ASTM D5411-93(1999)
(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
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 This standard does not purport to address all of the safety problems, 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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An American National Standard
Designation: D 5411 – 93 (Reapproved 1999)
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 D 5411; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope in the coolant of a nuclear reactor (1). The resultant value is
periodically reported upon, by the operators of nuclear power
1.1 This practice applies to the calculation of the average
plants, in order to ensure that the 2-h radiation dose, measured
¯
energy per disintegration (E) for a mixture of radionuclides in
at the plant boundary, will not exceed an appropriately small
reactor coolant water.
fraction of the Code of Federal Regulations, Title 10, part 100
1.2 This standard does not purport to address all of the
dose guidelines.
safety concerns, if any, associated with its use. It is the
¯
5.2 In calculating E, all the energy dissipated in each
responsibility of the user of this standard to establish appro-
nuclear radioactive transformation is included.This accounting
priate safety and health practices and determine the applica-
includes the energy released in the form of beta particles and
bility of regulatory limitations prior to use.
gamma rays as well as energy released from extra-nuclear
2. Referenced Documents
transitions in the form of X-rays,Auger electrons, and conver-
sion electrons. However, not all radionuclides present in a
2.1 ASTM Standards:
¯
sample are included in the calculation of E.
D 1066 Practice for Sampling Steam
5.3 Individual, nuclear reactor, technical specifications vary
D 1129 Terminology Relating to Water
and each nuclear operator must be aware of limitations
D 3370 Practices for Sampling Water from Closed Con-
affecting their operation. Typically, radio-iodines, radionu-
duits
clides with half lives of less than 10 min (except those in
D 3648 Practices for the Measurement of Radioactivity
equilibrium with the parent), and those radionuclides, identi-
2.2 Code of Federal Regulations:
fied using gamma spectrometry, with less than a 95 % confi-
10 CFR 100 Reactor Cite Criteria
dence level, are not typically included in the calculation.
3. Terminology
However, the operator must account for at least 95 % of the
remaining activity. There are individual bases for each exclu-
3.1 Definitions—For definitions of terms used in this prac-
sion.
tice, refer to Terminology D 1129.
5.3.1 Radio-iodines are typically excluded from the calcu-
¯
4. Summary of Practice
lation of E because many commercial nuclear reactors are
¯
required to operate under a more conservative restriction of 1
4.1 The average energy per disintegration, E (pronounced E
microCurie per gram dose equivalent I-131 in the reactor
bar), for a mixture of radionuclides is calculated from the
¯
coolant.
known composition of the mixture. E is computed by calcu-
5.3.2 Excluding radionuclides with half-lives less than 10
lating the total beta/gamma energy release rate, in MeV, and
¯
min, except those in equilibrium with the parent, has several
dividing it by the total disintegration rate. The resultant E has
bases.
units of MeV per disintegration.
5.3.2.1 The first basis considers the nuclear characteristics
5. Significance and Use
of a typical reactor coolant. The radionuclides in a typical
reactor coolant have half-lives of less than 4 min or have
5.1 This practice is useful for the determination of the
half-lives greater than 14 min.This natural separation provides
average energy per disintegration of the isotopic mixture found
a distinct window for choosing a 10 min half-life cutoff.
5.3.2.2 The second consideration is the predictable time
delay,approximately30min,whichoccursbetweentherelease
This practice is under the jurisdiction ofASTM Committee D-19 on Water and
is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical
of the radioactivity from the reactor coolant to its release to the
Analysis.
environmentandtransporttothesiteboundary.Inthistime,the
Current edition approved May 15, 1993. Published November 1993.
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 11.02.
4 5
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.
D 5411 – 93 (1999)
short lived radionuclides have undergone the decay associated beta/gamma emitters such as cobalt-60, electron capture iso-
with several half-lives and are no longer considered a signifi- topes such as iron-55, and reactor coolant suspended and
¯
cant contributor to E. particulate material (commonly referred to as crud).
5.3.2.3 A final practical basis is the difficulty associated
with identifying short-lived radionuclides in a sample that
10. Calculation
requires some significant time, relative to 10 min, to collect,
¯
10.1 Calculate the average energy per disintegration, E,in
transport, and analyze.
MeV according to the following equation:
5.3.3 Radionuclides identified using less than a 95 % con-
n
fidence level are not typically included in the calculation to
~A * E !
(
i i
n 5 1
improve the accuracy of the calculation (2).
¯
E 5 (1)
n
A
( i
6. Interferences
n 5 1
6.1 There are no true interferences to this practice. How-
where:
¯
ever, errors may result in the calculation of E from incorrectly
¯
E = average energy per disintegration, MeV/
analyzing the sample mixture.
disintegration,
A = activity of the ith radionuclide uniformly measured,
i
7. Sampling
µCi/cc or µCi/g, and
7.1 If samples are collected for analysis in support of this
E = isotopic energy emission for the ith radionuclide,
i
practice they should be representative of the matrix, be of
MeV/disintegration.
sufficient volume to ensure adequate analysis, and be collected
10.2 The values for A are simply the measured activity
i
in accordance with Practices D 1066, D 3370, and D 3648.
levels, uniformly measured in µCi/cc or µCi/g, for each
7.2 In addition to the requirements of 7.1, if samples of
appropriate radionuclide identified in the sample (for example,
reactor coolant are required in support of this practice, they
Co-60, Sr-90, Xe-133, etc.).
should typically be collected only after a minimum of 2
10.3 The values for E are constant for each radionuclide
i
effective full-power days and 20 days of power operation have
and depend upon the decay scheme for that radioisotope. E is
i
elapsed since the reactor was subcritical for 48 h or longer.
calculated from the following equation:
Individual nuclear operator technical specifications vary and
E 5 E ~beta!1 E ~CE! 1 E ~A! 1 E ~gamma!1 E ~X! (2)
should be reviewed to determine specific requirements. i i i i i i
where:
8. Calibration and Standardization
E (beta) = the average, abundance weighted, beta en-
i
8.1 Any calibrations and standardizations required in sup-
ergy per disintegration, MeV/disintegration,
port of this practice should be in accordance with the appli-
E (CE) = the average, abundance weighted, conversion
i
cable sections of Practice D 3648.
electron energy per disintegration, MeV/
disintegration,
9. Procedure
E (A) = the average, abundance weighted, Auger
i
9.1 Conduct all analyses in support of this practice in
electron energy per disintegration, MeV/
accordance with the applicable sections of Practice D 3648.
disintegration,
9.2 Perform sufficient gamma isotopic analyses of the liq-
E(gamma) = the average, abundance weighted, gamma
i
uid, gaseous, and suspended fractions of the sample to ensure
energy per disintegration, MeV/
thatatleast95 %ofthecoolantactivityduetogammaemitting
disintegration, and
isotopes has been quantified. Samples should be analyzed at
E (X) = the average, abundance weighted, X-ray en-
i
approximately 2 h, 24 h, and 7 days following sample
ergy per disintegration, MeV/disintegration.
collection. Multiple sample analyses are required to ensure
10.4 An example for the calculation of E for the disinte-
i
accurate quantification of the longer-lived isotopes because of
gration of xenon-133 (E ) follows.
Xe-133
masking caused by the high initial activity of the sample. If
10.4.1 The decay scheme for Xe-133 (3) is given in Fig. 1.
interferences continue to be a concern with the results of the
10.4.2 First, calculate E (beta).
Xe-133
analysis conducted on Day 7, it may be necessary to conduct
additional gamma isotopic analyses of the sample at approxi-
mately 30 days after collection.
9.3 Perform sufficient isotopic analyses of the liquid, gas-
eous, and suspended fractions of the sample to ensure that at
least 95 % of the coolant activity due to nongamma emitting
isotopes has been quantified.
9.4 Tabulate the concentrations, uniformly measured in
µCi/cc or µCi/g, of all applicable gamma and nongamma
emittingradioisotopesi
...
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