ASTM C1295-24

Standard Test Method for Gamma Energy Emission from Fission and Decay Products in Uranium Hexafluoride and Uranyl Nitrate Solution

SIGNIFICANCE AND USE
5.1 Specific gamma-ray emitting radionuclides in UF6 are identified and quantified using a high-resolution gamma-ray energy analysis system, which includes a high-resolution germanium detector. This test method shall be used to meet the health and safety specifications of C787, C788, and C996 regarding applicable fission products in reprocessed uranium solutions. This test method may also be used to provide information to parties such as conversion facilities on the level of uranium decay products in such materials. Pa-231 is a specific uranium decay product that may be present in uranium ore concentrate and is amenable to analysis by gamma spectrometry.
SCOPE
1.1 This test method covers the measurement of gamma energy emitted from fission products in uranium hexafluoride (UF6) and uranyl nitrate solution. This test method may also be used to measure the concentration of some uranium decay products. It is intended to provide a method for demonstrating compliance with UF6 Specifications C787 and C996, uranyl nitrate Specification C788, and uranium ore concentrate Specification C967.  
1.2 The lower limit of detection is estimated at 5000 MeV Bq/kg (MeV kg-1/s-1) of uranium and is the square root of the sum of the squares of the individual reporting limits of the nuclides to be measured. The limit of detection was determined on a pure, aged natural uranium (ANU) solution. The value is dependent upon the detector efficiency and background that can be achieved.  
1.3 The fission product nuclides to be measured are 106Ru/106Rh, 103Ru, 137Cs, 144Ce, 144Pr, 141Ce, 95Zr, 95Nb, and 125Sb. Among the uranium decay product nuclides that may be measured is 231Pa. Other gamma energy-emitting fission and uranium decay nuclides present in the spectrum at detectable levels should be identified and quantified as required by the data quality objectives.  
1.4 The values stated in SI units are to be regarded as standard. Additionally, the non-SI units of kiloelectron volts and megaelectron volts are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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

• Status: Published
• Publication Date: 14-Jan-2024
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: C26 - Nuclear Fuel Cycle
• Drafting Committee: C26.05 - Methods of Test

Relations

• Replaces: ASTM C1295-15 - Standard Test Method for Gamma Energy Emission from Fission and Decay Products in Uranium Hexafluoride and Uranyl Nitrate Solution
• Effective Date: 15-Jan-2024
• Refers: ASTM C859-24 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C859-23 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Feb-2023
• Referred By: ASTM C1462-21 - Standard Specification for Uranium Metal Enriched to Less Than 20 % <sup> 235</sup >U
• Effective Date: 15-Jan-2024
• Referred By: ASTM C757-16(2021) - Standard Specification for Nuclear-Grade Plutonium Dioxide Powder for Light Water Reactors
• Effective Date: 15-Jan-2024
• Referred By: ASTM C799-19 - Standard Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Nuclear-Grade Uranyl Nitrate Solutions
• Effective Date: 15-Jan-2024
• Referred By: ASTM C761-18 - Standard Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Uranium Hexafluoride
• Effective Date: 15-Jan-2024
• Referred By: ASTM C788-03(2021) - Standard Specification for Nuclear-Grade Uranyl Nitrate Solution or Crystals
• Effective Date: 15-Jan-2024
• Referred By: ASTM C787-20 - Standard Specification for Uranium Hexafluoride for Enrichment
• Effective Date: 15-Jan-2024

Overview

ASTM C1295-24: Standard Test Method for Gamma Energy Emission from Fission and Decay Products in Uranium Hexafluoride and Uranyl Nitrate Solution provides a standardized approach for identifying and quantifying specific gamma-ray emitting radionuclides in uranium hexafluoride (UF₆) and uranyl nitrate solutions. This standardized method is essential for ensuring safety, regulatory compliance, and data reliability within the nuclear fuel cycle. By using high-resolution gamma-ray spectrometry, laboratories can analyze emissions from various fission and uranium decay products, supporting health and environmental safety, material accountability, and process control.

Key Topics

• Scope of Testing:

  • Designed for measurement of gamma energy emissions from fission and uranium decay products in UF₆ and uranyl nitrate solutions.
  • Supports compliance with ASTM standards for UF₆ (C787, C996), uranyl nitrate (C788), and uranium ore concentrate (C967).
  • Applicable to reprocessed uranium and materials containing uranium decay products.

• Detectable Nuclides:

  • Fission products: 106Ru/106Rh, 103Ru, 137Cs, 144Ce, 144Pr, 141Ce, 95Zr, 95Nb, and 125Sb.
  • Uranium decay product: Notably 231Pa (protactinium-231), among others, if present at detectable levels.
  • The method allows for the identification of any gamma energy-emitting nuclides present within the detectable spectrum.

• Measurement Method:

  • Utilizes high-resolution germanium detectors for gamma-ray spectrometry.
  • Calibration and measurement are based on detector efficiency, sample geometry, and uranium mass.
  • Standard units: SI units, kiloelectron volts (keV), and megaelectron volts (MeV).

• Detection Limits and Quality Assurance:

  • Lower limit of detection is estimated at 5000 MeV Bq/kg uranium, based on detector efficiency and background levels.
  • Laboratories are responsible for establishing and maintaining their own precision and bias in alignment with quality assurance programs.

Applications

• Nuclear Fuel Cycle Monitoring:

  • Ensures that uranium hexafluoride and uranyl nitrate meet health and safety criteria for fission products and decay products, in accordance with ASTM specifications.
  • Provides conversion facilities and regulatory bodies with critical data on the composition of uranium compounds.

• Health, Safety, and Environmental Compliance:

  • Enables stakeholders to verify compliance with safety specifications, minimizing radiological risks associated with nuclear materials processing or transport.
  • Useful for assessing the presence of decay products such as 231Pa, which may impact downstream processes or regulatory acceptance.

• Quality Control in Analytical Laboratories:

  • Standardizes testing to facilitate material accountability and traceability throughout the nuclear supply chain.
  • Supports laboratories in developing consistent measurement protocols for radionuclide quantification.

Related Standards

• ASTM C787 – Specification for Uranium Hexafluoride for Enrichment
• ASTM C788 – Specification for Nuclear-Grade Uranyl Nitrate Solution or Crystals
• ASTM C996 – Specification for Uranium Hexafluoride Enriched to Less Than 5% 235U
• ASTM C967 – Specification for Uranium Ore Concentrate
• ASTM C761, C1022 – Test Methods for Chemical and Radiochemical Analysis of Uranium
• ASTM D3649, E3376 – Practices and Guides for Detector Calibration and Gamma-Ray Spectrometry

Practical Value

Implementing ASTM C1295-24 enables nuclear facilities and analytical laboratories to reliably determine and report gamma energy emissions from fission and decay products in uranium compounds. This facilitates compliance with international regulations, enhances safety and environmental stewardship, and streamlines quality assurance processes within the nuclear materials supply chain.

Keywords: gamma energy, gamma-ray spectrometry, uranium hexafluoride, uranyl nitrate, fission products, decay products, high purity germanium detector, ASTM C1295-24, uranium analysis, nuclear safety, radioactive materials analysis.

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: C1295 − 24
Standard Test Method for
Gamma Energy Emission from Fission and Decay Products
in Uranium Hexafluoride and Uranyl Nitrate Solution
This standard is issued under the fixed designation C1295; 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 Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This test method covers the measurement of gamma
Barriers to Trade (TBT) Committee.
energy emitted from fission products in uranium hexafluoride
(UF ) and uranyl nitrate solution. This test method may also be
2. Referenced Documents
used to measure the concentration of some uranium decay
2.1 ASTM Standards:
products. It is intended to provide a method for demonstrating
C761 Test Methods for Chemical, Mass Spectrometric,
compliance with UF Specifications C787 and C996, uranyl
Spectrochemical, Nuclear, and Radiochemical Analysis of
nitrate Specification C788, and uranium ore concentrate Speci-
Uranium Hexafluoride
fication C967.
C787 Specification for Uranium Hexafluoride for Enrich-
1.2 The lower limit of detection is estimated at 5000 MeV
ment
-1 -1
Bq/kg (MeV kg /s ) of uranium and is the square root of the
C788 Specification for Nuclear-Grade Uranyl Nitrate Solu-
sum of the squares of the individual reporting limits of the
tion or Crystals
nuclides to be measured. The limit of detection was determined
C859 Terminology Relating to Nuclear Materials
on a pure, aged natural uranium (ANU) solution. The value is
C967 Specification for Uranium Ore Concentrate
dependent upon the detector efficiency and background that
C996 Specification for Uranium Hexafluoride Enriched to
can be achieved. 235
Less Than 5 % U
1.3 The fission product nuclides to be measured are Ru/ C1022 Test Methods for Chemical and Atomic Absorption
106 103 137 144 144 141 95 95 125
Rh, Ru, Cs, Ce, Pr, Ce, Zr, Nb, and Sb. Analysis of Uranium-Ore Concentrate
Among the uranium decay product nuclides that may be D3649 Practice for High-Resolution Gamma-Ray Spectrom-
measured is Pa. Other gamma energy-emitting fission and etry of Water
uranium decay nuclides present in the spectrum at detectable
E3376 Practice for Calibration and Usage of Germanium
levels should be identified and quantified as required by the Detectors in Radiation Metrology for Reactor Dosimetry
data quality objectives.
3. Terminology
1.4 The values stated in SI units are to be regarded as
3.1 Except as otherwise defined herein, definitions of terms
standard. Additionally, the non-SI units of kiloelectron volts
are as given in Terminology C859.
and megaelectron volts are to be regarded as standard. No other
units of measurement are included in this standard.
4. Summary of Test Method
1.5 This standard does not purport to address all of the
4.1 A solution of the uranium sample is counted on a
safety concerns, if any, associated with its use. It is the
high-resolution gamma-ray spectrometry system. The resulting
responsibility of the user of this standard to establish appro-
spectrum is analyzed to determine the identity and activity of
priate safety, health, and environmental practices and deter-
the gamma-ray-emitting fission and decay products. The num-
mine the applicability of regulatory limitations prior to use.
ber of counts recorded from one or more of the peaks identified
1.6 This international standard was developed in accor-
with each fission nuclide is converted to disintegrations of that
dance with internationally recognized principles on standard-
nuclide per second (Bq). The gamma-ray energy for a fission
ization established in the Decision on Principles for the
nuclide is calculated by multiplying the number of disintegra-
tions per second of the nuclide by the mean gamma-ray energy
This test method is under the jurisdiction of ASTM Committee C26 on Nuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
Test. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 15, 2024. Published March 2024. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1995. Last previous edition approved in 2015 as C1295 – 15. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1295-24. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1295 − 24
emission rate of the nuclide. The calculated gamma-ray energy 7. Calibration and Standardization of Detector
emission rates for all observed fission nuclides are summed,
7.1 Prepare a mixed radionuclide calibration standard stock
then divided by the mass of the uranium in the sample to
solution covering the energy range of approximately 50 keV to
calculate the overall rate of gamma energy production in units
2000 keV.
of million electron volts per second per kilogram of uranium.
231 7.1.1 Commercial calibration standards are available which
Decay product nuclides such as Pa will be separately
are traceable to NIST or other national standards laboratories.
quantified and reported based on specific needs.
7.2 Prepare a solution of ANU with a uranium concentration
5. Significance and Use
of 6.74 g/100 g. The uranium and its progeny’s relationship
must not have been altered for at least eight months.
5.1 Specific gamma-ray emitting radionuclides in UF are
identified and quantified using a high-resolution gamma-ray
7.3 Transfer a known, suitable activity of the mixed nuclide
energy analysis system, which includes a high-resolution
calibration standard stock solution (40 kBq to 50 kBq) to a
germanium detector. This test method shall be used to meet the
container identical to that used for the sample measurement.
health and safety specifications of C787, C788, and C996
Add ANU solution to the mixed nuclide standard so that the
regarding applicable fission products in reprocessed uranium
final volume and uranium concentration match those expected
solutions. This test method may also be used to provide
in the sample measurement. Practices D3649 and E3376
information to parties such as conversion facilities on the level
provide information on calibration of detector energy,
of uranium decay products in such materials. Pa-231 is a
efficiency, resolution, and other parameters.
specific uranium decay product that may be present in uranium
7.4 The detector energy scale and efficiency are calibrated
ore concentrate and is amenable to analysis by gamma spec-
by placing the container with the mixed nuclide calibration
trometry.
standard in a sample holder that provides a reproducible
6. Apparatus geometry relative to the detector. Collect a spectrum over a
period up to 1 h that includes all the gamma photopeaks in the
6.1 High-Resolution Gamma-Ray Spectrometry System, as
energy range up to ;2000 keV. All counting conditions (except
specified in Practice D3649. The energy response range of the
count duration) must be identical to those that will be used for
spectrometry system may need to be tailored to address all the
analysis of the actual sample.
needed fission and uranium decay product nuclides that need to
be analyzed for.
7.5 Determine the net counts under each peak of every
nuclide in the mixed radionuclide standard, then divide by the
6.2 Sample Container with Fitted Cap—A leak-proof plastic
count duration (live time) to determine the rate in counts per
container capable of holding the required sample volume. The
second for each radionuclide. If a background count on the
dimensions must be consistent between containers used for
detector shows any net peak area for the peaks of interest, these
samples and standard to keep the counting geometry constant.
must be subtracted from the standard counts per second.
The greatest detection efficiency will be achieved with a
low-height sample container with a diameter slightly smaller
7.6 Divide the observed count rate determined for each
than the detector being used.
gamma peak by the calculated emission rate of the gamma ray
that produced the peak in the mixed calibration standard
6.3 Sample Holder, shall be used to position the sample
(gammas per second).
container such that the detector view of the sample is repro-
ducible. To reduce the effects of coincident summing, the 7.6.1 Calculation of the gamma emission rate for each peak
sample holder shall provide a minimum separation of 5 mm from the mixed calibration standard must account for the
between the sample container and the detector end cap. following:
TABLE 1 Gamma-Ray-Emitting Fission and Decay Products Found in UF
Mean Gamma
Abundance
Decay Measurement Energy
Half- Gamma/
Nuclide Constant Peaks, Disintegration,
Life Disintegration
(λ ) MeV MeV
I
(G )
I
Bq (E )
I
103 103
Ru/ Rh 39.35d 0.01761/d 0.4971 0.889 0.484
0.6103 0.056
106 106
Ru/ Rh 366.5d 0.001891/d 0.5119 0.207 0.209
0.6222 0.0981
Ce 32.55d 0.02129/d 0.1454 0.484 0.0718
144 144
Ce/ Pr 284.5d 0.002436/d 0.1335 0.1110 0.0518
137 137
Cs/ Ba 30.17y 0.02297/y 0.6616 0.851 0.5655
Nb 34.97d 0.01982/d 0.7658 1.000 0.766
Zr 63.98d 0.01083/d 0.7242 0.444 0.737
0.7567 0.549
Sb 2.71y 0.256/y 0.4279 0.294 0.433
0.6008 0.178
Pa 32760y 2.1158E-05/y 0.002736 0.103 n/a
C1295 − 24
7.6.1.1 Activity of the nuclide that produces the peak in its 8.1.2 Peaks that are determined for this analysis are listed in
original standard (disintegrations/second/unit volume). This is Table 1, along with the abundance factors, decay constants,
taken from the standard certificate of measurement supplied and the mean gamma energy per disintegration for each
with the standard. nuclide. Needed information for uranium decay products can
be found in Footnote 4 or other available sources.
7.6.1.2 Volume of each isotopic standard taken for the
mixed standard and the final volume of the mixed standard.
8.2 While most full-energy gamma emissions are generally
7.6.1.3 Fraction of the volume of the mixed standard taken
characteristic of specific radionuclides, it is possible that
for counting.
unresolved multiplets may produce biased peak areas. Deter-
...

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: C1295 − 15 C1295 − 24
Standard Test Method for
Gamma Energy Emission from Fission and Decay Products
in Uranium Hexafluoride and Uranyl Nitrate Solution
This standard is issued under the fixed designation C1295; 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 test method covers the measurement of gamma energy emitted from fission products in uranium hexafluoride (UF ) and
uranyl nitrate solution. This test method may also be used to measure the concentration of some uranium decay products. It is
intended to provide a method for demonstrating compliance with UF specificationsSpecifications C787 and C996, uranyl nitrate
specificationSpecification C788, and uranium ore concentrate specificationSpecification C967.
-1 -1
1.2 The lower limit of detection is estimated at 5000 MeV Bq/kg (MeV/kg(MeV kg /s per second) ) of uranium and is the square
root of the sum of the squares of the individual reporting limits of the nuclides to be measured. The limit of detection was
determined on a pure, aged natural uranium (ANU) solution. The value is dependent upon the detector efficiency and
background.background that can be achieved.
106 106 103 137 144 144 141 95 95 125
1.3 The fission product nuclides to be measured are Ru/ Rh, Ru, Cs, Ce, Pr, Ce, Zr, Nb, and Sb. Among
the uranium decay product nuclides that may be measured is Pa. Other gamma energy-emitting fission and uranium decay
nuclides present in the spectrum at detectable levels should be identified and quantified as required by the data quality objectives.
1.4 The values stated in SI units are to be regarded as standard. Additionally, the non-SI units of kiloelectron volts and
megaelectron volts are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.6 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
2.1 ASTM Standards:
C761 Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Uranium
Hexafluoride
C787 Specification for Uranium Hexafluoride for Enrichment
C788 Specification for Nuclear-Grade Uranyl Nitrate Solution or Crystals
This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.
Current edition approved June 1, 2015Jan. 15, 2024. Published July 2015March 2024. Originally approved in 1995. Last previous edition approved in 20142015 as
C1295 – 14.C1295 – 15. DOI: 10.1520/C1295-15.10.1520/C1295-24.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’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
C1295 − 24
C859 Terminology Relating to Nuclear Materials
C967 Specification for Uranium Ore Concentrate
C996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % U
C1022 Test Methods for Chemical and Atomic Absorption Analysis of Uranium-Ore Concentrate
D3649 Practice for High-Resolution Gamma-Ray Spectrometry of Water
E181E3376 GuidePractice for Detector Calibration and Analysis of Radionuclides Usage of Germanium Detectors in Radiation
Metrology for Reactor Dosimetry
3. Terminology
3.1 Except as otherwise defined herein, definitions of terms are as given in Terminology C859.
4. Summary of Test Method
4.1 A solution of the uranium sample is counted on a high-resolution gamma-ray spectrometry system. The resulting spectrum is
analyzed to determine the identity and activity of the gamma-ray-emitting radioactive fission and decay products. The number of
counts recorded from one or more of the peaks identified with each fission nuclide is converted to disintegrations of that nuclide
per second (Bq). The gamma-ray energy for a fission nuclide is calculated by multiplying the number of disintegrations per second
of the nuclide by the mean gamma-ray energy emission rate of the nuclide. The calculated gamma-ray energy emission rates for
all observed fission nuclides are summed, then divided by the mass of the uranium in the sample to calculate the overall rate of
gamma energy production in units of million electron volts per second per kilogram of uranium. Decay product nuclides such as
Pa will be separately quantified and reported based on specific needs.
5. Significance and Use
5.1 Specific gamma-ray emitting radionuclides in UF are identified and quantified using a high-resolution gamma-ray energy
analysis system, which includes a high-resolution germanium detector. This test method shall be used to meet the health and safety
specifications of C787, C788, and C996 regarding applicable fission products in reprocessed uranium solutions. This test method
may also be used to provide information to parties such as conversion facilities on the level of uranium decay products in such
materials. Pa-231 is a specific uranium decay product that may be present in uranium ore concentrate and is amenable to analysis
by gamma spectrometry.
6. Apparatus
6.1 High-Resolution Gamma-Ray Spectrometry System, as specified in Practice D3649. The energy response range of the
spectrometry system may need to be tailored to address all the needed fission and uranium decay product nuclides that need to be
analyzed for.
6.2 Sample Container with Fitted Cap—A leak-proof plastic container capable of holding the required sample volume. The
dimensions must be consistent between containers used for samples and standard to keep the counting geometry constant. The
greatest detection efficiency will be achieved with a low-height sample container with a diameter slightly smaller than the detector
being used.
6.3 Sample Holder, shall be used to position the sample container such that the detector view of the sample is reproducible. To
reduce the effects of coincident summing, the sample holder shall provide a minimum separation of 5 mm between the sample
container and the detector end cap.
7. Calibration and Standardization of Detector
7.1 Prepare a mixed radionuclide calibration standard stock solution covering the energy range of approximately 5050 keV to 2000
keV.
7.1.1 Commercial calibration standards are available which are traceable to NIST or other national standards laboratories.
7.2 Prepare a solution of ANU at 6.74 gU/100with a uranium concentration of 6.74 g/100 g. The uranium and its progeny’s
relationship must not have been altered for at least eight months.
C1295 − 24
7.3 Transfer a known, suitable activity of the mixed nuclide calibration standard stock solution (40(40 kBq to 50 kBq) to a
container identical to that used for the sample measurement. Add ANU solution to the mixed nuclide standard so that the final
volume and uranium concentration match those expected in the sample measurement. Test Methods Practices E181D3649 and
Practice D3649E3376 providesprovide information on calibration of detector energy, efficiency, resolution, and other parameters.
7.4 The detector energy scale and efficiency are calibrated by placing the container with the mixed nuclide calibration standard
in a sample holder that provides a reproducible geometry relative to the detector. Collect a spectrum over a period up to 1 h that
includes all the gamma photopeaks in the energy range up to ;2000 keV. All counting conditions (except count duration) must
be identical to those that will be used for analysis of the actual sample.
7.5 Determine the net counts under each peak of every nuclide in the mixed radionuclide standard, then divide by the count
duration (live time) to determine the rate in counts per second for each radionuclide. If a background count on the detector shows
any net peak area for the peaks of interest, these must be subtracted from the standard counts per second.
7.6 Divide the observed count rate determined for each gamma peak by the calculated emission rate of the gamma ray that
produced the peak in the mixed calibration standard (gammas per second).
7.6.1 Calculation of the gamma emission rate for each peak from the mixed calibration standard must account for the following:
7.6.1.1 Activity of the nuclide that produces the peak in its original standard (disintegrations/second/unit volume). This is taken
from the standard certificate of measurement supplied with the standard.
7.6.1.2 Volume of each isotopic standard taken for the mixed standard and the final volume of the mixed standard.
7.6.1.3 Fraction of the volume of the mixed standard taken for counting.
7.6.1.4 Decay of the activity of each isotope in the standard between its date of standardization and the date of counting according
to the equation:
2λ t
i
A 5 A e (1)
i i
where:
A = activity of isotope i on the date of counting in Bq,
i
A = activity of isotope i on the date of counting in becquerel,
i
A = activity of isotope i on the date of standard characterization in Bq,
i
A = activity of isotope i on the date of standard characterization in becquerel,
i
λ = decay constant of isotope i in units of inverse time (values for some isotopes of interest may be found in column 3 of Table
i
1), and
TABLE 1 Gamma-Ray-Emitting Fission and Decay Products Found in UF
Mean Gamma
Abundance
Decay Measurement Energy
Half- Gamma/
Nuclide Constant Peaks, Disintegration,
Life Disintegration
(λ ) MeV MeV
I
(G )
I
Bq (E )
I
103 103
Ru/ Rh 39.35d 0.01761/d 0.4971 0.889 0.484
0.6103 0.056
106 106
Ru/ Rh 366.5d 0.001891/d 0.5119 0.207 0.209
0.6222 0.0981
Ce 32.55d 0.02129/d 0.1454 0.484 0.0718
144 144
Ce/ Pr 284.5d 0.002436/d 0.1335 0.1110 0.0518
137 137
Cs/ Ba 30.17y 0.02297/y 0.6616 0.851 0.5655
Nb 34.97d 0.01982/d 0.7658 1.000 0.766
Zr 63.98d 0.01083/d 0.7242 0.444 0.737
0.7567 0.549
Sb 2.71y 0.256/y 0.4279 0.294 0.433
0.6008 0.178
Pa 32760y 2.1158E-05/y 0.002736 0.103 n/a
C1295 − 24
t = elapsed time between the calibration reference date and the date of counting. Time un
...