ASTM C1475-00
(Guide)Standard Guide for Determination of Neptunium-237 in Soil
Standard Guide for Determination of Neptunium-237 in Soil
SCOPE
1.1 This guide covers the detemination of neptunium-237 in soil by means of radiochemical separations and alpha spectrometry. This guide provides options in the selection of sample preparation, separation, and measurement. Although neptunium-237 is not a component of global fallout, it is a product of production reactors and spent fuel processing. This guide is designed for analysis of ten grams of soil previously collected and treated in accordance with Practices C998 and C999. Larger-size samples of environmental soil may also be analyzed, as long as the concentrations of interferences such as uranium and thorium are at or near environmental concentrations. Depending on the choice of a sample dissolution method, all chemical forms of neptunium may not be completely solubilized. This guide should allow the determination of neptunium-237 concentrations from sub becquerel per gram levels to applicable standards depending on count time, sample size, detector efficiency, background, and tracer yield.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of limitations prior to use. Specific precautionary statements are given in Section 8.
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 1475 – 00
Standard Guide for
Determination of Neptunium-237 in Soil
This standard is issued under the fixed designation C 1475; 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 C 1317 Practice for Dissolution of Silicate or Acid-
Resistant Matrix Samples
1.1 This guide covers the determination of neptunium-237
C 1342 Practice for Flux Fusion Sample Dissolution
in soil by means of radiochemical separations and alpha
C 1387 Guide for Determination of Technetium-99 in Soil
spectrometry. This guide provides options in the selection of
C 1412 Practice for Microwave Oven Dissolution of Glass
sample preparation, separation, and measurement. Although
Containing Radioactive and Mixed Wastes
neptunium-237 is not a component of global fallout, it is a
D 1193 Specification for Reagent Water
product of production reactors and spent fuel processing. This
D 1890 Test Method for Beta Particle Radioactivity of
guide is designed for analysis of ten grams of soil previously
Water
collected and treated in accordance with Practices C 998 and
D 3084 Practice for Alpha-Particle Spectrometry of Water
C 999. Larger-size samples of environmental soil may also be
D 4962 Practice for NaI(TI) Gamma-Ray Spectrometry of
analyzed, as long as the concentrations of interferences such as
Water
uranium and thorium are at or near environmental concentra-
IEEE/ASTM SI-10 StandardfortheUseoftheInternational
tions.Dependingonthechoiceofasampledissolutionmethod,
System of Units (SI): The Modern Metric System
all chemical forms of neptunium may not be completely
solubilized. This guide should allow the determination of
3. Summary of Guide
neptunium-237 concentrations from sub becquerel per gram
3.1 This guide may be used to determine neptunium-237 in
levels to applicable standards depending on count time, sample
soil at potential release sites.Aneptunium-239 yield monitor is
size, detector efficiency, background, and tracer yield.
added to the soil aliquot and the sample solubilized by one of
1.2 This standard does not purport to address all of the
several methods, such as those described in Guide C 1387.The
safety concerns, if any, associated with its use. It is the
neptunium is separated from the resulting solution using an
responsibility of the user of this standard to establish appro-
extraction chromatography column. A valence adjustment is
priate safety and health practices and determine the applica-
performed prior to loading the sample onto the conditioned
bility of limitations prior to use. Specific precautionary state-
chromatography column. The sample is passed through the
ments are given in Section 8.
column, which retains the neptunium in the +4 oxidation state.
2. Referenced Documents The column is washed to remove interferences and selectively
eluted with dilute acid. The samples are prepared for measure-
2.1 ASTM Standards:
ment by neodymium fluoride co-precipitation or electrodepo-
C 998 Practice for Sampling Surface Soil for Radionu-
sition, and the neptunium-237 content determined by alpha
clides
spectrometry. The neptunium-239 yield monitor is determined
C 999 Practice for Soil Sample Preparation for the Deter-
by beta or gamma-ray counting.
mination of Radionuclides
C 1000 Test Method for Radiochemical Determination of
4. Significance and Use
Uranium Isotopes in Soil by Alpha Spectrometry
4.1 A soil sampling and analysis program provides a direct
C 1001 Test Method for Radiochemical Determination of
2 means of determining the concentration and distribution of
Plutonium in Soil by Alpha Spectroscopy
radionuclides in soil. The presence and extent of neptunium-
C 1163 Test Method for Mounting Actinides for Alpha
2 237isofparticularinterestbecauseitisoneofthemoremobile
Spectrometry Using Neodymium Fluoride
transuranics in terms of migration and plant uptake. Since soil
C 1284 Practice for Electrodeposition of the Actinides for
2 isanintegratorandareservoironlong-livedradionuclides,and
Alpha Spectrometry
serves as an intermediary in several pathways of potential
This guide is under the jurisdiction ofASTM Committee C26 on Nuclear Fuel
Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test. Annual Book of ASTM Standards, Vol 11.01.
Current edition approved June 10, 2000. Published August 2000. Annual Book of ASTM Standards, Vol 11.02.
2 5
Annual Book of ASTM Standards, Vol 12.01. Annual Book of ASTM Standards, Vol 14.04.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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.
C1475–00
importance to humans, knowledge of the concentration of 7.11 0.02 M Nitric Acid-0.02 M Hydrofluoric Acid—Mix
neptunium-237 in soil is essential. 1.25 mLof concentrated nitric acid and 0.7 mLof concentrated
hydrofluoric acid in water and dilute to 1.0 L.
5. Interferences
7.12 Radiometric Yield Tracer—Neptunium-239 is nor-
5.1 Phosphates present in the sample matrix will interfere
mally used as a yield monitor in the determination of
with the separation chemistry.Aluminum nitrate may be added
neptunium-237. Where beta counting is used to determine the
to the load solution to minimize this problem.
neptunium-239 yield, a relatively low amount of activity, for
5.2 Highconcentrationsofuraniumorthoriumcanoverload
example, 5 to 15 Bq, is typically required to obtain the desired
the column, resulting in low recoveries of neptunium or
precision with a 60-min count duration. Another option is the
spectral interferences. A preliminary separation may be re-
addition of a known quantity of americium-243, in secular
quired to avoid spectral interference from uranium, see Test
equilibrium with neptunium-239, directly to the sample. This
Method C 1000. The presence of uranium-233 and uranium-
approach has the advantage of allowing the use of americium-
234 could cause spectral interferences with the neptunium-237
243 solutions of NIST-traceable activity. Where gamma-ray
determination.
countingisusedtodeterminetheneptunium-239yield,alarger
amount of activity, for example, 120 to 1200 Bq, may be
6. Apparatus
required to obtain the desired precision with a 10-min count
6.1 Apparatus for the sample dissolution and measurement
duration dependent on the use of a NaI(TI) or HPGe detector.
are identified within the selected test method.
In this situation, it may be preferred to obtain the neptunium-
6.2 Extraction Columns, with a bed volume of several
239 from an americium-243 8cow.’ This approach has the
millilitres for the extraction chromatography resin.
advantage of conserving the americium-243 parent with the
neptunium-239 activity being replenished over time. However,
7. Reagents
it has the disadvantage that the neptunium-239 activity of the
7.1 Purity of Reagents—Reagent grade chemicals shall be
milked solution must be determined with high precision in
used in all tests. Unless otherwise indicated, it is intended that
order to not adversely impact the precision of the sample
all reagents shall conform to the specifications of the Commit-
neptunium-237 activity determination.
tee on Analytical Reagents of the American Chemical Society
7.13 Sodium Nitrite (NaNO ).
where such specifications are available. Other grades may be
7.14 Sodium Nitrite, 3.0 M—Dissolve 2.1 g of sodium
used, provided it is first ascertained that the reagent is of
nitrite in 10 mL of water. Prepare fresh daily.
sufficiently high purity to permit its use without lessening the
7.15 If prepacked columns are not available, prepare the
accuracy of the determination.
resin by combining it with an equal volume of water, mix well,
7.2 Purity of Water—Unless otherwise indicated, references
and allow to settle overnight. Decant the supernatant water and
to water shall be understood to mean reagent water as defined
add a fresh volume of water prior to storage. Replace the water
in Specification D 1193.
with a fresh aliquot before each use. Prepare a column for each
7.3 Aluminum Nitrate Hydrate [Al(NO ) ·9H O].
3 3 2 sample by pouring resin into each column. Adjust the settled
7.4 Extraction Chromatography Resin.
resin bed volume to approximately 2 mL.
7.5 Ferrous Sulfamate [Fe(SO NH ) ], 1.0 M—Dissolve
3 2 2
38.8 g of sulfamic acid (NH SO H) and 11.6 g of iron powder 8. Precautions
2 3
in approximately 150 mL of water. Stir while heating until
8.1 Refer to the laboratory’s chemical hygiene plan and
dis
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