ASTM D4962-18
(Practice)Standard Practice for NaI(Tl) Gamma-Ray Spectrometry of Water
Standard Practice for NaI(Tl) Gamma-Ray Spectrometry of Water
SIGNIFICANCE AND USE
5.1 Gamma-ray spectrometry is used to identify radionuclides and to make quantitative measurements. Use of a computer and a library of standard spectra will be required for quantitative analysis of complex mixtures of nuclides.
5.2 Variation of the physical geometry of the sample and its relationship with the detector will produce both qualitative and quantitative variations in the gamma-ray spectrum. To adequately account for these geometry effects, calibrations are designed to duplicate all conditions including source-to-detector distance, sample shape and size, and sample matrix encountered when samples are measured. This means that a complete set of library standards may be required for each geometry and sample to detector distance combination that will be used.
5.3 Since some spectrometry systems are calibrated at many discrete distances from the detector, a wide range of activity levels can be measured on the same detector. For high-level samples, extremely low efficiency geometries may be used. Quantitative measurements can be made accurately and precisely when high activity level samples are placed at distances of 1 m or more from the detector.
5.4 Electronic problems, such as erroneous deadtime correction, loss of resolution, and random summing, may be avoided by keeping the gross count rate below 2000 counts per second and also keeping the deadtime of the analyzer below 5 %. Total counting time is governed by the activity of the sample, the detector source distance, and the acceptable Poisson counting uncertainty.
SCOPE
1.1 This practice covers the measurement of radionuclides in water by means of gamma-ray spectrometry. It is applicable to nuclides emitting gamma-rays with energies greater than 50 keV. For typical counting systems and sample types, activity levels of about 40 Bq (1080 pCi) are easily measured and sensitivities of about 0.4 Bq (11 pCi) are found for many nuclides (1-10).2 Count rates in excess of 2000 counts per second should be avoided because of electronic limitations. High count rate samples can be accommodated by dilution or by increasing the sample to detector distance.
1.2 This practice can be used for either quantitative or relative determinations. In tracer work, the results may be expressed by comparison with an initial concentration of a given nuclide which is taken as 100 %. For radioassay, the results may be expressed in terms of known nuclidic standards for the radionuclides known to be present. In addition to the quantitative measurement of gamma-ray activity, gamma-ray spectrometry can be used for the identification of specific gamma-ray emitters in a mixture of radionuclides but that ability is limited when using low energy resolution Na(Tl) detectors as compared to High Purity Germanium (HPGe) detectors. General information on radioactivity and the measurement of radiation has been published (11 and 12). Information on specific application of gamma-ray spectrometry is also available in the literature (13-16).
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are included for information only and are not considered standard.
1.4 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.
1.5 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.
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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: D4962 − 18
Standard Practice for
1
NaI(Tl) Gamma-Ray Spectrometry of Water
This standard is issued under the fixed designation D4962; 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 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This practice covers the measurement of radionuclides
ization established in the Decision on Principles for the
in water by means of gamma-ray spectrometry. It is applicable
Development of International Standards, Guides and Recom-
to nuclides emitting gamma-rays with energies greater than 50
mendations issued by the World Trade Organization Technical
keV. For typical counting systems and sample types, activity
Barriers to Trade (TBT) Committee.
levels of about 40 Bq (1080 pCi) are easily measured and
sensitivities of about 0.4 Bq (11 pCi) are found for many
2. Referenced Documents
2
nuclides (1-10). Count rates in excess of 2000 counts per
3
2.1 ASTM Standards:
second should be avoided because of electronic limitations.
D1129 Terminology Relating to Water
High count rate samples can be accommodated by dilution or
D3648 Practices for the Measurement of Radioactivity
by increasing the sample to detector distance.
D7902 Terminology for Radiochemical Analyses
1.2 This practice can be used for either quantitative or
E181 Test Methods for Detector Calibration andAnalysis of
relative determinations. In tracer work, the results may be
Radionuclides
expressed by comparison with an initial concentration of a
3. Terminology
given nuclide which is taken as 100 %. For radioassay, the
results may be expressed in terms of known nuclidic standards
3.1 Definitions:
for the radionuclides known to be present. In addition to the
3.1.1 For definitions of terms used in this standard, refer to
quantitative measurement of gamma-ray activity, gamma-ray
Terminologies D1129 and D7902.
spectrometry can be used for the identification of specific
4. Summary of Practice
gamma-ray emitters in a mixture of radionuclides but that
ability is limited when using low energy resolution Na(Tl)
4.1 Gamma-ray spectra are commonly measured with
detectors as compared to High Purity Germanium (HPGe)
modular equipment consisting of a detector, amplifier, analog-
detectors. General information on radioactivity and the mea-
to-digital converter, multi-channel analyzer device, and a
surement of radiation has been published (11 and 12). Infor-
computer (17 and 18).
mation on specific application of gamma-ray spectrometry is
4.2 Thallium-activated sodium-iodide crystals, NaI(Tl),
also available in the literature (13-16).
which can be operated at ambient temperatures, are often used
1.3 The values stated in SI units are to be regarded as
as gamma-ray detectors in spectrometer systems. However,
standard. The values given in parentheses after SI units are
their energy resolution limits their use to the analysis of single
included for information only and are not considered standard.
nuclides or simple mixtures of a few nuclides. A resolution of
137
about7 %(45keVfullwidthatonehalfthe Cspeakheight)
1.4 This standard does not purport to address all of the
at 662 keV can be expected for a NaI(Tl) detector in a 76 mm
safety concerns, if any, associated with its use. It is the
by 76 mm-configuration. There are solid scintillators such as
responsibility of the user of this standard to establish appro-
cerium doped LaBr that may provide a performance advan-
priate safety, health, and environmental practices and deter-
3
tage over NaI(Tl) in terms of energy resolution but whose
mine the applicability of regulatory limitations prior to use.
suitability should be evaluated and documented before being
considered as a substitute for NaI(Tl).
1
4.3 Interaction of a gamma-ray with the atoms in a NaI(Tl)
This practice is under the jurisdiction ofASTM Committee D19 on Water and
is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical
detector results in light photons that can be detected by a
Analysis.
Current edition approved Oct. 1, 2018. Published November 2018. Originally
3
approved in 1989. Last previous edition approved in 2017 as D4962 – 17. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D4962-18. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
The boldface numbers in parentheses refer to the references
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4962 − 17 D4962 − 18
Standard Practice for
1
NaI(Tl) Gamma-Ray Spectrometry of Water
This standard is issued under the fixed designation D4962; 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
1.1 This practice covers the measurement of radionuclides in water by means of gamma-ray spectrometry. It is applicable to
nuclides emitting gamma-rays with energies greater than 50 keV. For typical counting systems and sample types, activity levels
2
of about 40 Bq (1080 pCi) are easily measured and sensitivities of about 0.4 Bq (11 pCi) are found for many nuclides (1-10).
Count rates in excess of 2000 counts per second should be avoided because of electronic limitations. High count rate samples can
be accommodated by dilution or by increasing the sample to detector distance.
1.2 This practice can be used for either quantitative or relative determinations. In tracer work, the results may be expressed by
comparison with an initial concentration of a given nuclide which is taken as 100 %. For radioassay, the results may be expressed
in terms of known nuclidic standards for the radionuclides known to be present. In addition to the quantitative measurement of
gamma-ray activity, gamma-ray spectrometry can be used for the identification of specific gamma-ray emitters in a mixture of
radionuclides. radionuclides but that ability is limited when using low energy resolution Na(Tl) detectors as compared to High
Purity Germanium (HPGe) detectors. General information on radioactivity and the measurement of radiation has been published
(11 and 12). Information on specific application of gamma-ray spectrometry is also available in the literature (13-16).
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are included for
information only and are not considered standard.
1.4 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.
1.5 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.
2. Referenced Documents
3
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D3648 Practices for the Measurement of Radioactivity
D7902 Terminology for Radiochemical Analyses
E181 Test Methods for Detector Calibration and Analysis of Radionuclides
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this standard, refer to Terminologies D1129 and D7902.
4. Summary of Practice
4.1 Gamma-ray spectra are commonly measured with modular equipment consisting of a detector, amplifier, analog-to-digital
converter, multi-channel analyzer device, and a computer (17 and 18).
1
This practice is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical Analysis.
Current edition approved Nov. 1, 2017Oct. 1, 2018. Published November 2017November 2018. Originally approved in 1989. Last previous edition approved in 20092017
as D4962 – 02 (2009).D4962 – 17. DOI: 10.1520/D4962-17.10.1520/D4962-18.
2
The boldface numbers in parentheses refer to the references at the end of this practice.
3
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’sstandard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4962 − 18
4.2 Thallium-activated sodium-iodide crystals, NaI(Tl), which can be operated at ambient temperatures, are often used as
gamma-ray detectors in spectrometer systems. However, their energy resolution limits their use to the analysis of single nuclides
137
or simple mixtures of a few nuclides. A
...
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