ASTM C1168-90(1995)e1

NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn.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.
e1
Designation: C 1168 – 90 (Reapproved 1995)
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 Practice for
Preparation and Dissolution of Plutonium Materials for
Analysis
This standard is issued under the fixed designation C 1168; 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.
e NOTE—Keywords were added editorially in August 1995.
1. Scope various mineral acids and, except for plutonium metal, with
applied heat. Dissolution-resistant materials are dissolved in
1.1 This practice is a compilation of dissolution techniques
heated and sealed containers in which pressurization provides
for plutonium materials that are applicable to the test methods
a higher temperature than is attained at ambient pressure.
used for characterizing these materials. Dissolution treatments
3.2 Another dissolution technique is fusion of refractory
for the major plutonium materials assayed for plutonium or
plutonium oxide with sodium bisulfate.
analyzed for other components are listed. Aliquants of the
3.3 The dissolved materials are quantitatively transferred to
dissolved samples are dispensed on a weight basis when one of
a tared polyethylene dispensing bottle for subsequent deliveries
the analyses must be highly reliable, such as plutonium assay;
of weight aliquants for high-precision analysis methods, such
otherwise they are dispensed on a volume basis.
as assays, or to a volumetric flask for deliveries of volume
1.2 The treatments, in order of presentation, are as follows:
aliquants for less precise analysis methods, such as impurity
Procedure Title Section analyses. Acids, usually 1 M, are used as rinses to effect
Dissolution of Plutonium Metal with Hydrochloric Acid 7.1
quantitative transfers and as diluents in the polyethylene
Dissolution of Plutonium Metal with Sulfuric Acid 7.2
dispensing bottles and volumetric flasks. The use of water for
Dissolution of Plutonium Oxide and Uranium-Plutonium Mixed 7.3
Oxide by the Sealed-Reflux Technique
these purposes can, in some cases, result in hydrolysis of
Dissolution of Plutonium Oxide and Uranium-Plutonium Mixed 7.4
plutonium to produce polymers that, although soluble, are
Oxides by Sodium Bisulfate Fusion
nonreactive in separation treatments or in plutonium assay
Dissolution of Uranium-Plutonium Mixed Oxides and Low-Fired 7.5
Plutonium Oxide in Beakers
methods that have no pretreatments, such as fuming with acid.
3.4 Plutonium metal is dissolved with hydrochloric acid or
1.3 The values stated in SI units are to be regarded as
with sulfuric acid.
standard.
3.5 Plutonium oxide, calcined at about 1000°C or lower, is
1.4 This standard does not purport to address all of the
dissolved with a mixture of hydrochloric, nitric, and hydrof-
safety concerns, if any, associated with its use. It is the
luoric acids using the sealed-reflux techniques (1). More
responsibility of the user of this standard to establish appro-
refractory plutonium oxide is dissolved with a fusion using
priate safety and health practices and determine the applica-
sodium bisuflate (2). Low-fired (<650°C) plutonium oxide can
bility of regulatory limitations prior to use.
also be dissolved in a mixture of nitric and hydrofluoric acids
2. Referenced Documents
in beakers.
3.6 Uranium-plutonium mixed oxide is dissolved in either
2.1 ASTM Standards:
of three ways: sodium bisulfate fusion, a heated mixture of
C 757 Specification for Nuclear-Grade Plutonium Dioxide
nitric and hydrofluoric acids in a beaker, or a mixture of
Powder, Sinterable
hydrochloric, nitric, and hydrofluoric acids by the sealed-reflux
C 833 Specification for Sintered (Uranium-Plutonium) Di-
technique.
oxide Pellets
3.7 Combinations of these dissolution techniques described
C 1008 Specification for Sintered (Uranium-Plutonium) Di-
in 3.4 to 3.6 are sometimes used on difficult-to-dissolve
oxide Pellets—Fast Reactor Fuel
samples.
3. Summary of Dissolution Methods
3.8 Quantitative transfers of samples and subsequent solu-
tion are required. Whenever a loss is incurred or even sus-
3.1 Most plutonium-containing samples are dissolved with
pected, the sample is rejected. Solutions of dissolved samples
are inspected for undissolved particles; if particles are present,
This practice 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
Test.
Current edition approved Nov. 30, 1990. Published March 1991. The boldface numbers in parentheses refer to a list of references at the end of
Annual Book of ASTM Standards, Vol 12.01. this practice.
C 1168
further treatment is necessary to attain complete solubility.
When analyzing the dissolved sample for trace impurities,
caution should be exercised so the dissolution process does not
cause the impurity to be lost or does not significantly increase
the level of impurity being determined.
4. Significance and Use
4.1 The materials covered are plutonium metal, plutonium
oxide, and uranium-plutonium mixed oxide, that must meet
ASTM specifications.
4.2 Plutonium and uranium mixtures are used as nuclear
reactor fuels. For use as a nuclear reactor fuel, the material
must meet certain criteria for combined uranium and pluto-
nium content, effective fissile content, and impurity content as
described in Specifications C 757, C 833, and C 1008. The
material is assayed for plutonium and uranium to determine if
the content is correct as specified by the purchaser.
4.3 The materials not covered are unique plutonium mate-
rials, including alloys, compounds, and scrap materials. The
user must determine the applicability of this practice to these
other materials. In general, these unique plutonium materials
are dissolved with various acid mixtures or by fusion with
FIG. 1 Sealed-Reflux Dissolution Tube
various fluxes. Many plutonium salts are soluble in hydrochlo-
ric acid.
5. Apparatus
5.1 Balances, for weighing samples and solutions. A bal-
ance with a sensitivity of 0.1 mg is necessary; however, a
balance with 0.01 mg sensitivity is more desirable. A calibrated
balance must be used.
5.2 Beakers, Test Tubes, and Erlenmeyer Flasks—
Generally, borosilicate glass is recommended; however, the
analyst should be sure that safety and sample contamination
from the container are considered when choosing appropriate
containers.
5.3 Furnace, with controller for timed operation. The fur-
nace must be capable of maintaining an even temperature of
610°C up to 700°C.
5.4 Heating Equipment—Hot plates and infrared lamps are
used.
5.5 Inert Atmosphere Glove-Box System—capability of
maintaining less than 10 ppm of H O and of O is preferred.
2 2
5.6 Sealed-Reflux Dissolution Apparatus—The example ap-
paratus is shown in Fig. 1 and Fig. 2 and is further described
in Ref (1).
6. Reagents FIG. 2 Heating Block
NOTE 1—Use distilled or demineralized water for all reagents.
6.6 Hydrofluoric Acid-Nitric Acid Mixture, 0.05 M HF-16 M
6.1 Hydrochloric Acid (sp gr 1.18), 12 M. HNO —Add 1.8 mL 28 M HF, using a plastic pipet, to 1 L of
6.2 Hydrochloric Acid,6 M—Add 500 mL of 12 M HCl to 16 M HNO .
<500 mL of water and dilute to 1 L with water. 6.7 Nitric Acid (sp gr 1.42), 16 M.
6.3 Hydrochloric Acid,1 M—Add 83 mL of 12 M HCl to 6.8 Nitric Acid,1 M—Add 62 mL of 16 M HNO to <900
<900 mL of water and dilute to 1 L with water. mL of water and dilute to 1 L with water.
6.4 Hydrofluoric Acid (sp gr 1.17), 28 M. 6.9 Sodium Bisulfate, Anhydrous, Fused, NaHSO —Grind
6.5 Hydrofluoric Acid, 1.3 M—Transfer 4.8 mL of 28 M HF, the sodium bisulfate just before use, if necessary.
using a plastic pipet, to a 100-mL plastic graduated cylinder 6.10 Sulfuric Acid (sp gr 1.84), 18 M.
containing <90 mL of water and dilute to 100 mL with water. 6.11 Sulfuric Acid, 0.5 M—Cautiously add 28 mL of 18 M
Transfer to a plastic bottle for storage. H SO to water and dilute to 1 L with water.
2 4
C 1168
7. Procedures Uranium-Plutonium Mixed Oxide by the Sealed-Reflux Tech-
nique:
7.1 Procedure 1—Dissolution of Plutonium Metal with Hy-
7.3.1 Tare a weighing pan or other type of container.
drochloric Acid:
7.3.2 Transfer sample to the tared pan or other container
7.1.1 Remove surface oxide, if present, from the bulk
until the desired weight of sample is obtained, usually 0.5 g.
sample before cutting into portions. This procedure can be
Weigh to at least 0.1 mg sensitivity.
done either by filing the plutonium metal in an inert atmo-
7.3.3 Quantitatively transfer the sample from the pan into a
sphere or by using other mechanical or chemical means.
sealed-reflux tube, see Fig. 1.
NOTE 2—Plutonium metal reacts with air and moisture to form PuO ,
7.3.4 Reweigh the pan. Compute the weight of sample
so it is recommended that it be cleaned and weighed in an inert-
transferred to the tube by subtracting the weight of the pan
atmosphere glove box.
from the weight of the sample plus the pan.
7.3.5 Add 5 mL of 12 M HCl, 3 drops 16 M HNO , and 3
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