ASTM C1475-05(2010)e1
(Guide)Standard Guide for Determination of Neptunium-237 in Soil
Standard Guide for Determination of Neptunium-237 in Soil
SIGNIFICANCE AND USE
A soil sampling and analysis program provides a direct means of determining the concentration and distribution of radionuclides in soil. The presence and extent of neptunium-237 is of particular interest because it is one of the more mobile transuranics in terms of migration and plant uptake. Since soil is an integrator and a reservoir on long-lived radionuclides, and serves as an intermediary in several pathways of potential importance to humans, knowledge of the concentration of neptunium-237 in soil is essential.
SCOPE
1.1 This guide covers the determination 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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. Specific precautionary statements are given in Section 8.
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´1
Designation: C1475 − 05 (Reapproved 2010)
Standard Guide for
Determination of Neptunium-237 in Soil
This standard is issued under the fixed designation C1475; 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.
ε NOTE—Editorial changes were made throughout in June 2010.
1. Scope C999 Practice for Soil Sample Preparation for the Determi-
nation of Radionuclides
1.1 This guide covers the determination of neptunium-237
C1000 Test Method for Radiochemical Determination of
in soil by means of radiochemical separations and alpha
Uranium Isotopes in Soil by Alpha Spectrometry
spectrometry. This guide provides options in the selection of
C1001 Test Method for Radiochemical Determination of
sample preparation, separation, and measurement. Although
Plutonium in Soil by Alpha Spectroscopy
neptunium-237 is not a component of global fallout, it is a
C1163 Practice for MountingActinides forAlpha Spectrom-
product of production reactors and spent fuel processing. This
etry Using Neodymium Fluoride
guide is designed for analysis of ten grams of soil previously
C1284 Practice for Electrodeposition of the Actinides for
collected and treated in accordance with Practices C998 and
Alpha Spectrometry
C999. Larger-size samples of environmental soil may also be
C1317 Practice for Dissolution of Silicate or Acid-Resistant
analyzed, as long as the concentrations of interferences such as
Matrix Samples (Withdrawn 2001)
uranium and thorium are at or near environmental concentra-
C1342 Practice for Flux Fusion Sample Dissolution (With-
tions.Dependingonthechoiceofasampledissolutionmethod,
drawn 2001)
all chemical forms of neptunium may not be completely
C1387 Guide for the Determination of Technetium-99 in
solubilized. This guide should allow the determination of
Soil
neptunium-237 concentrations from sub becquerel per gram
C1412 Practice for Microwave Oven Dissolution of Glass
levels to applicable standards depending on count time, sample
Containing Radioactive and Mixed Wastes (Withdrawn
size, detector efficiency, background, and tracer yield.
2001)
1.2 The values stated in SI units are to be regarded as
D1193 Specification for Reagent Water
standard. No other units of measurement are included in this
D1890 Test Method for Beta Particle Radioactivity of Water
standard.
D3084 Practice for Alpha-Particle Spectrometry of Water
1.3 This standard does not purport to address all of the D4962 Practice for NaI(Tl) Gamma-Ray Spectrometry of
safety concerns, if any, associated with its use. It is the
Water
responsibility of the user of this standard to establish appro-
2.2 Other Documents:
priate safety and health practices and determine the applica-
IEEE/ASTM SI-10 Standard for the Use of the International
bility of regulatory limitations prior to use. Specific precau-
System of Units (SI): The Modern Metric System
tionary statements are given in Section 8.
3. Summary of Guide
2. Referenced Documents
3.1 This guide may be used to determine neptunium-237 in
2.1 ASTM Standards: soil at potential release sites.Aneptunium-239 yield monitor is
C859 Terminology Relating to Nuclear Materials added to the soil aliquot and the sample solubilized by one of
several methods, such as those described in Guide C1387. The
C998 Practice for Sampling Surface Soil for Radionuclides
neptunium is separated from the resulting solution using an
extraction chromatography column. A valence adjustment is
performed prior to loading the sample onto the conditioned
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.
chromatography column. The sample is passed through the
Current edition approved June 1, 2010. Published June 2010. Originally
column, which retains the neptunium in the +4 oxidation state.
approved in 2000. Last previous edition approved in 2005 as C1475 – 05. DOI:
The column is washed to remove interferences and selectively
10.1520/C1475-05R10E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
C1475 − 05 (Reapproved 2010)
eluted with dilute acid. The samples are prepared for measure- 7.4 Aliphatic Quaternary Amine Extraction Chromatogra-
ment by neodymium fluoride co-precipitation or phy Resin.
electrodeposition, and the neptunium-237 content determined
7.5 Ferrous Sulfamate [Fe(SO NH ) ], 1.0 M—Dissolve
3 2 2
by alpha spectrometry. The neptunium-239 yield monitor is
38.8 g of sulfamic acid (NH SO H) and 11.6 g of iron powder
2 3
determined by beta or gamma-ray counting.
in approximately 150 mL of water. Stir while heating until
dissolved and then dilute to 200 mL with water. Prepare fresh
4. Significance and Use
each week or keep under a nitrogen blanket to minimize
4.1 A soil sampling and analysis program provides a direct
oxidation.
means of determining the concentration and distribution of
7.6 Hydrofluoric Acid (48 to 51 %)—Concentrated hydro-
radionuclides in soil. The presence and extent of neptunium-
fluoric acid (HF).
237isofparticularinterestbecauseitisoneofthemoremobile
7.7 Iron Powder.
transuranics in terms of migration and plant uptake. Since soil
isanintegratorandareservoironlong-livedradionuclides,and
7.8 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
serves as an intermediary in several pathways of potential
(HNO ).
importance to humans, knowledge of the concentration of
7.9 Nitric Acid, 3.0 M—Add 189 mL of concentrated nitric
neptunium-237 in soil is essential.
acidto400mLofwateranddiluteto1.0Lwithwaterandmix.
7.10 2.5 M Nitric Acid-0.5 M Aluminum Nitrate—Dissolve
5. Interferences
187.6 g of aluminum nitrate in about 500 mLof water, add 159
5.1 Phosphates present in the sample matrix will interfere
mL of concentrated nitric acid, and dilute to 1.0 L.
with the separation chemistry.Aluminum nitrate may be added
7.11 0.02 M Nitric Acid-0.02 M Hydrofluoric Acid—Add
to the load solution to minimize this problem.
1.25 mLof concentrated nitric acid and 0.7 mLof concentrated
5.2 Highconcentrationsofuraniumorthoriumcanoverload
hydrofluoric acid to 800 mL of water and dilute to 1.0 L with
the column, resulting in low recoveries of neptunium or
water and mix.
spectral interferences. A preliminary separation may be re-
quired to avoid spectral interference from uranium, see Test 7.12 Radiometric Yield Tracer—Neptunium-239isnormally
used as a yield monitor in the determination of neptunium-237.
Method C1000. The presence of uranium-233 and uranium-
234 could cause spectral interferences with the neptunium-237 Where beta counting is used to determine the neptunium-239
yield, a relatively low amount of activity, for example, 5 to 15
determination.
Bq, is typically required to obtain the desired precision with a
6. Apparatus 60-min count duration. Another option is the addition of a
known quantity of americium-243, in secular equilibrium with
6.1 Apparatus for the sample dissolution and measurement
neptunium-239, directly to the sample. This approach has the
are identified within the selected test method.
advantage of allowing the use of americium-243 solutions of
6.2 Extraction Columns, with a bed volume of several
NIST-traceable activity. Where gamma-ray counting is used to
millilitres for the extraction chromatography resin.
determinetheneptunium-239yield,alargeramountofactivity,
for example, 120 to 1200 Bq, may be required to obtain the
7. Reagents
desired precision with a 10-min count duration dependent on
7.1 Purity of Reagents—Reagent grade chemicals shall be
the use of a NaI(TI) or HPGe detector. In this situation, it may
used in all tests. Unless otherwise indicated, it is intended that
be preferred to obtain the neptunium-239 from an americium-
all reagents shall conform to the specifications of the Commit-
243 ‘cow.’ This approach has the advantage of conserving the
tee on Analytical Reagents of the American Chemical Society
americium-243 parent with the neptunium-239 activity being
where such specifications are available. Other grades may be
replenished over time. However, it has the disadvantage that
used, provided it is first ascertained that the reagent is of
the neptunium-239 activity of the milked solution must be
sufficiently high purity to permit its use without lessening the
determinedwithhighprecisioninordertonotadverselyimpact
accuracy of the determination.
the precision of the sample neptunium-237 activity determina-
tion.
7.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water as defined
7.13 Sodium Nitrite (NaNO ).
in Specification D1193.
7.14 Sodium Nitrite, 3.0 M—Dissolve 2.1 g of sodium
7.3 Aluminum Nitrate Hydrate [Al(NO ) ·9H O].
nitrite in 10 mL of water. Prepare
...
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