ASTM C1415-01a(2007)
(Test Method)Standard Test Method for 238Pu Isotopic Abundance by Alpha Spectrometry
Standard Test Method for <sup>238</sup>Pu Isotopic Abundance by Alpha Spectrometry
SIGNIFICANCE AND USE
This test method is used when the determined of 238Pu isotopic abundance is required for plutonium samples.
SCOPE
1.1 This test method covers the use of alpha spectrometry for determining the 238Pu isotopic abundance in plutonium samples. It is particularly useful for samples in which the 238Pu content is less than 1 % of the total plutonium content. For such samples, mass spectrometric results are less reliable than those from alpha spectrometry because of interference from any 238U isobar remaining after ion exchange.
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.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C1415 − 01a (Reapproved 2007)
StandardTest Method for
238 1
Pu Isotopic Abundance By Alpha Spectrometry
This standard is issued under the fixed designation C1415; 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.
1. Scope tative recovery of the plutonium is not required. The alpha
spectruminthe5to6-MeVregionisobtained.Thetotalcounts
1.1 This test method covers the use of alpha spectrometry
238 239 240
238 in the Pu and the Pu + Pu peaks are obtained and
for determining the Pu isotopic abundance in plutonium
238 corrected for background. The Pu abundance is calculated
samples.Itisparticularlyusefulforsamplesinwhichthe Pu
from the ratio of the alpha activity due to Pu and that due to
contentislessthan1 %ofthetotalplutoniumcontent.Forsuch
239 240 239 240
Pu + Pu.The abundance of Pu and Pu is determined
samples, mass spectrometric results are less reliable than those
238 by mass spectrometry (see Test Methods C697) on a separate
fromalphaspectrometrybecauseofinterferencefromany U
portion of the purified sample.
isobar remaining after ion exchange.
1.2 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 This test method is used when the determined of Pu
responsibility of the user of this standard to establish appro-
isotopic abundance is required for plutonium samples.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5. Interferences
2. Referenced Documents
241 241
5.1 Am is always present as a result of Pu decay and
2.1 ASTM Standards:
is a direct interference that must be removed prior to the
238 230
C697 Test Methods for Chemical, Mass Spectrometric, and
determination of Pu. The very small amount of Th and
Spectrochemical Analysis of Nuclear-Grade Plutonium
Th which could be present causes insignificant interference
Dioxide Powders and Pellets
with the determination of Pu at the level of uncertainty of
C1168 PracticeforPreparationandDissolutionofPlutonium
this test method. Other nuclides that would interfere,
238 243 245 249
Materials for Analysis
such as U, Am, Cm, and Bk, are removed by the
D1193 Specification for Reagent Water
anion-exchange separation. Any residual uranium, while it
does not directly interfere with the alpha-pulse height
3. Summary of Test Method
determination, can raise the salt content of the sample. A high
3.1 Thisdeterminationmethodinvolvesthemeasurementof
salt content can decrease the resolution of the alpha spectra,
238 239 240
the alpha-activity ratio of Pu and Pu + Pu. The
and, consequently, decrease the sensitivity of the test method.
isotopic analysis of plutonium for the Pu isotope requires
the prior separation of interferences. After dissolution of the
6. Apparatus
sample (see Practice C1168), the plutonium is separated from
6.1 Counting disks of polished platinum, tantalum, or stain-
interferences by an anion-exchange purification technique.
less steel, sized to fit the detection chamber. A disk 25 mm in
Nitric acid (HNO ) is used to adsorb the plutonium fraction on
diameter and 0.5 mm thick has been found to be acceptable.
the resin. Interfering ions, principally uranium and americium,
are not adsorbed. The plutonium is then eluted with dilute
6.2 Alpha spectrometer. This instrument should typically
HNO (0.1 M). Because an alpha-activity ratio is used, quanti-
consist of the following components:
6.2.1 Silicon surface barrier detector, with an active area of
1 atleast100mm ,adepletiondepthofgreaterthan100µm,and
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
a resolution of 30 keV or less full width at half maximum
Test.
(FWHM) (for Am 5.486 MeV alpha).
Current edition approved Feb. 15, 2007. Published April 2007. Originally
6.2.2 Evacuable, light-tight chamber in which the detector
approved in 1999. Last previous edition approved in 2001 as C1415 – 01a. DOI:
10.1520/C1415-01AR07. and the counting plate on its support can be mounted.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2.3 Preamplifier (charge-sensitive field-effect transistor)
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
with noise less than 4.6 keV when used with above detector
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. (100 pF capacitance).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1415 − 01a (Reapproved 2007)
6.2.4 Detector bias supply, 0 to 150 V, continuously 8.2 Resolution—Count the standard source and determine
variable, well-regulated and stable, with noise and ripple less the energy span at half the peak height. A full width half
than 0.0002 %. maximum of 30 keVor less is desirable, but a FWHM up to 50
6.2.5 Main spectroscopy amplifier, low noise, with variable keV can be tolerated.
shaping constants and baseline restoration.
8.3 Background—Obtain a background spectrum with a
6.2.6 Biased amplifier and pulse stretcher, with continu-
clean counting disk in the chamber.
ously adjustable post-gain and automatic pile-up rejection.
6.2.7 Multichannel pulse-height analyzer. A multichannel
8.4 Frequency of Calibration—The system gain and resolu-
analyzer is most versatile and convenient, since is can be used
tion should be checked periodically, to maintain the same
for the acquisition of data from one to four detectors, simul- operatingconditionsandtocheckwhetherthespectrometerhas
taneously. Even if only one detector is used, such an analyzer
deteriorated.Dailybackgroundcountingisadvisable,toensure
has the advantages that background may be stored in another that neither the chamber nor the detector has been contami-
subgroup and subtracted electronically from the spectrum of
nated.
interest, and that several spectra can be stored and compared.
An analyzer that permits the analyst to set windows around the
9. Procedure
peaks of interest and perform electronic integration is espe-
9.1 Transfer an aliquot of approximately 1 mg Pu from a
cially convenient. The analyzer should accept pulses 0 to 10 V
6 sample obtained from Practice C1168 or equivalent procedure
and3to6µsinwidthandshouldhaveacapacityofatleast10
into a 30-mL beaker and take to dryness on a hot plate.
counts full scale per channel.
6.2.8 Acomputer printerforoutputprintingofthedatafrom
9.2 Add 3-4 mL of 4 M HNO and take to dryness on a hot
the multichannel analyzer (optional).
plate. Cool to room temperature. Repeat this process two more
times.
6.3 Heat lamp.
6.4 Bunsen burner. 9.3 Add 15 mLof 4 M HNO to an anion-exchange column
to precondition it.
6.5 Sample beaker, 30-mL, borosilicate glass.
9.4 Dissolve the sample with 2-3 mL 4 M HNO and
6.6 Bottles or vials. 3
transfer it to the preconditioned anion-exchange column. Let
the efflue
...
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