ASTM C1206-91(1996)

Standard Test Method for Plutonium by Iron (II)/Chromium (VI) Amperometric Titration

SCOPE
1.1 This test method covers the determination of plutonium in unirradiated nuclear-grade plutonium dioxide, uranium-plutonium mixed oxides with uranium (U)/plutonium (Pu) ratios up to 21, plutonium metal, and plutonium nitrate solutions. Optimum quantities of plutonium to measure are 7 to 15 mg.
1.2 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.

General Information

• Status: Historical
• Publication Date: 09-Jan-2002
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: C26 - Nuclear Fuel Cycle
• Drafting Committee: C26.05 - Methods of Test

Relations

• Replaced By: ASTM C1206-02 - Standard Test Method for Plutonium by Iron (II)/Chromium (VI) Amperometric Titration
• Effective Date: 10-Jan-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn. Contact ASTM International (www.astm.org) for the latest information.
Designation: C 1206 – 91 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Plutonium by Iron (II)/Chromium (VI) Amperometric
Titration
This standard is issued under the fixed designation C 1206; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope regulations governing their possession and use. This analytical
test method has been designated as technically acceptable for
1.1 This test method covers the determination of plutonium
generating safeguards accountability measurement data for
in unirradiated nuclear-grade plutonium dioxide, uranium-
plutonium.
plutonium mixed oxides with uranium (U)/plutonium (Pu)
3.2 When used in conjunction with appropriate standard
ratios up to 21, plutonium metal, and plutonium nitrate
reference material this test method can demonstrate traceability
solutions. Optimum quantities of plutonium to measure are 7 to
to the national measurement base. However, adherence to this
15 mg.
test method does not automatically guarantee regulatory accep-
1.2 This standard does not purport to address all of the
tance of the resulting safeguards measurements. It remains the
safety concerns, if any, associated with its use. It is the
sole responsibility of the user of this test method to ensure that
responsibility of the user of this standard to establish appro-
its application to safeguards has the approval of the proper
priate safety and health practices and determine the applica-
regulatory authorities.
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 Amperometric titrations are based on the measured
2.1 ASTM Standards:
change in the current flow between two electrodes, held at
C 697 Test Methods for Chemical, Mass Spectrometric, and
constant potential, when a titrant is added. The plutonium is
Spectrochemical Analysis of Nuclear-Grade Plutonium
first oxidized to the +6 oxidation state in a dilute sulfuric acid
Dioxide Powders and Pellets
solution with argentic oxide. The excess oxidant is destroyed
C 698 Test Methods for Chemical, Mass Spectrometric, and
by heating, and the Pu(VI) is then reduced to Pu(IV) by excess
Spectrochemical Analysis of Nuclear-Grade Mixed Oxides
Fe(II) during the titration. The excess Fe(II) is titrated by
((U, Pu)O )
Cr(VI), and the Pu determined by difference from the quanti-
C 757 Specification for Nuclear-Grade Plutonium Dioxide
2 ties of the two titrants.
Powder, Sinterable
4.2 Oxide and metal samples are prepared to produce final
C 758 Test Methods for Chemical, Mass Spectrometric,
solutions as a soluble sulfate. Plutonium-nitrate solutions can
Spectrochemical, Nuclear, and Radiochemical Analysis of
be introduced directly at the beginning of the procedure and are
Nuclear-Grade Plutonium Metal
later diluted with sulfuric acid. Chlorides must be removed.
C 759 Test Methods for Chemical, Mass Spectrometric,
Spectrochemical, Nuclear, and Radiochemical Analysis of
5. Significance and Use
Nuclear-Grade Plutonium Nitrate Solutions
5.1 All plutonium materials covered in this test method are
C 833 Specification for Sintered (Uranium-Plutonium) Di-
2 used in the preparation of nuclear-reactor fuels. In order to be
oxide Pellets
suitable for this purpose, the materials must meet specified
C 1168 Practice for Preparation and Dissolution of Pluto-
2 criteria for plutonium content. This test method is used to
nium Materials for Analysis
verify the plutonium content.
3. Committee C-26 Safeguards Statement 5.2 A primary standard dichromate or a dichromate trace-
able to a primary standard such as a National Institute of
3.1 The materials [nuclear-grade mixed oxides (U, Pu)O
Standards and Technology (NIST) plutonium standard is re-
powders, pellets, Pu metal, Pu oxides, and Pu nitrates] to which
quired for this technique.
this test method applies, are subject to nuclear safeguards
6. Interferences
6.1 Interference is caused by ions that are oxidized by
This test method is under the jurisdiction of ASTM Committee C-26 on Nuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
argentic oxide and reduced by ferrous ion in sulfuric-acid
Test.
solution. Elements that may be present in plutonium materials
Current edition approved Nov. 15, 1991. Published June 1992.
2 and that will produce quantitative positive errors include
Annual Book of ASTM Standards, Vol 12.01.
C 1206
vanadium (V), chromium (Cr), and manganese (Mn). Correc-
tion can be made for these elements by calculation when they
do not individually exceed 200 μg impurity elements per gram
of plutonium.
6.2 Other elements that will cause positive errors include
cerium (Ce), ruthenium (Ru), gold (Au), rhodium (Rh), plati-
num (Pt), lead (Pb), and neptunium (Np). Americium (Am)
does not interfere because it is not oxidized to higher valency
states during the argentic oxidation.
6.3 Thallium (Tl), selenium (Se), calcium (Ca), and barium
(Ba) give low results.
7. Apparatus
7.1 Weighing Burets, polyethylene drop-dispenser bottles
with polypropylene dropping closure and cap, 30 and 60-mL
sizes. Squeeze deliveries are made with these burets. They are
placed in a secondary, cut-off, slightly larger diameter polyeth-
ylene bottle to prevent mass changes from contact with the
hands. Burets are transferred to and from the balance using
forceps.
7.2 Digital Voltmeter, d-c precision, readable to 0.2 mv.
7.3 Microelectrode, rotating platinum.
7.4 Reference Mercury Electrode, saturated mercurous sul-
fate.
7.5 Titrator/Detector, amperometric (see Fig. 1).
FIG. 1 Amperometric Detector Circuit
8. Reagents
136e or equivalent. Weigh approximately 4.9 g to nearest
8.1 Purity of Reagents—Reagent grade chemicals shall be
0.0001 g of potassium dichromate (K Cr O ) and dissolve in
2 2 7
used in all tests. Unless otherwise indicated, it is intended that
water. Transfer to a tared 2-L volumetric flask. Dilute to
all reagents conform to the specifications of the Committee on
volume with water. Weigh the flask and contents. Make the
Analytical Reagents of the American Chemical Society where
buoyancy correction and determine the mass of the solution.
such specifications are available. Other grades may be used,
Express the oxidizing strength as milliequivalents per gram of
provided it is first ascertained that the reagent is of sufficient
solution (C1).
high purity to permit its use without lessening the accuracy of
K 3 P 3 B
C1 5 (1)
the determination.
E 3 S
8.2 Purity of Water—Unless otherwise indicated, references
where:
to water shall be understood to mean deionized or distilled
C1 5 K Cr O concentration, milliequivalents per gram,
water. 2 2 7
K 5 weight, mg, K Cr O ,
2 2 7
8.3 Argentic Oxide (AgO).
P 5 purity of K Cr O ,
2 2 7
8.4 Ferrous Ammonium Sulfate Solution, Iron (II) Titrant—
B 5 buoyancy correction for K Cr O , 1.00031 (use only
2 2 7
Dissolve 19.6 g of Fe(NH ) (SO ) ·6 H O in 500 mL of cold
4 2 4 2 2
if significant),
1 N H SO and dilute to 1 L with 1 N H SO . The solution is
2 4 2 4
E 5 equivalent weight of K Cr O , 49.0320, and
2 2 7
standardized daily or before beginning a series of plutonium
S 5 weight of solution, g.
standard and sample titrations, or both.
8.6 Sulfuric Acid (0.5 N)—Prepare by adding 14 mL of
8.5 Potassium Dichromate Solution—Use NIST SRM
sulfuric acid (H SO , sp gr 1.84) to water with stirring and
2 4
dilute to 1 L.
8.7 Sulfuric Acid (1 N)—Prepare by adding 28 mL of
H SO (sp gr 1.84) to water with stirring and dilute to 1 L.
Nalgene drop-dispenser bottles, Nos. 2411-0030 and 2411-0060 have been 2
8.8 Sulfuric Acid (18 N)—Prepare by carefully adding
found satisfactory.
Both Ealing Pye Scalamp Microammeter No. 29-222 and Keithley Model 197
(with continuous stirring) 500 mL of H SO (sp gr 1.84) slowly
2 4
Digital Multimeter have been found satisfactory.
to 450 mL water, cool, and dilute to 1 L.
Both Sargent & Co. No. S-30420 with No. S-76485 synchronous rotator and
Brinkmann Model 2.628.0010 (628-10, 68-50) have been found satisfactory.
9. Standardization of Iron (II) Titrant
Brinkmann Model EA 406 has been found satisfactory.
“Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi- 9.1 Transfer 20 mL water and 10
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