ASTM C698-16

Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O<inf>2</inf>)

SIGNIFICANCE AND USE
4.1 Mixed oxide, a mixture of uranium and plutonium oxides, is used as a nuclear-reactor fuel in the form of pellets. The plutonium content may be up to 10 weight %, and the diluent uranium may be of any 235U enrichment. In order to be suitable for use as a nuclear fuel, the material must meet certain criteria for combined uranium and plutonium content, effective fissile content, and impurity content as described in Specification C833.  
4.1.1 The material is assayed for uranium and plutonium to determine whether the plutonium content is as specified by the purchaser, and whether the material contains the minimum combined uranium and plutonium contents specified on a dry weight basis.  
4.1.2 Determination of the isotopic content of the plutonium and uranium in the mixed oxide is made to establish whether the effective fissile content is in compliance with the purchaser's specifications.  
4.1.3 Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC) as described in Practice C1233.  
4.2 Fitness for Purpose of Safeguards and Nuclear Safety Applications—Methods intended for use in safeguards and nuclear safety applications shall meet the requirements specified by Guide C1068 for use in such applications.
SCOPE
1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade mixed oxides, (U, Pu)O2, powders and pellets to determine compliance with specifications.  
1.2 The analytical procedures appear in the following order:    
Sections  
Uranium in the Presence of Pu by Potentiometric Titration  
2  
Plutonium by Controlled-Potential Coulometry  
2  
Plutonium by Amperometric Titration with Iron (II)  
2  
Nitrogen by Distillation Spectrophotometry Using Nessler Reagent  
8 to 15  
Carbon (Total) by Direct Combustion-Thermal Conductivity  
16 to 26  
Total Chlorine and Fluorine by Pyrohydrolysis  
27 to 34  
Sulfur by Distillation-Spectrophotometry  
35 to 43  
Moisture by the Coulometric, Electrolytic Moisture Analyzer  
44 to 51  
Isotopic Composition by Mass Spectrometry  
3  
Rare Earths by Copper Spark Spectroscopy  
52 to 59  
Trace Impurities by Carrier Distillation Spectroscopy  
60 to 68  
Impurities by Spark-Source Mass Spectrography  
69 to 75  
Total Gas in Reactor-Grade Mixed Dioxide Pellets  
4  
Tungsten by Dithiol-Spectrophotometry  
76 to 84  
Rare Earth Elements by Spectroscopy  
85 to 88  
Plutonium-238 Isotopic Abundance by Alpha Spectrometry  
5  
Americium-241 in Plutonium by Gamma-Ray Spectrometry  
Uranium and Plutonium Isotopic Analysis by Mass Spectrometry  
89 to 97  
Oxygen-to-Metal Atom Ratio by Gravimetry  
98 to 105  
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.  
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 and health practices and determine the applicability of regulatory limitations prior to use. (For specific safety precaution statements, see Sections 6, 13.2.5, 41.7, and 93.6.1.)

General Information

• Status: Published
• Publication Date: 31-May-2016
• 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 C698-10 - Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O₂)
• Effective Date: 01-Jun-2016
• Refers: ASTM C859-24 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C1672-23 - Standard Test Method for Determination of the Uranium, Plutonium or Americium Isotopic Composition or Concentration by the Total Evaporation Method Using a Thermal Ionization Mass Spectrometer
• Effective Date: 01-Dec-2023
• Refers: ASTM C1432-23 - Standard Test Method for Determination of Impurities in Plutonium: Acid Dissolution, Ion Exchange Matrix Separation, and Inductively Coupled Plasma-Atomic Emission Spectroscopic (ICP/AES) Analysis
• Effective Date: 01-Dec-2023
• Refers: ASTM C1168-23 - Standard Practice for Preparation and Dissolution of Plutonium Materials for Analysis
• Effective Date: 01-Oct-2023
• Refers: ASTM C1268-23 - Standard Test Method for Quantitative Determination of ²⁴¹Am in Plutonium by Gamma-Ray Spectrometry
• Effective Date: 01-Oct-2023
• Refers: ASTM C1625-19 - Standard Test Method for Uranium and Plutonium Concentrations and Isotopic Abundances by Thermal Ionization Mass Spectrometry
• Effective Date: 15-Sep-2019
• Refers: ASTM C1415-18 - Standard Test Method for ²³⁸Pu Isotopic Abundance By Alpha Spectrometry
• Effective Date: 01-Jun-2018
• Refers: ASTM C1672-17 - Standard Test Method for Determination of Uranium or Plutonium Isotopic Composition or Concentration by the Total Evaporation Method Using a Thermal Ionization Mass Spectrometer
• Effective Date: 01-Jan-2017
• Refers: ASTM C697-16 - Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium Dioxide Powders and Pellets
• Effective Date: 01-Jun-2016
• Refers: ASTM C1817-16 - Standard Test Method for The Determination of the Oxygen to Metal (O/M) Ratio in Sintered Mixed Oxide ((U, Pu)O<inf>2</inf>) Pellets by Gravimetry
• Effective Date: 15-Jan-2016
• Refers: ASTM C1168-15 - Standard Practice for Preparation and Dissolution of Plutonium Materials for Analysis
• Effective Date: 01-Sep-2015
• Refers: ASTM C1817-15 - Standard Test Method for The Determination of the Oxygen to Metal (O/M) Ratio in Sintered Mixed Oxide ((U, Pu)O<inf>2</inf>) Pellets by Gravimetry
• Effective Date: 01-Jun-2015
• Refers: ASTM C1268-15 - Standard Test Method for Quantitative Determination of ²⁴¹Am in Plutonium by Gamma-Ray Spectrometry
• Effective Date: 01-Jun-2015
• Refers: ASTM C1432-15 - Standard Test Method for Determination of Impurities in Plutonium: Acid Dissolution, Ion Exchange Matrix Separation, and Inductively Coupled Plasma-Atomic Emission Spectroscopic (ICP/AES) Analysis
• Effective Date: 01-Jun-2015

Overview

ASTM C698-16 is a globally recognized standard specifying test methods for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade mixed oxides ((U, Pu)O₂). Developed by ASTM International, this standard plays a crucial role in qualifying (U, Pu)O₂ materials, commonly used as nuclear reactor fuel. The standard outlines analytical procedures for determining uranium, plutonium, and impurity levels in both powder and pellet forms, ensuring compliance with industry requirements for nuclear fuel performance, safety, and regulatory acceptance.

Key Topics

• Analytical Techniques: The standard covers a suite of analytical approaches:

  • Chemical analysis (e.g., potentiometric and amperometric titrations, direct combustion)
  • Mass spectrometric analysis (assessing isotopic composition)
  • Spectrochemical methods (e.g., spark spectroscopy)

• Quality and Compliance: Testing determines if mixed oxide fuel meets key parameters:

  • Correct uranium and plutonium content
  • Defined isotopic composition for effective fissile content
  • Low impurity levels, as excessive contaminants can impact fuel integrity and reactor safety

• Safety and Best Practices:

  • Emphasizes appropriate laboratory infrastructure, such as gloveboxes, fume hoods, and safe handling procedures for radioactive and toxic materials
  • Users must follow institutional safety protocols and be aware of relevant regulatory limitations

Applications

ASTM C698-16 is vital across areas involving nuclear-grade mixed oxide (MOX) fuels:

• Nuclear Reactor Fuel Manufacturing: Ensures fabricated MOX fuel pellets conform to quality specifications, supporting efficient and safe reactor operation.
• Fuel Qualification and Safeguards: Analytical methods assist in verifying material for safeguard and nuclear safety applications, as required by industry guides (e.g., ASTM Guide C1068).
• Research and Development: Laboratories developing advanced fuel forms or processing technologies use these methods for precise characterization.
• Regulatory Compliance: Conformance with ASTM C698-16 demonstrates adherence to international standards for nuclear fuel analysis-an essential element in quality assurance and licensing.
• Impurity Control: Determining trace impurities and calculating equivalent boron content (EBC) per Practice C1233 is critical to minimizing reactor neutron absorption not due to fissile material.

Related Standards

ASTM C698-16 references and aligns with several essential standards within the nuclear materials field, including:

• ASTM C833: Specification for Sintered Uranium-Plutonium Dioxide Pellets, detailing required characteristics for nuclear fuel pellets.
• ASTM C697: Test methods for analyzing nuclear-grade plutonium dioxide.
• ASTM C1068: Guide for the qualification of measurement methods relevant to nuclear applications.
• ASTM C1233: Practice for determining equivalent boron content in nuclear materials.
• ASTM C1165, C1108, C1204, C1268, C1625: Specific procedures for various chemical and spectrometric analyses.
• ASTM D1193: Specification for reagent water, which outlines the purity required for analytical procedures.

Practical Value

Adhering to ASTM C698-16 provides nuclear fuel producers and laboratories with:

• Standardized, validated methods to ensure fuel quality and compliance
• Enhanced nuclear safety through accurate determination of material composition and impurities
• Support for meeting regulatory requirements and customer specifications
• Confidence in the consistency, reliability, and global acceptability of measured results

By leveraging these rigorous analytical protocols, organizations protect reactor performance, maintain safety margins, and demonstrate their commitment to best practices in nuclear materials management.

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: C698 − 16
Standard Test Methods for
Chemical, Mass Spectrometric, and Spectrochemical
Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O )
This standard is issued under the fixed designation C698; 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
1.1 These test methods cover procedures for the chemical, 2.1 ASTM Standards:
mass spectrometric, and spectrochemical analysis of nuclear- C697Test Methods for Chemical, Mass Spectrometric, and
grade mixed oxides, (U, Pu)O , powders and pellets to deter- Spectrochemical Analysis of Nuclear-Grade Plutonium
mine compliance with specifications. Dioxide Powders and Pellets
C833Specification for Sintered (Uranium-Plutonium) Diox-
1.2 Theanalyticalproceduresappearinthefollowingorder:
ide Pellets
Sections
C852Guide for Design Criteria for Plutonium Gloveboxes
Uranium in the Presence of Pu by Potentiometric Titration
Plutonium by Controlled-Potential Coulometry C859Terminology Relating to Nuclear Materials
Plutonium by Amperometric Titration with Iron (II)
C1068Guide for Qualification of Measurement Methods by
Nitrogen by Distillation Spectrophotometry Using Nessler 8 to 15
a Laboratory Within the Nuclear Industry
Reagent
Carbon (Total) by Direct Combustion-Thermal Conductivity 16 to 26 C1108Test Method for Plutonium by Controlled-Potential
Total Chlorine and Fluorine by Pyrohydrolysis 27 to 34
Coulometry
Sulfur by Distillation-Spectrophotometry 35 to 43
C1165 Test Method for Determining Plutonium by
Moisture by the Coulometric, Electrolytic Moisture Analyzer 44 to 51
Isotopic Composition by Mass Spectrometry
Controlled-Potential Coulometry in H SO at a Platinum
2 4
Rare Earths by Copper Spark Spectroscopy 52 to 59
Working Electrode
Trace Impurities by Carrier Distillation Spectroscopy 60 to 68
C1168PracticeforPreparationandDissolutionofPlutonium
Impurities by Spark-Source Mass Spectrography 69 to 75
Total Gas in Reactor-Grade Mixed Dioxide Pellets Materials for Analysis
Tungsten by Dithiol-Spectrophotometry 76 to 84
C1204Test Method for Uranium in Presence of Plutonium
Rare Earth Elements by Spectroscopy 85 to 88
5 by Iron(II) Reduction in Phosphoric Acid Followed by
Plutonium-238 Isotopic Abundance by Alpha Spectrometry
Americium-241 in Plutonium by Gamma-Ray Spectrometry Chromium(VI) Titration
Uranium and Plutonium Isotopic Analysis by Mass 89 to 97
C1206Test Method for Plutonium by Iron (II)/Chromium
Spectrometry
(VI) Amperometric Titration (Withdrawn 2015)
Oxygen-to-Metal Atom Ratio by Gravimetry 98 to 105
C1233Practice for Determining Equivalent Boron Contents
1.3 The values stated in SI units are to be regarded as
of Nuclear Materials
standard. The values given in parentheses are for information
C1268 Test Method for Quantitative Determination of
only.
Am in Plutonium by Gamma-Ray Spectrometry
1.4 This standard does not purport to address all of the 238
C1415Test Method for Pu Isotopic Abundance By Alpha
safety concerns, if any, associated with its use. It is the
Spectrometry
responsibility of the user of this standard to establish appro-
C1432Test Method for Determination of Impurities in
priate safety and health practices and determine the applica-
Plutonium: Acid Dissolution, Ion Exchange Matrix
bility of regulatory limitations prior to use. (For specific safety
Separation, and Inductively Coupled Plasma-Atomic
precautionstatements,seeSections6,13.2.5,41.7,and93.6.1.)
Emission Spectroscopic (ICP/AES) Analysis
C1625Test Method for Uranium and Plutonium Concentra-
tions and Isotopic Abundances by Thermal Ionization
These test methods are under the jurisdiction of ASTM Committee C26 on
Mass Spectrometry
Nuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.05 on
Methods of Test.
CurrenteditionapprovedJune1,2016.PublishedJuly2016.Originallyapproved
in 1972. Last previous edition approved in 2010 as C698–10. DOI: 10.1520/ For referenced ASTM standards, visit the ASTM website, www.astm.org, or
C0698-16. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Discontinued as of November 15, 1992. Standards volume information, refer to the standard’s Document Summary page on
Discontinued as of May 30, 1980. the ASTM website.
4 7
Discontinued as of June 2016. The last approved version of this historical standard is referenced on
Discontinued as of January 1, 2004. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C698 − 16
C1637Test Method for the Determination of Impurities in tee onAnalytical Reagents of theAmerican Chemical Society,
PlutoniumMetal:AcidDigestionandInductivelyCoupled where such specifications are available. Other grades may be
Plasma-Mass Spectroscopy (ICP-MS) Analysis used, provided it is first ascertained that the reagent is of
C1672Test Method for Determination of Uranium or Pluto- sufficiently high purity to permit its use without lessening the
nium Isotopic Composition or Concentration by the Total accuracy of the determination.
Evaporation Method Using a Thermal Ionization Mass
5.2 Purity of Water—Unless otherwise indicated, references
Spectrometer
towatershallbeunderstoodtomeanreagentwaterconforming
C1817Test Method forThe Determination of the Oxygen to
to Specification D1193.
Metal (O/M) Ratio in Sintered Mixed Oxide ((U, Pu)O )
Pellets by Gravimetry
6. Safety Precautions
D1193Specification for Reagent Water
6.1 Since plutonium- and uranium-bearing materials are
D4327Test Method for Anions in Water by Suppressed Ion
radioactive and toxic, adequate laboratory facilities, glove
Chromatography
boxes, fume hoods, and so forth, along with safe techniques
E60Practice for Analysis of Metals, Ores, and Related
must be used in handling samples containing these materials.
Materials by Spectrophotometry
Glove boxes should be fitted with off-gas filters capable of
E115Practice for Photographic Processing in Optical Emis-
sustained operation with dust-laden atmospheres. A detailed
sion Spectrographic Analysis (Withdrawn 2002)
discussion of all the precautions necessary is beyond the scope
E116Practice for Photographic Photometry in Spectro-
of these test methods; however, personnel who handle these
chemical Analysis (Withdrawn 2002)
materials should be familiar with such safe handling practices
E130Practice for Designation of Shapes and Sizes of
as are given in Guide C852 and in Refs (1-3).
Graphite Electrodes (Withdrawn 2013)
6.2 Adequate laboratory facilities, such as fume hoods and
controlledventilation,alongwithsafetechniques,mustbeused
3. Terminology
in this procedure. Extreme care should be exercised in using
3.1 Except as otherwise defined herein, definitions of terms
hydrofluoric acid and other hot, concentrated acids. Use of
are as given in Terminology C859.
proper gloves is recommended. Refer to the laboratory’s
chemical hygiene plan and other applicable guidance for
4. Significance and Use
handling chemical and radioactive materials and for the man-
4.1 Mixed oxide, a mixture of uranium and plutonium
agement of radioactive, mixed, and hazardous waste.
oxides, is used as a nuclear-reactor fuel in the form of pellets.
6.3 Hydrofluoric acid is a highly corrosive acid that can
The plutonium content may be up to 10 weight%, and the
severelyburnskin,eyesandmucousmembranes.Hydrofluoric
diluent uranium may be of any U enrichment. In order to be
acid differs from other acids because the fluoride ion readily
suitableforuseasanuclearfuel,thematerialmustmeetcertain
penetrates the skin, causing destruction of deep tissue layers.
criteriaforcombineduraniumandplutoniumcontent,effective
Unlike other acids that are rapidly neutralized, hydrofluoric
fissile content, and impurity content as described in Specifica-
acid reactions with tissue may continue for days if left
tion C833.
untreated.FamiliarizationandcompliancewiththeSafetyData
4.1.1 The material is assayed for uranium and plutonium to
Sheet is essential.
determine whether the plutonium content is as specified by the
purchaser, and whether the material contains the minimum
6.4 Perchloric acid (HClO ) forms explosive compounds
combined uranium and plutonium contents specified on a dry
withorganicsandmanymetalsalts.Avoidexposurebycontact
weight basis.
withtheskinoreyes,orbyinhalationoffumes.Familiarization
4.1.2 Determinationoftheisotopiccontentoftheplutonium
and compliance with the Safety Data Sheet is essential. Carry
and uranium in the mixed oxide is made to establish whether
out sample dissolution with perchloric acid in a fume hood
the effective fissile content is in compliance with the purchas-
with a scrubber unit that is specially designed for use with
er’s specifications.
HClO .
4.1.3 Impurity content is determined to ensure that the
7. Sampling and Dissolution
maximum concentration limit of certain impurity elements is
not exceeded. Determination of impurities is also required for
7.1 Criteria for sampling this material are given in Specifi-
calculationoftheequivalentboroncontent(EBC)asdescribed
cation C833.
in Practice C1233.
7.2 Samples can be dissolved using the appropriate disso-
4.2 Fitness for Purpose of Safeguards and Nuclear Safety
lution techniques described in Practice C1168.
Applications—Methods intended for use in safeguards and
nuclear safety applications shall meet the requirements speci-
Reagent Chemicals, American Chemical Society Specifications, American
fied by Guide C1068 for use in such applications.
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
5. Reagents
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
5.1 Purity of Reagents—Reagent grade chemicals shall be
MD.
used in all tests. Unless otherwise indicated, it is intended that
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
all reagents shall conform to the specifications of the Commit- these test methods.
C698 − 16
URANIUM IN THE PRESENCE OF PLUTONIUM BY 11.2 Boric Acid Solution (40 g/litre)—Dissolve40gofboric
POTENTIOMETRIC TITRATION acid (H BO ) in 800 mL of hot water. Cool to approximately
3 3
(This test method was discontinued in 1992 and replaced by 20°C and dilute to 1 L.
Test Method C1204.)
11.3 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
chloric acid (HCl).
PLUTONIUM BY CONTROLLED POTENTIAL
COULOMETRY 11.4 Hydrofluoric Acid (sp gr 1.15)—Concentrated hydro-
(This test method was discontinued in 1992 and replaced by fluoric acid (HF). See safety precaution in 6.3.
Test Method C1165.)
11.5 Nessler Reagent—To prepare, dissolve 50 g of potas-
sium iodide (KI) in a minimum of cold ammonia-free water,
PLUTONIUM BY CONTROLLED-POTENTIAL
approximately 35 mL. Add a saturated solution of mercuric
COULOMETRY
chloride (HgCl , 22 g/350 mL) slowly until the first slight
(With appropriate sample preparation, controlled-potential
precipitate of red mercuric iodide persists.Add 400 mLof 9 N
coulometric measurement as described in Test Method
sodium hydroxide (NaOH) and dilute to 1 L with water. Mix,
C1108 may be used for plutonium determination.)
and allow the solution to stand overnight. Decant the superna-
PLUTONIUM BY AMPEROMETRIC TITRATION tant liquid and store in a brown bottle.
WITH IRON(II)
11.6 Nitrogen, Standard Solution (1 mL = 0.01 mg N)—
(This test method was discontinued in 1992 and replaced by
Dissolve 3.819 g of NH Cl in water and dilute to 1 L.Transfer
Test Method C1206, which was withdrawn in 2015.)
10 mL of this solution to a 1-L volumetric flask and dilute to
volume with ammonia-free water.
NITROGEN BY DISTILLATION
11.7 Sodium Hydroxide (9N)—Dissolve 360 g of sodium
SPECTROPHOTOMETRY USING NESSLER
REAGENT hydroxide (NaOH) in ammonia-free water and dilute to 1 L.
11.8 Sodium Hydroxide Solution—(50 %)—Dissolve NaOH
8. Scope
in an equal weight of ammonia-free water.
8.1 This test method covers the determination of 5 to 100
11.9 Water, Ammonia-Free—Toprepare,passdistilledwater
µg/g of nitride nitrogen in mixtures of plutonium and uranium
through a mixed-bed resin demineralizer and store in a tightly
oxides in either pellet or powder form.
stoppered chemical-resistant glass bottle.
9. Summary of Test Method
12. Precautions
9.1 The sample is dissolved in hydrochloric acid by the
sealed tube test method or by phosphoric acid-hydrofluoric 12.1 The use of ammonia or other volatile nitrogenous
acid solution, after which the solution is made basic with compounds in the vicinity can lead to serious error. The
sodium hydroxide and nitrogen is separated as ammonia by following precautionary measures should be taken: (1) Clean
steam distillation. Nessler reagent is added to the distillate to all glassware and rinse with ammonia-free water immediately
formtheyellowammoniumcomplexandtheabsorbanceofthe prior to use, and (2) avoid contamination of the atmosphere in
solution is measured at approximately 430 nm (4, 5). the vicinity of the test by ammonia or other volatile nitrog-
enous compounds.
10. Apparatus
10.1 Distillation Apparatus (see Fig. 1 for an example). 13. Procedure
13.1 Dissolution of Sample:
10.2 Spectrophotometer, visible-range.
13.1.1 Transfer a weighed sample, in the range from 1.0 to
11. Reagents
1.5 g, to a 50-mL beaker.
11.1 Ammonium Chloride (NH Cl)—Dry the salt for2hat 13.1.2 Crushthepelletsamplestoaparticlesizeof1mmor
110 to 120°C. less in a diamond mortar.
FIG. 1 Distillation Apparatus
C698 − 16
13.1.3 To the sample add 5 mL of HCl (sp gr 1.19) and 3 Then, add 5 mL of HCl and 3 drops of HF plus 20 mL of
drops of HF (sp gr 1.15). Heat to put the sample into solution. ammonia-free water to each flask.
13.4.2 Process each solution by the procedure in 13.2
NOTE 1—Concentrated phosphoric acid or mixtures of phosphoric acid
through 13.3 (omit step 13.2.9).
andhydrofluoricacidsorofphosphoricandsulfuricacidsmaybeusedfor
13.4.3 Correct for the reagent blank reading and plot the
the dissolution of mixed oxide samples. Such acids may require a
purificationstepinordertoreducethenitrogenblankbeforebeingusedin
absorbance of each standard against micrograms of nitrogen
this procedure.
per 50 mL of solution.
13.2 Distillation:
14. Calculation
13.2.1 Quantitatively transfer the sample solution to the
distilling flask of the apparatus. Add 20 mL of ammonia-free
14.1 From the calibration chart, read the micrograms of
water and then clamp the flask into place on the distillation
nitrogen corresponding to the absorbance of the sample solu-
apparatus (see Fig. 2 for an example).
tion.
13.2.2 Turnonthesteamgeneratorbutdonotclosewiththe
14.2 Calculate the nitrogen content of the sample as fol-
stopper.
lows:
13.2.3 Add 5 mL of boric acid solution (4%) to a 50-mL
N, µg/g 5 ~A 2 B!/W (1)
graduated flask and position this trap so that the condenser tip
is below the surface of the boric acid solution.
where:
13.2.4 Transfer 20 mL of NaOH solution (50%) to the
A = micrograms of nitrogen from sample plus reagents,
funnel in the distillation head.
B = micrograms of nitrogen in blank, and
13.2.5 Whenthewaterbeginstoboilinthesteamgenerator,
W = grams of sample.
replace the stopper and slowly open the stopcock on the
distilling flask to allow the NaOH solution to run into the
15. Precision and Bias
sample solution. (Warning—The NaOH solution must be
15.1 The estimated relative standard deviation for a single
added slowly to avoid a violent reaction, which may lead to a
measurement by this test method is 20% for 3 µg of nitrogen
loss of sample.)
and 3% for 50 to 90 µg of nitrogen.
13.2.6 Steamdistilluntil25mLofdistillatehascollectedin
the trap.
CARBON (TOTAL) BY DIRECT COMBUSTION-
13.2.7 Remove the trap containing the distillate from the
THERMAL CONDUCTIVITY
distillation apparatus, and remove the stopper from the steam
generator.
16. Scope
13.2.8 Transfer the cooled distillate to a 50-mL volumetric
16.1 This test method covers the determination of 10 to 200
flask.
µgofresidualcarboninnucleargrademixedoxides,(U,Pu)O .
13.2.9 Prepare a reagent blank solution by following steps
13.1.1 through 13.2.8.
17. Summary of Test Method
13.3 Measurement of Nitrogen:
17.1 Powdered samples are covered and mixed with an
13.3.1 Add 1.0 mL of Nessler reagent to each of the
accelerator in carbon-free crucibles and burned with oxygen in
distillatescollectedin13.2.8and13.2.9.Dilutetovolumewith
an induction heating furnace. Traces of sulfur compounds and
ammonia-free water, mix, and let stand for 10 min.
water vapor are removed from the combustion products by a
13.3.2 Measuretheabsorbanceofthesolutionsat430nmin
purification train and the resultant carbon monoxide is con-
a 1-cm cell. Use water as the reference.
verted to carbon dioxide. The purified carbon dioxide is
13.4 Calibration Curve: trappedonamolecularsieve,elutedtherefromwithastreamof
13.4.1 Add 0, 5, 10, 25, 100, and 150 µg of nitrogen from heliumuponapplicationtoheattothetrap,andpassedthrough
the nitrogen standard solution to separate distilling flasks. a thermal conductivity cell. The amount of carbon present,
FIG. 2 Quartz Reaction Tube
C698 − 16
being a function of the integrated change in the current of the 20. Reagents and Materials
detectorcell,isreaddirectlyfromacalibrated-digitalvoltmeter
20.1 Quartz Wool, used as a dust trap at the top of the
or strip-chart recorder.
combustion tube.
20.2 Sulfuric Acid (H SO , sp gr 1.84), used in the oxygen
2 4
18. Interferences
purification train.
18.1 Therearenoknowninterferencesnoteliminatedbythe
20.3 Standard Materials—Certified reference material stan-
purification system.
dardsfromanationalstandardsbodysuchastheU.S.National
Institute for Standards and Technology (NIST) or equivalent.
19. Apparatus
Certifiedmaterialsinsteelmatrices(steelpinssteelrings,steel
19.1 Commercial Combustion Apparatus, suitable for the
granules,andsteelpowder)rangingfrom5µgcarbon/gsample
carbon determination, is often modified to facilitate mainte-
to 1500 µg carbon/g sample are available and have been found
nanceandoperationwithinthegloveboxwhichisrequiredfor
satisfactory.
all work with plutonium materials.
21. Sampling and Preparation
19.2 Combustion Apparatus, consisting of an induction
21.1 Sample Size—The normal size for mixed oxide [(U,
furnace, suitable for operation at 1600°C, a catalytic furnace, a
Pu)O ] fuel materials shall be 1 g. If necessary, this amount
purification train, a carbon dioxide trap, thermal conductivity
shall be altered as required to contain less than 200 µg of
cell with appropriate readout equipment, and a regulated
carbon.
supply of oxygen and helium.
21.2 Sample Preparation—Pellet or particulate samples
19.3 Combustion Tubes—Quartz combustion tubes with in-
shall be reduced such that approximately 90% of the particles
tegral baffle shall be used.
are less than 149 µm (equivalent to approximately−100-mesh
19.4 Crucibles—Expendable alumina or similar refractory
powder) prior to the weighing of the specimens. Exposure of
crucibles shall be used. The use of crucible covers is optional.
the powdered sample to atmospheric carbon dioxide should be
Satisfactory operation with covers must be established by
minimized by storage of the powder in a closed vial.
analysis of standards. Crucibles and covers (if used) must be
ignited at a temperature of 1000°C or higher for a time
22. Preparation of Apparatus
sufficient to produce constant blank values.
22.1 Analysis System Purge—After having properly set the
19.5 Accelerators—Granular tin, copper, iron, and copper
operating controls of the instrument system, condition the
oxide accelerators shall be used to obtain satisfactory results.
apparatus by combustion of several blanks prepared with the
The criterion for satisfactory results is the absence of signifi-
sample crucible and accelerator in the amount to be used with
cant additional carbon release upon recombustion of the
the test specimen analyses. Successive blank values should
specimen.
approach a constant value, allowing for normal statistical
fluctuations. The instrument should be adjusted for a 2-min
19.6 Catalytic Furnace and Tube—This unit, which is used
combustion period.
toensurecompleteconversionofCOtoCO ,consistsofatube
containing copper oxide and maintained at a temperature of
23. Calibration
300°C by a small furnace.
23.1 Preparation of Standards for Combustion—Mix a
19.7 Carbon Dioxide Purifiers—The purifiers that follow
weighed portion of an accelerator and an accurately weighed
the combustion tube must remove finely divided solid metallic
portion of approximately1gof reference material with a
oxides and oxides of sulfur and selenium, dry the gases before
certified carbon value of about 0.005% in each of the three
they enter the CO trap, and protect the absorber from outside
sample crucibles. Repeat with NIST SRM 336 or a reference
effects.Finelydividedsolidmetaloxidesareremovedfromthe
material with a certified carbon value of about 0.5% (Note 2),
gases during their passage through the quartz wool. The SO
using an accurately weighed portion of approximately 30 to 40
given off by materials containing sulfur is removed by MnO
mg.
and any water vapor is absorbed in a tube containing Mg-
(ClO ) .Hotcopperoxideconvertscarbonmonoxidetocarbon NOTE 2—These portions represent about 50 µg and 200 µg of carbon,
4 2
respectively.
dioxide.Additionalcomponentsinthepurificationtrainmaybe
required when materials containing very high amounts of
23.1.1 Weighthesteelintoataredcontainer,suchasasmall
sulfur or of halides are being analyzed. The materials used in
nickel sample boat, obtaining the mass to the nearest 0.01 mg.
the purification train must be checked frequently to ensure that
Transfer the chips to a 30-mm square of aluminum foil
their absorbing capacity has not been exhausted.
(previously acetone washed), and fold the foil into a wrapper
with the aid of stainless steel tongs and spatulas. The foil
19.8 Vibratory Sample Pulverizer Apparatus, capable of
should not be touched by the hands. Place the wrapped
reducing ceramic materials such that 90% or more of the
standard in a numbered glass sample vial and transfer to the
particles are less than 149 µm (equivalent to a−100-mesh
analyzer glove box.
powder). A stainless steel capsule and mixing ball must be
used, in order to reduce contamination of the sample with 23.2 Combustion of Standards—Loadandcombustthestan-
carbon. dards and record the results. Adjust the calibration controls in
C698 − 16
suchawayastoproducethecorrectreadoutvalueonthedirect 26.2 Bias—The results obtained by six laboratories partici-
readout meter. Combust additional standards as required to pating in a recent comparative analytical program averaged
produce the correct direct readout. As an alternative, consider 85% of the expected 100 µg/g of carbon in the sample. The
the readout digits as arbitrary numbers and prepare a calibra- incomplete recovery is thought to represent a lack of experi-
tion curve of known micrograms of carbon versus readout ence on the part of two laboratories inasmuch as 95 to 100%
value.Astripchartrecorderconnectedtopresenttheintegrated recovery was obtained by three of the participating laborato-
value of the carbon dioxide response signal is helpful in ries.
detecting and correcting for analyzer drift and noise.
TOTAL CHLORINE AND FLUORINE BY
24. Procedure PYROHYDROLYSIS
24.1 Pulverize the pellet samples for 15 s in the stainless
27. Scope
steel capsule of the sample pulverizer.
27.1 Thistestmethodisapplicabletothedeterminationof5
24.2 Weigh a sample crucible containing the required
to 100µ g/g of chlorine and 1 to 100 µg/g of fluorine in 1-g
amount of accelerator to the nearest 0.01 g.
samples of nuclear-grade mixed oxides, (U, Pu)O .
24.3 Transfer the sample powder, not to exceed1gorof
such size as to give not more than 200 µg of carbon, to the 28. Summary of Test Method
crucible. Weigh the crucible and contents to the nearest 0.01 g
28.1 A1 to 2-g sample of the mixed oxide is pyrohydro-
and find the specimen mass by difference.
lyzed at 950°C with a stream of moist air or oxygen. The
24.4 Mix the specimen powder and the accelerator with a halogensarevolatilizedasacidsduringthepyrohydrolysisand
stainless steel spatula. are trapped as chloride and fluoride in a buffered solution.
Several procedures are outlined for the measurement of chlo-
24.5 Load the sample crucible into the furnace and combust
ride and fluoride in the resultant condensate. Chloride is
the specimen for 2 min.
measured by spectrophotometry, microtitrimetry, or with ion-
24.6 Remove the sample crucible and examine it for evi-
selective electrodes and fluoride with ion-selective electrodes
dence of incomplete combustion.The crucible contents should
or spectrophotometry (6-9).
be a uniform fused mass.
29. Interferences
25. Calculation
29.1 Bromide, iodide, cyanide, sulfide, and thiocyanate, if
25.1 Calculate the concentration of carbon in the sample by
presentinthecondensate,wouldinterferewiththespectropho-
dividing the net micrograms of carbon found by the sample
tometric and microtitrimetric measurement of chloride.
mass expressed in grams as follows:
Bromide, iodide, sulfide, and cyanide interfere in the measure-
C, µg/g 5 C 2 C /W (2)
~ !
ment of chloride with ion-selective electrodes, but have very
s b
little effect upon the measurement of fluoride with selective
where:
electrodes.
C = carbon in sample and reagents, µg,
s
C = carbon in reagent blank, µg, and
b
30. Apparatus (See Fig. 2 and Fig. 3 for examples)
W = grams of mixed oxide sample.
30.1 Gas-Flow Regulator—Aflowmeter and a rate control-
26. Precision and Bias ler are required to adjust the flow of sparge gas between 1 to 3
L/min.
26.1 Precision—The average standard deviation for a single
measurementfromtheresultsofsixlaboratoriesisontheorder 30.2 Hot Plate—A heater used to keep the water bubbler
of 10µ g carbon/g of sample. temperature between 50 and 90°C is required.
FIG. 3 Pyrohydrolysis Apparatus
C698 − 16
30.3 Furnace—Atube furnace is required that is capable of 31.9 Gelatin Solution—Add6.2gofdrygelatinmixture(60
maintainingatemperaturefrom900to1000°C.Theboreofthe parts of dry gelatin+1 part of thymol blue+1 part of thymol)
furnaceshouldbeabout32mm(1.25in.)indiameterandabout to 1 L of hot water and heat while stirring until the solution is
305 mm (12 in.) in length. clear.
30.4 Reactor Tube,madefromfused-silicaorplatinum.The 31.10 Lanthanum-Alizarin Complexone—Dissolve 0.048 g
deliverytubeshouldbeapartoftheexitendofthereactortube of alizarin complexone (3-aminomethylalizarin-N,N-
and be within 51 mm (2 in.) of the furnace. (See Fig. 3 for diaceticacid)in100µLofconcentratedammoniumhydroxide,
proper tube positioning.) 1 mL of an ammonium acetate solution (NH C H O,20
4 2 3 2
mass%), and 5 mL of water. Filter the solution through high
30.5 Combustion Boats, made from fused-silica or plati-
grade,rapidfilterpaper.Washthepaperwithasmallvolumeof
num. A boat about 102 mm (4 in.) long is made by cutting
water and add 8.2 g of anhydrous sodium acetate (NaC H O )
2 3 2
lengthwisea20-mmdiametersilicatubeandflatteningoneend
and6mLofCH CO H(spgr1.05)tothefiltrate.Add100mL
3 2
to provide a handle.Afused-silica inner sleeve for the reactor
ofacetonewhileswirlingthefiltrate.Add0.040goflanthanum
tube can facilitate the movement of the boat into the tube,
oxide (La O ) dissolved in 2.5 mL of warm 2 N HCl. Mix the
2 3
prevent spillage, and thus prolong the life of the combustion
two solutions and dilute to 200 mL. After 30 min readjust the
tube.
solution volume.
30.6 Collection Vessel—A plastic graduate or beaker de-
NOTE 3—A 0.1-g/L solution is prepared by dissolving 100 mg of the
signed to maintain most of the scrubber solution above the tip
reagent in water and diluting with isopropyl alcohol to obtain a 60%
of the delivery tube is required.
alcoholic medium.
30.7 Automatic Chloride Titrator.
31.11 Mercuric Thiocyanate Solution—Prepare a saturated
solution by adding 0.3 g of mercuric thiocyanate [Hg(SCN) ]
30.8 Ion-selective Electrodes, chloride and fluoride.
to100mLofethanol(95%).Shakethemixturethoroughlyfor
30.9 Reference Electrode—Use a double-junction type such
maximum dissolution of the solid. Filter the solution.
as mercuric sulfate, sleeve-junction type electrode. Do not use
31.12 Nitric Acid-Acetic Acid Solution (1 N nitric acid and
a calomel electrode.
4 N acetic acid)—Prepare by adding 64 mL of nitric acid
30.10 Spectrophotometer—Ultraviolet to visible range and
(HNO , sp gr 1.42) to a 1-L volumetric flask which contains
absorption cells. For a discussion on spectrophotometers and
500 mL of water. Swirl the solution in the flask and add 230
their use see Practice E60.
mLofCH CO H(spgr1.05).Dilutethesolutionwithwaterto
3 2
1L.
30.11 Meter, pH,withexpandedscalewithasensitivityof1
mV.
32. Pyrohydrolysis Procedure
31. Reagents
32.1 Prepare the pyrohydrolysis apparatus for use as fol-
lows:
31.1 Accelerator (U O )—Halogen free U O powder used
3 8 3 8
32.1.1 Regulate the gas flow between 1 and 3 L/min.
as a flux to enhance the release of chloride and fluoride.
32.1.2 Adjust the temperature of the hot plate to heat the
31.2 Air or Oxygen, compressed.
water to approximately 90°C.
31.3 Buffer Solution (0.001 N Acetic Acid, 0.001 N Potas-
32.1.3 Adjustthetemperatureofthefurnaceto950 650°C.
sium Acetate)—Prepare by adding 50 µL of glacial acetic acid
32.1.4 Add 15 mLof buffer solution to the collection vessel
(CH CO H, sp gr 1.05) and 0.10 g of potassium acetate
3 2 and place around the delivery tube.
(KC H O ) to 1 L of water.
2 3 2
32.2 Weighaccurately1to2gofthepowderedmixedoxide
31.4 Chloride Standard Solution (1 mL = 1 mg Cl)—
and transfer to a combustion boat. If an accelerator, U O,is
3 8
Dissolve 1.65 g of sodium chloride (NaCl) in water and dilute
used, mix 4 g with the sample before loading the powdered
to1L.
mixed oxide into the boat.
31.5 Chloride Standard Solution(1 mL = 5 µg Cl)—Prepare
32.3 Place the boat containing the sample into the reactor
by diluting 5 mLof chloride solution (1 mL=1 mg Cl) to 1 L
tube and quickly close the tube. The boat should be in the
with water.
middle of the furnace.
31.6 Ferric Ammonium Sulfate (0.25 M in 9 M Nitric 32.4 Allow the pyrohydrolysis to proceed for at least 30
Acid)—Dissolve 12 g of FeNH (SO ) ·12 HOin58mLof
min.
4 4 2 2
concentrated nitric acid (HNO , sp gr 1.42) and dilute to 100
32.5 Remove the collection vessel and wash down the
mL with water.
delivery tube with some buffer solution. Dilute the solution to
31.7 Fluoride, Standard Solution (1 mL=1 mg F)—
25 mL with the acetate buffer. Determine the chloride and
Dissolve2.21gofsodiumfluoride(NaF)inwateranddiluteto fluoride by one or more of the measurement procedures
1L.
covered in Section 33.
31.8 Fluoride, Standard Solution (1mL=10µgF)—Dilute 32.6 Remove the boat from the reactor tube and dispose of
10 mLof fluoride solution (1 mL=1 mg F) to 1 Lwith water. the sample residue.
C698 − 16
32.7 Runapyrohydrolysisblankwithhalogen-freeU O by 33.2.4 Calculate the chlorine as follows:
3 8
following the procedure in 32.3 through 32.6.
Cl, µg/g 5 V F T 2 T /V W (4)
~ !
1 s B 2
33. Measurement of Chloride and Fluoride
where:
33.1 Determination of Chloride by Spectrophotometry:
V = volume of scrub solutions=25,
33.1.1 Prepare a calibration curve by adding 0, 1, 2, 5, and
V = aliquot, in millilitres, of scrub solution analyzed,
10 mL of chloride standard solution (1 mL=5 µg Cl) to
F = micrograms of Cl standard titrated/titration time of
separate 25-mL flasks. Dilute each to 20 mL with the buffer
standard−titration time of blank or
solution, add 2 mL of ferric ammonium sulfate solution and 2
F = 50/(T −T ),
Cl B
mL of mercuric thiocyanate reagent. Mix the solution and T = titration time to titrate sample and blank,
s
dilute to 25 mL with water. Mix the solutions again and allow T = titration time to titrate 50 µg Cl and blank,
Cl
T = titration time to titrate reagent blank, and
them to stand 10 min. Transfer some of the solution from the
B
W = grams of mixed oxide pyrohydrolyzed.
flask to a 1-cm absorption cell and read the absorbance at 460
nm using water as the reference liquid. Plot the micrograms of
33.3 Determination of Chloride and Fluoride With Ion-
chloride per 25 mL versus the absorbance reading.
Selective Electrodes:
33.1.2 To determine the chloride in the pyrohydrolysis
33.3.1 Preparation of the calibration curves requires the
condensate transfer 15 mL of buffer solution to a 25-mL
assembly of the meter and the ion-selective electrode with a
volumetric flask. Add 2 mL of ferric ammonium sulfate
suitable reference electrode. From these standards take the
solution and 2 mL of mercuric thiocyanate solution. Mix the
millivolt readings for each ion-selective electrode and deter-
solutions, dilute to volume with water, and mix again. Allow
mine the halogen content per 25 mL versus millivolts, using
the solution to stand 10 min. Transfer some of the solution
computersoftwareoraplotonsemi-logpaper.Prepareaseries
from the flask to a 1-cm absorption cell and read the absor-
of standards in acetate buffer solution by pipeting aliquots of
bance at 460 nm versus water as the reference. Read the
the halogen standards into separate 25-mL flasks ranging in
micrograms of chloride present from the calibration curve.
concentrations as follows:
NOTE 4—A calibration curve can be prepared by drying measured
chloride 10 to 100 µg/25 mL
aliquots of a standard chloride solution on some halogen-free U O and
3 8
fluoride 5 to 100 µg/25 mL
proceeding through pyrohydrolysis steps.
33.3.2 Determine the chloride and fluoride in the scrub
33.1.3 Calculate the chlorine as follows:
solution from the pyrohydrolysis by using the appropriate
Cl, µg/g 5 A 2 B /W V /V (3)
@~ ! # ~ !
1 2
ion-selective electrode. Record the micrograms of chloride or
where: fluoride from the calibration curve and calculate the halide as
follows:
A = micrograms of chlorine in aliquot measured,
B = micrograms of chlorine in blank,
ClorF, µg/g 5 ~H 2 H !/W (5)
s b
W = grams of mixed oxide pyrohydrolyzed,
where:
V = millilitres of scrub solution, and
V = aliquot in millilitres of scrub solution analyzed. H = micrograms of halide in aliquot of scrub solution plus
s
blank,
33.2 Determination of Chloride by Amperometric Microtit-
H = micrograms of halide in pyrohydrolysis blank, and
b
rimetry:
W = grams of sample.
33.2.1 Calibrate the titrimeter by adding 5 mL of buffer
solution, 1 mL of nitric acid-acetic acid solution, and 2 drops
33.4 Determination of Fluoride by Spectrophotometry:
of the gelatin solution to a titration cell. Pipet 50 µL of the
33.4.1 Prepare a calibration curve by adding to separate
chloride standard solution (1 mL=1 mg Cl) into the titration
10-mL flasks 0, 50, 100, 200, 500, and 1000 µL of fluoride
cell. Place the cell on the chloride titrator and follow the
standardsolution(1mL=10µgF).Add2.0mLoflanthanum-
manufacturer’s suggested sequence of operations for titrating
alizarin complexone solution and dilute to volume with water.
chloride. Record the time required to titrate 50 µg. Run a
Mix and let stand 1 h. Read the absorbance at 622 nm versus
reagent blank titration.
the reagent blank. Plot the micrograms of fluoride per 10 mL
NOTE 5—The chloride analyzer generates silver ions which react to versus the absorbance reading.
precipitate the chloride ion. The instrument uses an amperometric end
33.4.2 Measure the fluoride in the pyrohydrolysis scrub
point to obtain an automatic shut-off of the generating current at a pre-set
solution by pipeting 5 mL into a 10-mL volumetric flask.Add
increment of indicator current. Since the rate of generating silver ion is
2.0 mL of lanthanum-alizarin complexone and dilute to vol-
constant, the amount of chloride precipitated is proportional to the time
required for the titration.
ume. Mix and let stand 1 h. Read the absorbance at 622 nm
versus a reagent blank and obtain the fluoride content from the
33.2.2 Determine the chloride in the pyrohydrolysis scrub
calibration curve.
solutionbyadding5mLtoatitrationcellwhichcontains1mL
of the nitric acid-acetic acid solution and 2 drops of the gelatin
33.4.3 Calculate the fluorine concentration in the mixed
solution.
oxide sample as follows:
33.2.3 Place the cell in position on the titrator. Start the
F, µg/g 5 @~F 2 F !/W# 3 V /V (6)
~ !
s b 1 2
titrator and record the time required to titrate the chloride
present. where:
C698 − 16
known sulfur contents. The relative standard deviation ranges
F = fluorine in aliquot of scrub solution plus the blank, µg,
s
from 12 to 3% for the concentration range from 10 to 600 µg
F = fluorine in pyrohydrolysis blank, µg,
b
of sulfur per gram of sample.
V = total volume of the scrub solution, mL,
V = aliquot of scrub solution analyzed, mL, and
W = grams of mixed oxide sample.
37. Interference
33.5 Determination of Chloride and Fluoride by Ion
37.1 None of the impurity elements interfere when present
Chromatography—Determine the Cl and F in the scrub solu-
in amounts up to twice their specification limits for uranium
tion from the pyrohydrolysis in accordance with Test Method
and plutonium mixed oxides.
D4327. Record the micrograms of Cl or F from the calibration
curve and calculate the halide using Eq 5.
38. Apparatus
38.1 Boiling Flask, adapted with a gas inlet line and fitted
34. Precision and Bias
with a water-cooled condenser and delivery tube.
34.1 The relative standard deviations for the measurements
38.2 Spectrophotometer, with matched 1-cm cells.
of fluorine are approximately 7% for the 5 to 50-µg/g range
and 10% for the 1 to 5-µg/g range. The relative standard
38.3 Sulfur Distillation Apparatus—see Fig. 4 for example.
deviations for the measurements of chlorine vary from 5% at
the 5 to 50-µg/g level and up to 10% below the 5-µg/g range.
39. Reagents
39.1 Argon Gas, cylinder.
SULFUR BY DISTILLATION-
SPECTROPHOTOMETRY
39.2 Ferric Chloride Solution, 2% ferric chloride (FeCl )
in 6 M HCl.
35. Scope
39.3 Formic Acid, redistilled.
35.1 This test method covers the determination of sulfur in
the concentration range from 10 to 600 µg/g for samples of 39.4 Hydriodic-Hypophosphorous Acid Reducing Mixture—
nuclear-grade uranium and plutonium mixed oxides, (U, Mix 400 mL of 47% hydriodic acid (HI) with 200 mL of
Pu)O . hypophosphorous acid (H PO ) (31%) and boil under reflux
2 3 2
for 30 min with a continuous argon sparge. Test for the sulfur
36. Summary of Test Method
content by analyzing a 15-mL aliquot as described in the
procedure. Reboil if necessary to reduce the sulfur content to
36.1 Sulfur is measured spectrophotometrically as Lauth’s
below 1 µg/mL.
Violet following its separation by distillation as hydrogen
sulfide (10). Higher oxidation states of sulfur are reduced to
39.5 Hydrochloric Acid (0.6 M)—Dilute 10 mL of 12 M
sulfide by a hypophosphorous-hydriodic acid mixture, the
hydrochloric acid (HCl) to 200 mL with water.
hydrogen sulfide is distilled into zinc acetate, and
39.6 Hydrochloric Acid (3M)—Dilute 50 mL of 12 M HCl
p-phenylenediamine and ferric chloride are added to form
to 200 mL with water.
Lauth’s Violet. The quantity of sulfur is calculated from the
measured absorbance at 595 nm and the absorbance per 39.7 Hydrochloric Acid(6M)—Dilute100mLof12 MHCl
microgram of sulfur obtained for calibration materials having to 200 mL with water.
FIG. 4 Sulfur Distillation Apparatus
C698 − 16
39.8 Hydrochloric Acid(12 M)—AnalyzeanaliquotofHCl 41.8 Dissolvetheresidueinaminimumvolumeof3 MHCl
(sp gr 1.19) for sulfur content. Use only a reagent in which the and dilute to approximately 5 mL with water. Heat to just
sulfur content is less than 1 µg/10 mL and prepare the diluted below the boiling point and add 20 drops of hydroxylamine
acids with this reagent. solution (Pu-III, blue, is formed).
39.9 Hydrofluoric Acid (HF), (sp gr 1.15)—Concentrated 41.9 Add 30 mL of water to the trap of the distillation
hydrofluoric acid (HF). See safety precaution in 6.3. apparatus (Fig. 4) and insert the trap tube.
39.10 Hydroxylamine Hydrochloride (NH OH·HCl), 20% 41.10 Pipet 10.0 mL of 4% zinc acetate solution into a
aqueous solution. 50-mL glass-stoppered graduated cylinder, dilute to 35 mL
with water, and position the cylinder so the end of the delivery
39.11 Nitric Acid (HNO)(15.6 M), 70%.
tube is immersed in the solution.
39.12 p-Phenylenediamine (1%)—Dissolve1gof
41.11 Transfer the sample solution (41.8) with a minimum
p-phenylenediamine in 100 mL of 0.6 M HCl.
of water rinses to the distillation flask and insert the reducing-
39.13 Silver Nitrate (AgNO ), 1% aqueous solution.
acid delivery tube.
39.14 Sulfur Calibration Solution (1 mL=5 µg S)—
41.12 Add 15 mL of the reducing acid mixture and 10 mL
Dissolve2.717gofdrypotassiumsulfate(K SO )inwaterand
2 4
of 12 M HCl to the delivery bulb. Insert the argon sweep gas
dilute to 1 L. Dilute 2.00 mL to 200 mL with water.
tube and start the flow of the reducing acid mixture to the
distillation flask.
39.15 Zinc Acetate Solution (4%)—Dissolve 20 g of zinc
acetate [Zn(C H O ) ] in 500 mL of water and filter.
2 3 2 2 41.13 Adjust the flow rate of argon to 100 cm /min; then
turn on the heating mantle and boil the solution for 35 min.
40. Calibration
41.14 Disconnect the distillate delivery tube, and rinse it
40.1 Use aliquots of standard sulfur solution (1 mL=5 µg
with 2.00 mLof 3 M HCl followed by approximately 2 mLof
S) to test the test method and check the apparatus. Ideally,
water,collectingtheserinsesinthezincacetatesolution.Rinse
blends of oxides and sulfur (20 to 600 µg S/g) should be
zinc sulfide (ZnS) formed inside the tube into the zinc acetate
analyzed to simulate actual sample conditions.
solution.
40.2 Prepareacalibrationcurveofabsorbance versussulfur
41.15 Pipet 1.00 mL of 1% p-phenylenediamine into the
(using aliquots of the sulfur standard solution) covering a
solution and mix rapidly by swirling. Pipet 1.00 mL of 2%
concentration range from 5 µg to 50 µg/50 mL.
ferric chloride solution and again mix rapidly.
NOTE 8—Rapid mixing after each reagent addition prevents formation
41. Procedure
of a brown reduction product that interferes with the spectrophotometric
measurement.
41.1 Pulverize mixed oxide pellets in a mixer-mill with a
tungsten carbide container and a tungsten carbide ball.
41.16 Dilute to 50 mLwith water, stopper the cylinder, mix
the solution, and let stand 1 h.
41.2 Transfer a sample, weighed to 60.2 mg, to a 20-mL
beakerora30-mLplatinumdish.Usea0.5-gsamplewhenthe
41.17 Measure the absorbance within 10 min at a wave-
expected level of sulfur is 100 µg/g or less.
length of 595 nm versus a reagent reference.
41.3 Add 5 mL of 15.6 M HNO and 3 to 4 drops of 28 M
42. Calculation
HFandheatthesolutionbelowitsboilingpoint.Watchglasses
42.1 Calculate the sulfur content as follows:
or platinum lids are recommended to avoid spattering.
S, µg/g 5 S 2 B /W (7)
~ !
41.4 Add additional amounts of HNO and HF acids until
the sample dissolves.
where:
NOTE 6—The sealed-tube technique described in USAEC Document S = micrograms of sulfur in sample,
LA-4622,1971 (10),p.5,isanalternativetestmethodwhichmaybeused
B = micrograms of sulfur in blank, and
to advantage for the dissolution of some samples.
W = grams of sample.
41.5 Evaporate the solution just to dryness, but do not fume
43. Precision and Bias
intensely to dryness.
43.1 The relative standard deviations in 0.1-g samples are 6
41.6 Dropwise add 0.5 mLof formic acid. Heat the solution
to 3% for the range from 50 to 600 µg/g and in 0.5-g samples
at moderate heat until the vigorous reaction subsides and gases
are 12 to 5% for the range from 10 to 20 µg/g.
are no longer evolved.
MOISTURE BY THE COULOMETRIC,
NOTE 7—The reduction of HNO by formic acid is vigorous. Keep the
dish or beaker covered with a watch glass between additions of formic ELECTROLYTIC MOISTURE ANALYZE
...

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: C698 − 10 C698 − 16
Standard Test Methods for
Chemical, Mass Spectrometric, and Spectrochemical
Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O )
This standard is issued under the fixed designation C698; 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 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade
mixed oxides, (U, Pu)O , powders and pellets to determine compliance with specifications.
1.2 The analytical procedures appear in the following order:
Sections
Uranium in the Presence of Pu by Potentiometric Titration
Plutonium by Controlled-Potential Coulometry
Plutonium by Amperometric Titration with Iron (II)
Nitrogen by Distillation Spectrophotometry Using Nessler 7 to 14
Reagent
Nitrogen by Distillation Spectrophotometry Using Nessler 8 to 15
Reagent
Carbon (Total) by Direct Combustion-Thermal Conductivity 15 to 26
Carbon (Total) by Direct Combustion-Thermal Conductivity 16 to 26
Total Chlorine and Fluorine by Pyrohydrolysis 27 to 34
Sulfur by Distillation-Spectrophotometry 35 to 43
Moisture by the Coulometric, Electrolytic Moisture Analyzer 44 to 51
Isotopic Composition by Mass Spectrometry
Rare Earths by Copper Spark Spectroscopy 52 to 59
Trace Impurities by Carrier Distillation Spectroscopy 60 to 69
Trace Impurities by Carrier Distillation Spectroscopy 60 to 68
Impurities by Spark-Source Mass Spectrography 70 to 76
Impurities by Spark-Source Mass Spectrography 69 to 75
Total Gas in Reactor-Grade Mixed Dioxide Pellets 77to 84
Total Gas in Reactor-Grade Mixed Dioxide Pellets
Tungsten by Dithiol-Spectrophotometry 85 to 93
Tungsten by Dithiol-Spectrophotometry 76 to 84
Rare Earth Elements by Spectroscopy 94 to 97
Rare Earth Elements by Spectroscopy 85 to 88
Plutonium-238 Isotopic Abundance by Alpha Spectrometry
Americium-241 in Plutonium by Gamma-Ray Spectrometry
Uranium and Plutonium Isotopic Analysis by Mass 98 to 106
Spectrometry
Uranium and Plutonium Isotopic Analysis by Mass 89 to 97
Spectrometry
Oxygen-to-Metal Atom Ratio by Gravimetry 107 to 115
Oxygen-to-Metal Atom Ratio by Gravimetry 98 to 105
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory
limitations prior to use. (For specific safeguard and safety precaution statements, see Sections 116, 2013.2.5, 6441.7, and 112 and
102.6.193.6.1.)
These test methods are under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.05 on Methods
of Test.
Current edition approved June 1, 2010June 1, 2016. Published July 2010July 2016. Originally approved in 1972. Last previous edition approved in 20042010 as
C698 – 04.C698 – 10. DOI: 10.1520/C0698-10.10.1520/C0698-16.
Discontinued as of November 15, 1992.
Discontinued as of May 30, 1980.
Discontinued as of January 1, 2004.June 2016.
Discontinued as of January 1, 2004.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C698 − 16
2. Referenced Documents
2.1 ASTM Standards:
C697 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium Dioxide
Powders and Pellets
C833 Specification for Sintered (Uranium-Plutonium) Dioxide Pellets
C852 Guide for Design Criteria for Plutonium Gloveboxes
C1008 Specification for Sintered (Uranium-Plutonium) DioxidePellets—Fast Reactor Fuel (Withdrawn 2014)
C1009C859 Guide for Establishing and Maintaining a Quality Assurance Program for Analytical Laboratories Within the
Nuclear IndustryTerminology Relating to Nuclear Materials
C1068 Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Industry
C1108 Test Method for Plutonium by Controlled-Potential Coulometry
C1128 Guide for Preparation of Working Reference Materials for Use in Analysis of Nuclear Fuel Cycle Materials
C1156 Guide for Establishing Calibration for a Measurement Method Used to Analyze Nuclear Fuel Cycle Materials
C1165 Test Method for Determining Plutonium by Controlled-Potential Coulometry in H SO at a Platinum Working Electrode
2 4
C1168 Practice for Preparation and Dissolution of Plutonium Materials for Analysis
C1204 Test Method for Uranium in Presence of Plutonium by Iron(II) Reduction in Phosphoric Acid Followed by
Chromium(VI) Titration
C1206 Test Method for Plutonium by Iron (II)/Chromium (VI) Amperometric Titration (Withdrawn 2015)
C1210C1233 Guide for Establishing a Measurement System Quality Control Program for Analytical Chemistry Laboratories
Within the Nuclear IndustryPractice for Determining Equivalent Boron Contents of Nuclear Materials
C1268 Test Method for Quantitative Determination of Am in Plutonium by Gamma-Ray Spectrometry
C1297 Guide for Qualification of Laboratory Analysts for the Analysis of Nuclear Fuel Cycle Materials
C1415 Test Method for Pu Isotopic Abundance By Alpha Spectrometry
C1432 Test Method for Determination of Impurities in Plutonium: Acid Dissolution, Ion Exchange Matrix Separation, and
Inductively Coupled Plasma-Atomic Emission Spectroscopic (ICP/AES) Analysis
C1625 Test Method for Uranium and Plutonium Concentrations and Isotopic Abundances by Thermal Ionization Mass
Spectrometry
C1637 Test Method for the Determination of Impurities in Plutonium Metal: Acid Digestion and Inductively Coupled
Plasma-Mass Spectroscopy (ICP-MS) Analysis
C1672 Test Method for Determination of Uranium or Plutonium Isotopic Composition or Concentration by the Total
Evaporation Method Using a Thermal Ionization Mass Spectrometer
C1817 Test Method for The Determination of the Oxygen to Metal (O/M) Ratio in Sintered Mixed Oxide ((U, Pu)O ) Pellets
by Gravimetry
D1193 Specification for Reagent Water
D4327 Test Method for Anions in Water by Suppressed Ion Chromatography
E60 Practice for Analysis of Metals, Ores, and Related Materials by Spectrophotometry
E115 Practice for Photographic Processing in Optical Emission Spectrographic Analysis (Withdrawn 2002)
E116 Practice for Photographic Photometry in Spectrochemical Analysis (Withdrawn 2002)
E130 Practice for Designation of Shapes and Sizes of Graphite Electrodes (Withdrawn 2013)
3. Terminology
3.1 Except as otherwise defined herein, definitions of terms are as given in Terminology C859.
4. Significance and Use
4.1 Mixed oxide, a mixture of uranium and plutonium oxides, is used as a nuclear-reactor fuel in the form of pellets. The
plutonium content may be up to 10 weight %, and the diluent uranium may be of any U enrichment. In order to be suitable for
use as a nuclear fuel, the material must meet certain criteria for combined uranium and plutonium content, effective fissile content,
and impurity content as described in Specification C833.
4.1.1 The material is assayed for uranium and plutonium to determine whether the plutonium content is as specified by the
purchaser, and whether the material contains the minimum combined uranium and plutonium contents specified on a dry weight
basis.
4.1.2 Determination of the isotopic content of the plutonium and uranium in the mixed oxide is made to establish 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.
The last approved version of this historical standard is referenced on www.astm.org.
C698 − 16
4.1.3 Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not
exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC).(EBC) as described
in Practice C1233.
4.2 Fitness for Purpose of Safeguards and Nuclear Safety Applications—Methods intended for use in safeguards and nuclear
safety applications shall meet the requirements specified by Guide C1068 for use in such applications.
5. Reagents
5.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall 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.
5.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to
Specification D1193.
6. Safety Precautions
6.1 Since plutonium- and uranium-bearing materials are radioactive and toxic, adequate laboratory facilities, glovedglove
boxes, fume hoods, etc., and so forth, along with safe techniques must be used in handling samples containing these materials.
Glove boxes should be fitted with off-gas filters capable of sustained operation with dust-laden atmospheres. A detailed discussion
of all the precautions necessary is beyond the scope of these test methods; however, personnel who handle these materials should
be familiar with such safe handling practices as are given in Guide C852 and in Refs (11-3) through (2).
5.2 Committee C26 Safeguards Statement:
5.2.1 The materials [nuclear grade mixed oxides (U, Pu)O powders and pellets] to which these test methods apply are subject
to nuclear safeguards regulations governing their possession and use. The following analytical procedures in these test methods
have been designated as technically acceptable for generating safeguards accountability measurement data: Uranium by Controlled
Potential Coulometry; Plutonium by Controlled-Potential Coulometry; Plutonium by Amperometric Titration with Iron(II);
Plutonium-238 Isotopic Abundance by Alpha Spectrometry; and Uranium and Plutonium Isotopic Analysis by Mass Spectrometry.
5.2.2 When used in conjunction with appropriate certified reference materials (CRMs), these procedures can demonstrate
traceability to the national measurements base. However, adherence to these procedures does not automatically guarantee
regulatory acceptance of the resulting safeguards measurements. It remains the sole responsibility of the user of these test methods
to assure that its application to safeguards has the approval of the proper regulatory authorities.
6.2 Adequate laboratory facilities, such as fume hoods and controlled ventilation, along with safe techniques, must be used in
this procedure. Extreme care should be exercised in using hydrofluoric acid and other hot, concentrated acids. Use of proper gloves
is recommended. Refer to the laboratory’s chemical hygiene plan and other applicable guidance for handling chemical and
radioactive materials and for the management of radioactive, mixed, and hazardous waste.
6.3 Hydrofluoric acid is a highly corrosive acid that can severely burn skin, eyes and mucous membranes. Hydrofluoric acid
is similar to other acids in that the initial extent of a burn depends on the concentration, the temperature, and the duration of contact
with the acid. 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. Due to the serious consequence of hydrofluoric acid burns, prevention of exposure or injury of personnel is the
primary goal. Utilization of appropriate laboratory controls (hoods) and wearing adequate personal protective equipment to protect
from skin and eye contact Familiarization and compliance with the Safety Data Sheet is essential.
6.4 Perchloric acid (HClO ) forms explosive compounds with organics and many metal salts. Avoid exposure by contact with
the skin or eyes, or by inhalation of fumes. Familiarization and compliance with the Safety Data Sheet is essential. Carry out
sample dissolution with perchloric acid in a fume hood with a scrubber unit that is specially designed for use with HClO .
7. Sampling and Dissolution
7.1 Criteria for sampling this material are given in Specification C833.
7.2 Samples can be dissolved using the appropriate dissolution techniques described in Practice C1168.
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 Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
The boldface numbers in parentheses refer to the list of references at the end of these test methods.
C698 − 16
URANIUM IN THE PRESENCE OF PLUTONIUM BY POTENTIOMETRIC TITRATION
(This test method was discontinued in 1992 and replaced by Test Method C1204.)
PLUTONIUM BY CONTROLLED POTENTIAL COULOMETRY
(This test method was discontinued in 1992 and replaced by Test Method C1165.)
PLUTONIUM BY CONTROLLED-POTENTIAL COULOMETRY
(With appropriate sample preparation, controlled-potential coulometric measurement as described in Test Method C1108 may
be used for plutonium determination.)
PLUTONIUM BY AMPEROMETRIC TITRATION WITH IRON(II)
(This test method was discontinued in 1992 and replaced by Test Method C1206.) , which was withdrawn in 2015.)
NITROGEN BY DISTILLATION SPECTROPHOTOMETRY USING NESSLER REAGENT
8. Scope
8.1 This test method covers the determination of 5 to 100 μg/g of nitride nitrogen in mixtures of plutonium and uranium oxides
in either pellet or powder form.
9. Summary of Test Method
9.1 The sample is dissolved in hydrochloric acid by the sealed tube test method or by phosphoric acid-hydrofluoric acid
solution, after which the solution is made basic with sodium hydroxide and nitrogen is separated as ammonia by steam distillation.
Nessler reagent is added to the distillate to form the yellow ammonium complex and the absorbance of the solution is measured
at approximately 430 nm (34, 45).
10. Apparatus
10.1 Distillation Apparatus (see Fig. 1). for an example).
10.2 Spectrophotometer, visible-range.
11. Reagents
11.1 Ammonium Chloride (NH Cl)—Dry the salt for 2 h at 110 to 120°C.
11.2 Boric Acid Solution (40 g/litre)—Dissolve 40 g of boric acid (H BO ) in 800 mL of hot water. Cool to approximately 20°C
3 3
and dilute to 1 L.
11.3 Hydrochloric Acid (sp gr 1.19)—Concentrated hydrochloric acid (HCl).
11.4 Hydrofluoric Acid (sp gr 1.15)—Concentrated hydrofluoric acid (HF). See safety precaution in 6.3.
11.5 Nessler Reagent—To prepare, dissolve 50 g of potassium iodide (KI) in a minimum of cold ammonia-free water,
approximately 35 mL. Add a saturated solution of mercuric chloride (HgCl , 22 g/350 mL) slowly until the first slight precipitate
of red mercuric iodide persists. Add 400 mL of 9 N sodium hydroxide (NaOH) and dilute to 1 L with water. Mix, and allow the
solution to stand overnight. Decant the supernatant liquid and store in a brown bottle.
11.6 Nitrogen, Standard Solution (1 mL = 0.01 mg N)—Dissolve 3.819 g of NH Cl in water and dilute to 1 L. Transfer 10 mL
of this solution to a 1-L volumetric flask and dilute to volume with ammonia-free water.
11.7 Sodium Hydroxide (9 N)—Dissolve 360 g of sodium hydroxide (NaOH) in ammonia-free water and dilute to 1 L.
11.8 Sodium Hydroxide Solution—(50 %)—Dissolve NaOH in an equal weight of ammonia-free water.
FIG. 1 Distillation Apparatus
C698 − 16
11.9 Water, Ammonia-Free—To prepare, pass distilled water through a mixed-bed resin demineralizer and store in a tightly
stoppered chemical-resistant glass bottle.
12. Precautions
12.1 The use of ammonia or other volatile nitrogenous compounds in the vicinity can lead to serious error. The following
precautionary measures should be taken: (1) Clean all glassware and rinse with ammonia-free water immediately prior to use, and
(2) avoid contamination of the atmosphere in the vicinity of the test by ammonia or other volatile nitrogenous compounds.
13. Procedure
13.1 Dissolution of Sample:
13.1.1 Transfer a weighed sample, in the range from 1.0 to 1.5 g, to a 50-mL beaker.
NOTE 1—Pellet samples should be crushed to a particle size of 1 mm or less with a diamond mortar.
13.1.2 Crush the pellet samples to a particle size of 1 mm or less in a diamond mortar.
13.1.3 To the sample add 5 mL of HCl (sp gr 1.19) and 3 drops of HF (sp gr 1.15). Heat to put the sample into solution.
NOTE 1—Concentrated phosphoric acid or mixtures of phosphoric acid and hydrofluoric acids or of phosphoric and sulfuric acids may be used for the
dissolution of mixed oxide samples. Such acids may require a purification step in order to reduce the nitrogen blank before being used in this procedure.
13.2 Distillation:
13.2.1 Quantitatively transfer the sample solution to the distilling flask of the apparatus. Add 20 mL of ammonia-free water and
then clamp the flask into place on the distillation apparatus (see Fig. 2). for an example).
13.2.2 Turn on the steam generator but do not close with the stopper.
13.2.3 Add 5 mL of boric acid solution (4 %) to a 50-mL graduated flask and position this trap so that the condenser tip is below
the surface of the boric acid solution.
13.2.4 Transfer 20 mL of NaOH solution (50 %) to the funnel in the distillation head.
13.2.5 When the water begins to boil in the steam generator, replace the stopper and slowly open the stopcock on the distilling
flask to allow the NaOH solution to run into the sample solution. (Warning—The NaOH solution must be added slowly to avoid
a violent reaction, which may lead to a loss of sample.)
NOTE 3—The NaOH solution must be added slowly to avoid a violent reaction which may lead to loss of sample.
13.2.6 Steam distill until 25 mL of distillate has collected in the trap.
13.2.7 Remove the trap containing the distillate from the distillation apparatus, and remove the stopper from the steam
generator.
13.2.8 Transfer the cooled distillate to a 50-mL volumetric flask.
13.2.9 Prepare a reagent blank solution by following steps 12.1.113.1.1 through 12.2.813.2.8.
13.3 Measurement of Nitrogen:
13.3.1 Add 1.0 mL of Nessler reagent to each of the distillates collected in 12.2.813.2.8 and 12.2.913.2.9. Dilute to volume with
ammonia-free water, mix, and let stand for 10 min.
13.3.2 Measure the absorbance of the solutions at 430 nm in a 1-cm cell. Use water as the reference.
13.4 Calibration Curve:
13.4.1 Add 0, 5, 10, 25, 100, and 150 μg of nitrogen from the nitrogen standard solution to separate distilling flasks. Then, add
5 mL of HCl and 3 drops of HF plus 20 mL of ammonia-free water to each flask.
13.4.2 Process each solution by the procedure in 12.213.2 through 12.313.3 (omit step 12.2.913.2.9).
13.4.3 Correct for the reagent blank reading and plot the absorbance of each standard against micrograms of nitrogen per 50
mL of solution.
FIG. 2 Quartz Reaction Tube
C698 − 16
14. Calculation
14.1 From the calibration chart, read the micrograms of nitrogen corresponding to the absorbance of the sample solution.
14.2 Calculate the nitrogen content of the sample as follows:
N, µg/g5 ~A 2 B!/W (1)
where:
A = micrograms of nitrogen from sample plus reagents,
B = micrograms of nitrogen in blank, and
W = grams of sample.
15. Precision and Bias
15.1 The estimated relative standard deviation for a single measurement by this test method is 20 % for 3 μg of nitrogen and
3 % for 50 to 90 μg of nitrogen.
CARBON (TOTAL) BY DIRECT COMBUSTION-THERMAL CONDUCTIVITY
16. Scope
16.1 This test method covers the determination of 10 to 200 μg of residual carbon in nuclear grade mixed oxides, (U,Pu)O .
17. Summary of Test Method
17.1 Powdered samples are covered and mixed with an accelerator in carbon-free crucibles and burned with oxygen in an
induction heating furnace. Traces of sulfur compounds and water vapor are removed from the combustion products by a
purification train and the resultant carbon monoxide is converted to carbon dioxide. The purified carbon dioxide is trapped on a
molecular sieve, eluted therefrom with a stream of helium upon application to heat to the trap, and passed through a thermal
conductivity cell. The amount of carbon present, being a function of the integrated change in the current of the detector cell, is
read directly from a calibrated-digital voltmeter or strip-chart recorder.
18. Interferences
18.1 There are no known interferences not eliminated by the purification system.
19. Apparatus
19.1 Commercial Combustion Apparatus, suitable for the carbon determination, is often modified to facilitate maintenance and
operation within the glove box which is required for all work with plutonium materials.
19.2 Combustion Apparatus, consisting of an induction furnace, suitable for operation at 1600°C, a catalytic furnace, a
purification train, a carbon dioxide trap, thermal conductivity cell with appropriate readout equipment, and a regulated supply of
oxygen and helium.
19.3 Combustion Tubes—Quartz combustion tubes with integral baffle shall be used.
19.4 Crucibles—Expendable alumina or similar refractory crucibles shall be used. The use of crucible covers is optional.
Satisfactory operation with covers must be established by analysis of standards. Crucibles and covers (if used) must be ignited at
a temperature of 1000°C or higher for a time sufficient to produce constant blank values.
19.5 Accelerators—Granular tin, copper, iron, and copper oxide accelerators shall be used to obtain satisfactory results. The
criterion for satisfactory results is the absence of significant additional carbon release upon recombustion of the specimen.
19.6 Catalytic Furnace and Tube—This unit, which is used to ensure complete conversion of CO to CO , consists of a tube
containing copper oxide and maintained at a temperature of 300°C by a small furnace.
19.7 Carbon Dioxide Purifiers—The purifiers that follow the combustion tube must remove finely divided solid metallic oxides
and oxides of sulfur and selenium, dry the gases before they enter the CO trap, and protect the absorber from outside effects.
Finely divided solid metal oxides are removed from the gases during their passage through the quartz wool. The SO given off by
materials containing sulfur is removed by MnO and any water vapor is absorbed in a tube containing Mg(ClO ) . Hot copper
2 4 2
oxide converts carbon monoxide to carbon dioxide. Additional components in the purification train may be required when materials
containing very high amounts of sulfur or of halides are being analyzed. The materials used in the purification train must be
checked frequently to ensure that their absorbing capacity has not been exhausted.
19.8 Vibratory Sample Pulverizer Apparatus, capable of reducing ceramic materials to a − 100-mesh powder.such that 90 % or
more of the particles are less than 149 μm (equivalent to a − 100-mesh powder). A stainless steel capsule and mixing ball must
be used, in order to reduce contamination of the sample with carbon.
C698 − 16
20. Reagents and Materials
20.1 Quartz Wool, used as a dust trap at the top of the combustion tube.
20.2 Sulfuric Acid (H SO , sp gr 1.84), used in the oxygen purification train.
2 4
20.3 Standard Materials—Certified reference material standards from a national standards body such as the U.S. National
Institute for Standards and Technology (NIST) SRMs 131c (0.0029 % carbon) and 336 (0.567 % carbon) or their replacements.or
equivalent. Certified materials in steel matrices (steel pins steel rings, steel granules, and steel powder) ranging from 5 μg carbon/g
sample to 1500 μg carbon/g sample are available and have been found satisfactory.
20. Safety Precautions
20.1 Samples Containing Plutonium—Due to the extreme toxicity of plutonium and the certainty that some plutonium will
become airborne during the analytical operations, it is mandatory to perform all operations within an approved glove box fitted
with off-gas filters capable of sustained operation with dust-laden atmospheres.
20.2 Samples Containing Uranium—Natural or depleted uranium presents a somewhat less serious toxicological hazard than
plutonium, but operations should be conducted in a fume hood with adequate ventilation, as a minimum precaution.
21. Sampling and Preparation
21.1 Sample Size—The normal size for mixed oxide [(U,Pu)O ] fuel materials shall be 1 g. If necessary, this amount shall be
altered as required to contain less than 200 μg of carbon.
21.2 Sample Preparation—Pellet or particulate samples shall be reduced to approximately − 100-mesh powdersuch that
approximately 90 % of the particles are less than 149 μm (equivalent to approximately − 100-mesh powder) prior to the weighing
of the specimens. Exposure of the powdered sample to atmospheric carbon dioxide should be minimized by storage of the powder
in a closed vial.
22. Preparation of Apparatus
22.1 Analysis System Purge—After having properly set the operating controls of the instrument system, condition the apparatus
by combustion of several blanks prepared with the sample crucible and accelerator in the amount to be used with the test specimen
analyses. Successive blank values should approach a constant value, allowing for normal statistical fluctuations. The instrument
should be adjusted for a 2-min combustion period.
23. Calibration
23.1 Preparation of Standards for Combustion—Mix a weighed portion of an accelerator and a an accurately weighed portion
of approximately 1 g of NIST 131c Low-Carbon Steel reference material with a certified carbon value of about 0.005 % in each
of the three sample crucibles. Repeat with NIST SRM 336 or a reference material with a certified carbon value of about 0.5 %
(Note 42), using an accurately weighed portion of approximately 30 to 40 mg.
NOTE 2—The NIST SRM 336 steel is assigned a carbon content of 0.567 % (5670 μg/g). Therefore, amounts ranging up to approximately 40 mg are
used for standardization. Weigh the steel into a tared container (a small nickel sample boat if convenient), obtaining the mass to the nearest 0.01 mg.
Transfer the chips to a 30-mm square of aluminum foil (previously acetone washed), and fold the foil into a wrapper with the aid of stainless steel tongs
and spatulas. The foil should not be touched by the hands. Place the wrapped standard in a numbered glass sample vial and transfer to the analyzer glove
box.These portions represent about 50 μg and 200 μg of carbon, respectively.
23.1.1 Weigh the steel into a tared container, such as a small nickel sample boat, obtaining the mass to the nearest 0.01 mg.
Transfer the chips to a 30-mm square of aluminum foil (previously acetone washed), and fold the foil into a wrapper with the aid
of stainless steel tongs and spatulas. The foil should not be touched by the hands. Place the wrapped standard in a numbered glass
sample vial and transfer to the analyzer glove box.
23.2 Combustion of Standards—Load and combust the standards and record the results. Adjust the calibration controls in such
a way as to produce the correct readout value on the direct readout meter. Combust additional standards as required to produce
the correct direct readout. As an alternative, consider the readout digits as arbitrary numbers and prepare a calibration curve of
known micrograms of carbon versus readout value. A strip chart recorder connected to present the integrated value of the carbon
dioxide response signal is helpful in detecting and correcting for analyzer drift and noise.
24. Procedure
24.1 Pulverize the pellet samples for 15 s in the stainless steel capsule of the sample pulverizer.
24.2 Weigh a sample crucible containing the required amount of accelerator to the nearest 0.01 g.
24.3 Transfer the sample powder, not to exceed 1 g or of such size as to give not more than 200 μg of carbon, to the crucible.
Weigh the crucible and contents to the nearest 0.01 g and find the specimen mass by difference.
24.4 Mix the specimen powder and the accelerator with a stainless steel spatula.
C698 − 16
24.5 Load the sample crucible into the furnace and combust the specimen for 2 min.
24.6 Remove the sample crucible and examine it for evidence of incomplete combustion. The crucible contents should be a
uniform fused mass.
25. Calculation
25.1 Calculate the concentration of carbon in the sample by dividing the net micrograms of carbon found by the sample mass
expressed in grams as follows:
C, µg/g5 C 2 C /W (2)
~ !
s b
where:
C = carbon in sample and reagents, μg,
s
C = carbon in reagent blank, μg, and
b
W = grams of mixed oxide sample.
26. Precision and Bias
26.1 Precision—The average standard deviation for a single measurement from the results of six laboratories is on the order of
10μ g carbon/g of sample.
26.2 Bias—The results obtained by six laboratories participating in a recent comparative analytical program averaged 85 % of
the expected 100 μg/g of carbon in the sample. The incomplete recovery is thought to represent a lack of experience on the part
of two laboratories inasmuch as 95 to 100 % recovery was obtained by three of the participating laboratories.
TOTAL CHLORINE AND FLUORINE BY
PYROHYDROLYSIS
27. Scope
27.1 This test method is applicable to the determination of 5 to 100μ g/g of chlorine and 1 to 100 μg/g of fluorine in 1-g samples
of nuclear-grade mixed oxides, (U, Pu)O .
28. Summary of Test Method
28.1 A 1 to 2-g sample of the mixed oxide is pyrohydrolyzed at 950°C with a stream of moist air or oxygen. The halogens are
volatilized as acids during the pyrohydrolysis and are trapped as chloride and fluoride in a buffered solution. Several procedures
are outlined for the measurement of chloride and fluoride in the resultant condensate. Chloride is measured by spectrophotometry,
microtitrimetry, or with ion-selective electrodes and fluoride with ion-selective electrodes or spectrophotometry (5–(66-9).).
29. Interferences
29.1 Bromide, iodide, cyanide, sulfide, and thiocyanate, if present in the condensate, would interfere with the spectrophoto-
metric and microtitrimetric measurement of chloride. Bromide, iodide, sulfide, and cyanide interfere in the measurement of
chloride with ion-selective electrodes, but have very little effect upon the measurement of fluoride with selective electrodes.
30. Apparatus (See Fig. 2 and Fig. 3 andfor Fig. 2)examples)
30.1 Gas-Flow Regulator—A flowmeter and a rate controller are required to adjust the flow of sparge gas between 1 to 3 L/min.
30.2 Hot Plate—A heater used to keep the water bubbler temperature between 50 and 90°C is required.
FIG. 3 Pyrohydrolysis Apparatus
C698 − 16
30.3 Furnace—A tube furnace is required that is capable of maintaining a temperature from 900 to 1000°C. The bore of the
furnace should be about 32 mm (1(1.25 ⁄4 in.) in diameter and about 305 mm (12 in.) in length.
30.4 Reactor Tube, made from fused-silica or platinum. The delivery tube should be a part of the exit end of the reactor tube
and be within 51 mm (2 in.) of the furnace. (See Fig. 3 for proper tube positioning.)
30.5 Combustion Boats, made from fused-silica or platinum. A boat about 102 mm (4 in.) long is made by cutting lengthwise
a 20-mm diameter silica tube and flattening one end to provide a handle. A fused-silica inner sleeve for the reactor tube can
facilitate the movement of the boat into the tube, prevent spillage, and thus prolong the life of the combustion tube.
30.6 Collection Vessel—A plastic graduate or beaker designed to maintain most of the scrubber solution above the tip of the
delivery tube is required.
30.7 Automatic Chloride Titrator.
30.8 Ion-selective Electrodes, chloride and fluoride.
30.9 Reference Electrode—Use a double-junction type such as mercuric sulfate, sleeve-junction type electrode. Do not use a
calomel electrode.
30.10 Spectrophotometer—Ultraviolet to visible range and absorption cells. For a discussion on spectrophotometers and their
use see Practice E60.
30.11 Meter, pH, with expanded scale with a sensitivity of 1 mV.
31. Reagents
31.1 Accelerator (U O )—Halogen free U O powder used as a flux to enhance the release of chloride and fluoride.
3 8 3 8
31.2 Air or Oxygen, compressed.
31.3 Buffer Solution (0.001 N Acetic Acid, 0.001 N Potassium Acetate)—Prepare by adding 50 μL of glacial acetic acid
(CH CO H, sp gr 1.05) and 0.10 g of potassium acetate (KC H O ) to 1 L of water.
3 2 2 3 2
31.4 Chloride Standard Solution (1 mL = 1 mg Cl)—Dissolve 1.65 g of sodium chloride (NaCl) in water and dilute to 1 L.
31.5 Chloride Standard Solution (1 mL = 5 μg Cl)—Prepare by diluting 5 mL of chloride solution (1 mL = 1 mg Cl) to 1 L with
water.
31.6 Ferric Ammonium Sulfate (0.25 M in 9 M Nitric Acid)—Dissolve 12 g of FeNH (SO ) ·12 H O in 58 mL of concentrated
4 4 2 2
nitric acid (HNO , sp gr 1.42) and dilute to 100 mL with water.
31.7 Fluoride, Standard Solution (1 mL = 1 mg F)—Dissolve 2.21 g of sodium fluoride (NaF) in water and dilute to 1 L.
31.8 Fluoride, Standard Solution (1 mL = 10 μg F)—Dilute 10 mL of fluoride solution (1 mL = 1 mg F) to 1 L with water.
31.9 Gelatin Solution—Add 6.2 g of dry gelatin mixture (60 parts of dry gelatin + 1 part of thymol blue + 1 part of thymol) to
1 L of hot water and heat while stirring until the solution is clear.
31.10 Lanthanum-Alizarin Complexone—Dissolve 0.048 g of alizarin complexone (3-aminomethylalizarin-N,N-
diacetic acid) in 100 μL of concentrated ammonium hydroxide, 1 mL of an ammonium acetate solution (NH C H O , 20 mass %),
4 2 3 2
and 5 mL of water. Filter the solution through high grade, rapid filter paper. Wash the paper with a small volume of water and add
8.2 g of anhydrous sodium acetate (NaC H O ) and 6 mL of CH CO H (sp gr 1.05) to the filtrate. Add 100 mL of acetone while
2 3 2 3 2
swirling the filtrate. Add 0.040 g of lanthanum oxide (La O ) dissolved in 2.5 mL of warm 2 N HCl. Mix the two solutions and
2 3
dilute to 200 mL. After 30 min readjust the solution volume.
NOTE 3—A 0.1-g/L solution of Amadac-F is prepared by dissolving 100 mg of the reagent in water and diluting with isopropyl alcohol to obtain a 60 %
alcoholic medium.
31.11 Mercuric Thiocyanate Solution—Prepare a saturated solution by adding 0.3 g of mercuric thiocyanate [Hg(SCN) ] to 100
mL of ethanol (95 %). Shake the mixture thoroughly for maximum dissolution of the solid. Filter the solution.
31.12 Nitric Acid-Acetic Acid Solution (1 N nitric acid and 4 N acetic acid)—Prepare by adding 64 mL of nitric acid (HNO ,
sp gr 1.42) to a 1-L volumetric flask which contains 500 mL of water. Swirl the solution in the flask and add 230 mL of CH CO H
3 2
(sp gr 1.05). Dilute the solution with water to 1 L.
32. Pyrohydrolysis Procedure
32.1 Prepare the pyrohydrolysis apparatus for use as follows:
32.1.1 Regulate the gas flow between 1 and 3 L/min.
32.1.2 Adjust the temperature of the hot plate to heat the water to approximately 90°C.
32.1.3 Adjust the temperature of the furnace to 950 6 50°C.
32.1.4 Add 15 mL of buffer solution to the collection vessel and place around the delivery tube.
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32.2 Weigh accurately 1 to 2 g of the powdered mixed oxide and transfer to a combustion boat. If an accelerator, U O , is used,
3 8
mix 4 g with the sample before loading the powdered mixed oxide into the boat.
32.3 Place the boat containing the sample into the reactor tube and quickly close the tube. The boat should be in the middle of
the furnace.
32.4 Allow the pyrohydrolysis to proceed for at least 30 min.
32.5 Remove the collection vessel and wash down the delivery tube with some buffer solution. Dilute the solution to 25 mL
with the acetate buffer. Determine the chloride and fluoride by one or more of the measurement procedures covered in Section
3360.
32.6 Remove the boat from the reactor tube and dispose of the sample residue.
32.7 Run a pyrohydrolysis blank with halogen-free U O by following the procedure in 32.3 through 32.6.
3 8
33. Measurement of Chloride and Fluoride
33.1 Determination of Chloride by Spectrophotometry:
33.1.1 Prepare a calibration curve by adding 0, 1, 2, 5, and 10 mL of chloride standard solution (1 mL = 5 μg Cl) to separate
25-mL flasks. Dilute each to 20 mL with the buffer solution, add 2 mL of ferric ammonium sulfate solution and 2 mL of mercuric
thiocyanate reagent. Mix the solution and dilute to 25 mL with water. Mix the solutions again and allow them to stand 10 min.
Transfer some of the solution from the flask to a 1-cm absorption cell and read the absorbance at 460 nm using water as the
reference liquid. Plot the micrograms of chloride per 25 mL versus the absorbance reading.
33.1.2 To determine the chloride in the pyrohydrolysis condensate transfer 15 mL of buffer solution to a 25-mL volumetric flask.
Add 2 mL of ferric ammonium sulfate solution and 2 mL of mercuric thiocyanate solution. Mix the solutions, dilute to volume
with water, and mix again. Allow the solution to stand 10 min. Transfer some of the solution from the flask to a 1-cm absorption
cell and read the absorbance at 460 nm versus water as the reference. Read the micrograms of chloride present from the calibration
curve.
NOTE 4—A calibration curve can be prepared by drying measured aliquots of a standard chloride solution on some halogen-free U O and proceeding
3 8
through pyrohydrolysis steps.
33.1.3 Calculate the chlorine as follows:
Cl, µg/g5 @~A 2 B!/W# ~V /V ! (3)
1 2
where:
A = micrograms of chlorine in aliquot measured,
B = micrograms of chlorine in blank,
W = grams of mixed oxide pyrohydrolyzed,
V = millilitres of scrub solution, and
V = aliquot in millilitres of scrub solution analyzed.
33.2 Determination of Chloride by Amperometric Microtitrimetry:
33.2.1 Calibrate the titrimeter by adding 5 mL of buffer solution, 1 mL of nitric acid-acetic acid solution, and 2 drops of the
gelatin solution to a titration cell. Pipet 50 μL of the chloride standard solution (1 mL = 1 mg Cl) into the titration cell. Place the
cell on the chloride titrator and follow the manufacturer’s suggested sequence of operations for titrating chloride. Record the time
required to titrate 50 μg. Run a reagent blank titration.
NOTE 5—The chloride analyzer generates silver ions which react to precipitate the chloride ion. The instrument uses an amperometric end point to
obtain an automatic shut-off of the generating current at a pre-set increment of indicator current. Since the rate of generating silver ion is constant, the
amount of chloride precipitated is proportional to the time required for the titration.
33.2.2 Determine the chloride in the pyrohydrolysis scrub solution by adding 5 mL to a titration cell which contains 1 mL of
the nitric acid-acetic acid solution and 2 drops of the gelatin solution.
33.2.3 Place the cell in position on the titrator. Start the titrator and record the time required to titrate the chloride present.
33.2.4 Calculate the chlorine as follows:
Cl, µg/g5 V F T 2 T /V W (4)
~ !
1 s B 2
where:
V = volume of scrub solutions = 25,
V = aliquot, in millilitres, of scrub solution analyzed,
F = micrograms of Cl standard titrated/titration time of standard − titration time of blank or
F = 50/(T − T ),
Cl B
T = titration time to titrate sample and blank,
s
T = titration time to titrate 50 μg Cl and blank,
Cl
T = titration time to titrate reagent blank, and
B
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W = grams of mixed oxide pyrohydrolyzed.
33.3 Determination of Chloride and Fluoride With Ion-Selective Electrodes:
33.3.1 Preparation of the calibration curves requires the assembly of the meter and the ion-selective electrode with a suitable
reference electrode. From these standards take the millivolt readings for each ion-selective electrode and plot on semi-log paper
determine the halogen content per 25 mL versus millivolts. millivolts, using computer software or a plot on semi-log paper. Prepare
a series of standards in acetate buffer solution by pipeting aliquots of the halogen standards into separate 25-mL flasks ranging in
concentrations as follows:
chloride 10 to 100 μg/25 mL
fluoride 5 to 100 μg/25 mL
33.3.2 Determine the chloride and fluoride in the scrub solution from the pyrohydrolysis by using the appropriate ion-selective
electrode. Record the micrograms of chloride or fluoride from the calibration curve and calculate the halide as follows:
Cl or F, µg/g5 ~H 2 H !/W (5)
s b
where:
H = micrograms of halide in aliquot of scrub solution plus blank,
s
H = micrograms of halide in pyrohydrolysis blank, and
b
W = grams of sample.
33.4 Determination of Fluoride by Spectrophotometry:
33.4.1 Prepare a calibration curve by adding to separate 10-mL flasks 0, 50, 100, 200, 500, and 1000 μL of fluoride standard
solution (1 mL = 10 μg F). Add 2.0 mL of lanthanum-alizarin complexone solution and dilute to volume with water. Mix and let
stand 1 h. Read the absorbance at 622 nm versus the reagent blank. Plot the micrograms of fluoride per 10 mL versus the
absorbance reading.
33.4.2 Measure the fluoride in the pyrohydrolysis scrub solution by pipeting 5 mL into a 10-mL volumetric flask. Add 2.0 mL
of lanthanum-alizarin complexone and dilute to volume. Mix and let stand 1 h. Read the absorbance at 622 nm versus a reagent
blank and obtain the fluoride content from the calibration curve.
33.4.3 Calculate the fluorine concentration in the mixed oxide sample as follows:
F, µg/g5 @~F 2 F !/W# 3 V /V (6)
~ !
s b 1 2
where:
F = fluorine in aliquot of scrub solution plus the blank, μg,
s
F = fluorine in pyrohydrolysis blank, μg,
b
V = total volume of the scrub solution, mL,
V = aliquot of scrub solution analyzed, mL, and
W = grams of mixed oxide sample.
33.5 Determination of Chloride and Fluoride by Ion Chromatography—Determine the Cl and F in the scrub solution from the
pyrohydrolysis in accordance with Test Method D4327. Record the micrograms of Cl or F from the calibration curve and calculate
the halide using Eq 5.
34. Precision and Bias
34.1 The relative standard deviations for the measurements of fluorine are approximately 7 % for the 5 to 50-μg/g range and
10 % for the 1 to 5-μg/g range. The relative standard deviations for the measurements of chlorine vary from 5 % at the 5 to 50-μg/g
level and up to 10 % below the 5-μg/g range.
SULFUR BY DISTILLATION-SPECTROPHOTOMETRY
35. Scope
35.1 This test method covers the determination of sulfur in the concentration range from 10 to 600 μg/g for samples of
nuclear-grade uranium and plutonium mixed oxides, (U, Pu)O .
36. Summary of Test Method
36.1 Sulfur is measured spectrophotometrically as Lauth’s Violet following its separation by distillation as hydrogen sulfide
(710). Higher oxidation states of sulfur are reduced to sulfide by a hypophosphorous-hydriodic acid mixture, the hydrogen sulfide
is distilled into zinc acetate, and p-phenylenediamine and ferric chloride are added to form Lauth’s Violet. The quantity of sulfur
is calculated from the measured absorbance at 595 nm and the absorbance per microgram of sulfur obtained for calibration
materials having known sulfur contents. The relative standard deviation ranges from 12 to 3 % for the concentration range from
10 to 600 μg of sulfur per gram of sample.
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37. Interference
37.1 None of the impurity elements interfere when present in amounts up to twice their specification limits for uranium and
plut
...