ASTM C1108-23

Standard Test Method for Plutonium by Controlled-Potential Coulometry

SIGNIFICANCE AND USE
5.1 Factors governing selection of a method for the determination of plutonium include available quantity of sample, sample purity, desired level of reliability, and equipment.  
5.1.1 This test method determines 5 mg to 20 mg of plutonium with prior dissolution using Practice C1168.  
5.1.2 This test method calculates plutonium mass fraction in solutions and solids using an electrical calibration based upon Ohm’s Law and the Faraday Constant.  
5.1.3 Chemical standards are used for quality control. When prior chemical separation of plutonium is necessary to remove interferences, the quality control standards should be included with each chemical separation batch (9).  
5.2 Fitness for Purpose of Safeguards and Nuclear Safety Application—Methods intended for use in safeguards and nuclear safety applications shall meet the requirements specified by Guide C1068 for use in such applications.
SCOPE
1.1 This test method describes the determination of dissolved plutonium from unirradiated nuclear-grade (that is, high-purity) materials by controlled-potential coulometry. Controlled-potential coulometry may be performed in a choice of supporting electrolytes, such as 0.9 mol/L (0.9 M) HNO3, 1 mol/L (1 M) HClO4, 1 mol/L (1 M) HCl, 5 mol/L (5 M) HCl, and 0.5 mol/L (0.5 M) H2SO4. Limitations on the use of selected supporting electrolytes are discussed in Section 6. Optimum quantities of plutonium for this procedure are 5 mg to 20 mg.  
1.2 Plutonium-bearing materials are radioactive and toxic. Adequate laboratory facilities, such as gloved boxes, fume hoods, controlled ventilation, etc., along with safe techniques must be used in handling specimens containing these materials.  
1.3 The values stated in SI units are to be regarded as the 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Dec-2022
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: C26 - Nuclear Fuel Cycle
• Drafting Committee: C26.05 - Methods of Test

Relations

• Refers: ASTM C859-24 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C1168-23 - Standard Practice for Preparation and Dissolution of Plutonium Materials for Analysis
• Effective Date: 01-Oct-2023
• Refers: ASTM C1156-18 - Standard Guide for Establishing Calibration for a Measurement Method Used to Analyze Nuclear Fuel Cycle Materials
• Effective Date: 01-Sep-2018
• Refers: ASTM C1297-18 - Standard Guide for Qualification of Laboratory Analysts for the Analysis of Nuclear Fuel Cycle Materials
• Effective Date: 01-Jul-2018
• Refers: ASTM C1168-15 - Standard Practice for Preparation and Dissolution of Plutonium Materials for Analysis
• Effective Date: 01-Sep-2015
• Refers: ASTM C1128-15 - Standard Guide for Preparation of Working Reference Materials for Use in Analysis of Nuclear Fuel Cycle Materials
• Effective Date: 01-Feb-2015
• Refers: ASTM C859-14a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Jun-2014
• Refers: ASTM C859-14 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Jan-2014
• Refers: ASTM C859-13a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jun-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM C859-13 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-May-2013
• Refers: ASTM C1009-13 - Standard Guide for Establishing and Maintaining a Quality Assurance Program for Analytical Laboratories Within the Nuclear Industry
• Effective Date: 01-Jan-2013
• Refers: ASTM C1210-12 - Standard Guide for Establishing a Measurement System Quality Control Program for Analytical Chemistry Laboratories Within the Nuclear Industry
• Effective Date: 01-Jun-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM C1068-03(2011) - Standard Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Industry
• Effective Date: 01-Jun-2011

Overview

ASTM C1108-23: Standard Test Method for Plutonium by Controlled-Potential Coulometry specifies procedures for quantifying dissolved plutonium in unirradiated, nuclear-grade materials. Developed by ASTM Committee C26 on the Nuclear Fuel Cycle, this test method uses controlled-potential coulometry, a highly precise electroanalytical technique, to determine the plutonium content in both solutions and solids. The optimized plutonium sample range is 5 mg to 20 mg, following sample dissolution according to ASTM C1168. Coulometric calculations are based on principles such as Ohm’s Law and the Faraday Constant, ensuring reliable, SI unit-based results.

Key Topics

• Controlled-Potential Coulometry: The method involves redox reactions at a working electrode under precisely maintained potentials to isolate plutonium measurement from interfering species.
• Sample Purity and Preparation: Only high-purity, nuclear-grade plutonium is suitable. Samples must be dissolved using prescribed acids and safety procedures due to the radioactivity and toxicity of plutonium.
• Electrolyte Selection: Compatible electrolytes include nitric acid, perchloric acid, hydrochloric acid, and sulfuric acid. Each electrolyte's suitability is influenced by the presence of interfering ions and specific analysis requirements.
• Interference Management: Procedures are outlined to identify and manage common interferences, such as iron, nitrites, sulfate, fluoride, and oxygen. Proper handling and chemical separation are critical to preventing inaccurate results.
• Calibration and Quality Control: Electrical calibration incorporates high-precision standards. Quality control standards, chemical separation, and compliance with ASTM nuclear measurement guidance ensure method integrity.
• Safety Considerations: Handling plutonium and associated chemicals requires specialized laboratory infrastructure, including gloveboxes, fume hoods, and strict adherence to safety, health, and regulatory requirements.

Applications

• Nuclear Safeguards and Non-Proliferation: Accurate plutonium measurement is vital for material accountability and safety within nuclear facilities. This test method supports compliance with international nuclear safeguards by delivering traceable, reproducible results.
• Quality Control in Nuclear Fuel Manufacturing: The method is employed in analytical laboratories to verify plutonium content in manufacturing processes and finished nuclear fuel materials.
• Research and Development: Laboratories utilize this technique for basic research into plutonium chemistry and the development of new nuclear materials.
• Environmental and Regulatory Compliance: Facilities dealing with nuclear materials use ASTM C1108-23 as part of their broader environmental monitoring and regulatory reporting obligations.
• Nuclear Safety Assurance: The method's accuracy and robustness provide essential data for nuclear criticality safety analysis.

Related Standards

Several ASTM standards supplement and support the implementation of ASTM C1108-23, ensuring a harmonized approach to plutonium measurement:

• ASTM C1168 – Practice for Preparation and Dissolution of Plutonium Materials for Analysis
• ASTM C1009 – Guide for Quality Assurance Programs in Analytical Laboratories Within the Nuclear Industry
• ASTM C1068 – Guide for Qualification of Measurement Methods in Nuclear Applications
• ASTM C1210 – Guide for Measurement System Quality Control in Analytical Chemistry for Nuclear Industry
• ASTM C859 – Terminology Relating to Nuclear Materials
• ASTM C1156 – Calibration for Analytical Measurement in the Nuclear Fuel Cycle
• ASTM C1128 – Guide for Preparation of Working Reference Materials for Nuclear Fuel Analysis
• ASTM E691 – Practice for Interlaboratory Precision Evaluation

By aligning with established international measurement practices, ASTM C1108-23 offers laboratories a robust, quality-controlled method for the sensitive, accurate determination of plutonium-crucial for regulatory compliance, nuclear safety, and efficient fuel cycle 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: C1108 − 23
Standard Test Method for
Plutonium by Controlled-Potential Coulometry
This standard is issued under the fixed designation C1108; 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 C1009Guide for Establishing and Maintaining a Quality
AssuranceProgramforAnalyticalLaboratoriesWithinthe
1.1 This test method describes the determination of dis-
Nuclear Industry
solved plutonium from unirradiated nuclear-grade (that is,
C1068Guide for Qualification of Measurement Methods by
high-purity) materials by controlled-potential coulometry.
a Laboratory Within the Nuclear Industry
Controlled-potential coulometry may be performed in a choice
C1128Guide for Preparation of Working Reference Materi-
of supporting electrolytes, such as 0.9 mol/L (0.9 M) HNO ,
als for Use in Analysis of Nuclear Fuel Cycle Materials
1mol⁄L(1 M)HClO ,1mol⁄L(1 M)HCl,5mol/L(5 M)HCl,
C1156Guide for Establishing Calibration for a Measure-
and 0.5mol⁄L (0.5 M)H SO . Limitations on the use of
2 4
ment Method Used toAnalyze Nuclear Fuel Cycle Mate-
selected supporting electrolytes are discussed in Section 6.
rials
Optimum quantities of plutonium for this procedure are 5mg
C1168PracticeforPreparationandDissolutionofPlutonium
to 20 mg.
Materials for Analysis
1.2 Plutonium-bearing materials are radioactive and toxic.
C1210Guide for Establishing a Measurement System Qual-
Adequate laboratory facilities, such as gloved boxes, fume
ity Control Program for Analytical Chemistry Laborato-
hoods, controlled ventilation, etc., along with safe techniques
ries Within Nuclear Industry
mustbeusedinhandlingspecimenscontainingthesematerials.
C1297Guide for Qualification of Laboratory Analysts for
1.3 The values stated in SI units are to be regarded as the the Analysis of Nuclear Fuel Cycle Materials
E691Practice for Conducting an Interlaboratory Study to
standard. The values given in parentheses are for information
only. Determine the Precision of a Test Method
1.4 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Except as otherwise defined herein, definitions of terms
responsibility of the user of this standard to establish appro-
are as given in Terminology C859.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4. Summary of Test Method
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.1 In a controlled-potential coulometric measurement, the
ization established in the Decision on Principles for the
substancebeingdeterminedreactsatastationaryelectrode,the
Development of International Standards, Guides and Recom-
potential of which is maintained at such a value that unwanted
mendations issued by the World Trade Organization Technical
electrode reactions are precluded under the prevailing experi-
Barriers to Trade (TBT) Committee.
mental conditions. Those substances which have reduction-
oxidation (redox) potentials near that of the ion being deter-
2. Referenced Documents
mined constitute interferences. Electrolysis current decreases
2.1 ASTM Standards: exponentially as the reaction proceeds, until constant back-
C859Terminology Relating to Nuclear Materials
ground current is obtained. Detailed discussions of the theory
andapplicationsofthistechniquehavebeenpublished (1, 2, 3,
4, 5, 6). Thecontrol-potentialadjustmenttechnique (7)canbe
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear
used to terminate the electrolysis of the specimen at constant
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
background current without exhaustive electrolysis with con-
Test.
siderable reduction in operating time. Use of the control-
Current edition approved Jan. 1, 2023. Published January 2023. Originally
approved in 1988. Last previous edition approved in 2022 as C1108–22. DOI:
potential adjustment technique requires that the coulometer
10.1520/C1108-23.
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 Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
the ASTM website. this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1108 − 23
integrator be capable of operations in a bipolar mode and that polymer may be converted to electrochemically active species
the plutonium-containing solution be of high purity, that is, by HF treatment (10).
nuclear grade.
6.3 Pu(VI)—Plutonium(VI) is only partially reduced to
4.2 Plutonium(IV) is reduced to Pu(III) at a working elec- Pu(III)in1mol⁄L(1 M)HNO ,1mol⁄L(1 M)HCl,or1mol/L
trode maintained at a potential more negative than the formal (1 M) HClO supporting electrolyte solutions; therefore, the
redox potential. Plutonium(III) is oxidized to Pu(IV) at a presence of Pu(VI) can lead to inaccurate results when present
potential more positive than the formal redox potential. The even as a small fraction of the total plutonium. Plutonium(VI)
quantity of plutonium electrolyzed is calculated from the net canbecompletelyreducedin0.5mol⁄L(0.5 M)H SO (10)or
2 4
number of coulombs required for the electrolysis, according to 5.5mol⁄L (5.5 M) HCl (11) supporting electrolyte, however,
Faraday’s law. Corrections for incomplete reaction, derived quantitative reduction has not been demonstrated when the
from the Nernst equation, must be applied for electrolysis of control-potential adjustment technique used in this standard
the sample aliquot (7, 8). test method is applied.
~Q 2 Q ! M 6.4 Iron—In 0.5 mol⁄L (0.5 M)H SO supporting
s b
2 4
m 5 (1)
Pu
nFf
electrolyte,ironisreducedandoxidizedatessentiallythesame
formal redox potentials as the Pu(III)-Pu(IV) couple and thus
where:
constitutesadirectinterference.Ironmustberemovedbyprior
m = mass of plutonium, g,
Pu
separation, or the effect of its presence must be corrected by a
Q = coulombs generated by electrolysis of sample aliquot,
s
separate measurement of the iron mass fraction in the sample
C,
solution. In 1mol⁄L (1 M) HCl, 1mol⁄L (1 M) HNO,or
Q = coulombs generated by electrolysis of supporting
b
1mol⁄L (1 M) HClO , iron interferes to a lesser extent. The
electrolyte (background current), C,
effect of iron in these supporting electrolytes may be mini-
M = molar mass of plutonium (must be adjusted for
mized by the choice of redox potentials, by a secondary
isotopic composition), g/mol,
titration (10), or by electrochemical correction (12, 13).
n = numberofelectronsinvolvedintheelectrodereaction
(for Pu(III) → Pu(IV), n=1), 6.5 Nitrites—Nitrites are electrochemically active;
F = Faraday constant, C/mol, and
therefore, saturated sulfamic acid solution should be added to
f = fraction electrolyzed of plutonium.
the electrolyte in the cell to destroy any interfering nitrites
when a nitric acid supporting electrolyte is used.
5. Significance and Use
6.6 Sulfate—Becauseofthecomplexingactionofsulfateon
5.1 Factors governing selection of a method for the deter-
Pu(IV) and the resultant shift in the redox potential of the
mination of plutonium include available quantity of sample,
Pu(III)-Pu(IV) couple, that is, the formal potential, only small
sample purity, desired level of reliability, and equipment.
amounts of sulfate are tolerable in HNO , HCl, and HClO
3 4
5.1.1 This test method determines 5mg to 20 mg of
electrolytes. When using these supporting electrolytes, speci-
plutonium with prior dissolution using Practice C1168.
mens should be fumed to dryness to assure adequate removal
5.1.2 Thistestmethodcalculatesplutoniummassfractionin
ofexcesssulfate(see12.3.1.3).Foraliquotsofdissolvedmixed
solutions and solids using an electrical calibration based upon
oxide (MOX) fuels that have not been purified by anion
Ohm’s Law and the Faraday Constant.
exchange to remove the uranium, the sulfate ion concentration
5.1.3 Chemicalstandardsareusedforqualitycontrol.When
afterfumingwillstillbeelevated.Aformalpotentialshouldbe
prior chemical separation of plutonium is necessary to remove
measured for the specific U:Pu ratio and used in the calcula-
interferences, the quality control standards should be included
tions for these aliquots.
with each chemical separation batch (9).
NOTE1—Interferencefromsulfateionsat>4mmol⁄Lin1mol⁄L(1 M)
5.2 Fitness for Purpose of Safeguards and Nuclear Safety
HClO has been reported (10).
Application—Methods intended for use in safeguards and
6.7 Fluoride—Freefluoridecannotbetoleratedandmustbe
nuclear safety applications shall meet the requirements speci-
removed from the specimen. Evaporation of the specimen in
fied by Guide C1068 for use in such applications.
HNO toalowvolumeandfumingwithH SO areeffectivein
3 2 4
removing fluoride.
6. Interferences
6.1 Interferenceiscausedbyionsthatareelectrochemically 6.8 Oxygen—In H SO supporting electrolyte, oxygen in-
2 4
terferes and must be removed. In HNO , HCl, and HClO
active in the range of redox potentials used or by species that
3 4
supporting electrolytes, oxygen may be an interference, de-
prevent attainment of 100% current efficiency (for example,
pending upon experimental conditions. Purging the specimen
reductants, oxidants, and organic matter).
with high-purity argon prior to and during the coulometric
6.2 Polymer—Polymerized plutonium is not electrochemi-
determination is recommended for all electrolytes.
cally active (10) and thus is neither reduced nor oxidized. The
presence of polymerized plutonium will give low results. The
7. Apparatus
7.1 Controlled-Potential Coulometer—A coulometer with
Committee on Data for Science and Technology, CODATA, internationally
the following specifications is recommended to achieve highly
recommended values for fundamental physical constants are available at URL
http://physics.nist.gov/cuu/Constants/index.html. precise and accurate results. (Room temperature stability of
C1108 − 23
FIG. 2 Working Electrode (Top View)
FIG. 1 Exploded View of Cell Assembly: (a) Counter Electrode,
(b) Cell Head, (c) Counter Electrode Frit Tube, (d) Reference Elec-
trode Frit Tube, (e) NBL-Designed S-Shaped Stirrer, (f) Working
7.2 Digital Voltmeter (DVM)—15V range, 5 ⁄2 digits accu-
Electrode, (g) Sample Cell, (h) Stirrer Motor, (i) Motor Pedestal
and Bearing, and (j) Stirrer Shaft
rate to 0.01% of full scale on all ranges. Input resistance
10 5
>10 Ω.
7.3 Cell Assembly—Thesuccessofcontrolled-potentialcou-
61°C is recommended to ensure optimum instrument perfor-
lometric methods is strongly dependent on the design of the
mance. Instruments with smaller output current or smaller
cell. The cell dimensions, electrode area, spacing, and stirring
voltage span may be satisfactory.)
rateareimportantparametersinadesignthatwillminimizethe
time required for titration. The following components are
Potentiostat (6)
Output voltage >25 V
required for the recommended cell assembly (Fig. 1).
Output current >200 mA
7.3.1 Cell—The coulometry cell is fabricated from a cut-off
Open-loop response d-c gain >10
Unity-gain bandwidth >300 kHz
50mL borosilicate glass beaker with an inside diameter of
Full-power response >10 kHz (slewing rate 0.5 V/µs)
38mm and a height of 42 mm; the cut edges are rounded and
Voltage zero offset stability >1 mV long term
polished smooth. Other cells conforming to these dimensions
Input d-c resistance >50 MΩ
Input d-c current <50 nA
are satisfactory.
d-c control voltage span ±4 V
7.3.2 Counter Electrode and Salt Bridge Tube—Thecounter
Resolution, hum, and drift <1 mV
Stability through extreme of line and ±5 mV
electrode is a coiled length of 0.51mm (0.020in.) diameter
load variation
platinum wire (Fig. 2). Platinum with a mass fraction of
Digital Integrator (14)
≥999.5mg⁄g (that is, Pt purity of ≥99.95%) has been used
Nonlinearity of V/F converter <0.01 % full scale
Full scale set-point adjustable to ±0.01 % of full scale
Input offset voltage set-point adjustable to ±0.01 % of full scale
Output readability <1 µg Pu
Integrating capacity >10 C 5
AHewlett-Packard3455ADVMhasbeenfoundtoexceedthesespecifications.
Bias <0.01 %
C1108 − 23
successfully. The salt bridge tube is unfired high-silica glass
filled with the supporting electrolyte solution.
7.3.3 Reference Electrode and Salt Bridge Tube—The ref-
erence electrode is a miniature saturated-calomel electrode
(SCE). The salt bridge is identical to the salt bridge described
in 7.3.2 and is also filled with supporting electrolyte solution.
7.3.4 Working Electrode, fabricated from either 8Au8-5/0
expanded annealed-gold metal (Fig. 2) or from 45mesh
platinumgauze.Goldwithamassfractionof ≥999.9mg⁄g(Au
purity of ≥99.99 %) and platinum with a mass fraction of
≥999.5mg⁄g (that is, Pt purity of ≥99.95 %) have been used
successfully.
7.3.4.1 Store and condition the working electrode in accor-
dance with instruction in Section 11.
7.3.5 Stirrer—Several types of stirrers have performed sat-
isfactorily. A paddle-type stirrer capable of being driven at
30r⁄s (1800 r/min) by a synchronous motor, or a magnetically
driven stirring bar, is adequate. Magnetic stirring slightly
simplifiesthearrangementofthecellcap.Foroptimumstirring
efficiency with freedom from losses due to splashing, an
S-shaped polytetrafluoroethylene stirrer (Fig. 3) (15) driven by
synchronous motor is recommended.
7.3.6 Inert Gas Inlet Tube—A polyvinyl chloride tube,
approximately 3mm in outside diameter (1 mm in inside
diameter), is inserted so that its tip is about 10mm above the
surface of the electrolyte solution. The gas flow is adjusted so
that the surface of the solution is depressed almost 3mm. The
gas is high-purity argon. While inert gas is not required for all
electrolytes, it is recommended for this procedure.
FIG. 3 S-Shaped Stirrer
7.4 Quartz Heating Lamps—Optimum heating or evaporat-
ing efficiency without bumping of solutions, or both, is
obtained using overhead heating with quartz heat lamps
such specifications are available. Other grades may be used,
controlled by a variable power supply. However, with proper
provided it is first ascertained that the reagent is of sufficiently
care, other conventional means of heating may be used.
high purity to permit its use without lessening the accuracy of
the determination.
7.5 Hot Plate—Recommended for heating during the pluto-
nium oxidation state adjustment with hydrogen peroxide.
8.2 Argon, greater than 99.99% purity.
7.6 Quartz Clock Timer—accurate to 0.001 s.
8.3 Hydrochloric Acid, concentrated hydrochloric acid
(HCl, specific gravity 1.19).
7.7 100 Ω Precision Resistor—accurate to better than
0.01%. 8.4 Hydrochloric Acid(1mol/L),preparebydiluting85mL
of hydrochloric acid to 1 L with water.
8. Reagents and Materials
8.5 Hydrochloric Acid-Nitric Acid-Hydrofluoric Acid Mix-
ture (5.4 mol/L HCl-1.6 mol/L HNO -0.014 mol/L HF)—
8.1 Purity of Reagents—Reagent grade chemicals shall be 3
Prepare by slowly adding 450 mL hydrochloric acid, 100 mL
used in all tests. Unless otherwise indicated, it is intended that
nitric acid, and 10 drops hydrofluoric acid to 450 mL water in
all reagents conform to the specifications of the Committee on
a polytetrafluoroethylene beaker. Cool and store in a tetrafluo-
Analytical Reagents of theAmerican Chemical Society where
roethylene (TFE) fluorocarbon bottle.
8.6 Hydrofluoric Acid, concentrated hydrofluoric acid (HF,
6 48%).
EitheratesttubewithunfiredVycorbottomsofType7930glassobtainedfrom
Corning GlassWorks, or a 0.5 cm long, 0.5-cm diameter rod of unfiredVycorType
7930 sealed into one end of a glass tube with heat-shrinkable TFE-fluorocarbon
tubing, has been found satisfactory for this application. ACS Reagent Chemicals, Specifications and Procedures for Reagents and
AFisher Calomel Reference Electrode Catalog No. 13-639-79 has been found Standard-Grade Reference Materials, American Chemical Society, Washington,
satisfactory. DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Quartz heating lamps and Quartz epiradiator lamps, Model 534 RCL, 500 Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
watts,120V(AtlasElectricSupplies,P.O.Box1300,Hialeah,Florida,33011)have U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
been found to be satisfactory. copeial Convention, Inc. (USPC), Rockville, MD.
9 11
A Julie 100-Ω precision resistor number NB102A, accurate to 0.0015%, has All reagents should be prepared with 18-MΩ-cm deionized (demineralized)
been found satisfactory. water.
C1108 − 23
FIG. 4 Coulometer with Digital Integrator
8.7 Hydrogen Peroxide, 30% solution of hydrogen perox- 9. Hazards
ide (H O ).
2 2
9.1 Review the safety data sheets and safety procedures in
8.8 Nitric Acid, concentrated nitric acid (HNO , specific the laboratory’s safety manual before performing this proce-
gravity 1.42). dure.
8.9 Nitric Acid (8 mol/L)—Prepare by diluting 500 mL 9.2 Warning—Hydrofluoric acid is highly corrosive acid
nitric acid to 1L with water. that can severely burn skin, eyes, and mucous membranes.
Hydrofluoric acid differs from the other acids because the
8.10 Nitric Acid (0.9 mol/L)—Prepare by diluting 57 mLof
12 fluoride ion readily penetrates the skin, causing destruction of
nitric acid to 1L with water.
deep tissue layers. Unlike other acids that are rapidly
8.11 Perchloric Acid (1 mol/L)—Prepare by diluting 85 mL
neutralized, hydrofluoric acid reactions with tissue may con-
of perchloric acid (HClO , specific gravity 1.76) to 1L with
tinue for days if left untreated. Familiarization and compliance
water.
with the Safety Data Sheet is essential.
8.12 Plutonium Standard Solution—Dissolve plutonium
9.3 Elemental plutonium is reactive and evolves hydrogen
metal(NBLCRM126,currentissue)inanErlenmeyerflaskby
and other gases during dissolution; assure that the dissolution
slow addition of approximately 30 mL of hydrochloric acid-
reactions are complete before sealing closed vessels.
nitric acid-hydrofluoric acid mixture. Add 30 mL of 8mol⁄L
9.4 Pressure protection and pressure relief is required when
(8 M) HNO ; evaporate to less than 15mL. Transfer to a tared
supplyingcompressedgasservicestoagloveboxorothertypes
container with the 8mol⁄L (8 M) HNO and dilute to about
of radiological containment units.
100mLwith 8 mol/L(8 M) HNO prior to aliquoting. Proceed
to 12.3.1.3. 9.5 Handling of hot acids during electrode conditions and
aliquot fuming requires appropriate ventilation of fumes and
8.13 Sulfamic Acid (NH SO H), saturated solution.
2 3
safe handling practices for hot, corrosive materials.
8.14 Sulfuric Acid (0.5mol⁄L)—Prepare by adding 28 mL
9.6 Thisstandardinvolvesworkwithnuclearmaterials.The
of sulfuric acid (H SO , specific gravity 1.84) to water with
2 4
unique hazards and controls required to conduct the work
constant stirring and dilute to 1 L.
contained in this standard from a safety, environmental, and
8.15 Sulfuric Acid(3mol⁄L)—Preparebyadding167mLof
security standpoint is the responsibility of the facility
sulfuric acid (H SO , specific gravity 1.84) to water with
2 4
operators, in compliance with any applicable regulations.Any
constant stirring and dilute to 1 L.
information given for handling these types of materials con-
8.16 Sulfuric Acid-Hydrofluoric Acid Mixture (8.1mol⁄L tained herein is meant only as a guide for consideration of the
user and not a requirement.
(8.1 M)H SO -2.9mol⁄L (2.9 M) HF)—Prepare by adding
2 4
45mLofsulfuricacid(H SO ,specificgravity1.84)to45mL
2 4
10. Calibration of Instrument
of water with constant stirring. Add 10 mL of hydrofluoric
acid, cool, and store in a TFE-fluorocarbon polymer bottle.
10.1 The type of instrumentation recommended herein (16,
17) includes an electronic integrator circuit. The digital
(voltage-to-frequency) integrator develops a series of pulses,
0.9mol ⁄L (0.9 M) HNO is used because the range from 0.8mol ⁄L to
3+ 4+
1.0mol ⁄L HNO provides a stable formal potential for the Pu /Pu couple. the sum of which is proportional to the integrated current
C1108 − 23
generated during electrolysis. Establish the relationship be- response. The gold electrode may be: (1) briefly dipped in
tween coulombs of electricity and integrator output by calibra- ambient temperature concentrated HCl and thoroughly rinsed
tion. (See 10.2 and 10.3.) with 8mol⁄L(8 M) HNO;(2) briefly dipped in warm or hot
concentrated HCl and thoroughly rinsed with 8mol⁄L (8 M)
10.2 Adjustment of the Digital Integrator:
HNO;(3) briefly dipped in aqua regia and thoroughly rinsed
10.2.1 Adjust the full-scale and input offset voltage trim
with HNO;or(4) soaked 600 s in the sulfuric acid-
pots on the voltage-to-frequency converter (V/F) using the
13 hydrofluoric acid mixture (8.16), the residual acid removed by
digital voltmeter and a frequency counter in accordance with
fuming and the hot electrode quenched in 8mol⁄L (8 M)
the manufacturer’s procedure and recommended frequency for
HNO .After each treatment, the electrode is stored in 8mol⁄L
this adjustment.
(8 M) HNO overnight. Following overnight storage,
10.3 Electrical Calibration:
conditioning, that is, alternating reduction and oxidation of the
10.3.1 C
...

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: C1108 − 22 C1108 − 23
Standard Test Method for
Plutonium by Controlled-Potential Coulometry
This standard is issued under the fixed designation C1108; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method describes the determination of dissolved plutonium from unirradiated nuclear-grade (that is, high-purity)
materials by controlled-potential coulometry. Controlled-potential coulometry may be performed in a choice of supporting
electrolytes, such as 0.9 mol/L (0.9 M) HNO , 1 mol ⁄L (1 M) HClO , 1 mol ⁄L (1 M) HCl, 5 mol/L (5 M) HCl, and 0.5 mol ⁄L (0.5
3 4
M) H SO . Limitations on the use of selected supporting electrolytes are discussed in Section 6. Optimum quantities of plutonium
2 4
for this procedure are 5 mg to 20 mg.
1.2 Plutonium-bearing materials are radioactive and toxic. Adequate laboratory facilities, such as gloved boxes, fume hoods,
controlled ventilation, etc., along with safe techniques must be used in handling specimens containing these materials.
1.3 The values stated in SI units are to be regarded as the 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C859 Terminology Relating to Nuclear Materials
C1009 Guide for Establishing and Maintaining a Quality Assurance Program for Analytical Laboratories Within the Nuclear
Industry
C1068 Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Industry
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
C1210 Guide for Establishing a Measurement System Quality Control Program for Analytical Chemistry Laboratories Within
Nuclear Industry
C1297 Guide for Qualification of Laboratory Analysts for the Analysis of Nuclear Fuel Cycle Materials
This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.
Current edition approved July 1, 2022Jan. 1, 2023. Published August 2022January 2023. Originally approved in 1988. Last previous edition approved in 20172022 as
C1108 – 17.C1108 – 22. DOI: 10.1520/C1108-22.10.1520/C1108-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1108 − 23
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Except as otherwise defined herein, definitions of terms are as given in Terminology C859.
4. Summary of Test Method
4.1 In a controlled-potential coulometric measurement, the substance being determined reacts at a stationary electrode, the
potential of which is maintained at such a value that unwanted electrode reactions are precluded under the prevailing experimental
conditions. Those substances which have reduction-oxidation (redox) potentials near that of the ion being determined constitute
interferences. Electrolysis current decreases exponentially as the reaction proceeds, until constant background current is obtained.
Detailed discussions of the theory and applications of this technique have been published (1, 2, 3, 4, 5, 6). The control-potential
adjustment technique (7) can be used to terminate the electrolysis of the specimen at constant background current without
exhaustive electrolysis with considerable reduction in operating time. Use of the control-potential adjustment technique requires
that the coulometer integrator be capable of operations in a bipolar mode and that the plutonium-containing solution be of high
purity, that is, nuclear grade.
4.2 Plutonium(IV) is reduced to Pu(III) at a working electrode maintained at a potential more negative than the formal redox
potential. Plutonium(III) is oxidized to Pu(IV) at a potential more positive than the formal redox potential. The quantity of
plutonium electrolyzed is calculated from the net number of coulombs required for the electrolysis, according to Faraday’s law.
Corrections for incomplete reaction, derived from the Nernst equation, must be applied for electrolysis of the sample aliquot (7,
8).
Q 2 Q M
~ !
s b
m 5 (1)
Pu
nFf
where:
m = mass of plutonium, g,
Pu
Q = coulombs generated by electrolysis of sample aliquot, C,
s
Q = coulombs generated by electrolysis of supporting electrolyte (background current), C,
b
M = molar mass of plutonium (must be adjusted for isotopic composition), g/mol,
n = number of electrons involved in the electrode reaction (for Pu(III) → Pu(IV), n = 1),
F = Faraday constant, C/mol, and
f = fraction electrolyzed of plutonium.
5. Significance and Use
5.1 Factors governing selection of a method for the determination of plutonium include available quantity of sample, sample
purity, desired level of reliability, and equipment.
5.1.1 This test method determines 5 mg to 20 mg of plutonium with prior dissolution using Practice C1168.
5.1.2 This test method calculates plutonium mass fraction in solutions and solids using an electrical calibration based upon Ohm’s
Law and the Faraday Constant.
5.1.3 Chemical standards are used for quality control. When prior chemical separation of plutonium is necessary to remove
interferences, the quality control standards should be included with each chemical separation batch (9).
5.2 Fitness for Purpose of Safeguards and Nuclear Safety Application—Methods intended for use in safeguards and nuclear safety
applications shall meet the requirements specified by Guide C1068 for use in such applications.
The boldface numbers in parentheses refer to the list of references at the end of this test method.
Committee on Data for Science and Technology, CODATA, internationally recommended values for fundamental physical constants are available at URL
http://physics.nist.gov/cuu/Constants/index.html.
C1108 − 23
6. Interferences
6.1 Interference is caused by ions that are electrochemically active in the range of redox potentials used or by species that prevent
attainment of 100 % current efficiency (for example, reductants, oxidants, and organic matter).
6.2 Polymer—Polymerized plutonium is not electrochemically active (10) and thus is neither reduced nor oxidized. The presence
of polymerized plutonium will give low results. The polymer may be converted to electrochemically active species by HF
treatment (10).
6.3 Pu(VI)—Plutonium(VI) is only partially reduced to Pu(III) in 1 mol ⁄L (1 M) HNO , 1 mol ⁄L (1 M) HCl, or 1 mol/L (1 M)
HClO supporting electrolyte solutions; therefore, the presence of Pu(VI) can lead to inaccurate results when present even as a
small fraction of the total plutonium. Plutonium(VI) can be completely reduced in 0.5 mol ⁄L (0.5 M) H SO (10) or 5.5 mol ⁄L (5.5
2 4
M) HCl (11) supporting electrolyte, however, quantitative reduction has not been demonstrated when the control-potential
adjustment technique used in this standard test method is applied.
6.4 Iron—In 0.5 mol ⁄L (0.5 M) H SO supporting electrolyte, iron is reduced and oxidized at essentially the same formal redox
2 4
potentials as the Pu(III)-Pu(IV) couple and thus constitutes a direct interference. Iron must be removed by prior separation, or the
effect of its presence must be corrected by a separate measurement of the iron mass fraction in the sample solution. In 1 mol ⁄L
(1 M) HCl, 1 mol ⁄L (1 M) HNO , or 1 mol ⁄L (1 M) HClO , iron interferes to a lesser extent. The effect of iron in these supporting
3 4
electrolytes may be minimized by the choice of redox potentials, by a secondary titration (10), or by electrochemical correction
(12, 13).
6.5 Nitrites—Nitrites are electrochemically active; therefore, saturated sulfamic acid solution should be added to the electrolyte
in the cell to destroy any interfering nitrites when a nitric acid supporting electrolyte is used.
6.6 Sulfate—Because of the complexing action of sulfate on Pu(IV) and the resultant shift in the redox potential of the
Pu(III)-Pu(IV) couple, that is, the formal potential, only small amounts of sulfate are tolerable in HNO , HCl, and HClO
3 4
electrolytes. When using these supporting electrolytes, specimens should be fumed to dryness to assure adequate removal of excess
sulfate (see 12.3.1.3). For aliquots of dissolved mixed oxide (MOX) fuels that have not been purified by anion exchange to remove
the uranium, the sulfate ion concentration after fuming will still be elevated. A formal potential should be measured for the specific
U:Pu ratio and used in the calculations for these aliquots.
NOTE 1—Interference from sulfate ions at >4 mmol ⁄L in 1 mol ⁄L (1 M) HClO has been reported (10).
6.7 Fluoride—Free fluoride cannot be tolerated and must be removed from the specimen. Evaporation of the specimen in HNO
to a low volume and fuming with H SO are effective in removing fluoride.
2 4
6.8 Oxygen—In H SO supporting electrolyte, oxygen interferes and must be removed. In HNO , HCl, and HClO supporting
2 4 3 4
electrolytes, oxygen may be an interference, depending upon experimental conditions. Purging the specimen with high-purity
argon prior to and during the coulometric determination is recommended for all electrolytes.
7. Apparatus
7.1 Controlled-Potential Coulometer—A coulometer with the following specifications is recommended to achieve highly precise
and accurate results. (Room temperature stability of 61 °C is recommended to ensure optimum instrument performance.
Instruments with smaller output current or smaller voltage span may be satisfactory.)
Potentiostat (6)
Output voltage >25 V
Output current >200 mA
Open-loop response d-c gain >10
Unity-gain bandwidth >300 kHz
Full-power response >10 kHz (slewing rate 0.5 V/μs)
Voltage zero offset stability >1 mV long term
Input d-c resistance >50 MΩ
Input d-c current <50 nA
d-c control voltage span ±4 V
Resolution, hum, and drift <1 mV
C1108 − 23
FIG. 1 Exploded View of Cell Assembly: (a) Counter Electrode, (b) Cell Head, (c) Counter Electrode Frit Tube, (d) Reference Electrode
Frit Tube, (e) NBL-Designed S-Shaped Stirrer, (f) Working Electrode, (g) Sample Cell, (h) Stirrer Motor, (i) Motor Pedestal and Bearing,
and (j) Stirrer Shaft
Stability through extreme of line and ±5 mV
load variation
Digital Integrator (14)
Nonlinearity of V/F converter <0.01 % full scale
Full scale set-point adjustable to ±0.01 % of full scale
Input offset voltage set-point adjustable to ±0.01 % of full scale
Output readability <1 μg Pu
Integrating capacity >10 C
Bias <0.01 %
10 5
7.2 Digital Voltmeter (DVM)—15 V range, 5 ⁄2 digits accurate to 0.01 % of full scale on all ranges. Input resistance >10 Ω.
7.3 Cell Assembly—The success of controlled-potential coulometric methods is strongly dependent on the design of the cell. The
cell dimensions, electrode area, spacing, and stirring rate are important parameters in a design that will minimize the time required
for titration. The following components are required for the recommended cell assembly (Fig. 1).
7.3.1 Cell—The coulometry cell is fabricated from a cut-off 50 mL borosilicate glass beaker with an inside diameter of 38 mm and
a height of 42 mm; the cut edges are rounded and polished smooth. Other cells conforming to these dimensions are satisfactory.
7.3.2 Counter Electrode and Salt Bridge Tube—The counter electrode is a coiled length of 0.51 mm (0.020 in.) diameter platinum
A Hewlett-Packard 3455A DVM has been found to exceed these specifications.
C1108 − 23
FIG. 2 Working Electrode (Top View)
wire (Fig. 2). Platinum with a mass fraction of ≥999.5 mg ⁄g (that is, Pt purity of ≥99.95 %) has been used successfully. The salt
bridge tube is unfired high-silica glass filled with the supporting electrolyte solution.
7.3.3 Reference Electrode and Salt Bridge Tube—The reference electrode is a miniature saturated-calomel electrode (SCE). The
salt bridge is identical to the salt bridge described in 7.3.2 and is also filled with supporting electrolyte solution.
7.3.4 Working Electrode, fabricated from either 8Au8-5/0 expanded annealed-gold metal (Fig. 2) or from 45 mesh platinum gauze.
Gold with a mass fraction of ≥999.9 mg ⁄g (Au purity of ≥99.99 %) and platinum with a mass fraction of ≥999.5 mg ⁄g (that is, Pt
purity of ≥99.95 %) have been used successfully.
7.3.4.1 Store and condition the working electrode in accordance with instruction in Section 11.
7.3.5 Stirrer—Several types of stirrers have performed satisfactorily. A paddle-type stirrer capable of being driven at 30 r ⁄s (1800
r/min) by a synchronous motor, or a magnetically driven stirring bar, is adequate. Magnetic stirring slightly simplifies the
arrangement of the cell cap. For optimum stirring efficiency with freedom from losses due to splashing, an S-shaped
polytetrafluoroethylene stirrer (Fig. 3) (15) driven by synchronous motor is recommended.
7.3.6 Inert Gas Inlet Tube—A polyvinyl chloride tube, approximately 3 mm in outside diameter (1 mm in inside diameter), is
inserted so that its tip is about 10 mm above the surface of the electrolyte solution. The gas flow is adjusted so that the surface
of the solution is depressed almost 3 mm. The gas is high-purity argon. While inert gas is not required for all electrolytes, it is
recommended for this procedure.
Either a test tube with unfired Vycor bottoms of Type 7930 glass obtained from Corning Glass Works, or a 0.5 cm long, 0.5-cm diameter rod of unfired Vycor Type 7930
sealed into one end of a glass tube with heat-shrinkable TFE-fluorocarbon tubing, has been found satisfactory for this application.
A Fisher Calomel Reference Electrode Catalog No. 13-639-79 has been found satisfactory.
C1108 − 23
FIG. 3 S-Shaped Stirrer
7.4 Quartz Heating Lamps—Optimum heating or evaporating efficiency without bumping of solutions, or both, is obtained using
overhead heating with quartz heat lamps controlled by a variable power supply. However, with proper care, other conventional
means of heating may be used.
7.5 Hot Plate—Recommended for heating during the plutonium oxidation state adjustment with hydrogen peroxide.
7.6 Quartz Clock Timer—accurate to 0.001 s.
7.7 100 Ω Precision Resistor—accurate to better than 0.01 %.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such
specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
Quartz heating lamps and Quartz epiradiator lamps, Model 534 RCL, 500 watts, 120 V (Atlas Electric Supplies, P.O. Box 1300, Hialeah, Florida, 33011) have been found
to be satisfactory.
A Julie 100-Ω precision resistor number NB102A, accurate to 0.0015 %, has been found satisfactory.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference Materials, 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.
All reagents should be prepared with 18-MΩ-cm deionized (demineralized) water.
C1108 − 23
FIG. 4 Coulometer with Digital Integrator
8.2 Argon, greater than 99.99 % purity.
8.3 Hydrochloric Acid, concentrated hydrochloric acid (HCl, specific gravity 1.19).
8.4 Hydrochloric Acid (1 mol/L), prepare by diluting 85 mL of hydrochloric acid to 1 L with water.
8.5 Hydrochloric Acid-Nitric Acid-Hydrofluoric Acid Mixture (5.4 mol/L HCl-1.6 mol/L HNO -0.014 mol/L HF)—Prepare by
slowly adding 450 mL hydrochloric acid, 100 mL nitric acid, and 10 drops hydrofluoric acid to 450 mL water in a
polytetrafluoroethylene beaker. Cool and store in a tetrafluoroethylene (TFE) fluorocarbon bottle.
8.6 Hydrofluoric Acid, concentrated hydrofluoric acid (HF, 48 %).
8.7 Hydrogen Peroxide, 30 % solution of hydrogen peroxide (H O ).
2 2
8.8 Nitric Acid, concentrated nitric acid (HNO , specific gravity 1.42).
8.9 Nitric Acid (8 mol/L)—Prepare by diluting 500 mL nitric acid to 1 L with water.
8.10 Nitric Acid (0.9 mol/L)—Prepare by diluting 57 mL of nitric acid to 1 L with water.
8.11 Perchloric Acid (1 mol/L)—Prepare by diluting 85 mL of perchloric acid (HClO , specific gravity 1.76) to 1 L with water.
8.12 Plutonium Standard Solution—Dissolve plutonium metal (NBL CRM 126, current issue) in an Erlenmeyer flask by slow
addition of approximately 30 mL of hydrochloric acid-nitric acid-hydrofluoric acid mixture. Add 30 mL of 8 mol ⁄L (8 M) HNO ;
evaporate to less than 15 mL. Transfer to a tared container with the 8 mol ⁄L (8 M) HNO and dilute to about 100 mL with 8 mol/L
(8 M) HNO prior to aliquoting. Proceed to 12.3.1.3.
8.13 Sulfamic Acid (NH SO H), saturated solution.
2 3
8.14 Sulfuric Acid (0.5 mol ⁄L)—Prepare by adding 28 mL of sulfuric acid (H SO , specific gravity 1.84) to water with constant
2 4
stirring and dilute to 1 L.
8.15 Sulfuric Acid (3 mol ⁄L)—Prepare by adding 167 mL of sulfuric acid (H SO , specific gravity 1.84) to water with constant
2 4
stirring and dilute to 1 L.
3+ 4+
0.9 mol ⁄L (0.9 M) HNO is used because the range from 0.8 mol ⁄L to 1.0 mol ⁄L HNO provides a stable formal potential for the Pu /Pu couple.
3 3
C1108 − 23
8.16 Sulfuric Acid-Hydrofluoric Acid Mixture (8.1 mol ⁄L (8.1 M) H SO -2.9 mol ⁄L (2.9 M) HF)—Prepare by adding 45 mL of
2 4
sulfuric acid (H SO , specific gravity 1.84) to 45 mL of water with constant stirring. Add 10 mL of hydrofluoric acid, cool, and
2 4
store in a TFE-fluorocarbon polymer bottle.
9. Hazards
9.1 Review the safety data sheets and safety procedures in the laboratory’s safety manual before performing this procedure.
9.2 Warning—Hydrofluoric acid is highly corrosive acid that can severely burn skin, eyes, and mucous membranes. Hydrofluoric
acid differs from the other acids because the fluoride ion readily penetrates the skin, causing destruction of deep tissue layers.
Unlike other acids that are rapidly neutralized, hydrofluoric acid reactions with tissue may continue for days if left untreated.
Familiarization and compliance with the Safety Data Sheet is essential.
9.3 Elemental plutonium is reactive and evolves hydrogen and other gases during dissolution; assure that the dissolution reactions
are complete before sealing closed vessels.
9.4 Pressure protection and pressure relief is required when supplying compressed gas services to a glovebox or other types of
radiological containment units.
9.5 Handling of hot acids during electrode conditions and aliquot fuming requires appropriate ventilation of fumes and safe
handling practices for hot, corrosive materials.
9.6 This standard involves work with nuclear materials. The unique hazards and controls required to conduct the work contained
in this standard from a safety, environmental, and security standpoint is the responsibility of the facility operators, in compliance
with any applicable regulations. Any information given for handling these types of materials contained herein is meant only as a
guide for consideration of the user and not a requirement.
10. Calibration of Instrument
10.1 The type of instrumentation recommended herein (16, 17) includes an electronic integrator circuit. The digital (voltage-to-
frequency) integrator develops a series of pulses, the sum of which is proportional to the integrated current generated during
electrolysis. Establish the relationship between coulombs of electricity and integrator output by calibration. (See 10.2 and 10.3.)
10.2 Adjustment of the Digital Integrator:
10.2.1 Adjust the full-scale and input offset voltage trim pots on the voltage-to-frequency converter (V/F) using the digital
voltmeter and a frequency counter in accordance with the manufacturer’s procedure and recommended frequency for this
adjustment.
10.3 Electrical Calibration:
10.3.1 Connect the circuit as shown in Fig. 4, with the potentiostat leads connected to the calibration precision resistor rather than
the cell. Place the timer in the STOP (open circuit) position. Connect the digital voltmeter to the integrator output.
10.3.2 Place the potentiostat and the integrator in the operating mode.
10.3.3 Place the timer in the START (circuit closed) position.
10.3.4 After 150 s, use the DVM to record the potential drop, P, across the resistor, R.
10.3.5 After 300 s, place the timer in the STOP (circuit open) position.
A Hewlett Packard 3458 digital multim
...