ASTM D5411-10(2015)
(Practice)Standard Practice for Calculation of Average Energy Per Disintegration (¯E) for a Mixture of Radionuclides in Reactor Coolant
Standard Practice for Calculation of Average Energy Per Disintegration (¯E) for a Mixture of Radionuclides in Reactor Coolant
SIGNIFICANCE AND USE
5.1 This practice is useful for the determination of the average energy per disintegration of the isotopic mixture found in the reactor-coolant system of a nuclear reactor (1).4 The E value is used to calculate a site-specific activity limit for the reactor coolant system, generally identified as
where
K = a power reactor site specific constant (usually in the range of 50 to 200). The activity of the reactor coolant system is routinely measured, then compared to the value of Alimiting. If the reactor coolant activity value is less than Alimiting then the 2-h radiation dose, measured at the plant boundary, will not exceed an appropriately small fraction of the Code of Federal Regulations, Title 10, part 100 dose guidelines. It is important to note that the measurement of the reactor coolant system radioactivity is determined at a set frequency by use of gamma spectrometry only. Thus the radionuclides that go into the calculation of E and subsequently Alimiting are only those that are calculated using gamma spectrometry.
5.2 In calculating E, the energy dissipated by beta particles (negatrons and positrons) and photons from nuclear decay of beta-gamma emitters. This accounting includes the energy released in the form of energy released from extra-nuclear transitions in the form of X-rays, Auger electrons, and conversion electrons. However, not all radionuclides present in a sample are included in the calculation of E.
5.3 Individual, nuclear reactor, technical specifications vary and each nuclear operator must be aware of limitations affecting their plant operation. Typically, radioiodines, radionuclides with half lives of less than 10 min (except those in equilibrium with the parent), and those radionuclides, identified using gamma spectrometry, with less than a 95 % confidence level, are not typically included in the calculation. However, the technical requirements are that the reported activity must account for at least 95 % of the activity af...
SCOPE
1.1 This practice applies to the calculation of the average energy per disintegration (E) for a mixture of radionuclides in reactor coolant water.
1.2 The microcurie (µCi) is the standard unit of measurement for this standard. The values given in parentheses are mathematical conversions to SI units, which are provided for information only and are not considered standard.
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.
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Designation: D5411 − 10 (Reapproved 2015)
Standard Practice for
¯
Calculation of Average Energy Per Disintegration (E) for a
Mixture of Radionuclides in Reactor Coolant
This standard is issued under the fixed designation D5411; 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 3. Terminology
1.1 This practice applies to the calculation of the average 3.1 Definitions—For definitions of terms used in this
¯
practice, refer to Terminology D1129.
energy per disintegration (E) for a mixture of radionuclides in
reactor coolant water.
4. Summary of Practice
1.2 The microcurie (µCi) is the standard unit of measure-
¯
4.1 The average energy per disintegration, E (pronounced E
ment for this standard. The values given in parentheses are
bar), for a mixture of radionuclides is calculated from the
mathematical conversions to SI units, which are provided for
¯
information only and are not considered standard. known composition of the mixture. E is computed by calcu-
lating the total beta/gamma energy release rate, in MeV, and
1.3 This standard does not purport to address all of the
¯
dividing it by the total disintegration rate. The resultant E has
safety concerns, if any, associated with its use. It is the
units of MeV per disintegration.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
5. Significance and Use
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor- 5.1 This practice is useful for the determination of the
dance with internationally recognized principles on standard- average energy per disintegration of the isotopic mixture found
¯
ization established in the Decision on Principles for the
in the reactor-coolant system of a nuclear reactor (1). The E
Development of International Standards, Guides and Recom-
value is used to calculate a site-specific activity limit for the
mendations issued by the World Trade Organization Technical
reactor coolant system, generally identified as
Barriers to Trade (TBT) Committee.
¯
A 5 K/E
limiting
where
2. Referenced Documents
2.1 ASTM Standards:
K = a power reactor site specific constant (usually in the
D1066 Practice for Sampling Steam
range of 50 to 200).
D1129 Terminology Relating to Water
The activity of the reactor coolant system is routinely
D3370 Practices for Sampling Water from Closed Conduits
measured, then compared to the value ofA . If the reactor
limiting
D3648 Practices for the Measurement of Radioactivity
coolantactivityvalueislessthanA thenthe2-hradiation
limiting
D7282 Practice for Set-up, Calibration, and Quality Control
dose, measured at the plant boundary, will not exceed an
of Instruments Used for Radioactivity Measurements
appropriately small fraction of the Code of Federal
2.2 Code of Federal Regulations:
Regulations, Title 10, part 100 dose guidelines. It is important
10 CFR 100 Reactor Site Criteria
to note that the measurement of the reactor coolant system
radioactivity is determined at a set frequency by use of gamma
spectrometry only. Thus the radionuclides that go into the
This practice is under the jurisdiction ofASTM Committee D19 on Water and
¯
calculation of E and subsequently A are only those that
limiting
is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical
are calculated using gamma spectrometry.
Analysis.
Current edition approved Dec. 15, 2015. Published December 2015. Originally
¯
5.2 In calculating E, the energy dissipated by beta particles
approved in 1993. Last previous edition approved in 2010 as D5411 – 10. DOI:
10.1520/D5411-10R15. (negatrons and positrons) and photons from nuclear decay of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
beta-gamma emitters. This accounting includes the energy
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700 The boldface numbers in parentheses refer to a list of references at the end of
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5411 − 10 (2015)
¯
released in the form of energy released from extra-nuclear
defect that would alter the E value and affectA . The two
limiting
¯
transitions in the form of X-rays,Auger electrons, and conver-
possible causes to reassess the value of E would be:
sion electrons. However, not all radionuclides present in a
(1) A significant fuel defect has occurred where the noble
¯
sample are included in the calculation of E.
gas activity has increased.
(2) A significant corrosion product increase has occurred.
5.3 Individual, nuclear reactor, technical specifications vary
and each nuclear operator must be aware of limitations For the case of a fuel defect, the plant staff may need to
include new radionuclides not normally used in the calculation
affecting their plant operation. Typically, radioiodines, radio-
239 239
¯
nuclides with half lives of less than 10 min (except those in
of E such as U and Np.
equilibrium with the parent), and those radionuclides, identi-
6. Interferences
fied using gamma spectrometry, with less than a 95 % confi-
dence level, are not typically included in the calculation.
6.1 The analytical determination of the radionuclides used
However, the technical requirements are that the reported
for this calculation is made by gamma ray spectrometry.
activity must account for at least 95 % of the activity after
Commercially available software is generally used to perform
excludingradioiodinesandshort-livedradionuclides.Thereare
the spectrum analysis and data reduction. However there can
individual bases for each exclusion.
be significant number of interferences from gamma ray emit-
5.3.1 Radioiodines are typically excluded from the calcula-
ters with multiple gamma ray emissions. The user must
¯
tion of E because United States commercial nuclear reactors
carefully select the appropriate interference free gamma ray
are required to operate under a more conservative restriction of energy for each radionuclide in order to determine accurately
131 56
1 µC (37 kBq) per gram dose equivalent I (DEI) in the
the activity of each radionuclide. As a specific example Mn
1 1
reactor coolant. (t ⁄2 = 2.6 h) has a gamma ray energy of 847 keV and I(t ⁄2
90 = 53 min) also has a gamma ray energy of 847 keV. The 847
5.3.2 Beta only emitting radio isotopes (for example, Sr
63 241 keV gamma ray is also the most abundant for each of these
or Ni) and alpha emitting radioisotopes (for example, Am
239 radionulcides. It would be inaccurate to use the 847 keV
or Pu) which comprise a small fraction of the activity,
gamma ray for the determination of either of these radionu-
should not be included in the E-bar calculation. These isotopes
clides.
are not routinely analyzed for in the reactor coolant, and thus
their inclusion in the E-bar calculation is not representative of
7. Sampling
whatisusedtoassessthe10CFR100doselimits.Tritium,also
7.1 If samples are collected for analysis in support of this
a beta only emitter, should not be included in the calculation.
practice they should be representative of the matrix, be of
Tritium has the largest activity concentration in the reactor
sufficient volume to ensure adequate analysis, and be collected
coolant system, but the lowest beta particle energy. Thus its
in accordance with Practices D1066, D3370, and D3648.
dose contribution is always negligible. However its inclusion
in the E-bar calculation would raise the value of A ,
7.2 In addition to the requirements of 7.1, if samples of
limiting
yielding a non-conservative value for dose assessment.
reactor coolant are required in support of this practice, they
5.3.3 Excluding radionuclides with half-lives less than 10
should typically be collected only after a minimum of 2
min, except those in equilibrium with the parent, has several
effective full-power days and 20 days of power operation have
bases. elapsed since the reactor was last subcritical for 48 h or longer.
5.3.3.1 The first basis considers the nuclear characteristics Individual nuclear operator technical specifications (or now for
many plants called “technical requirements”) vary and should
of a typical reactor coolant. The radionuclides in a typical
reactor coolant have half-lives of less than 4 min or have be reviewed to determine specific requirements.
half-lives greater than 14 min.This natural separation provides
8. Calibration and Standardization
a distinct window for choosing a 10-min half-life cutoff.
5.3.3.2 The second consideration is the predictable time
8.1 Any calibrations and standardizations required in sup-
delay,approximately30min,whichoccursbetweentherelease
port of this practice should be in accordance with the appli-
of the radioactivity from the reactor coolant to its release to the
cable sections of Practices D3648 and D7282 and in accor-
environmentandtransporttothesiteboundary.Inthistime,the
dance with the manufacturer’s specifications for the gamma
short-lived radionuclides have undergone the decay associated
spectrometry system used.
with several half-lives and are no longer considered a signifi-
¯
9. Procedure
cant contributor to E.
9.1 Conduct all analyses in support of this practice in
5.3.3.3 A final practical basis is the difficulty associated
accordance with the applicable sections of Practice D3648.
with identifying short-lived radionuclides in a sample that
requires some significant time, relative to 10 min, to collect,
9.2 Perform sufficient gamma isotopic analyses of the
transport, and analyze.
liquid, gaseous, and suspended fractions of the sample to
5.3.4 The value of E-bar is usually calculated once every 6 ensure that at least 95 % of the coolant activity due to gamma
months. However, anytime a significant increase in the activity emitting isotopes has been quantified. Samples should be
of the reactor coolant occurs, the value of E-bar should be analyzed at approximately 0.5 h, 2 h, 24 h, and 7 days
reassessed to ensure compliance with 10 CFR 100. Such following sample collection. Multiple sample analyses are
reassessmentshouldbedoneanytimethereisasignificantfuel required to ensure accurate quantification of the longer-lived
D5411 − 10 (2015)
isotopes because of masking caused by the high initial activity
E (CE) = theaverage,abundanceweighted,conversion
i
of short-lived radionuclides in the sample. If interferences
electron energy per disintegration, MeV/
continue to be a concern with the results of the analysis
disintegration,
conducted on Day 7, it may be necessary to conduct additional
E (A) = the average, abundance weighted, Auger
i
gamma isotopic analyses of the sample at approximately 30 electron energy per disintegration, MeV/
days after collection.
disintegration,
E (gamma) = the average, abundance weighted, gamma
i
9.3 Sample fractions that are going to be stored for recount-
energy per disintegration, MeV/
ing (at 24 h, 7 days, or 30 days) should be preserved with at
disintegration, and
least 2 mL of concentrated nitric acid per litre of sample
E (X) = the average, abundance weighted, X-ray en-
i
immediately after the sample is taken to preserve the sample
ergy per disintegration, MeV/disintegration.
geometry. This mitigates the precipitation of radionuclides or
10.4 An example for the calculation of E for the disinte-
i
adhesion of radionuclides onto container walls.
gration of Xe (E ) follows.
Xe-133
9.4 Tabulate the concentrations, uniformly measured in
10.4.1 The decay scheme for Xe (2) is given in Fig. 1.
µCi/cc(37kBq/cc)orµCi/g(37kBq/g),ofallapplicablegamma
10.4.2 First, calculate E (beta).
Xe-133
radioisotopes identified in the sample. Examples of the most
10.4.2.1 To determine each E (beta), multiply the average
i
¯
significant contributing radioisotopes to E are:
energy per disintegration for each beta emitted by its abun-
131m 131 133m
(1) Noble gas fission products: Xe, Xe, Xe,
danceandsumtheproducts.Theaveragebetaenergiesforeach
133 87
Xe, Kr (others),
isotope may be found in the literature (2, 3). Or, it may be
137 134 141
(2) Soluble fission products: Cs, Cs, Ce, approximated by multiplying the maximum beta particle en-
140 140 92
Ba, La, Sr (others),
ergypertransformationbyafactorofone-third.Onlyone-third
58 56 54
(3) Corrosion activation products: Co, Mn, Mn, of the maximum beta energy is included in the calculation
60 51 59 95 95
Co, Cr, Fe, Zr, Nb (others),
because the remaining two-thirds of the radionuclide decay
41 24 18 7
(4) Miscellaneous radionuclides: Ar, Na, F, Be energy is dissipated by neutrino emission (4). Neutrinos are
(others), and very high energy, chargeless particles that do not undergo
(5) Reactor coolant suspended and particulate material interaction with matter like the human body. Therefore, their
(commonly referred to as crud) will also have the activated contribution is ignored when considering the total energy
products in them and must be included in the calculation available for absorption by a person at the site boundary of the
¯
nuclear facility.
of E.
10.4.2.2 The average energies and abundances of the major
beta emissions for the decay of Xe are (2):
10. Calculation
beta # Average Energy Abundance
¯
10.1 Calculate the average energy per disintegration, E,in
2 0.0751 MeV 0.69 %
MeV according to the following equation: 3 0.101 MeV 99.3 %
n 10.4.2.3 Therefore, E (beta) is:
Xe-133
A *E
~ !
( i i
E (beta) = (beta #2 average energy) * (beta 2 abundance) + (beta
Xe-133
i51
¯
E 5 (1) #3 average energy) * (beta 3 abundance)
n
E (beta) = 0.0751 * 0.0069 + 0.101 * 0.993,
Xe-133
A
i
(
E (beta) = 0.101 MeV/disintegration.
i51 Xe-133
10.4.3 Next, calculate E (CE).
i
where:
10.4.3.1 Unlike beta particle emissions, conversion elec-
¯
= average energy per disintegration, MeV/disintegration,
E
tronsaremonoenergeticemissionsandarenotaccompaniedby
A = activity of the ith radionuclide uniformly measured,
i
neutrino emission. Therefore, their contributions to E (beta) is
i
µCi/cc or µCi/g, and
includedattheirfullemissionenergyminusthebindingenergy
E = isotopic energy emission for the ith radionuclide, MeV/
i
of the emitted electron. Here again the abundance for each
disintegration.
transformation is an include
...
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: D5411 − 10 D5411 − 10 (Reapproved 2015)
Standard Practice for
Calculation of Average Energy Per Disintegration (E¯) for a
Mixture of Radionuclides in Reactor Coolant
This standard is issued under the fixed designation D5411; 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 applies to the calculation of the average energy per disintegration (E¯) for a mixture of radionuclides in reactor
coolant water.
1.2 The microcurie (μCi) is the standard unit of measurement for this standard. The values given in parentheses are
mathematical conversions to SI units, which are provided for information only and are not considered standard.
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.
2. Referenced Documents
2.1 ASTM Standards:
D1066 Practice for Sampling Steam
D1129 Terminology Relating to Water
D3370 Practices for Sampling Water from Closed Conduits
D3648 Practices for the Measurement of Radioactivity
D7282 Practice for Set-up, Calibration, and Quality Control of Instruments Used for Radioactivity Measurements
2.2 Code of Federal Regulations:
10 CFR 100 Reactor Site Criteria
3. Terminology
3.1 Definitions—For definitions of terms used in this practice, refer to Terminology D1129.
4. Summary of Practice
4.1 The average energy per disintegration, E¯ (pronounced E bar), for a mixture of radionuclides is calculated from the known
composition of the mixture. E¯ is computed by calculating the total beta/gamma energy release rate, in MeV, and dividing it by
the total disintegration rate. The resultant E¯ has units of MeV per disintegration.
5. Significance and Use
5.1 This practice is useful for the determination of the average energy per disintegration of the isotopic mixture found in the
reactor-coolant system of a nuclear reactor (1). The E¯ value is used to calculate a site-specific activity limit for the reactor coolant
system, generally identified as
¯
A 5 K/E
limiting
where
K = a power reactor site specific constant (usually in the range of 50 to 200).
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 June 1, 2010Dec. 15, 2015. Published December 2010December 2015. Originally approved in 1993. Last previous edition approved in 20052010
as D5411 – 05.D5411 – 10. DOI: 10.1520/D5411-10.10.1520/D5411-10R15.
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’s Document Summary page on the ASTM website.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
The boldface numbers in parentheses refer to a list of references at the end of this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5411 − 10 (2015)
The activity of the reactor coolant system is routinely measured, then compared to the value of A . If the reactor coolant
limiting
activity value is less than A then the 2-h radiation dose, measured at the plant boundary, will not exceed an appropriately
limiting
small fraction of the Code of Federal Regulations, Title 10, part 100 dose guidelines. It is important to note that the measurement
of the reactor coolant system radioactivity is determined at a set frequency by use of gamma spectrometry only. Thus the
radionuclides that go into the calculation of E¯ and subsequently A are only those that are calculated using gamma
limiting
spectrometry.
5.2 In calculating E¯, the energy dissipated by beta particles (negatrons and positrons) and photons from nuclear decay of
beta-gamma emitters. This accounting includes the energy released in the form of energy released from extra-nuclear transitions
in the form of X-rays, Auger electrons, and conversion electrons. However, not all radionuclides present in a sample are included
in the calculation of E¯.
5.3 Individual, nuclear reactor, technical specifications vary and each nuclear operator must be aware of limitations affecting
their plant operation. Typically, radioiodines, radionuclides with half lives of less than 10 min (except those in equilibrium with
the parent), and those radionuclides, identified using gamma spectrometry, with less than a 95 % confidence level, are not typically
included in the calculation. However, the technical requirements are that the reported activity must account for at least 95 % of
the activity after excluding radioiodines and short-lived radionuclides. There are individual bases for each exclusion.
5.3.1 Radioiodines are typically excluded from the calculation of E¯ because United States commercial nuclear reactors are
required to operate under a more conservative restriction of 1 μC (37 kBq) per gram dose equivalent I (DEI) in the reactor
coolant.
90 63 241
5.3.2 Beta only emitting radio isotopes (for example, Sr or Ni) and alpha emitting radioisotopes (for example, Am
or Pu) which comprise a small fraction of the activity, should not be included in the E-bar calculation. These isotopes are not
routinely analyzed for in the reactor coolant, and thus their inclusion in the E-bar calculation is not representative of what is used
to assess the 10 CFR 100 dose limits. Tritium, also a beta only emitter, should not be included in the calculation. Tritium has the
largest activity concentration in the reactor coolant system, but the lowest beta particle energy. Thus its dose contribution is always
negligible. However its inclusion in the E-bar calculation would raise the value of A , yielding a non-conservative value for
limiting
dose assessment.
5.3.3 Excluding radionuclides with half-lives less than 10 min, except those in equilibrium with the parent, has several bases.
5.3.3.1 The first basis considers the nuclear characteristics of a typical reactor coolant. The radionuclides in a typical reactor
coolant have half-lives of less than 4 min or have half-lives greater than 14 min. This natural separation provides a distinct window
for choosing a 10-min half-life cutoff.
5.3.3.2 The second consideration is the predictable time delay, approximately 30 min, which occurs between the release of the
radioactivity from the reactor coolant to its release to the environment and transport to the site boundary. In this time, the
short-lived radionuclides have undergone the decay associated with several half-lives and are no longer considered a significant
contributor to E¯.
5.3.3.3 A final practical basis is the difficulty associated with identifying short-lived radionuclides in a sample that requires some
significant time, relative to 10 min, to collect, transport, and analyze.
5.3.4 The value of E-bar is usually calculated once every 6 months. However, anytime a significant increase in the activity of
the reactor coolant occurs, the value of E-bar should be reassessed to ensure compliance with 10 CFR 100. Such reassessment
should be done any time there is a significant fuel defect that would alter the E¯ value and affect A . The two possible causes
limiting
to reassess the value of E¯ would be:
(1) A significant fuel defect has occurred where the noble gas activity has increased.
(2) A significant corrosion product increase has occurred.
¯
For the case of a fuel defect, the plant staff may need to include new radionuclides not normally used in the calculation of E such
239 239
as U and Np.
6. Interferences
6.1 The analytical determination of the radionuclides used for this calculation is made by gamma ray spectrometry.
Commercially available software is generally used to perform the spectrum analysis and data reduction. However there can be
significant number of interferences from gamma ray emitters with multiple gamma ray emissions. The user must carefully select
the appropriate interference free gamma ray energy for each radionuclide in order to determine accurately the activity of each
56 134
1 1
radionuclide. As a specific example Mn (t ⁄2 = 2.6 h) has a gamma ray energy of 847 keV and I (t ⁄2 = 53 min) also has a gamma
ray energy of 847 keV. The 847 keV gamma ray is also the most abundant for each of these radionulcides. It would be inaccurate
to use the 847 keV gamma ray for the determination of either of these radionuclides.
7. Sampling
7.1 If samples are collected for analysis in support of this practice they should be representative of the matrix, be of sufficient
volume to ensure adequate analysis, and be collected in accordance with Practices D1066, D3370, and D3648.
D5411 − 10 (2015)
7.2 In addition to the requirements of 7.1, if samples of reactor coolant are required in support of this practice, they should
typically be collected only after a minimum of 2 effective full-power days and 20 days of power operation have elapsed since the
reactor was last subcritical for 48 h or longer. Individual nuclear operator technical specifications (or now for many plants called
“technical requirements”) vary and should be reviewed to determine specific requirements.
8. Calibration and Standardization
8.1 Any calibrations and standardizations required in support of this practice should be in accordance with the applicable
sections of Practices D3648 and D7282 and in accordance with the manufacturer’s specifications for the gamma spectrometry
system used.
9. Procedure
9.1 Conduct all analyses in support of this practice in accordance with the applicable sections of Practice D3648.
9.2 Perform sufficient gamma isotopic analyses of the liquid, gaseous, and suspended fractions of the sample to ensure that at
least 95 % of the coolant activity due to gamma emitting isotopes has been quantified. Samples should be analyzed at
approximately 0.5 h, 2 h, 24 h, and 7 days following sample collection. Multiple sample analyses are required to ensure accurate
quantification of the longer-lived isotopes because of masking caused by the high initial activity of short-lived radionuclides in the
sample. If interferences continue to be a concern with the results of the analysis conducted on Day 7, it may be necessary to conduct
additional gamma isotopic analyses of the sample at approximately 30 days after collection.
9.3 Sample fractions that are going to be stored for recounting (at 24 h, 7 days, or 30 days) should be preserved with at least
2 mL of concentrated nitric acid per litre of sample immediately after the sample is taken to preserve the sample geometry. This
mitigates the precipitation of radionuclides or adhesion of radionuclides onto container walls.
9.4 Tabulate the concentrations, uniformly measured in μCi/cc (37kBq/cc) or μCi/g (37kBq/g), of all applicable gamma
radioisotopes identified in the sample. Examples of the most significant contributing radioisotopes to E¯ are:
131m 131 133m
(1) Noble gas fission products: Xe, Xe, Xe,
133 87
Xe, Kr (others),
137 134 141
(2) Soluble fission products: Cs, Cs, Ce,
140 140 92
Ba, La, Sr (others),
58 56 54
(3) Corrosion activation products: Co, Mn, Mn,
60 51 59 95 95
Co, Cr, Fe, Zr, Nb (others),
41 24 18 7
(4) Miscellaneous radionuclides: Ar, Na, F, Be (others), and
(5) Reactor coolant suspended and particulate material (commonly referred to as crud) will also have the activated products
in them and must be included in the calculation
of E¯.
10. Calculation
10.1 Calculate the average energy per disintegration, E¯, in MeV according to the following equation:
n
A *E
~ !
( i i
i51
¯
E 5 (1)
n
A
( i
i51
where:
¯
= average energy per disintegration, MeV/disintegration,
E
A = activity of the ith radionuclide uniformly measured, μCi/cc or μCi/g, and
i
E = isotopic energy emission for the ith radionuclide, MeV/disintegration.
i
10.2 The values for A are the measured activity levels of a representative sample in μCi/cc (37 kBq/cc) or μCi/g (37 kBq/g),
I
60 133 137
for each appropriate radionuclide identified in the sample (for example, Co, Xe, Cs, etc.).
10.3 The values for E are constant for each radionuclide and depend upon the decay scheme for that radioisotope. E is
i i
calculated from the following equation:
beta 1E CE 1E A 1E gamma 1E X (2)
E 5 E ~ ! ~ ! ~ ! ~ ! ~ !
i i i i i i
where:
E (beta) = the average, abundance weighted, beta energy per disintegration, MeV/disintegration,
i
E (CE) = the average, abundance weighted, conversion electron energy per disintegration, MeV/disintegration,
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E (A) = the average, abundance weighted, Auger electron energy per disintegration, MeV/disintegration,
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E (gamma) = the average, abundance weighted, gamma energy per disintegration, MeV/disintegration, and
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D5411 − 10 (2015)
E (X) = the average, abundance weighted, X-ray energy per disintegration, MeV/disintegration.
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10.4 An example for the calculation of E for the disintegration of Xe (E ) follows.
i Xe-133
10.4.1 The decay scheme for Xe (2) is given in Fig. 1.
10.4.2 First, calculate E (beta).
Xe-133
10.4.2.1 To determine each E (beta), multiply the average energy per disintegration for each beta emitted by its abundance and
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sum the products. The average beta energies for each isotope may be found in the literature (2, 3). Or, it may be approximated by
multiplying the maximum beta particle energy per transformation by a factor of one-third. Only one-third of the maximum beta
energy is included in the calculation because the remaining two-thirds of the radionuclide decay energy is dissipated by neutrino
emission (4). Neutrinos are very high energy, chargeless particles that do not undergo interaction with matter like the human body.
Therefore, their contribution is ignored when considering the total energy available for absorption by a person at the site boundary
of the nuclear facility.
10.4.2.2 The average energies and abundances of the major beta emissions for the d
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