SIST EN 17462:2021
(Main)Animal feeding stuffs: Methods of sampling and analysis - Determination of the radionuclides Iodine-131, Caesium-134 and Caesium-137 in feed
Animal feeding stuffs: Methods of sampling and analysis - Determination of the radionuclides Iodine-131, Caesium-134 and Caesium-137 in feed
This standard describes a method of Iodium-131, Caesium-134 and Caesium-137 massic activity (Bq/kg) determination in animal feed.
Today, the most commonly used method for identification and quantification of radioactivity from these radionuclides in feed samples is high-resolution gamma-ray spectrometry. It is based on analysis of full-energy peaks (FEP) of the emitted gamma rays. Therefore, care should be taken to use appropriate energy and efficiency calibrations for each detector and test portion used.
In this standard, general guidance on the preparation of feed samples is provided together with specific information on high resolution gamma-ray spectrometry of the three radionuclides Iodium-131, Caesium-134 and Caesium-137. More information on these and related topics can be found in specific standards referred to in this document. For example, generic advice on the equipment selection, detectors and quality assurance for gamma-ray spectrometry can be found in ISO 20042:2016. The current standard aims to be complementary to existing standards, as an aid to laboratory practitioners that are faced with a situation, which requires response to the current topic without having to go through and interpret standards with general descriptions of gamma-ray spectrometry in order to measure in a standardised way. This standard contains information specific to the three radionuclides that it covers. Examples are provided in Annex …(to be added).
Futtermittel: Probenahme- und Untersuchungsverfahren - Bestimmung der Radionuklide Jod-131, Cäsium-134 und Cäsium-137 in Futtermittel
Dieses Dokument beschreibt ein Verfahren zur Bestimmung der massenbezogenen Aktivität (Bq/kg) von 131I, 134Cs und 137Cs in Futtermitteln in Überwachungslaboren.
Es werden allgemeine Leitlinien zur Herstellung von Futtermittelproben und zur Messung der drei Radionuklide 131I, 134Cs und 137Cs mittels hochauflösender Gammaspektrometrie dargelegt. Zweck des vorliegenden Dokuments ist die Ergänzung von bereits vorhandenen Normen. Weiterführende Informationen zur Probenvorbereitung, Bestimmung des Feuchtegehalts und Gammaspektrometrie können den spezifischen Normen, auf die in diesem Dokument verwiesen wird, entnommen werden. Beispielsweise enthält ISO 20042 allgemeine Empfehlungen zur Auswahl von Geräten, zu Detektoren und zur Qualitätssicherung bei der Gammaspektrometrie.
Das Verfahren wurde in einem Ringversuch mit fünf Futtermittelproben für die Radionuklide 131I, 134Cs und 137Cs umfassend statistisch geprüft und evaluiert. Details zu den erfolgreich geprüften Arbeitsbereichen für jedes der untersuchten Radionuklide sind in Anhang C beschrieben.
Aliments des animaux : Méthodes d’échantillonnage et d’analyse - Détermination des radionucléides iode 131, césium 134 et césium 137 dans les matières premières et aliments composés pour animaux
Le présent document décrit une méthode de détermination de l’activité massique (Bq/kg) de l’131I, du 134Cs et du 137Cs dans les aliments composés pour animaux dans des laboratoires de surveillance.
Des recommandations générales relatives à la préparation d’échantillons d’aliments composés pour animaux et au mesurage des trois radionucléides 131I, 134Cs et 137Cs par spectrométrie gamma haute résolution sont fournies. Le présent document a pour vocation de compléter des normes existantes. De plus amples informations sur la préparation des échantillons, la détermination de la teneur en eau et la spectrométrie gamma sont proposées dans les normes spécifiques mentionnées dans le présent document. Par exemple, l’ISO 20042 fournit des conseils généraux relatifs à la sélection de l’équipement, aux détecteurs et à l’assurance qualité pour la spectrométrie gamma.
La méthode a fait l’objet d’une évaluation et de tests statistiques complets dans le cadre d’un essai interlaboratoires impliquant cinq échantillons d’aliments pour animaux pour les radionucléides 131I, 134Cs et 137Cs. Les détails concernant le domaine de mesure soumis à essai et validé pour chacun des radionucléides examinés sont présentés dans l’Annexe C.
Krma: metode vzorčenja in analize - Določevanje radionuklidnega joda-131, cezija-134 in cezija-137 v krmi
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 17462:2021
01-julij-2021
Krma: metode vzorčenja in analize - Določevanje radionuklidnega joda-131, cezija-
134 in cezija-137 v krmi
Animal feeding stuffs: Methods of sampling and analysis - Determination of the
radionuclides Iodine-131, Caesium-134 and Caesium-137 in feed
Futtermittel: Probenahme- und Untersuchungsverfahren - Bestimmung der Radionuklide
Jod-131, Cäsium-134 und Cäsium-137 in Futtermittel
Aliments des animaux : Méthodes d’échantillonnage et d’analyse - Détermination des
radionucléides iode 131, césium 134 et césium 137 dans les matières premières et
aliments composés pour animaux
Ta slovenski standard je istoveten z: EN 17462:2021
ICS:
65.120 Krmila Animal feeding stuffs
SIST EN 17462:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN 17462:2021
---------------------- Page: 2 ----------------------
SIST EN 17462:2021
EN 17462
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2021
EUROPÄISCHE NORM
ICS 65.120
English Version
Animal feeding stuffs: Methods of sampling and analysis -
Determination of the radionuclides Iodine-131, Caesium-
134 and Caesium-137 in feed
Aliments des animaux : Méthodes d'échantillonnage et Futtermittel: Probenahme- und
d'analyse - Détermination des radionucléides iode 131, Untersuchungsverfahren - Bestimmung der
césium 134 et césium 137 dans les matières premières Radionuklide Jod-131, Cäsium-134 und Cäsium-137 in
et aliments composés pour animaux Futtermittel
This European Standard was approved by CEN on 22 February 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17462:2021 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Symbols and abbreviations . 8
4.1 Symbols . 8
4.2 Abbreviations . 10
5 Principle . 11
6 Safety precautions . 11
7 Apparatus . 11
7.1 General . 11
7.2 Equipment for test portion preparation . 11
7.3 Containers to be used . 12
8 Procedure. 12
8.1 Calibration . 12
8.2 Test portion preparation . 15
8.3 Spectrum recording . 16
8.4 Spectrum analysis . 16
8.5 Quality assurance . 17
9 Expression of results . 18
9.1 Massic activity calculation . 18
9.2 Characteristic limits . 23
9.3 Precision . 24
9.4 Test report . 25
Annex A (informative) List of possible interfering gamma rays . 26
Annex B (informative) Example of uncertainty budget in gamma-ray spectrometry using an
HPGe detector . 27
Annex C (informative) Results of the collaborative trial . 28
Bibliography . 33
2
---------------------- Page: 4 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
European foreword
This document (EN 17462:2021) has been prepared by Technical Committee CEN/TC 327 “Animal
feeding stuffs - Methods of sampling and analysis”, the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2021, and conflicting national standards shall
be withdrawn at the latest by October 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request given to CEN by the European
Commission and the European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
3
---------------------- Page: 5 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
Introduction
131 134 137
This document describes a method for I, Cs and Cs massic activity determination (Bq/kg) in
animal feeding stuffs. It was initiated by Directorate General for Health and Food Safety (DG SANTE) of
the European Commission following the accident in the Fukushima Daiichi nuclear power plant in
March 2011. The event highlighted the need for standardized measurements of the three most common
radioactive contaminants following such type of nuclear accident.
The most commonly used method for identification and quantification of these radionuclides in animal
feeding stuffs samples is high-resolution gamma-ray spectrometry. As this is a secondary measurement
method based on analysis of photopeaks of the emitted gamma rays, care should be taken to use
appropriate energy and efficiency calibrations for the detector and test portion used. This method of
massic activity determination is described in the present document.
4
---------------------- Page: 6 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
1 Scope
131 134
This document describes a method for determination of the massic activity (Bq/kg) of I, Cs and
137
Cs in animal feeding stuffs in monitoring laboratories.
General guidance on the preparation of feed samples and the measurement of the three radionuclides
131 134 137
I, Cs and Cs by high resolution gamma-ray spectrometry is provided. The current document aims
to be complementary to existing standards. More information on sample preparation, moisture content
determination and gamma-ray spectrometry can be found in specific standards referred to in this
document. For example, generic advice on the equipment selection, detectors and quality assurance for
gamma-ray spectrometry can be found in ISO 20042 [4].
The method was fully statistically tested and evaluated in a collaborative trial comprising five animal
131 134 137
feeding stuff samples for the radionuclides I, Cs and Cs. Details on the successfully tested
working range for each of the examined radionuclides are described in Annex C.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the cited edition applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 662, Animal and vegetable fats and oils — Determination of moisture and volatile matter content
(ISO 662)
EN ISO 665, Oilseeds — Determination of moisture and volatile matter content (ISO 665)
EN ISO 712, Cereals and cereal products — Determination of moisture content — Reference method
(ISO 712)
EN ISO 6497, Animal feeding stuffs — Sampling (ISO 6497)
EN ISO 6540, Maize — Determination of moisture content (on milled grains and on whole grains)
(ISO 6540)
EN ISO 11929-1:2019, Determination of the characteristic limits (decision threshold, detection limit and
limits of the coverage interval) for measurements of ionizing radiation — Fundamentals and application
— Part 1: Elementary applications (ISO 11929-1)
ISO 771, Oilseed residues – Determination of moisture and volatile matter content
ISO 6496, Animal feeding stuffs — Determination of moisture and other volatile matter content
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 6497 and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
5
---------------------- Page: 7 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
3.1
background
spectrum recorded by the gamma-ray detector when no sample is measured
Note 1 to entry: The spectral data, including full energy peaks, in such a spectrum is resulting from radioactive
decay occurring in the environment surrounding the detector (including the cosmic ray interactions) or in the
detector.
3.2
background continuum
events in the spectrum that form a smooth curve onto which the photopeaks are superimposed
Note 1 to entry: The continuum may arise from gamma-rays scattered inside the test sample or any surrounding
materials, from cosmic radiation or from radionuclides in the surrounding materials.
[SOURCE: ISO 20042:2019, 3.1 [4]]
3.3
blank sample
sample, liquid or solid, with very low to no activity for radiation of the same type and region of interest,
with a mass and a composition as close as possible to those of the test sample
[SOURCE: EN ISO 19581:2020, 3.1 [1]]
3.4
dead time
time during spectrum acquisition (real time) during which pulses are not recorded or processed
Note 1 to entry: Dead time is given by real time minus live time.
Note 2 to entry: The time is given in seconds.
[SOURCE: ISO 20042:2019, 3.5 [4]]
3.5
efficiency transfer
detection efficiency transfer
calculation that enables the user to establish the value of the detection efficiency for a given gamma-ray
peak in the spectrum of the test portion, when only the detection efficiency from an experimental
calibration with a reference source that may have a different composition, density and/or geometry
compared to the test portion is known
3.6
high resolution gamma-ray spectrometry
energy resolution obtained with a Ge(Li) or an HPGe detector
Note 1 to entry: This definition is specific to gamma-ray spectrometry.
3.7
laboratory sample
sample as prepared (from the lot) for sending to the laboratory and intended for inspection or testing
[SOURCE: EN ISO 6498:2012, 2.1.2 [2]]
6
---------------------- Page: 8 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
3.8
live time
time during which pulses are processed during an acquisition (real) time
Note 1 to entry: The time is given in seconds.
[SOURCE: ISO 20042:2019, 3.12 [4]]
3.9
photopeak
full energy peak (FEP)
peak observed above the background continuum in a gamma-ray spectrum due to events that deposit
the full energy of the photon in the detector material, usually approximately Gaussian in shape
[SOURCE: ISO 20042:2019, 3.17 [4]]
3.10
real time
time taken to acquire a spectrum
Note 1 to entry: The time is given in seconds.
[SOURCE: ISO 20042:2019, 3.19 [4]]
3.11
sample holder
device that is specially designed to enable the placement of a given sample container in a well-defined
position on top of a specific detector
3.12
spectrometry system
complete assembly of the sensor and associated pulse-processing electronics that converts the gamma-
rays detected by the sensor into a pulse-height spectrum
[SOURCE: ISO 20042:2019, 3.22 [4]]
3.13
test portion
quantity of material drawn from the test sample (or from the laboratory sample if both are the same)
[SOURCE: EN ISO 6498:2012, 2.1.4 [2]]
3.14
test sample
subsample or sample prepared from the laboratory sample and from which test portions will be taken
[SOURCE: EN ISO 6498:2012, 2.1.3 [2]]
7
---------------------- Page: 9 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
3.15
true coincidence summing
TCS
coincidence summing
cascade-summing
simultaneous detection of two or more gamma-rays in the spectrometry system, due to the emission of
a cascade of gamma-rays in the decay of a single nucleus in the test sample
[SOURCE: ISO 20042:2019, 3.24 [4]]
4 Symbols and abbreviations
4.1 Symbols
For the purposes of this document, the following symbols apply:
Symbol Name of quantity Unit
A activity of a reference radionuclide emitting photons of energy E in the calibration Bq
source, at the time of calibration
a annum (year), the tropical year which is approximately equal to 365,2422 d year
a massic activity at energy E of a radionuclide in the sample Bq/kg
m
134
a ; massic activity of Cs obtained using the gamma-ray of energy i, which is either Bq/kg
m,605
a 604,72 keV or 795,86 keV
m,796
134
'
massic activity of Cs based on the weighted mean calculation including the two Bq/kg
a
m
major gamma rays of this radionuclide
*
decision threshold Bq/kg
a
m
#
detection limit Bq/kg
a
m
true value of massic activity at energy E of a radionuclide in the sample Bq/kg
a
d day (1 day = 86 400 s) day
f factor to correct for gamma-ray attenuation within the test portion (self- -
att(E)
attenuation)
f factor to correct for decay between the reference time and the start of the -
d
measurement and during the measurement
131
NOTE 1 The latter is important for short-lived radionuclides like I.
f is the factor to correct for decay between the reference time and the start of the -
d1
measurement
f is the factor to correct for decay during the measurement -
d2
f composite correction factor for the gamma ray with energy E considering all -
E
necessary corrections as shown in Formula (6)
f factor to correct for geometry differences -
g
ftcs,E factor to correct for true coincidence summing effects -
NOTE 2 In this case, this is only applicable to 134Cs.
k coverage factor -
8
---------------------- Page: 10 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
Symbol Name of quantity Unit
m quantity of the test portion kg
m corrected quantity of the test portion kg
c
m dry mass of the moisture content determination portion kg
d
m fresh mass of the test portion kg
f
m fresh mass of the moisture content determination portion kg
w
134
N number of gamma rays used for the calculation of massic activity for Cs -
n number of counts in the net area of the photopeak at energy E, in the background -
b,E
spectrum
n number of counts in the net area of the photopeak at energy E, in the test portion -
N,E
spectrum
P probability (per 100 decays) of the emission of a gamma ray with energy E by a -
E
radionuclide
NOTE 3 The probability can be expressed in percentage (%) or in absolute values.
−1
r net count rate in the full energy peak at energy E s
N,E
T temperature °C
t background spectrum live time s
b
t test portion spectrum live time s
g
t time elapsed between the reference time and the start of the measurement s
i
NOTE 4 It will have a negative value when the measurement was started before the
reference time and a positive value when the measurement was started after the reference
time.
t test portion spectrum real time s
r
t calibration spectrum live time s
s
t1/2 half-life of a radionuclide s
U(a ) expanded uncertainty with coverage factor k calculated as U = k × u Bq/kg
m
u(a ) standard uncertainty of the massic activity Bq/kg
m
u(a ); standard uncertainty of the massic activity calculated for the two most intense Bq/kg
m,605
134
gamma rays (604,72 keV and 795,86 keV) of Cs
u(a )
m,796
u(n ) uncertainty of the net number of counts in the photopeak at energy E in the -
b,E
background spectrum
u(n ) uncertainty of the net number of counts in the photopeak at energy E in the test -
N,E
portion spectrum
u(r ) uncertainty of the net count rate -
N,E
u random uncertainty component -
rand
u (A) relative uncertainty of the activity of a reference radionuclide emitting photons of -
rel
energy E in the calibration source, at the time of calibration
9
---------------------- Page: 11 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
Symbol Name of quantity Unit
u (f ) relative uncertainty of the factor to correct for decay between the reference time -
rel d
and the start of the measurement and during the measurement
u (f ) relative uncertainty of the composite correction factor for the gamma ray with -
rel E
energy E considering all necessary corrections as shown in Formula (6)
u (f ) relative uncertainty of the factor to correct for true coincidence summing effects -
rel tcs,E
u (m) relative uncertainty of the quantity of the test portion -
rel
u (P ) relative uncertainty of the probability (per 100 decays) of the emission of a gamma -
rel E
ray with energy E by a radionuclide
u (r ) relative uncertainty of the net count rate -
rel N,E
u (ε ) relative uncertainty of the detection efficiency at energy E for the specific -
rel E
measurement geometry and detector used
u systematic uncertainty component -
sys
utot total uncertainty calculated based on random and systematic components -
u(w) total standard uncertainty for coverage factor w -
u (w) relative value of total standard uncertainty for coverage factor w -
rel
standard uncertainty of a as a function of its true value Bq/kg
m
ua
( )
m
134
v ; v weighting factor for the calculation of massic activity of Cs using the two most -
605 796
intense gamma rays (604,72 keV and 795,86 keV)
w calibration factor -
ɛ detection efficiency at energy E for the specific measurement geometry and -
E
detector used
−1
λ decay constant of a radionuclide s
4.2 Abbreviations
ALARA As low as reasonably achievable
FEP Full energy peak
FWHM Full width at half maximum
HPGe High purity germanium
IEC International Electrotechnical Commission
ISO International Organization for Standardization
TCS True coincidence summing
10
---------------------- Page: 12 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
5 Principle
A homogenous test portion is placed in a measurement container. The container is positioned in front of
a high energy resolution (e.g. high purity germanium) detector in a well-defined position. The full-
energy peaks of the emitted gamma particles present in the test portion are analysed and massic
131 134 137
activities of I, Cs and Cs are quantified using the high resolution gamma-ray spectrometry
technique. Appropriate energy and efficiency calibration shall be applied for each detector and sample
used.
6 Safety precautions
The optimization (ALARA) principle shall be applied at all times.
Handling of the samples should be performed according to the local safety regulations.
Personal protective equipment like laboratory coat, gloves, protective eyewear and personal dosimeter
shall be worn during the test portion preparation. The gloves shall be changed when the preparation is
finished to avoid cross-contamination.
Laboratory samples shall be stored in a cool and dark place, at a temperature not exceeding room
temperature and not lower than 0 °C. Perishable materials shall be kept at a temperature of
1 °C < T < 5 °C.
Care shall be taken as losses of iodine can occur if the material is not properly preserved. If presence of
gaseous iodine is suspected hermetically sealed containers shall be used and empty space or air pockets
between the sample and the lid of the container shall be avoided. Bound iodine can also easily become
volatile in the presence of microorganisms (due to methylation), in acidic environments or at
temperatures higher than 80 °C.
7 Apparatus
7.1 General
All equipment used during sample preparation shall be cleaned after each use to avoid cross-
contamination.
7.2 Equipment for test portion preparation
7.2.1 General
This document only provides guidance specific to its scope concerning the equipment for test portion
preparation. More details and a comprehensive description can be found in EN ISO 6498 [2].
7.2.2 Balance
In the test portion preparation process a balance or scale sensitive to 0,1 % of the mass of the test
portion and with a capacity of at least the wet mass of the test portion shall be used to determine the
mass.
7.2.3 Thermostatically controlled heating chamber
If results normalized to the dry mass are required, an oven or another suitable thermostatically
controlled heating chamber shall be used. The equipment shall be calibrated and capable of maintaining
the temperature needed to analyse the moisture content of the material with an uncertainty that is at
most 2 °C.
11
---------------------- Page: 13 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
7.2.4 Equipment for particle size reduction and homogenization
Mills and mixers should be used to reduce the particle size and homogenize the test portion, in
particular if the particle size of the initial material is > 6 mm.
7.2.5 Equipment for handling dry powdered materials
An ion blower or other type of equipment should be used to reduce static electricity.
After the transfer of the test portion to the measurement container, a tapper or vibrating table could be
used to compact the test portion and equalize its height.
7.2.6 Gamma-ray spectrometry equipment
A gamma-ray spectrometer with high energy resolution (e.g. an HPGe) detector coupled to a pulse
processing, a data acquisition system and a computer shall be used to collect the spectra.
It is recommended to use detectors whose energy resolution (FWHM) is better than 2,2 keV (for the
60 137
Co peak at 1 332 keV) and with a peak/Compton ratio between 50 and 80 for Cs. For more
information, see IEC 61452 [5].
7.3 Containers to be used
7.3.1 Moisture content determination container
A container able to withstand the drying temperature shall be used if moisture content determination is
required. It shall be suitable for containing a portion of a test sample required by the relevant ISO
standard used for moisture content determination without loss of sample material while permitting
water to evaporate.
7.3.2 Measurement container
Guidance information on a proper container for the test portion is given in ISO 20042 [4].
If the measurement container is to be reused, it shall first be emptied, cleaned and checked for
radiopurity as it could have become contaminated by the previously measured test portion.
8 Procedure
8.1 Calibration
8.1.1 General
The gamma-ray spectrometry detector shall be calibrated for energy and peak detection efficiency. The
calibration should follow the requirements of IEC 61452 [5].
8.1.2 Energy calibration
The sources used for the energy calibration may be point sources of a single nuclide emitting gamma
152
rays of different energies (e.g. Eu), multiple nuclide point sources or a series of sources containing
radionuclides emitting one or more gamma rays.
Emphasis should be placed on the energy interval 364 keV to 911 keV, as the main gamma rays of both
the radionuclides in the scope of this document and the potentially interfering radionuclides (listed in
Annex A) have energies in that interval.
12
---------------------- Page: 14 ----------------------
SIST EN 17462:2021
EN 17462:2021 (E)
8.1.3 Detection efficiency calibration
The counting detection efficiency for a gamma-ray energy is affected by five major factors:
— the intrinsic detector efficiency;
— the position of the source in relation to the detector;
— the physical dimensions of the measurement container;
— the density, matrix composition and the filling height of the test portion;
— the shield (indirectly by minimizing interfering radiation or environmental background).
The experimental calibration of the detection efficiency should be performed using a reference volume
source (i.e. not a point source) measured in the same container and position as the test portion. The
properties of the reference volume source should be as similar as possible to those of the test portion.
To account for differences in their properties proper techniques for efficiency transfer should be
applied (see below).
As spiking can result in an inhomogeneous activity distribution preparation of a reference volume
source in the laboratory is only possible if a reliable and validated spiking procedure is available. Blank
material can be spiked with a multi-nuclide solution, several individual solutions containing suitable
radionuclides or a solution of a single nuclide emitting many gamma rays. Attention should be paid to
cover the region of interest (364 keV to 911 keV).
The net count rate (r ) shall be calculated using Formula (1).
N,E
t
g
nn−×
Nb,,E E
t
b
r = (1)
N,E
t
g
where
−1
r is the net count rate in the full energy peak at energy E, in s ;
N,E
n is the net number of counts in the peak, at energy E, in the test portion spectrum;
N,E
n is the number of net counts in the peak, at energy E, in the background spectrum;
b,E
is the test portion spectrum live time, in s;
t
g
is the background spectrum live time, in s.
t
b
The detection efficiency at the energy E (ε ) shoul
...
SLOVENSKI STANDARD
oSIST prEN 17462:2020
01-februar-2020
Krma: metode vzorčenja in analize - Določevanje radionuklidnega joda-131, cezija-
134 in cezija-137 v krmi
Animal feeding stuffs: Methods of sampling and analysis - Determination of the
radionuclides Iodine-131, Caesium-134 and Caesium-137 in feed
Futtermittel: Probenahme- und Untersuchungsverfahren - Bestimmung der Radionuklide
Jod-131, Cäsium-134 und Cäsium-137 in Futtermittel
Aliments des animaux : Méthodes d’échantillonnage et d’analyse - Détermination des
radionucléides iode 131, césium 134 et césium 137 dans les aliments composés pour
animaux
Ta slovenski standard je istoveten z: prEN 17462
ICS:
65.120 Krmila Animal feeding stuffs
oSIST prEN 17462:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN 17462:2020
---------------------- Page: 2 ----------------------
oSIST prEN 17462:2020
DRAFT
EUROPEAN STANDARD
prEN 17462
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2019
ICS 65.120
English Version
Animal feeding stuffs: Methods of sampling and analysis -
Determination of the radionuclides Iodine-131, Caesium-
134 and Caesium-137 in feed
Aliments des animaux : Méthodes d'échantillonnage et Futtermittel: Probenahme- und
d'analyse - Détermination des radionucléides iode 131, Untersuchungsverfahren - Bestimmung der
césium 134 et césium 137 dans les aliments composés Radionuklide Jod-131, Cäsium-134 und Cäsium-137 in
pour animaux Futtermittel
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 327.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17462:2019 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Symbols and abbreviations . 8
4.1 Symbols . 8
4.2 Abbreviations . 11
5 Principle . 11
6 Safety precautions . 11
7 Equipment . 12
7.1 General . 12
7.2 Equipment for test portion preparation . 12
7.3 Gamma-ray spectrometry equipment . 12
7.4 Containers to be used . 12
8 Procedure . 13
8.1 Calibration. 13
8.2 Test portion preparation . 16
8.3 Spectrum recording . 16
8.4 Spectrum analysis . 17
8.5 Quality assurance . 17
9 Expression of results . 18
9.1 Massic activity calculation . 18
9.2 Characteristic limits . 24
9.3 Precision . 25
9.4 Test report . 26
Annex A (informative) List of possible interfering gamma rays from naturally occurring
radionuclides as well as from radionuclides that could be present in
environmental samples immediately after a nuclear accident or incident . 27
Annex B (informative) Example of uncertainty budget in gamma-ray spectrometry using
an HPGe detector . 28
Annex C (informative) Results of the collaborative trial . 29
Bibliography . 34
2
---------------------- Page: 4 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
European foreword
This document (prEN 17462:2019) has been prepared by Technical Committee CEN/TC 327
“Animal feeding stuffs: Methods of sampling and analysis”, the secretariat of which is held by NEN.
This document is currently submitted to the CEN Enquiry.
This document has been prepared under a standardization request given to CEN by the European
Commission and the European Free Trade Association.
3
---------------------- Page: 5 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
Introduction
131 134 137
This document describes a method for I, Cs and Cs massic activity determination (Bq/kg)
in animal feed. It was initiated by Directorate General for Health and Food Safety (DG SANTE) of
the European Commission following the accident in the Fukushima Daiichi nuclear power plant
in March 2011. The event highlighted the need for standardized measurements of the three most
common radioactive contaminants following such type of nuclear accident.
The most commonly used method for identification and quantification of these radionuclides in
animal feed samples is high-resolution gamma-ray spectrometry. As this is a secondary
measurement method based on analysis of photopeaks of the emitted gamma rays care should be
taken to use appropriate energy and efficiency calibrations for the detector and test portion used.
This method of massic activity determination is described in the present document.
4
---------------------- Page: 6 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
1 Scope
131 134
This document describes a method for determination of the massic activity (Bq/kg) of I, Cs
137
and Cs in animal feed in monitoring laboratories.
General guidance on the preparation of feed samples and the measurement of the three
131 134 137
radionuclides I, Cs and Cs by high resolution gamma-ray spectrometry is provided. The
current document aims to be complementary to existing standards. More information on sample
preparation, moisture content determination and gamma-ray spectrometry can be found in
specific standards referred to in this document. For example, generic advice on the equipment
selection, detectors and quality assurance for gamma-ray spectrometry can be found in
ISO 20042.
The method was fully statistically tested and evaluated in a collaborative trial comprising five
131 134 137
animal feeding stuff samples for the radionuclides I, Cs and Cs. Details on the successfully
tested working range for each of the examined radionuclides are described in Annex C.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the cited edition applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
EN ISO 6497, Animal feeding stuffs - Sampling (ISO 6497)
ISO 11929-1, Determination of the characteristic limits (decision threshold, detection limit and
limits of the coverage interval) for measurements of ionizing radiation - Fundamentals and
application - Part 1: Elementary applications
ISO 20042:2019, Measurement of radioactivity - Gamma-ray emitting radionuclides - Generic test
method using gamma-ray spectrometry
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 6497 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
background
spectrum recorded by the gamma-ray detector when no sample is measured; the spectral data,
including full energy peaks, in such a spectrum is resulting from radioactive decay occurring in
the environment surrounding the detector (including the cosmic ray interactions) or in the
detector
5
---------------------- Page: 7 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
3.2
background continuum
events in the spectrum that form a smooth curve onto which the photopeaks are superimposed
Note 1 to entry: The continuum may arise from gamma rays scattered inside the test sample or any
surrounding materials, from cosmic radiation or from radionuclides in the surrounding materials.
[SOURCE: ISO 20042:2019, 3.1]
3.3
blank sample
sample, liquid or solid, with very low to no activity for radiation of the same type and region of
interest, with a mass and a composition as close as possible to those of the test sample
[SOURCE: ISO 19581:2017, 3.1, see [1]]
3.4
coincidence summing
true coincidence summing (TCS)
cascade-summing
simultaneous detection of two or more gamma-rays in the spectrometry system, due to the
emission of a cascade of gamma-rays in the decay of a single nucleus in the test sample
[SOURCE: ISO 20042:2019, 3.24]
3.5
dead time
time during spectrum acquisition (real time) during which pulses are not recorded or processed
Note 1 to entry: Dead time is given by real time minus live time.
Note 2 to entry: The time is given in seconds.
[SOURCE: ISO 20042:2019, 3.5]
3.6
detection efficiency transfer
efficiency transfer
calculation that enables the user to establish the value of the detection efficiency for a given
gamma-ray peak in the spectrum of the test portion, when only the detection efficiency from an
experimental calibration with a reference source that may have a different composition, density
and/or geometry compared to the test portion is known
3.7
full energy peak (FEP)
see photopeak [3.12]
3.8
high energy resolution
relative term which in gamma-ray spectrometry refers to the energy resolution obtained with a
Ge(Li) or an HPGe detector
6
---------------------- Page: 8 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
3.9
laboratory sample
sample as prepared (from the lot) for sending to the laboratory and intended for inspection or
testing
[SOURCE: EN ISO 6498:2012, 2.1.2 [9]]
3.10
live time
time during which pulses are processed during an acquisition (real) time
Note 1 to entry: The time is given in seconds.
[SOURCE: ISO 20042:2019, 3.12]
3.11
photopeak
full energy peak (FEP)
peak observed above the background continuum in a gamma-ray spectrum due to events that
deposit the full energy of the photon in the detector material, usually approximately Gaussian in
shape
[SOURCE: ISO 20042:2019, 3.17]
3.12
real time
time taken to acquire a spectrum
Note 1 to entry: The time is given in seconds.
[SOURCE: ISO 20042:2019, 3.10]
3.13
sample holder
device that is specially designed to enable the placement of a given sample container in a well-
defined position on top of a specific detector
3.14
spectrometry system
complete assembly of the sensor and associated pulse-processing electronics that converts the
gamma rays detected by the sensor into a pulse-height spectrum
[SOURCE: ISO 20042:2019, 3.22
3.15
test portion
quantity of material drawn from the test sample (or from the laboratory sample if both are the
same)
[SOURCE: EN ISO 6498:2012, 2.1.4 [9]]
7
---------------------- Page: 9 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
3.16
test sample
subsample or sample prepared from the laboratory sample and from which test portions will be
taken
[SOURCE: EN ISO 6498:2012, 2.1.3 [9]]
4 Symbols and abbreviations
4.1 Symbols
For the purposes of this document, the following symbols apply.
Symbol Name of quantity Unit
A activity of a reference radionuclide emitting photons of energy E in the Bq
calibration source, at the time of calibration
massic activity at energy E of a radionuclide in the sample Bq/kg
a
m
134
massic activity of Cs obtained using the gamma-ray of energy i, Bq/kg
aa;
m,605 m,796
which is either 604,72 keV or 795,86 keV
134
'
massic activity of Cs based on the weighted mean calculation Bq/kg
a
m
including the two major gamma rays of this radionuclide
a true value of massic activity at energy E of a radionuclide in the sample Bq/kg
*
decision threshold Bq/kg
a
m
#
detection limit Bq/kg
a
m
a annum (year), the tropical year which is approximately equal to year
365,2422 d
d day (1 day = 86 400 s) day
ɛ detection efficiency at energy E for the specific measurement geometry -
E
and detector used
factor to correct for gamma-ray attenuation within the test portion -
f
att E
( )
(self-attenuation)
factor to correct for decay between the reference time and the start of -
f
d
the measurement and during the measurement
131
NOTE 1 The latter is important for short-lived radionuclides like I.
is the factor to correct for decay between the reference time and the -
f
d1
start of the measurement
is the factor to correct for decay during the measurement -
f
d2
composite correction factor for the gamma ray with energy E -
f
E
considering all necessary corrections as shown in Formula (5)
8
---------------------- Page: 10 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
Symbol Name of quantity Unit
factor to correct for geometry differences -
f
g
factor to correct for true coincidence summing effects -
f
tcs,E
134
NOTE 2 In this case, this is only applicable to Cs.
-1
λ
decay constant of a radionuclide s
m
quantity of the test portion kg
corrected quantity of the test portion kg
m
c
fresh mass of the test portion kg
m
f
dry mass of the moisture content determination portion kg
m
d
fresh mass of the moisture content determination portion kg
m
w
N
number of gamma rays used for the calculation of massic activity for -
134
Cs
number of counts in the net area of the photopeak at energy E, in the -
n
NE,
test portion spectrum
number of counts in the net area of the photopeak at energy E, in the
-
n
bE,
background spectrum
P probability (per 100 decays) of the emission of a gamma ray with -
E
energy E by a radionuclide
NOTE 3 The probability can be expressed in percentage (%) or in
absolute values.
-1
net count rate in the full energy peak at energy E s
r
NE,
background spectrum live time s
t
b
t test portion spectrum live time s
g
t time elapsed between the reference time and the start of the s
i
measurement
NOTE 4 It will have a negative value when the measurement was
started before the reference time and positive value when the
measurement was started after the reference time.
t test portion spectrum real time s
r
t calibration spectrum live time s
s
half-life of a radionuclide s
t
12/
relative uncertainty of the activity of a reference radionuclide emitting -
uA
( )
rel
photons of energy E in the calibration source, at the time of calibration
9
---------------------- Page: 11 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
Symbol Name of quantity Unit
ua standard uncertainty of the massic activity Bq/kg
( )
m
expanded uncertainty with coverage factor k calculated as U =k× u
Bq/kg
U a
( )
m
standard uncertainty of the massic activity calculated for two most Bq/kg
ua ;
( )
m,605
134
intense gamma rays (604,72 keV and 795,86 keV) of Cs
ua
( )
m,796
standard uncertainty of a as a function of its true value Bq/kg
ua
( ) m
m
relative uncertainty of the detection efficiency at energy E for the -
u ε
( )
rel E
specific measurement geometry and detector used
relative uncertainty of the composite correction factor for the gamma -
uf
( )
rel E
ray with energy E considering all necessary corrections as shown in
Formula (5)
relative uncertainty of the factor to correct for decay between the -
uf
( )
rel d
reference time and the start of the measurement and during the
measurement
relative uncertainty of the factor to correct for true coincidence -
uf
( )
rel tcs,E
summing effects
relative uncertainty of the quantity of the test portion -
um
( )
rel
uncertainty of the net number of counts in the photopeak at energy E -
un
( )
NE,
in the test portion spectrum
uncertainty of the net number of counts in the photopeak at energy E -
un()
b,E
in the background spectrum
relative uncertainty of the probability (per 100 decays) of the emission -
uP
( )
rel E
of a gamma ray with energy E by a radionuclide
uncertainty of the net count rate -
ur
( )
NE,
relative uncertainty of the net count rate -
ur
( )
rel N,E
random uncertainty component -
u
rand
systematic uncertainty component -
u
sys
total uncertainty calculated based on random and systematic -
u
tot
components
total standard uncertainty for coverage factor w
-
uw
( )
relative value of total standard uncertainty for coverage factor w
-
uw
( )
rel
10
---------------------- Page: 12 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
Symbol Name of quantity Unit
134
weighting factor for the calculation of massic activity of Cs using the -
v v
605 796
;
two most intense gamma rays (604,72 keV and 795,86 keV)
w
calibration factor -
k
coverage factor -
T
temperature °C
4.2 Abbreviations
ALARA As Low As Reasonably Achievable
CEN European Committee for Standardization (Comité Européen de Normalisation)
FEP Full Energy Peak
FWHM Full Width at Half Maximum
HPGe detector High Purity Germanium detector
IEC International Electrotechnical Commission
ISO International Organization for Standardization
TCS True Coincidence Summing
5 Principle
A homogenous test portion is placed in a measurement container. The container is positioned in
front of a high energy resolution (e.g. High Purity Germanium) detector in a well-defined position.
The full-energy peaks of the emitted gamma particles present in the test portion are analysed and
131 134 137
massic activities of I, Cs and Cs are quantified using the high resolution gamma-ray
spectrometry technique. Appropriate energy and efficiency calibration shall be applied for each
detector and sample used.
6 Safety precautions
The ALARA principle shall be applied at all times.
Handling of the samples shall be performed according to the local safety regulations.
Personal protective equipment like laboratory coat, gloves, protective eyewear and personal
dosimeter shall be worn during the test portion preparation. The gloves shall be changed when
the preparation is finished to avoid cross-contamination.
Laboratory samples shall be stored in a cool and dark place, at a temperature not exceeding room
temperature and not lower than 0 °C. Perishable materials shall be kept at a temperature of
1 °C < T < 5 °C.
Care shall be taken as losses of iodine may occur if the material is not properly preserved. If
presence of gaseous iodine is suspected hermetically sealed containers shall be used and empty
space or air pockets between the sample and the lid of the container shall be avoided. Bound
iodine may also easily become volatile in the presence of microorganisms (due to methylation), in
acidic environments or at temperatures higher than 80 °C.
11
---------------------- Page: 13 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
7 Equipment
7.1 General
All equipment used during sample preparation shall be cleaned after each use to avoid
cross-contamination.
7.2 Equipment for test portion preparation
7.2.1 General
This document only provides guidance specific to its scope concerning the equipment for test
portion preparation. More details and a comprehensive description can be found in EN ISO 6498
[9].
7.2.2 Balance
In the test portion preparation process a balance or scale sensitive to 0,1 % of the mass of the test
portion and with a capacity of at least the wet mass of the test portion shall be used to determine
the mass.
7.2.3 Thermostatically controlled heating chamber
If results normalised to the dry mass are required, an oven or another suitable thermostatically
controlled heating chamber shall be used. The equipment shall be calibrated and capable of
maintaining the temperature needed to analyse the moisture content of the material with an
uncertainty that is at most 2 °C.
7.2.4 Equipment for particle size reduction and homogenisation
Mills and mixers should be used to reduce the particle size and homogenise the test portion, in
particular if the particle size of the initial material is > 6 mm.
7.2.5 Equipment recommended for handling dry powdered materials
It is recommended to use an ion blower or other type of equipment to reduce static electricity.
After the transfer of the test portion to the measurement container, a tapper or vibrating table
could be used to compact the test portion and equalise its height.
7.3 Gamma-ray spectrometry equipment
A gamma-ray spectrometer with high energy resolution (e.g. an HPGe) detector coupled to a pulse
processing, a data acquisition system and a computer shall be used to collect the spectra.
It is recommended to use detectors whose energy resolution (FWHM) is better than 2,2 keV (for
60 137
the Co peak at 1 332 keV) and with a peak/Compton ratio between 50 and 80 for Cs. For more
information, see IEC 61452 [13].
7.4 Containers to be used
7.4.1 Moisture content determination container
A container able to withstand the drying temperature shall be used. It shall be suitable for
containing a portion of a test sample required by the relevant ISO standard used for moisture
content determination without loss of sample material while permitting water to evaporate.
12
---------------------- Page: 14 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
7.4.2 Measurement container
Guidance information on a proper container for the test portion is given in ISO 20042.
If the measurement container is to be reused, it shall first be emptied, cleaned and checked for
radiopurity as it could have become contaminated by the previously measured test portion.
8 Procedure
8.1 Calibration
8.1.1 General
The gamma-ray spectrometry detector shall be calibrated for energy and peak detection
efficiency. The calibration should follow the requirements of IEC 61452 [13].
8.1.2 Energy calibration
The sources used for the energy calibration may be point sources of a single nuclide emitting
152
gamma rays of different energies (e.g. Eu), multiple nuclide point sources or a series of sources
containing radionuclides emitting one or more gamma rays.
Emphasis should be placed on the energy interval 364 keV to 796 keV, as the four main gamma
rays of the three radionuclides in the scope of this standard have energies in that interval.
8.1.3 Detection efficiency calibration
The counting detection efficiency for a gamma-ray energy is affected by five major factors:
— the intrinsic detector efficiency,
— the position of the source in relation to the detector,
— the physical dimensions of the measurement container,
— the density, matrix composition and the filling height of the test portion,
— the shield (indirectly by minimising interfering radiation or environmental background).
The experimental calibration of the detection efficiency should be performed using a reference
volume source (i.e. not a point source) measured in the same container and position as the test
portion. The properties of the reference volume source should be as similar as possible to those
of the test portion. To account for differences in their properties proper techniques for efficiency
transfer should be applied (see below).
As spiking may result in an inhomogeneous activity distribution preparation of a reference
volume source in the laboratory is only possible if a reliable and validated spiking procedure is
available. Blank material can be spiked with a multi-nuclide solution, several individual solutions
containing suitable radionuclides or a solution of a single nuclide emitting many gamma rays.
Attention should be paid to cover the region of interest (364 keV to 796 keV).
The net count rate (r ) shall be calculated using Formula (1).
N,E
13
---------------------- Page: 15 ----------------------
oSIST prEN 17462:2020
prEN 17462:2019 (E)
t
g
nn−×
NE,,b E
t
b
r =
NE,
t
g
(1)
-1
is the net count rate in the full energy peak at energy E, in s ;
r
NE,
is the net number of counts in the peak, at energy E, in the test portion spectrum;
n
NE,
is the number of net counts in the peak, at energy E, in the background spectrum;
n
b,E
is the test portion spectrum live time, in s;
t
g
is the background spectrum live time, in s.
t
b
where
ε )
The detection efficiency at the energy E ( should be calculated according to Formula (2).
E
r
NE,
ε =
E
AP× ××f f
E d tcs,E
(2)
where
ε is the detection efficiency at energy E for the specific measurement geometry and
E
detector used;
is the net count rate in the full energy peak at energy E calculated using Formula (1);
r
NE,
A is the activity of the reference radionuclide emitting photons of energy E in the
calibration source, at the time of the calibration, in Bq;
P is the absolute probability of the emission of a photon with energy E, per decay;
E
is the factor to correct for decay between the reference time and the start of the
f
d
measurement and during the measurement;
is the factor to correct for true coincidence summing effects.
f
tcs,E
Once the detection efficiencies for the radionuclides present in the reference volume source are
calculated, they should be plotted against the energy of the emitted photon. Then, an efficiency
curve should be constructed by suitable fitting [2] (Figure 1).
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.