EN ISO 10703:2021

SLOVENSKI STANDARD
01-oktober-2021
Nadomešča:
SIST EN ISO 10703:2016
SIST ISO 10703:2010
Kakovost vode - Radionuklidi, ki sevajo žarke gama - Preskusna metoda z gama
spektrometrijo visoke ločljivosti (ISO 10703:2021)
Water quality - Gamma-ray emitting radionuclides - Test method using high resolution
gamma-ray spectrometry (ISO 10703:2021)
Wasserbeschaffenheit - Gammastrahlung emittierende Radionukliden - Verfahren mittels
Gammaspektrometrie (ISO 10703:2021)
Qualité de l'eau - Radionucléides émetteurs gamma - Méthode d’essai par spectrométrie
gamma à haute résolution (ISO 10703:2021)
Ta slovenski standard je istoveten z: EN ISO 10703:2021
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10703
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2021
EUROPÄISCHE NORM
ICS 13.060.60; 17.240 Supersedes EN ISO 10703:2015
English Version
Water quality - Gamma-ray emitting radionuclides - Test
method using high resolution gamma-ray spectrometry
(ISO 10703:2021)
Qualité de l'eau - Radionucléides émetteurs gamma - Wasserbeschaffenheit - Gammastrahlung emittierende
Méthode d'essai par spectrométrie gamma à haute Radionukliden - Verfahren mittels
résolution (ISO 10703:2021) Gammaspektrometrie (ISO 10703:2021)
This European Standard was approved by CEN on 28 June 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 ISO 10703:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10703:2021) has been prepared by Technical Committee ISO/TC 147 "Water
quality" in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of
which is held by DIN.
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 January 2022, and conflicting national standards shall
be withdrawn at the latest by January 2022.
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 supersedes EN ISO 10703:2015.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN websites.
According to the CEN-CENELEC Internal Regulations, the national standards organizations 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.
Endorsement notice
The text of ISO 10703:2021 has been approved by CEN as EN ISO 10703:2021 without any modification.

INTERNATIONAL ISO
STANDARD 10703
Third edition
2021-06
Water quality — Gamma-ray emitting
radionuclides — Test method
using high resolution gamma-ray
spectrometry
Qualité de l'eau — Radionucléides émetteurs gamma — Méthode
d’essai par spectrométrie gamma à haute résolution
Reference number
ISO 10703:2021(E)
©
ISO 2021
ISO 10703:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO 10703:2021(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 3
5 Principle . 4
6 Reference sources . 4
6.1 Source(s) for energy calibration . 4
6.2 Reference source(s) for efficiency calibration . 5
6.2.1 General. 5
6.2.2 Reference sources for laboratory systems . 5
6.2.3 Reference sources used with numerical methods . 5
7 Reagents . 5
8 Gamma-ray spectrometry equipment . 6
8.1 General description . 6
8.2 Detector types . 6
8.3 High voltage power supply . 7
8.4 Preamplifier . 7
8.5 Cryostat or electric cooler . 7
8.6 Shielding . 7
8.7 Analogue or digital acquisition electronics . 7
8.7.1 General. 7
8.7.2 Analogue electronic (ADC) . 8
8.7.3 Digital electronic (DSP) . 8
8.8 Computer, including peripherical devices and software . 8
9 Nuclear decay data . 9
10 Sampling . 9
11 Procedure. 9
11.1 Sample preparation . 9
11.1.1 General. 9
11.1.2 Direct measurement without preparation .10
11.1.3 Evaporation without iodine retention.10
11.1.4 Evaporation with iodine retention .10
11.2 Calibration .10
11.2.1 General.10
11.2.2 Energy calibration .10
11.2.3 Efficiency calibration.11
12 Expression of results .12
12.1 Calculation of the activity concentration .12
12.1.1 General.12
12.1.2 Dead time and pile up corrections (see ISO 20042) .13
12.1.3 Decay corrections .13
12.1.4 True coincidence summing .13
12.2 Standard uncertainty .15
12.3 Decision threshold .15
12.4 Detection limit .16
12.5 Limits of the coverage intervals .16
12.5.1 Limits of the probabilistically symmetric coverage interval.16
ISO 10703:2021(E)
12.5.2 The shortest coverage interval .17
12.6 Corrections for contributions from other radionuclides and background .17
12.6.1 General.17
12.6.2 Contribution from other radionuclides .18
12.6.3 Contribution from background .19
13 Test report .19
Annex A (informative) Example of a carrier solution which can be added to the water
sample when waste water from a nuclear power plant is investigated.21
Annex B (informative) True coincidence summing .22
Annex C (informative) Calculation of the activity concentration from a gamma spectrum
using a linear background subtraction (undisturbed peak) .24
Bibliography .26
iv © ISO 2021 – All rights reserved

ISO 10703:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, subcommittee SC 3,
Radioactivity measurements, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 230, Water analysis, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 10703:2007), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— new common Introduction;
— Scope enlarged to emergency situation and to wastewater, upper dead time increase to 10 %;
— the sample storage conditions are in compliance with ISO 5667-3 (see Clause 10);
— modification of the reference source for calibration (see 6.2);
— calibration efficiency determination by Monte Carlo method (see 11.2.3);
— complete revision of the pulse pile up and dead time;
— complete revision of the true coincidence summing subclause (see 12.1.4);
— addition of the correction factor for dead time and pile up (see 12.1.2);
— introduction of the shortest coverage interval in accordance with the new ISO 11929 series
(see 12.5.2);
— modification of the test report (see Clause 13).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
ISO 10703:2021(E)
Introduction
Radioactivity from several naturally-occurring and anthropogenic sources is present throughout
the environment. Thus, water bodies (e.g. surface waters, ground waters, sea waters) can contain
radionuclides of natural, human-made, or both origins.
40 3 14
— Natural radionuclides, including K, H, C, and those originating from the thorium and uranium
226 228 234 238 210
decay series, in particular Ra, Ra, U, U, and Pb, can be found in water for natural reasons
(e.g. desorption from the soil and washoff by rain water) or can be released from technological
processes involving naturally occurring radioactive materials (e.g. the mining and processing of
mineral sands or phosphate fertilizer production and use).
— Human-made radionuclides, such as transuranium elements (americium, plutonium, neptunium,
3 14 90
curium), H, C, Sr, and gamma emitting radionuclides can also be found in natural waters.
Small quantities of these radionuclides are discharged from nuclear fuel cycle facilities into the
environment as the result of authorized routine releases. Some of these radionuclides used for
medical and industrial applications are also released into the environment after use. Anthropogenic
radionuclides are also found in waters as a result of past fallout contaminations resulting from
the explosion in the atmosphere of nuclear devices and accidents such as those that occurred in
Chernobyl and Fukushima.
Radionuclide activity concentration in water bodies can vary according to local geological
characteristics and climatic conditions and can be locally and temporally enhanced by releases from
[7]
nuclear installation during planned, existing and emergency exposure situations . Drinking water
may thus contain radionuclides at activity concentrations which could present a risk to human health.
The radionuclides present in liquid effluents are usually controlled before being discharged into the
[8]
environment . Water bodies and drinking waters are monitored for their radioactivity content as
[9]
recommended by the World Health Organization (WHO) so that proper actions can be taken to ensure
that there is no adverse health effect to the public. Following these international recommendations,
national regulations usually specify radionuclide authorized concentration limits for liquid effluent
discharged to the environment and radionuclide guidance levels for water bodies and drinking waters
for planned, existing and emergency exposure situations. Compliance with these limits can be assessed
using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3 and
ISO 5667-20.
Depending on the exposure situation, there are different limits and guidance levels that would result
in an action to reduce health risk. As an example, during a planned or existing situation, the WHO
−1 134/137 131
guidelines for guidance level in drinking water is 10 Bq·l for Cs and I activity concentration,
−1 241 −1 210
1 Bq·l for Am and 0,1 Bq·l for Pb.
NOTE 1 The guidance level is the activity concentration with an intake of 2 l/d of drinking water for one year
that results in an effective dose of 0,1 mSv/a for members of the public. This is an effective dose that represents a
[9]
very low level of risk and which is not expected to give rise to any detectable adverse health effects .
[10]
In the event of a nuclear emergency, the WHO Codex guideline levels mentioned that the activity
−1 134/137 −1 131
concentration for infant food might not be greater than 1 000 Bq·kg for Cs, 100 Bq·kg for I
−1 241
and 1 Bq·kg for Am. For food other than infant food, the activity concentration might not be greater
−1 134/137 −1 131 −1 241
than 1 000 Bq·kg for Cs, 100 Bq·kg for I and 10 Bq·kg for Am.
NOTE 2 The Codex guidelines levels (GLs) apply to radionuclides contained in food destined for human
consumption and traded internationally, which have been contaminated following a nuclear or radiological
emergency. These GLs apply to food after reconstitution or as prepared for consumption, i.e. not to dried or
concentrated food, and are based on an intervention exemption level of 1 mSv in a year for members of the public
[10]
(infant and adult) .
Thus, the test method can be adapted so that the characteristic limits, decision threshold, detection
limit and uncertainties ensure that the radionuclide activity concentrations test results can be verified
to be below the guidance levels required by a national authority for either planned/existing situations
[11][12]
or for an emergency situation .
vi © ISO 2021 – All rights reserved

ISO 10703:2021(E)
Usually, the test methods can be adjusted to measure the activity concentration of the radionuclide(s) in
either wastewaters before storage or in liquid effluents before discharge to the environment. The test
results will enable the plant/installation operator to verify that, before their discharge, wastewaters/
liquid effluent radioactive activity concentrations do not exceed authorized limits.
The test method described in this document may be used during planned, existing and emergency
exposure situations as well as for wastewaters and liquid effluents with specific modifications that
could increase the overall uncertainty, detection limit, and threshold.
The test method may be used for water samples after proper sampling, sample handling, and test
sample preparation (see the relevant part of the ISO 5667 series).
This document has been developed to answer the need of test laboratories carrying out these
measurements, that are sometimes required by national authorities, as they may have to obtain a
specific accreditation for radionuclide measurement in drinking water samples.
This document is one of a set of International Standards on test methods dealing with the measurement
of the activity concentration of radionuclides in water samples.
INTERNATIONAL STANDARD ISO 10703:2021(E)
Water quality — Gamma-ray emitting radionuclides — Test
method using high resolution gamma-ray spectrometry
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
IMPORTANT — It is absolutely essential that tests conducted according to this document be
carried out by suitably trained staff.
1 Scope
This document specifies a method for the physical pre-treatment and conditioning of water samples
and the determination of the activity concentration of various radionuclides emitting gamma-rays with
energies between 40 keV and 2 MeV, by gamma-ray spectrometry according to the generic test method
described in ISO 20042.
The method is applicable to test samples of drinking water, rainwater, surface and ground water as well
as cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample
handling, and test sample preparation (filtration when necessary and taking into account the amount
of dissolved material in the water). This method is only applicable to homogeneous samples or samples
which are homogeneous via timely filtration.
The lowest limit that can be measured without concentration of the sample or by using only passive
-2 137 1)
shield of the detection system is about 5·10 Bq/l for e.g. Cs . The upper limit of the activity
corresponds to a dead time of 10 %. Higher dead times may be used but evidence of the accuracy of the
dead-time correction is required.
Depending on different factors, such as the energy of the gamma-rays, the emission probability per
nuclear disintegration, the size and geometry of the sample and the detector, the shielding, the counting
time and other experimental parameters, the sample may require to be concentrated by evaporation
-2
if activities below 5·10 Bq/l need to be measured. However, volatile radionuclides (e.g. radon and
radioiodine) can be lost during the source preparation.
This method is suitable for application in emergency situations.
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 edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste water
ISO 5667-14, Water quality — Sampling — Part 14: Guidance on quality assurance and quality control of
environmental water sampling and handling
1) The sample geometry: 3l Marinelli beaker; detector: GE HP N relative efficiency 55 % ; counting time: 18h.
ISO 10703:2021(E)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 80000-10 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
blank sample
container of an identical composition to the one used for the water test sample, filled with demineralized
water
3.2
dead time
time during spectrum acquisition (real time) during which pulses are not recorded or processed
Note 1 to entry: Dead time is expressed in percent, calculated as follows: real time minus live time, all divided by
real time then multiplied by 100
3.3
dead time correction
correction to be applied to the observed number of pulses to take into account the number of pulses lost
during the dead time (3.2)
3.4
decay constant
λ
quotient of the rate at which a population of radioactive atoms decreases because of radioactive decay
by the size of that population of radioactive atoms
Note 1 to entry: It can also be expressed as the quotient of dP by dt,
dP 1 dN
λ== −
dtN dt
where
dP is the probability of a given nucleus undergoing a spontaneous nuclear transition from that en-
ergy state in the time interval dt;
N is the number of nuclei of concern existing at time t.
Note 2 to entry: The time required for half of the original population of radioactive atoms to decay is called
the half-life. The relationship between the half-life, T1/2, and the decay constant is given by T1/2 = ln(2)/λ.
3.5
efficiency
ratio of the number of gamma photons detected in the full energy peak to the number of the same type
emitted by the radiation source in the same time interval, under stated conditions of detection
2 © ISO 2021 – All rights reserved

ISO 10703:2021(E)
3.6
energy resolution
measure, at a given energy, of the smallest difference between the energy of two gamma-rays which can
be distinguished by the apparatus used for gamma‑ray spectrometry (3.10)
Note 1 to entry: The energy resolution is measured as the full width at half maximum height of the energy peak
(FWHM).
3.7
full energy peak
peak of spectral response corresponding to the total absorption of the photon energy in the detector
by the photoelectric effect or by consecutive photon interactions of pair production (only for photon
energy >1 022 keV), Compton scattering and photoelectric absorption
3.8
gamma cascade
two or more different gamma-photons emitted successively from one nucleus when it de-excites
through one or more intermediate energy levels
3.9
gamma radiation
electromagnetic radiation emitted in the process of nuclear transition or particle annihilation
3.10
gamma-ray spectrometry
method of measuring gamma-rays yielding the energy spectrum of the gamma radiation (3.9)
3.11
pile-up
processing by a radiation spectrometer of pulses resulting from the simultaneous absorption of
particles, or photons, originating from different decaying nuclei, in the radiation detector
Note 1 to entry: As a result, pulses are counted as one single particle or photon with an energy between the
individual energies and the sum of these energies.
3.12
transition probability
probability of de-excitation of the nucleus occurring by one specific transition at a given energy state to
a less energetic state or to the ground state
4 Symbols
For the purposes of this document, the following symbols apply.
V Volume of the water sample for test l
A Activity of each radionuclide in calibration source, at the calibration time Bq
-1
cc, Activity concentration of each radionuclide, without and with corrections Bq·l
AA,c
t Test sample spectrum counting time s
g
t Background spectrum counting time s
t Time between the reference time and the start of the measuring time s
i
t Calibration spectrum counting time s
S
nn,,n Number of counts in the net area of the peak, at energy E, in the test sample
NE,,NE0sNE,
spectrum, in the background spectrum and in the calibration spectrum,
respectively
ISO 10703:2021(E)
nn,,n Number of counts in the gross area of the peak, at energy E, in the test
gg,,EE0 gs,E
sample spectrum, in the background spectrum and in the calibration
spectrum, respectively
nn,,n
Number of counts in the background of the peak, at energy E, in the test
bb,,EE0 bs,E
sample spectrum in the background spectrum and in the calibration spec-
trum, respectively
ε
Detection efficiency at energy E at actual measurement geometry
E
f Correction factor considering all necessary corrections
E
Correction factor for decay for a reference date
f
d
Correction factor for coincidence losses (summing-out)
f
cl ,E
Correction factor for summing-in effects by coincidences
f
su,E
Correction factor for dead time and pile up
f
dt ,pu E
P Probability of the emission of a gamma-ray with energy E of each radio-
E
nuclide, per decay
-1
λ Decay constant of each radionuclide s
-1
Standard uncertainty associated with the measurement result (without Bq·l
uc(),,uc uf()it
()
AA,c
and with corrections) and with fitting efficiency curve respectively
-1
U Expanded uncertainty calculated with k = 2. Bq·l
-1
∗∗
Decision threshold, without and with corrections Bq·l
cc,
AA,c
-1
# #
Detection limit, without and with corrections Bq·l
cc,
AA,c
-1

Lower and upper limits of the probabilistically symmetric coverage interval Bq·l
cc,
AA
-1
<>
Lower and upper limits of the shortest coverage interval Bq·l
cc,
AA
5 Principle
Gamma-rays produce electron-hole pairs when interacting with matter. When a voltage is applied
across a semiconductor detector, these electron hole-pairs are, after proper amplification, detected as
current pulses. The pulse height is related to the energy absorbed from the gamma-photon or photons
in the resolving time of the detector and electronics. By discriminating between the height of the pulses,
a gamma-ray pulse height spectrum is obtained. After analysis of the spectrum, the various peaks
are assigned to the radionuclides which emitted the corresponding gamma-rays using an established
detector energy calibration response curve. The concentration of the radionuclides present in the
sample is calculated using the established energy-dependent detector efficiency curve.
The determination of the activity concentration of radionuclides emitting gamma-rays with energy
below 40 keV and above 2 MeV is also possible within the scope of this document, provided both the
calibration of the measuring system and the shielding are adapted to this purpose.
6 Reference sources
6.1 Source(s) for energy calibration
The energy calibration of the spectrometer shall be established using one or more sources containing
radionuclides that emit gamma-rays that cover the energy range of interest. Sources can be of any form
but the dead time of the spectrometer for the measurements shall be such that the full energy peak
shape is not distorted and pulse pile-up is avoided.
The number of peaks (full energy peaks) required depends on the order of polynomial needed for the
energy vs. channel calibration curve; normally 5 to 10 peaks should be sufficient. Sources containing
4 © ISO 2021 – All rights reserved

ISO 10703:2021(E)
152 241 60 137
long-lived radionuclides (for example Eu, Am, Co or Cs) are recommended for this purpose.
For periodical checks of the energy calibration, a smaller number of energy peaks may be used.
6.2 Reference source(s) for efficiency calibration
6.2.1 General
The general method to calibrate the spectrometer is to establish the detection efficiency as a function
of energy for a defined geometry and energy range. One or more reference sources containing single or
multiple radionuclides may be used for this purpose. The activity or emission rates of the radionuclide(s)
in the reference source(s) shall be traceable to national or international standards.
The energies of the emitted gamma-rays shall be distributed over the entire energy range of interest, in
such a way that the energy-dependent efficiency of the spectrometer can be determined in a sufficiently
accurate way. For most purposes, the accuracy is sufficient for an energy range of 60 keV to 1 836 keV if
241 109
a multi-radionuclide source is used containing all or most of the following radionuclides: Am, Cd,
57 139 203 51 113 85 137 54 59 60 65 88
Co, Ce, Hg, Cr, Sn, Sr, Cs, Mn, Fe, Co, Zn or Y.
For determining the activity of radionuclides emitting gamma-ray or X–rays in the energy region
less than 60 keV, the spectrometry system can be calibrated using a reference source containing the
radionuclides of interest.
It may be necessary to take into account true coincidence summing corrections for the calibration
60 88
radionuclides (for example Co and Y).
6.2.2 Reference sources for laboratory systems
Reference sources for laboratory-based spectrometry systems shall match, as closely as possible, the
geometry, density and matrix of the samples to be measured. Reference sources may be prepared
from standardised solutions or purchased as sealed sources. Only standardised solutions or reference
sources that are traceable to national or international primary standards of radioactivity shall be used.
If no reference materials are available to match the samples, correction factors shall be calculated,
documented and be applied to results from the measurements to take into account differences in
detection efficiency due to geometry, density and matrix effects.
If a reference source is prepared by dilution from a standardised solution, the supplier’s recommendation
on the chemical form of the diluent shall be followed. It is also recommended that the dispensing process
includes checks for possible losses of active material and on the accuracy of dispensing (for example
gravimetric, volumetric and radiometric techniques should be used and cross-checked).
6.2.3 Reference sources used with numerical methods
Reference sources for gamma-ray spectrometry systems based on numerical models shall be used
following the manufacturer’s recommendations. The activity or the emission rates of the reference
sources shall be traceable to national or international standards.
7 Reagents
The following reagents shall be used when the sample is concentrated by evaporation with iodine
retention. Use only reagents of recognized analytical grade and only water complying with grade 3 of
ISO 3696.
7.1 Nitric acid, concentrated, c(HNO ) = 15,8 mol/l, 69 % volume fraction or mass fraction,
[ρ(HNO ) = 1,42 g/ml].
7.2 Sulfuric acid, concentrated, c(H SO ) = 17,9 mol/l, 95 % volume fraction or mass fraction,
2 4
[ρ(H SO ) = 1,84 g/ml].
2 4
ISO 10703:2021(E)
7.3 Silver nitrate solution, c(AgNO ) = 3,2 g/l.
Dissolve 3,2 g of silver nitrate in water acidified with 0,1 ml of nitric acid and dilute to a total volume of
1 l with water.
7.4 Potassium iodide solution, c(KI) = 1,3 g/l.
Dissolve 1,3 g of potassium iodide in 1 l of water.
7.5 Sodium sulfite, Na SO .
2 3
7.6 Hydrogen peroxide solution, c(H O ) = 0,3 g/l.
2 2
7.7 Sodium carbonate solution, Na CO , saturated at 20 °C.
2 3
8 Gamma-ray spectrometry equipment
8.1 General description
The operation of the measurement system is as follows: in semi-conductor detectors, freed charge is
generated by the interaction of ionising radiation with the detector material (through the photoelectric
effect, the Compton effect or pair production). A high-voltage supply applies a bias voltage to the
detector crystal resulting in an electric field. The freed charge is accelerated by the electric field
towards the detector electrodes. The collected charge is converted into an output voltage pulse by a
preamplifier and the output pulse is shaped and amplified by the main amplifier.
Two types of electronic systems can be used to process the signal from the detector preamplifier; an
analogue amplifier combined with an analogue-to-digital converter (ADC), or a digital DSP (Digital
Signal Processor) system. Both systems convert the pulse amplitude and the pulse-height histogram
(spectrum) is stored using a multichannel analyzer (MCA). The height of the pulse is proportional to the
amount of freed charge and hence to the energy of the ionising radiation striking the detector.
The spectrum stored by the MCA shows a set of peaks (full energy peaks) superimposed on a
background continuum from scattered radiation. The full energy peaks are approximately Gaussian
in shape. The channel number of the peak centroid depends on the energy of the photon detected. The
net full energy peak area is proportional to the number of photons of that energy that have interacted
with the detector during the counting period (corrected for dead time). The net full energy peak area is
normally determined in the analysis software package by one of two different techniques – summation
or fitting
For laboratory use, the spectrometer should be located in a facility with stable temperature following
the manufacturer recommendations. It should be noted that changes in temperature can affect the
amplifier gain, changing the energy calibration substantially.
The apparatus shall consist of the following necessary parts from 8.2 to 8.8.
8.2 Detector types
The three main geometries of germanium detectors available are planar, coaxial and well-type. Each
has specific advantages depe
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