ASTM C1001-00
(Test Method)Standard Test Method for Radiochemical Determination of Plutonium in Soil by Alpha Spectroscopy
Standard Test Method for Radiochemical Determination of Plutonium in Soil by Alpha Spectroscopy
SCOPE
1.1 This test method covers the determination of plutonium in soils at levels of detection dependent on count time, sample size, detector efficiency, background, and tracer yield. This test method describes one acceptable approach to the determination of plutonium in soil.
1.2 This test method is designed for 10 g of soil, previously collected and treated as described in Practices C998 and C999, but sample sizes up to 50 g may be analyzed by this test method. This test method may not be able to completely dissolve all forms of plutonium in the soil matrix.
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 hazard statements are given in Sections 6 and 9.
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Designation:C1001–00
Standard Test Method for
Radiochemical Determination of Plutonium
in Soil by Alpha Spectroscopy
This standard is issued under the fixed designation C 1001; 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.
242 236
1. Scope Pu or Pu isotopic tracer (See Appendix for purification
and standardization of Pu tracer). Plutonium is isolated by
1.1 This test method covers the determination of plutonium
anion exchange, then electrodeposited onto a polished metal
in soils at levels of detection dependent on count time, sample
disk for determination by alpha spectrometry.As an option, the
size, detector efficiency, background, and tracer yield.This test
plutonium may be prepared for alpha spectrometry measure-
methoddescribesoneacceptableapproachtothedetermination
ment by using coprecipitation with neodynium fluoride. The
of plutonium in soil.
range of chemical yield is between 40 and 90 %. The test
1.2 This test method is designed for 10 g of soil, previously
method is based on a published procedure (1).
collected and treated as described in Practices C 998 and
C 999, but sample sizes up to 50 g may be analyzed by this test
4. Significance and Use
method. This test method may not be able to completely
4.1 A soil sampling and analysis program provides a direct
dissolve all forms of plutonium in the soil matrix.
means of determining the concentration and distribution of
1.3 This standard does not purport to address all of the
radionuclides in soil. A soil analysis program has the most
safety concerns, if any, associated with its use. It is the
significance for the preoperational monitoring program to
responsibility of the user of this standard to establish appro-
establish baseline concentrations prior to the operation of a
priate safety and health practices and determine the applica-
nuclear facility. Soil analysis, although useful in special cases
bility of regulatory limitations prior to use. Specific hazard
involving unexpected releases, is a poor technique for assess-
statements are given in Sections 6 and 9.
ing small incremental releases and is therefore not recom-
2. Referenced Documents mended as a method for routine monitoring releases of
radioactive material. Nevertheless, because soil is an integrator
2.1 ASTM Standards:
and a reservoir of long-lived radionuclides, and serves as an
C 998 Practice for Sampling Surface Soil for Radionu-
intermediary in several of the plutonium pathways of potential
clides
importance to humans, knowledge of the concentration of
C 999 Practice for Soil Sample Preparation for the Deter-
2 plutonium in soil is essential.
mination of Radionuclides
C 1163 Test Method for Mounting Actinides for Alpha
5. Apparatus
Spectrometry Using Neodymium Fluoride
3 5.1 Electrodeposition Apparatus (2).
D 1193 Specification for Reagent Water
4 5.2 Alpha Spectrometer, capable of 40 to 50 keV resolution
D 3084 Practice for Alpha-Particle Spectrometry of Water
on actual samples electrodeposited on a flat, mirror-finished
IEEE/ASTM SI-10 StandardfortheUseoftheInternational
5 metal planchet, and a counting efficiency greater than 17 %,
System of Units (SI): The Modern Metric System
and a background less than 0.010 cpm over each designated
3. Summary of Test Method energy region. Resolution is defined as the full width half
maximum (FWHM) in keV, the distance between those points
3.1 Plutonium is extracted from the soil with a mixture of
on either side of the alpha peak where the count is equal to
nitric, hydrofluoric, and hydrochloric acids in the presence of
one-half the maximum count.
NOTE 1—Aregular program of measurement control operations should
be conducted for the alpha spectrometry system, such as regular back-
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Test ground checks, daily source check to determine system stability, control
Methods.
charting, and careful handling of samples during changing.
Current edition approved Aug. 10, 2000. Published September 2000. Originally
5.3 PTFE-polytetrafluoroethylene beakers, 250-mL.
published as C 1001 – 83. Last previous edition C 1001 – 90.
Annual Book of ASTM Standards, Vol 12.01.
Annual Book of ASTM Standards, Vol 11.01.
4 6
Annual Book of ASTM Standards, Vol 11.02. The boldface numbers in parentheses refer to the list of references at the end of
Annual Book of ASTM Standards, Vol 14.04. this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1001
6. Reagents 6.23 Plutonium-242 Reagent.
6.1 Purity of Reagents—Reagent grade chemicals shall be
7. Sampling
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
7.1 Collect the sample in accordance with Practice C 998.
tee onAnalytical Reagents of theAmerican Chemical Society,
7.2 Prepare the sample for analysis in accordance with
where such specifications are available (3). Other grades may
Practice C 999.
be used, provided it is first ascertained that the reagent is of
7.3 Samples consisting of 10 to 50 g of soil can be readily
sufficiently high purity to permit its use without lessening the
analyzed by the procedure. The analysis of large soil aliquots
accuracy of the determination.
is desirable because of more representative samples, as well as
6.2 Purity of Water— Unless otherwise indicated, refer-
lowering the minimum detectable concentration. In general, it
ences to water shall be understood to mean reagent water as
ispoorpracticetouselessthan10gofsample,unlessreplicate
defined in Specification D 1193, Type III.
analyses are performed, because of needed sensitivity to
6.3 Reagent blanks should be run to determine their contri-
determine lower levels of activity.
bution to the sample result.
6.4 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
8. Calibration and Standardization
monium hydroxide (NH OH).
8.1 The counting efficiency of the alpha spectrometer is
6.5 Ammonium Iodide (NH I) (1 M)—Dissolve 14.5 g of
used to determine the minimum detectable concentration
NH I in 100 mL water.
(MDC), lower limit of detection (LLD), and chemical recov-
6.6 Ammonium Iodide, Hydrochloric Acid Solution (NH I-
ery. The efficiency of the alpha spectrometer is determined as
HCl)— Add 25 mL 1 M ammonium iodide to 500 mL
the ratio of the observed count rate to the known disintegration
concentrated hydrochloric acid.
rate times the counting efficiency of the 2p counter. The
NOTE 2—Caution: Prepare fresh prior to use.
procedure is as follows:
8.1.1 Count a NIST-certified Am source on a 2p alpha
6.7 Analytical Grade Anion Exchange Resin (AG) 1-X8
counter. The 2p counter efficiency is determined by:
(100 to 200 mesh, nitrate form) —Store the resin in water in a
wash bottle, transfer sufficient resin to a 1.3-cm ID ion
CE 5 C /~A !~T!~1.023! (1)
2p 1 1
exchange column to give a 10-cm bed of settled resin. Convert
where:
the resin to the nitrate form by passing 100 mLof HNO (8M)
C = net counts of the Am source,
through the column at maximum flow rate.
A = certified activity of the Am source (cps), cor-
6.8 Boric Acid (H BO ).
3 3
rected for decay,
6.9 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
T = duration of the count time, s, and
chloric acid (HCl).
1.023 = backscatter factor correcting the counting effi-
6.10 Hydrochloric Acid (3M)—Mix 1 volume of concen-
ciency of a source on platinum to that on stainless
trated HCl (sp gr 1.19) with 3 volumes of water.
steel.
6.11 Hydrochloric Acid (1.7M)—Mix 1 volume of concen-
8.1.2 Electrodeposit Pu on a polished metal disk, using
trated HCl (sp gr 1.19) with 6 volumes of water.
the equipment and procedure listed in this method, and
6.12 HydrofluoricAcid (48 to 51 %)—Concentrated hydrof-
counting on the 2p counter. This gives the known disintegra-
luoric acid (HF).
tion rate, C .
2p
6.13 Iron Carrier solution (10 g Iron (III)/L)—Dissolve
8.1.3 The counting efficiency of the alpha spectrometer is
10.0 g iron metal in HCl (1.7M) and dilute to 1 L with HCl
determined as follows:
(1.7M).
CE 5 ~C !~CE !/~C ! (2)
6.14 Nitric Acid (sp gr 1.42)—Concentrated nitric acid s 2p 2p
(HNO ).
where:
6.15 Nitric Acid (8M)—Mix 1 volume of concentrated
C = net count rate of the electroplated source over the
s
HNO (sp gr 1.42) with 1 volume of water.
entire energy region on the alpha spectrometer
6.16 Nitric Acid (1.8M)—Mix 1 volume of concentrated
(cps); the observed count rate,
HNO (sp gr 1.42) with 8 volumes of water.
CE = counting efficiency of the 2p counter, and
2p
6.17 Octyl alcohol.
C = net counting rate of the same source on the 2p
2p
6.18 Sodium Bisulfite (NaHSO ).
counter (cps).
6.19 SodiumHydroxide(50%)—Dissolve500gofNaOHin
8.2 The quantity of the tracer to be used should be in the
500 mL water. A 50% NaOH solution is available commer-
expected range (but not less than 0.17 Bq) of the isotopic
cially.
activity being determined so that the statistical uncertainty in
6.20 Sodium Nitrite (NaNO ).
the yield determination will not be larger than that of the
6.21 Thymol Blue Indicator, Sodium Salt, 0.02 % Solution.
nuclide being determined.
6.22 Plutonium-236 Reagent.
7 8
Resin obtainable from Bio-Rad Laboratories, or its equivalent, has been found Plutonium-242 is available as a Standard Reference Material from the National
satisfactory for this purpose. Institute of Standards and Technology, Gaithersburg, MD 20899.
C1001
9. Procedure 9.14 Dissolve each precipitate with about 30 mL HNO
(8M) (60 mL total) saturated with boric acid. (Approximately
9.1 Weigh a 10 6 0.01 g soil aliquot into a 250 mL PTFE
7gofboricacid/30mLHNO (8M).)Digestinahotwaterbath
beaker.
for 10 min.
9.2 Wet sample with distilled water and add a known
9.15 Cool and centrifuge for approximately 5 min. Decant
236 242
quantity of Pu or Pu tracer.
the supernate into the original 250 mL PTFE beaker and save.
9.3 Add concentrated HNO (sp gr 1.42) a few drops at a
9.16 Washeachresiduewithapproximately10to20mL(20
time as fast as the frothing and vigor of the reaction will permit
to 40 mL total) of HNO (8M) saturated with boric acid.
until the entire sample is covered.
Centrifuge for 5 min and combine the supernates with those in
9.4 Add 60 mL of the concentrated HNO (sp gr 1.42) and
9.15.
30 mL of concentrated HF (48 to 51 %) and digest on a
9.17 Heat the supernate on a hotplate and evaporate to
hotplate with frequent stirring (TFE fluorocarbon stirring rod)
approximately 5 mL.
for about 1 h (Note 4 and Note 5).
9.18 Add approximately 30 mL water and heat to dissolve
the salts. Cool and transfer into a centrifuge tube.
NOTE 3—Precaution: Adequate laboratory facilities, such as fume
hoodsandcontrolledventilation,alongwithsafetechniques,mustbeused
9.19 Addconcentratedammoniumhydroxidedropwisewith
in this procedure. Extreme care should be exercised in using hydrofluoric
stirring to a pH of approximately 9 (using pH paper).
and other hot, concentrated acids. Use of rubber gloves is recommended.
9.20 Centrifuge and discard the supernate.
NOTE 4—For organic soils, first add the nitric acid only in small
9.21 Dissolve the precipitate with a volume of concentrated
portions while stirring. If the solution threatens to overflow as a result of
nitric acid approximately equal to the volume of the precipitate
froth generation, add a few drops of octyl alcohol and stir. Digest on a
hotplate until the evolution of reddish-brown fumes is reduced to a barely and transfer using nitric acid (8M) into a 250-mL beaker. Add
visible level. Cool to room temperature before carefully adding the
nitric acid (8M) to a total volume of approximately 75 mL. If
concentrated hydrochloric acid (sp gr 1.19) and digesting for an hour.
the volume of the hydroxide precipitate is considerably greater
NOTE 5—For larger soil aliquots, larger amounts of the acids (in the
than should be expected from the 10 mg of Fe(III) added, the
sameproportions)shouldbeused.Forexample,fora50gsample,use200
final volume should be brought up to approximately 100 mL
mL concentrated. HNO and 100 mL HF, etc., with appropriately sized
with nitric acid (8M) or, alternatively, the dissolved hydroxides
containers.
should be evaporated to salts before the addition of the nitric
9.5 Remove from the hotplate and cool somewhat before
acid (8M) solution. The final molarity of the solution is not
adding 30 mL concentrated HNO (sp gr 1.42) and 30 mL
3 extremely critical, but should be in the range of 7 to 9.
concentrated HF (48 to 51 %). Digest on the hotplate with
9.22 Add approximately 200 mg of sodium nitrite crystals
intermittent stirring for an additional 1 h.
and stir with a stirring rod. Bring to a quick gentle boil on a
9.6 Remove from the hotplate and cool. Carefully add 20
hotplate and cool. Avoid prolonged heating.
mLconcentrated HCl (sp gr 1.19) and stir. Heat on hotplate for
9.23 Prepare an anion-exchange column as described in 6.7.
45 min with occasional stirring.
9.24 Pass the sample (at maximum flow rate) through an
9.7 Add about5gof powdered boric acid and digest for an
anion-exchange resin column (nitrate form).
additional 15 min with occasional stirring.
9.25 When the solution just drains to the top of the resin
9.8 Add approximately 200 mg of sodium bisulfite and
bed, wash the column with six column volumes of HNO (8M).
continue heating until the solution has evaporated to a liquid
A column volume is approximately 9.5 mL.
volume of approximately 20 mL.
9.26 Wash the resin column with six column volumes of
9.9 Add 50 mL of water and digest on a hotplate while
concentrated HCl.
stirring for 10 min to dissolve soluble salts.
9.27 Elute the plutonium with four column volumes of
9.10 Coolandtransferapproximatelyequalpartsofthetotal freshly prepared NH I-HCl solution, and collect in a 150-mL
sample into centrifuge bottles with a minimum of water from beaker.
a wash bottle. If equipment for large volume centrifugation is
9.28 Evaporate the solution to approximately 5 mL on a
not available, the two precipitations in 9.11-9.21 may be
hotplate.Rinsedownthesidesofthebeakerdropwisewith1to
performed in a beaker, allowing the precipitate to settle,
2 mL of concentrated HNO . Add six drops of concentrated
decanting the supernate, and then completing the separation by
HCl and evaporate to near dryness.
centrifugation on a smaller scale.
9.29 Add 50
...
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