SIST EN ISO 23548:2025

SLOVENSKI STANDARD
01-december-2025
Merjenje radioaktivnosti - Radionuklidi, ki oddajajo sevanje alfa - Generična
preskusna metoda z uporabo alfa spektrometrije (ISO 23548:2024)
Measurement of radioactivity - Alpha emitting radionuclides - Generic test method using
alpha spectrometry (ISO 23548:2024)
Messung der Radioaktivität - Alpha emittierende Radionuklide - Generisches
Prüfverfahren mit Alphaspektrometrie (ISO 23548:2024)
Mesurage de la radioactivité - Radionucléides émetteurs alpha - Méthode d’essai
générique par spectrométrie alpha (ISO 23548:2024)
Ta slovenski standard je istoveten z: EN ISO 23548:2025
ICS:
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 23548
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2025
EUROPÄISCHE NORM
ICS 17.240
English Version
Measurement of radioactivity - Alpha emitting
radionuclides - Generic test method using alpha
spectrometry (ISO 23548:2024)
Mesurage de la radioactivité - Radionucléides Messung der Radioaktivität - Alpha emittierende
émetteurs alpha - Méthode d'essai générique par Radionuklide - Generisches Prüfverfahren mit
spectrométrie alpha (ISO 23548:2024) Alphaspektrometrie (ISO 23548:2024)
This European Standard was approved by CEN on 22 September 2025.

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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 23548:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 23548:2024 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 23548:2025 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
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 March 2026, and conflicting national standards shall
be withdrawn at the latest by March 2026.
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.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 23548:2024 has been approved by CEN as EN ISO 23548:2025 without any modification.

International
Standard
ISO 23548
First edition
Measurement of radioactivity —
2024-09
Alpha emitting radionuclides —
Generic test method using alpha
spectrometry
Mesurage de la radioactivité — Radionucléides émetteurs alpha
— Méthode d’essai générique par spectrométrie alpha
Reference number
ISO 23548:2024(en) © ISO 2024
ISO 23548:2024(en)
© ISO 2024
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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 23548:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and units. 3
5 Principle . 4
6 Chemical reagents and equipment . 5
6.1 General .5
6.2 Chemical reagents .5
6.2.1 Water quality .5
6.2.2 Tracer solution.5
6.3 Equipment .6
7 Sampling and samples . . 9
8 Procedure . 9
8.1 General .9
8.2 Calcination .10
8.3 Sample dissolution processes.10
8.4 Specific radiochemical separation procedures .11
8.5 Methods of deposition . 12
8.5.1 Direct deposition . 12
8.5.2 Spontaneous deposition of polonium. 12
8.5.3 Microprecipitation . 13
8.5.4 Electrodeposition . 13
8.6 Measurement .14
8.6.1 Measurement geometry .14
8.6.2 Spectrum exploitation .14
8.6.3 Energy calibration. 15
8.6.4 Efficiency calibration .16
8.6.5 Global background .17
8.6.6 Chemical yield and total efficiency .17
8.6.7 Quality control sources .18
8.7 Recommended nuclear decay data .18
9 Expression of results . 19
9.1 Calculation of activity .19
9.1.1 General .19
9.1.2 Alpha activity .19
9.1.3 Uncertainty .19
9.1.4 Decision threshold . 20
9.1.5 Detection limit . 20
9.2 Calculation of sample activity .21
9.2.1 General .21
9.2.2 Calculation of derived alpha activity.21
9.2.3 Relative uncertainty . .21
9.2.4 Decision threshold .21
9.2.5 Detection limit . 22
9.2.6 Coverage interval limits . . 22
10 Test report .23
Annex A (informative) Generic alpha test method processes .24
Annex B (informative) Examples of melting flux .25

iii
ISO 23548:2024(en)
Annex C (informative) Preparation of the source by coprecipitation .26
Annex D (informative) Preparation of the source by electrodeposition .30
Annex E (informative) Alpha peak integration with minimized uncertainty.33
Bibliography .35

iv
ISO 23548:2024(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
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.

v
ISO 23548:2024(en)
Introduction
Everyone is exposed to natural radiation. The natural sources of radiation are cosmic rays and naturally
occurring radioactive substances which exist in the earth and flora and fauna, including the human body.
Human activities involving the use of radiation and radioactive substances add to the radiation exposure
from this natural exposure. Some of those activities, such as the mining and use of ores containing naturally-
occurring radioactive materials (NORM) and the production of energy by burning coal that contains
such substances, simply enhance the exposure from natural radiation sources. Nuclear power plants and
other nuclear installations use radioactive materials and produce radioactive effluents and wastes during
operation and decommissioning. The use of radioactive materials in industry, agriculture, medicine and
research is expanding around the globe.
All these human activities give rise to radiation exposures that are only a small fraction of the global average
level of natural exposure. The medical use of radiation is the largest and a growing man-made source of
radiation exposure in developed countries. It includes diagnostic radiology, radiotherapy, nuclear medicine
and interventional radiology.
Radiation exposure also occurs as a result of occupational activities. It is incurred by workers in industry,
medicine and research using radiation or radioactive substances, as well as by passengers and crew during
air travel. The average level of occupational exposures is generally similar to the global average level of
natural radiation exposure (see Reference [1]).
As uses of radiation increase, so do the potential health risk and the public's concerns. Thus, all these
exposures are regularly assessed in order to
a) improve the understanding of global levels and temporal trends of public and worker exposure,
b) evaluate the components of exposure so as to provide a measure of their relative importance, and
c) identify emerging issues that may warrant more attention and study.
While doses to workers are mostly directly measured, doses to the public are usually assessed by indirect
methods using the results of radioactivity measurements of waste, effluent and/or environmental samples.
To ensure that the data obtained from radioactivity monitoring programs support their intended use, it is
essential that the stakeholders, for example, nuclear site operators, regulatory and local authorities agree
on appropriate methods and procedures for obtaining representative samples and for handling, storing,
preparing and measuring the test samples. An assessment of the overall measurement uncertainty also
needs to be carried out systematically. As reliable, comparable and ‘fit for purpose’ data are an essential
requirement for any public health decision based on radioactivity measurements, international standards of
tested and validated radionuclide test methods are an important tool for the production of such measurement
results. The application of standards serves also to guarantee comparability of the test results over time and
between different testing laboratories. Laboratories apply them to demonstrate their technical competences
and to complete proficiency tests successfully during interlaboratory comparisons, two prerequisites for
obtaining accreditation.
Today, over a hundred International Standards are available to testing laboratories for measuring
radionuclides in different matrices.
Generic standards help testing laboratories to manage the measurement process by setting out the general
requirements and methods to calibrate equipment and validate techniques. These standards underpin
specific standards which describe the test methods to be performed by staff, for example, for different types
of sample. The specific standards cover test methods for
40 3 14
— natural radionuclides (including K, H, C and those originating from the thorium and uranium decay
226 228 234 238 210
series, in particular Ra, Ra, U, U and Pb), can be found in the environmental components
for natural reasons 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), and
vi
ISO 23548:2024(en)
— human-made radionuclides, such as transuranium elements (americium, plutonium, neptunium, and
3 14 90
curium), H, C, Sr and gamma-ray emitting radionuclides found in waste, liquid and gaseous effluents,
in environmental matrices (water, air, soil and biota), in food and in animal feed as a result of authorized
releases into the environment, fallout from the explosion in the atmosphere of nuclear devices and
fallout from accidents, such as those that occurred in Chernobyl and Fukushima. Natural components
and foodstuff may thus contain radionuclides at activity concentrations which could present a risk to
human health. In order to assess the radiological levels of environment and food, including the quality of
drinking-water (mineral waters and spring waters) with respect to its radionuclide content and to provide
guidance on reducing health risks by taking measures to decrease radionuclide activity concentrations,
natural resources and food are monitored for their radioactivity content as recommended by the World
Health Organization (WHO) and the International Atomic Energy Agency (IAEA).
An international standard on a generic test method using alpha spectrometry for the determination of the
activity concentration of alpha emitting radionuclides in natural and food samples or other kind of samples
from nuclear facilities is justified for test laboratories carrying out these measurements, required sometimes
by national authorities, as laboratories may have to obtain a specific accreditation for radionuclide
measurements in natural, food or nuclear facilities samples.
Artificial alpha emitting radionuclide activity concentrations can vary according to authorized local effluent
discharges from nuclear plant and environmental characteristics.
This document is one of a set of generic International Standards on measurement of radioactivity such as
[2] [3]
ISO 19361 and ISO 20042 .
vii
International Standard ISO 23548:2024(en)
Measurement of radioactivity — Alpha emitting radionuclides
— Generic test method using alpha spectrometry
1 Scope
This document describes a generic test method for measuring alpha emitting radionuclides, for all types
of samples (soil, sediment, construction material, foodstuff, water, airborne, environmental bio-indicator,
human biological samples as urine, faeces etc.) by alpha spectrometry. This method can be used for any type
of environmental study or monitoring of alpha emitting radionuclides activities.
If relevant, this test method requires appropriate sample pre-treatment followed by specific chemical
separation of the test portion in order to obtain a thin source proper to alpha spectrometry measurement.
This test method can be used to determine the activity, specific activity or activity concentration of a sample
210 226 228 229 230 232 232 234 235 238
containing alpha emitting radionuclides such as Po, Ra, Th, Th, Th, Th, U, U, U, U,
238 239+240 241 243+244
Pu, Pu, Am or Cm.
This test method can be used to measure very low levels of activity, one or two orders of magnitude less than
the usual natural levels of alpha emitting radionuclides. Annexes B of UNSCEAR 2000 and UNSCEAR 2008
(References [4] and [5]) give, respectively, typical natural activity concentrations for air, foods, drinking
waters and, soils and building materials. The detection limit of the test method depends on the amount of the
sample material analysed (mass or volume) after concentration, chemical yield, thickness of measurement
source and counting time.
The quantity of the sample to be collected and analysed depends on the expected activity of the sample and
the detection limit to achieve.
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/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO 661, Animal and vegetable fats and oils — Preparation of test sample
ISO 707, Milk and milk products — Guidance on sampling
ISO 874, Fresh fruits and vegetables — Sampling
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5500, Oilseed residues — Sampling
ISO 5538, Milk and milk products — Sampling — Inspection by attributes
ISO 5555, Animal and vegetable fats and oils — Sampling
ISO 5667 (all parts), Water quality — Sampling
ISO 11929 (all parts), Determination of the characteristic limits (decision threshold, detection limit and limits of
the confidence interval) for measurements of ionizing radiation — Fundamentals and application

ISO 23548:2024(en)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 17604, Microbiology of the food chain — Carcass sampling for microbiological analysis
ISO 18400 (all parts), Soil quality — Sampling
ISO 18589-2, Measurement of radioactivity in the environment — Soil — Part 2: Guidance for the selection of
the sampling strategy, sampling and pre-treatment of samples
ISO 24333, Cereals and cereal products — Sampling
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 ISO 11929 series
and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
thin test source
measurement source with a very thin layer deposited on a substrate containing the radionuclides of interest
in order to obtain an optimal spectral resolution previously defined by the laboratory according to the
expected level of activity
3.2
substrate
medium containing the source to be measured on its surface e.g. stainless steel disk, test dish or membrane filter
3.3
reference source
radioactive secondary standard source for use in the calibration of the measuring instruments, i.e. material
-1 -1
(solid, liquid) containing one or more radionuclides of known activity (Bq or Bq·g or Bq·ml ), prepared
such that the activity is traceable to national or international primary standards of radioactivity
3.4
alpha emitter radionuclide
radioactive nuclide with a specified atomic number and mass which emits alpha particles
3.5
energy resolution
FWHM
full width at half of the maximum of the alpha peak distribution
Note 1 to entry: The width is given in kiloelectronvolts (keV).
3.6
adsorption
process in which a substance forms a very thin layer onto the surface of a solid by attraction of the molecules
3.7
resolution
ratio between energy resolution (3.5) and energy corresponding to the maximum of the peak distribution
Note 1 to entry: The resolution is the spectral resolution and it is given in per cent.

ISO 23548:2024(en)
3.8
tracer
radionuclide, which has the same chemical properties as the alpha radionuclides of interest and whose
activity in the test source is used to determine the chemical yield or the total efficiency
3.9
carrier
a stable chemical element which is added to the test sample to ensure that the radionuclide of interest will
behave normally in the radiochemical separation procedures
4 Symbols and units
Table 1 — Symbols and definitions
Symbol Definition Unit
A activity of certified calibration source, at the date of the measurement Bq
activity of the tracer added, at the date of measurement Bq
A
T
a
activity of the measured radionuclides on thin test source, at the date of measurement Bq
 true activity (see ISO 11929-1) Bq
a
*
decision threshold of the activity Bq
a
#
detection limit of the activity Bq
a
a derived activity measured from the thin test source in the unit of w (see w )
j 1 1
*
decision threshold of the derived activity in the unit of w (see w )
a 1 1
j
#
detection limit of the derived activity in the unit of w (see w )
a 1 1
j
  lower and upper limits of the probabilistically symmetric coverage interval of derived
(see w )
a , a 1
j j
activity in the unit of w
< >
lower and upper limits of the shortest coverage interval of derived activity in the unit (see w )
a , a 1
j j
of w
ε
detection efficiency
G geometrical factor of alpha detection as a function of the effective solid angle of
measurement, Ω with Ω =4π· G
summation of alpha emission intensity
I
α
k coverage factor with k=…12,,3
quantiles of the standardized normal distribution for the probabilities: 1−α , 1−β
k , k
1−α 1−β
and 12−γ /
and
k
12−γ/
n
number of counts in the region of interest of the spectrum
number of gross counts in the region of interest of the spectrum
n
g
n number of counts of the global background in the region of interest of the spectrum
N number of channels of alpha peak integration
R
total efficiency with RR= ·ε
c
chemical yield
R
c
r -1
count rate in the region of interest of the spectrum s
-1
r background count rate of the test sample region s
-1
background count rate of the blank sample region s
r
0T
-1
background count rate of the detection efficiency region s
r
0ε
ISO 23548:2024(en)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Definition Unit
-1
r gross count rate of the test sample region s
g
-1
gross count rate of the detection efficiency region s
r
gε
-1
r gross count rate of the tracer region s
gT
S reference area of alpha peak integration
ref
t counting time s
t background counting time of the test sample s
background counting time of detection efficiency s
t
0ε
background counting time of tracer s
t
0T
t counting time of the test sample s
g
counting time of detection efficiency s
t
gε
t counting time of tracer s
gT
uy() standard uncertainty associated with parameter y result ()k = 1 in unit of the
measurand y
Uy() expanded uncertainty calculated by Uy()=ku· ()y with k> 1 , in unit of the
measurand y
relative standard uncertainty associated with parameter y result calculated by
uy()
rel
−1
uy()=uy()· y
rel
Uy() relative expanded uncertainty calculated by Uy()=ku·1()y withk >
rel relrel
w
correction factor for activity of the thin test source (see w )
correction factor for derived activity of the test sample in the inverse of the sample
w
unit, i.e.:
-1
— per kilogram for a solid sample for a specific activity concentration; kg
-1
— per litre for a liquid sample for an activity concentration; l
-2
— per square metre for a contaminated surface sampled with a wipe-test; m
-3
— per cubic metre for an activity concentration of particles in air or gases sampled; m
— per one unit for specific thin test sample directly measured.
5 Principle
Generally, the test sample solution, containing alpha emitter radionuclides of interest, is mixed with an
aliquot of a solution of similar physico-chemical properties and containing a radioactive tracer. This solution
has at least one isotope of the radionuclides of interest contained in the sample, except if the chemical
properties of the tracing radionuclide are close enough to the alpha radionuclides of interest, for example
as in the case of curium and americium (see Table 2). This is followed by a specific preparation according
to the type of sample matrix by dissolution entailing either dissolution with an acid or fusion by melting an
inorganic base (e.g. alkaline fusion).
After a valence cycle to adjust the oxidation states, chemical separation of the radionuclide is achieved by a
concentration step (e.g. a precipitation) followed by one or more specific separation steps (e.g. ion exchange
chromatography, extraction chromatography, liquid-liquid extraction or selective precipitation).
The sample can also be measured directly by alpha spectrometry, i.e. without sample preparation or pre-
treatment, no addition of carrier or radionuclide tracer, no chemical separation, or some combination of these
considerations. If relevant, in this case, the user shall ensure that the quality of the measurement source
allows to quantify its activity or to qualitatively determine the energies of the alpha-emitter present with a
sufficient resolution previously defined by the user without degrading the performance of the detector by
radioactive contamination due to a poor quality of the deposit or by volatile decay parent products, e.g. Po,

ISO 23548:2024(en)
radon isotopes and their daughter nuclides. Other alpha emitting radionuclides can be present in the sample
and can interfere with the counting of the radionuclide of interest to measure if no chemical separation is
carried out to remove these interfering radionuclides from the test sample.
The thin test source is usually prepared by electro-deposition, by coprecipitation or by spontaneous
deposition and assayed by alpha spectrometry using a grid chamber or a semiconductor-type device. The
measurement relies on the interaction of the alpha particles with the detecting medium. This interaction
creates an electric charge, which is amplified and output as a voltage pulse proportional to the deposited
energy of the incoming alpha particle.
The electric pulse from the detector is analysed by the electronic systems and stored by a multichannel
analyser (MCA). Data analysis software shows the alpha emitter radionuclides spectrum which is the
distribution of number of pulses (counts) as a function of energy.
The analysis of the count rates in the region of interest (ROI) of the alpha spectra for the radionuclide
considered allows the determination of the test sample activity concentration after correcting by blank
count rate, chemical yield and detection efficiency.
The chemical yield and the detection efficiency are not necessarily determined separately. In this case, they
are often obtained as of the total efficiency combined from the net count rate of the radionuclide added as
a chemical yield tracer. In order to quantify any potential interference coming from the reagents, a blank
sample is prepared in the same way as the test sample. This blank sample is prepared using an appropriate
blank material.
For quality control, in order to quantify potential impurities in the tracer solution, another blank sample
shall be prepared with addition of the tracer.
Even with a good energy resolution of approximately (20 to 30) keV (FWHM) several isotopes of one
radioactive element cannot easily be resolved by alpha spectrometry due to the very close similarity of their
233 234 235 236 239 240 243 244
alpha emission energies, e.g. U and U, U and U, Pu and Pu or even Cm and Cm.
The dissolution, radiochemical and evaluation parts of an analytical process are summarized in Figure A.1.
6 Chemical reagents and equipment
6.1 General
Use only reagents of recognized analytical grade.
6.2 Chemical reagents
6.2.1 Water quality
Laboratory water is used as a blank, as free as possible from chemical and radioactive impurities, complying
with ISO 3696, grade 3 or an equivalent purity (e.g. distilled or demineralized water).
6.2.2 Tracer solution
The radionuclide tracer solution for determining the total yield can also be used to calculate the chemical
yield. The solution is prepared by the dilution of a suitable, traceable standard. The tracer solution shall be
homogeneous and chemically stable by adding suitable acids.
The concentration of the tracer solution should be chosen such that a small yet accurately determined
amount may be added with activity in the range of the test sample.
It is important to check the activity and the purity of the tracer solutions periodically after preparation.
Those checks which ensure method validity and performance, can be done by liquid scintillation counting,
grid ionization chamber counting or alpha spectrometry. Performing a blank analysis with tracer is a
potential way to identify any presence of radioactive impurity in the tracer.

ISO 23548:2024(en)
228 232
For example, Th can be present in the U tracer solution and has a very close energy to that of its parent
U. Therefore, a complete separation of Th and U prior to or during the chemical purification process is
228 232
required (References [6] and [7]) to minimize the interference of Th so that the counting yield of U
is not overestimated (see Clause 4). Table 2 gives a list of alpha emitter tracers with possible radioactive
impurities and their decay products.
Before using a purified tracer, the user shall ensure that the purified tracer has been properly referenced to
the activity in becquerel, if the activity of the tracer no longer corresponds to that of the certificate which
accompanies the standardized material.
Table 2 — Alpha emitter tracers and possible radioactive impurities
Radionuclide of interest Used tracer Alpha impurity Origin
234 235 238 233 236 232 232
U, U and U, U, U U U
Th
238 239+240 242 236 241
Pu and Pu Pu, Pu Pu
Am
241 242 243+244 243 a
Am, Cm and Cm Am
237 235 236
Np Np, Np
238 239
Np, Np
227 228 230 232 229 229 225 221 217 229
Th, Th, Th, Th Th Decay products of Th: Ac, Fr, At Th
213 225
and Po from which Ac can
interfere with the determination of Th
226 133 b
Ra Ba
or
224 228
Ra (from Th)
210 208 209
Po Po, Po
a
The chemical property of curium is so similar to that of americium that there is no need of a curium tracer, i.e. the americium
[8]
tracer is used as a chemical yield monitor for those both radionuclides .
b 133
The measurement of Ba activity is achieved by gamma spectrometry.
6.3 Equipment
Usual laboratory device and in particular the following.
6.3.1 Detector.
Alpha spectrometry can be performed with a grid chamber device (high detection efficiency, low resolution),
an ion implanted semiconductor device (low detection efficiency, high resolution) or a liquid scintillation
counter (near 100 % detection efficiency, low resolution). Those measurement devices operate at constant
temperature following the manufacturer's instructions.
6.3.1.1 Grid ionization chamber.
A grid ionization chamber is a pulse ionization chamber. It detects variations in charges due to the ionization
of a gas by alpha particles. Under the action of an electric field the charges created migrate to their respective
electrodes. The amplitude of the corresponding signal depends on the energy of the incident particle but
also on the distance of its interaction between the cathode and the anode. This difficulty was solved with a
grid placed between the anode and the cathode where the alpha particles interact only in the space between
the cathode and the grid. This grid subjected as an intermediate potential captures only a negligible
number of electrons during their migration to the anode. Signals thus created become usable for alpha
spectrometry. The energy resolution is not less than 30 keV. The detection efficiency depends on the quality
of the measurement source to be measured (thickness, chemical and elemental purities) and on the region
of interest (ROI) of the spectra defined by the user. As the measurement source is inside of the detector
the detection efficiency can reach 50 % i.e. a detection geometry of 2π steradian or more considering
possible backscatters. In addition, the grid chamber works with an ionization
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