 3
the uranium from the impurities has also been studied (16).
<900mL of water, and dilute to 1L.
6.4 A list of impurities with brief references to their treat-
8.6 HNO (8 M)—Sulfamic Acid (NH SO H, 0.15 M)—
ment for elimination is given in Table A1.1 in AnnexA1, and
3 2 3
Ammonium Molybdate ((NH ) Mo O ·4H O, 0.4 %)—
the details are given in Refs 2, 8, 9, 10, and 12-16.
4 6 7 24 2
Dissolve4gof(NH ) Mo O ·4H O in 400 mLof water, and
4 6 7 24 2
7. Apparatus
add 500 mL of HNO (sp gr 1.42). Mix and add 100mL of
1.5 M NH SO H solution (see 8.10) and mix.
7.1 Buret, polyethylene bottle (preparation instructions can 2 3
be found in Appendix X1), glass weight, or glass volumetric.
8.7 Orthophosphoric Acid (H PO ), 85%—Test for reduc-
3 4
7.2 pH Meter, with indicator (a 16-gauge platinum wire has ing substances prior to use (see Annex A2).
beenfoundtobesatisfactory)andreference(saturatedcalomel
8.8 Potassium Dichromate (K Cr O ) Solution (2%)—
2 2 7
has been found to be satisfactory) electrodes.
Dissolve2gofK Cr O in water, and dilute to 100 g with
2 2 7
7.2.1 The indicator electrode should be changed or cleaned
water.
if there is a titration problem such as less distinct than normal
end point break or end point drift, or, if desired, prior to use
8.9 K Cr O (0.0045 M)—Dissolve 2.65 g of reagent grade
2 2 7
whenmorethanaweekhaspassedsinceitslastuse.Suggested or purer grade K Cr O in water; transfer this solution to a
2 2 7
cleaning procedures for platinum wire electrodes are detailed
pre-weighed, 2L volumetric flask or suitable alternative and
in Appendix X2. dilute to volume, or use equivalent weight/volume ratios for
7.2.2 Asbestos and glass bead tipped saturated calomel
larger quantities of solution.
electrodescanbeplaceddirectlyinthetitrationsolution.Glass
8.9.1 If National Institute of Standards and Technology
frit tipped saturated calomel electrodes may have a faster leak
(NIST) standard reference material K Cr O (SRM 136e or its
2 2 7
rate and may need to be used with a separator tube containing
equivalent) was used, proceed as in 8.9.1.1 and 8.9.1.2 before
the electrolyte to prevent titration problems due to chloride.
going to 8.9.3; otherwise go to 8.9.2.
7.2.3 The reference electrode should be covered with a
8.9.1.1 Allow the solution to equilibrate to room
rubber tip or submerged in a solution (saturated potassium
temperature, obtain the weight of the solution. Compute the
chloride solution for the calomel electrode) for overnight
dichromate concentration (11.2.2) and the uranium titration
storage.
factor (12.3.2) after correcting the weight of dichromate for
7.3 Magnetic Stirrer and TFE-Fluorocarbon Coated Mag-
buoyancy (12.1.2) and for purity (12.1.3).
net.
8.9.1.2 As a good quality practice, a check on the material
handling of the K Cr O solution within laboratory accepted
2 2 7
8. Reagents
uncertaintiesmaybedonebytitrationwithaworkingreference
8.1 Purity of Reagents—Reagent grade chemicals shall be
uraniumsolution.Forguida
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