ASTM C1030-10(2018)
(Test Method)Standard Test Method for Determination of Plutonium Isotopic Composition by Gamma-Ray Spectrometry
Standard Test Method for Determination of Plutonium Isotopic Composition by Gamma-Ray Spectrometry
SIGNIFICANCE AND USE
4.1 The determination of plutonium isotopic composition by gamma-ray spectrometry is a nondestructive technique and when used with other nondestructive techniques, such as calorimetry (Test Method C1458) or neutron counting (Test Methods C1207, C1316, C1493, and C1500), can provide a wholly nondestructive plutonium assay necessary for material accountancy and safeguards needs.
4.2 Because gamma-ray spectrometry systems are typically automated, the routine use of the test method is fast, reliable, and is not labor intensive. The test method is nondestructive, requires no sample preparation, and does not create waste disposal problems.
4.3 This test method assumes that all plutonium in the measured item has the same isotopic distribution, often called isotopic homogeneity (see 7.2.4 and 7.2.5).
4.4 The 242Pu abundance is not measured by this test method and must be estimated from isotopic correlation techniques, stream averages, historical information, or other measurement techniques.
4.5 Americium-241 is a daughter product of 241Pu. The 241Am/239Pu atom ratio can also be determined by means of this test method (assuming a homogeneous isotopic distribution of plutonium and 241Am). The determination of the 241Am/239Pu atom ratio is necessary for the correct interpretation of a calorimetric heat measurement.
4.6 The isotopic composition of a given batch or item of plutonium is an attribute of that item and, once determined, can be used in subsequent inventory measurements to verify the identity of an item within the measurement uncertainties.
4.7 The method can also measure the ratio of other gamma-emitting isotopes to plutonium assuming they have the same spatial distribution as the plutonium in the item. Some of these “other” gamma-emitting isotopes include isotopes of uranium, neptunium, curium, cesium, and other fission products. The same methods of this standard can be used to measure the isotopic composition of uranium in items containing only u...
SCOPE
1.1 This test method is applicable to the determination of isotopic abundances in isotopically homogeneous plutonium-bearing materials. This test method may be applicable to other plutonium-bearing materials, some of which may require modifications to the described test method.
1.2 The procedure is applicable to items containing plutonium masses ranging from a few tens of milligrams up to the maximum plutonium mass allowed by criticality limits.
1.3 Measurable gamma ray emissions from plutonium cover the energy range from approximately 30 keV to above 800 keV. K-X-ray emissions from plutonium and its daughters are found in the region around 100 keV. This test method has been applied to all portions of this broad spectrum of emissions.
1.4 The isotopic abundance of the 242Pu isotope is not directly determined because it has no useful gamma-ray signature. Isotopic correlation techniques may be used to estimate its relative abundance Refs (1) and (2).2
1.5 This test method has been demonstrated in routine use for isotopic abundances ranging from 99 to 239Pu. This test method has also been employed for isotopic abundances outside this range.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1030 − 10 (Reapproved 2018)
Standard Test Method for
Determination of Plutonium Isotopic Composition by
Gamma-Ray Spectrometry
This standard is issued under the fixed designation C1030; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method is applicable to the determination of
mendations issued by the World Trade Organization Technical
isotopic abundances in isotopically homogeneous plutonium-
Barriers to Trade (TBT) Committee.
bearing materials. This test method may be applicable to other
plutonium-bearing materials, some of which may require
2. Referenced Documents
modifications to the described test method.
2.1 ASTM Standards:
1.2 The procedure is applicable to items containing pluto-
C697Test Methods for Chemical, Mass Spectrometric, and
nium masses ranging from a few tens of milligrams up to the
Spectrochemical Analysis of Nuclear-Grade Plutonium
maximum plutonium mass allowed by criticality limits.
Dioxide Powders and Pellets
1.3 Measurablegammarayemissionsfromplutoniumcover
C698Test Methods for Chemical, Mass Spectrometric, and
theenergyrangefromapproximately30keVtoabove800keV.
Spectrochemical Analysis of Nuclear-Grade Mixed Ox-
K-X-rayemissionsfromplutoniumanditsdaughtersarefound
ides ((U, Pu)O )
in the region around 100 keV. This test method has been
C982 Guide for Selecting Components for Energy-
applied to all portions of this broad spectrum of emissions.
Dispersive X-Ray Fluorescence (XRF) Systems (With-
1.4 The isotopic abundance of the Pu isotope is not
drawn 2008)
directly determined because it has no useful gamma-ray
C1207Test Method for Nondestructive Assay of Plutonium
signature. Isotopic correlation techniques may be used to
in Scrap and Waste by Passive Neutron Coincidence
estimate its relative abundance Refs (1) and (2).
Counting
1.5 This test method has been demonstrated in routine use
C1316Test Method for Nondestructive Assay of Nuclear
for isotopic abundances ranging from 99 to <50% Pu. This
Material in Scrap and Waste by Passive-Active Neutron
test method has also been employed for isotopic abundances
Counting Using Cf Shuffler
outside this range.
C1458Test Method for NondestructiveAssay of Plutonium,
1.6 The values stated in SI units are to be regarded as
Tritium and Am by Calorimetric Assay
standard. No other units of measurement are included in this
C1493Test Method for Non-Destructive Assay of Nuclear
standard.
Material in Waste by Passive and Active Neutron Count-
1.7 This standard does not purport to address all of the ing Using a Differential Die-Away System (Withdrawn
safety concerns, if any, associated with its use. It is the
2018)
responsibility of the user of this standard to establish appro-
C1500Test Method for Nondestructive Assay of Plutonium
priate safety, health, and environmental practices and deter-
by Passive Neutron Multiplicity Counting
mine the applicability of regulatory limitations prior to use.
E181Test Methods for Detector Calibration andAnalysis of
1.8 This international standard was developed in accor-
Radionuclides
dance with internationally recognized principles on standard-
E267Test Method for Uranium and Plutonium Concentra-
tions and Isotopic Abundances
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.10 on Non
Destructive Assay. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2018. Published April 2018. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1984. Last previous edition approved in 2010 as C1030–10. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1030-10R18. the ASTM website.
2 4
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof The last approved version of this historical standard is referenced on
this standard. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1030 − 10 (2018)
2.2 ANSI Standards: Methods C1207, C1316, C1493, and C1500), can provide a
ANSI/IEEE Std 325-1996IEEE Standard Test Procedures wholly nondestructive plutonium assay necessary for material
for Germanium Gamma-Ray Detectors accountancy and safeguards needs.
ANSIN15.36Measurement Control Program – Nondestruc-
4.2 Because gamma-ray spectrometry systems are typically
tive Assay Measurement Control and Assurance
automated, the routine use of the test method is fast, reliable,
and is not labor intensive. The test method is nondestructive,
3. Summary of Test Method
requires no sample preparation, and does not create waste
3.1 The intensities of gamma-rays emitted from a
disposal problems.
plutonium-bearing item are determined from a gamma-ray
4.3 This test method assumes that all plutonium in the
spectrum obtained with a High-Purity Germanium (HPGe)
measured item has the same isotopic distribution, often called
detector. The method has also been used with CdTe detectors.
isotopic homogeneity (see 7.2.4 and 7.2.5).
i k
3.2 The atom ratio, N/N , for isotopes i and k is related to
i
4.4 The Pu abundance is not measured by this test
the photopeak counting intensity,C(E ), for gamma ray j with
j
method and must be estimated from isotopic correlation
energy E emitted from isotope i by:
j
techniques, stream averages, historical information, or other
i i i k
N C E T BR RE E
~ ! ~ !
j 1/2 l l
measurement techniques.
5 · · · (1)
k k k i
N C ~E ! T BR RE~E !
l 1/2 j j
4.5 Americium-241 is a daughter product of Pu.
241 239
where:
The Am/ Pu atom ratio can also be determined by means
RE(E) = relative detection efficiency for a gamma-ray of
of this test method (assuming a homogeneous isotopic distri-
i
energy E,
bution of plutonium and Am). The determination of
i
i
241 239
T = half-life of isotope i, and
1/2 the Am/ Pu atom ratio is necessary for the correct inter-
i
BR = gamma-ray branching ratio or branching intensity
j pretation of a calorimetric heat measurement.
(usually expressed as gamma-rays per disintegra-
4.6 The isotopic composition of a given batch or item of
tion) of gamma ray j from isotope i.
plutoniumisanattributeofthatitemand,oncedetermined,can
3.3 The half lives T and the branching ratios BR are
1/2
be used in subsequent inventory measurements to verify the
known, published nuclear data.The photopeak counting inten-
identity of an item within the measurement uncertainties.
sity C(E) is determined from the gamma ray spectrum of the
4.7 The method can also measure the ratio of other gamma-
measured item.
emitting isotopes to plutonium assuming they have the same
3.4 The relative detection efficiency, RE(E), is a function of
spatialdistributionastheplutoniumintheitem.Someofthese
gamma-ray energy and arises from the combined effects of
“other” gamma-emitting isotopes include isotopes of uranium,
detector response, attenuation due to absorbers and container
neptunium, curium, cesium, and other fission products. The
walls, and self-absorption within the measured item for
same methods of this standard can be used to measure the
gamma-rays of differing energies. The relative detection effi-
isotopic composition of uranium in items containing only
ciencies are determined for each measured item from the
uranium (3, 4, 5, 6).
observed gamma spectrum by considering a series of gamma
rays from a single isotope. The quotient of the photopeak
5. Interferences
countingintensityforgammaray jwithenergy E emittedfrom
j
5.1 Because of the finite resolution of even the best quality
isotope i and the branching ratio of gamma ray j from isotope
HPGedetectors,thepresenceofothergamma-emittingsources
iisproportionaltotherelativedetectionefficiencyatenergy E.
j
must be assessed for their effects on the isotopic abundance
This quotient defines the shape of the relative efficiency as a
determination.
function of energy.
5.1.1 The detector used for the spectral measurements shall
i i
C~E ! N
j
be adequately shielded from other nearby plutonium sources.
α ·RE E (2)
S D ~ !
i i
j
BR T
j 1/2
Background spectra shall be collected to ensure the effective-
3.5 All factors in Eq 1 are either determined from the
ness of detector shielding and to identify the background
gamma ray spectrum of the measured item or are known,
radiations.
published nuclear constants. The absolute atom ratios are
5.1.2 If fission products are present in the item being
determined without recourse to standards or calibration by this
measured, they will contribute additional gamma-ray spectral
so-called Intrinsic Calibration technique.
peaks.Thesepeaksoccurmainlyinthe500to800-keVenergy
range and may affect the intensity determination of plutonium
4. Significance and Use
and americium peaks in this region. These high-energy
4.1 Thedeterminationofplutoniumisotopiccompositionby
gamma-rays from fission products also produce contributions
gamma-ray spectrometry is a nondestructive technique and
to the Compton background below 500 keV that decrease the
when used with other nondestructive techniques, such as
precision for peak intensity determination in this region.
calorimetry (Test Method C1458) or neutron counting (Test
5.1.3 For mixed plutonium-uranium oxide-bearing items,
the appropriate corrections for the spectral peaks produced by
uranium gamma emission shall be applied. The main interfer-
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. ences from uranium are listed in Table 1.
C1030 − 10 (2018)
TABLE 1 Principal Gamma-Ray Interferences from Uranium in
6.3 High count rate applications require the use of pile-up
A
Mixed Pu/U Materials
rejection circuitry. Digital stabilization may be desirable for
Branching
long count times under conditions of poor environmental
Intensity
Energy (keV) Isotope
control to ensure the quality of the spectral data. High quality
γ/disintegration,
(%)
digital spectroscopy systems fulfill all of these requirements
143.76 10.96 U
and have been shown to have minimal degradation on pluto-
163.33 5.08 U
niumisotopiccompositionmeasurementresultsatinputcount-
185.715 57.2 U
ing rates as high as 100 kHz (9).
202.11 1.08 U
205.311 5.01 U
6.4 Because of the complexity of plutonium spectra, data
A
Branching Intensity and Energy from Ref (7).
reduction is usually performed by computer. Computerized
analysis methods are well developed and have been highly
automated with the development of various analysis software
5.1.4 Other interference-producing nuclides can be rou-
codes (9, 10, 11, 12, 13, 14, 15). Analysis software is
tinelypresentinplutonium-bearingmaterials.Thegammarays
commercially available as are all of the required data acquisi-
from these nuclides must be assessed for their interference
tion components.
effects on the multiplets used for the plutonium isotopic
analysis and the proper spectral corrections applied. Some of
7. Precautions
these interfering nuclides include: Np and its daugh-
7.1 Safety Precautions—Plutonium-bearing materials are
233 243 239 233
ter Pa, Am and its daughter Np, U, and the Th
both radioactive and toxic. Use adequate laboratory facilities
232 236
decay chain daughters of U and Pu.
and safe operating procedures in handling items containing
5.2 Count-rate and coincident-summing effects may also
these materials. Follow all safe operating procedures and
affect the isotopic abundance determination. This is especially
protocolsspecifictothefacilityorlocationwherethemeasure-
important for items having high Am concentrations. Ran- ments are being made.
dom summing of the intense 59.5-keV Am gamma ray with
7.2 Technical Precautions:
other intense gamma radiations produces spurious spectral
7.2.1 Preclude or rectify counting conditions that may
peaks (8) that can interfere with the isotopic analysis. Thin
produce spectral distortions. Use pulse pile-up rejection tech-
(typically 0.5 to 2 mm) cadmium or tin (which is less toxic)
niquesifhighcountratesareencountered.Useabsorberswhen
absorbers should be placed on the front face of the detector to
appropriate to reduce the intensity of the 59.5 keV gamma-ray
keep the height of the 59.5 keV gamma-ray peak equal to or
of americium (see 5.2).Temperature and humidity fluctuations
less than the height of the most intense peaks in the 100-keV
in the measurement environment may cause gain and zero-
region.
levelshiftsinthegamma-rayspectrum.Employenvironmental
controls or digital stabilization, or both, in this case. Failure to
6. Apparatus
isolate the electronic components from other electrical equip-
6.1 Cooled High-Purity Germanium Detector,
ment or the presence of noise in the AC power may also
Preamplifier—Cooling of the HPGe crystal may come from
produce spectral distortions.
liquid nitrogen (LN ) or from electric or electro-mechanical
7.2.2 The decay of Pu is shown in Fig. 1. The alpha
coolers that do not use LN . The configuration of the HPGe 237
decay branch proceeds through the daughter U which
detector may be planar, semi-planar, or coaxial with the type,
decays with a 6.75 day half-life to Np. It takes 67 days to
size and energy resolution of the detector chosen to accommo-
reach 99.9% of secular equilibrium for this branch of the
datetheenergyrangeofanalysisforthedesiredmeasurements.
decay. After secular equilibrium has been attained the strong
Planar or semi-planar detectors with energy resolution (full-
gamma rays at 164.6, 208.0, 267.5, 332.4, 335.4, 368.6, and
widthathalfmaximum)at122keVbetterthan650eVarebest 237
370.9 keV from the decay of U may be used to directly
for analysis of spectra in the 60 to 450 keV region. Larger 241
determine Pu. These major gamma rays from the decay of
volume coaxial detectors with efficiencies (relative toa3×3 237
U also have an identical energy component from the beta
NaI(Tl) at 1332 keV for a point source at a distance of 10 cm 241 241 241
decay branch of Pu proceeding through Am. The Am
(ANSI/IEEE Std 325-1996)) of 25 to 100% are used for
component of these “co-energetic” peaks must be accounte
...
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