ISO/FDIS 13169

• Abstract:

  This document specifies the measurement method for the determination of total activity concentration of uranium isotopes in non-saline waters by extraction and liquid scintillation counting. This method covers the measurement of soluble uranium isotopes in water in activity concentrations between approximately 2·10−3 Bq/kg and 10 Bq/kg when analysing a 1 l test sample volume with a 60 000 s counting time with a typical alpha LSC instrument. The ratio 234U/238U can also be determined. This method has not been tested for the measurement of other uranium isotopes.

• Status: Not Published
• ICS: 13.060.60 - Examination of physical properties of water
• ICS: 17.240 - Radiation measurements
• Technical Committee: ISO/TC 147/SC 3 - Radioactivity measurements
• Drafting Committee: ISO/TC 147/SC 3/WG 15 - Liquid scintillation counting and proportional counting
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 02-Oct-2026
• Completion Date: 02-Oct-2026

• Consolidates: FprEN ISO 13169 - Water quality - Uranium - Test method using alpha liquid scintillation counting (ISO/FDIS 13169:2026)
• Effective Date: 12-Feb-2026
• Consolidates: ISO 7124:2023 - Eggs and egg products — Determination of fipronil and metabolites residues — Liquid chromatography tandem mass spectrometry method
• Effective Date: 16-Oct-2025
• Revises: ISO 13169:2018 - Water quality — Uranium — Test method using alpha liquid scintillation counting
• Effective Date: 22-Jun-2024

ISO/FDIS 13169 is an ISO draft International Standard for measuring uranium isotopes in non-saline waters by extraction and alpha liquid scintillation counting. It specifies how laboratories determine the total activity concentration of soluble uranium isotopes in water, and it can also be used to determine the 234U/238U ratio.

What does ISO/FDIS 13169 specify?

ISO/FDIS 13169 specifies a test method for uranium in water samples after proper sampling, handling and preparation. The method is intended for non-saline waters, and it is also applicable in emergency situations.

The document is organized into clauses on scope, normative references, terms and definitions, symbols, principle, sampling, reagents and equipment, instrument set up and calibration, procedure, quality assurance and quality control, expression of results, and test report. Annex A gives set-up parameters and validation data.

Annex	What it covers
Annex A	Set-up parameters and validation data, including example spectra, spillover, calibration parameters, characteristic limits, and validation checks

What are the key requirements of ISO/FDIS 13169?

ISO/FDIS 13169 requires a laboratory workflow that starts with representative sampling and ends with a documented result, uncertainty and decision limit. In practice, the method is not just a measurement step - it also defines how to prepare the sample, verify the instrument, calculate the result, and report it in a defensible way.

Sampling and sample handling

Clause 6 requires sampling, handling and storage according to ISO 5667-1, ISO 5667-3 and ISO 5667-10. The sample must reach the laboratory representative of the water body and without damage or change during transport or storage.

The sample is filtered to remove suspended matter, acidified with HNO3 to pH below 2, and stored cold if it is not analysed immediately. This matters because uranium needs to stay in a measurable dissolved form and because poor preservation can change the result.

Reagents, equipment and extractant cocktail

Clause 7 lists the required reagents and apparatus, including analytical-grade acids, ultrapure water, a liquid scintillation counter with α/β discrimination, and PTFE-coated polyethylene scintillation vials. The document also specifies the extractant scintillation cocktail components.

This matters because alpha-beta separation, low background and clean vial materials directly affect the detection limit and the ability to distinguish uranium from interference.

Instrument set up, calibration and blank measurement

Clause 8 requires preparation of alpha and beta calibration sources, optimization of counting conditions, and determination of alpha and beta spillover parameters. It also requires a blank prepared by the same route as the samples.

In practice, the laboratory has to choose a working point that minimizes cross-talk between alpha and beta windows, check detection efficiency, and establish blank acceptance limits. The method relies on regular verification and recalibration when equipment or materials change.

Sample procedure, with or without pre-concentration

Clause 9 gives two routes: direct measurement and pre-concentration by evaporation. The pre-concentration option is used when a lower detection limit is needed, especially for soft waters.

This is important because the laboratory can adapt the method to the water matrix and required sensitivity. The clause also describes the extraction of uranium into the scintillation cocktail and the actual counting step.

Quality assurance, interference control and use of qualified staff

Clause 10 requires a quality assurance and quality control program. It also warns that thorium isotopes can co-extract with uranium and can prevent correct uranium quantification when thorium alpha peaks are visible.

In practice, this means the laboratory must control interference and switch to another method when thorium is demonstrated. The document also states that the work shall be performed by suitably qualified staff under a quality assurance program such as ISO/IEC 17025.

Calculation of results, uncertainty and decision criteria

Clause 11 defines how to calculate activity per unit mass and, if needed, activity concentration using water density. It also sets out the calculation of standard uncertainty, decision threshold, limit of detection, and coverage intervals in line with ISO 11929-1.

This matters because the reported result is not only a number - it must be accompanied by uncertainty and compared with the decision threshold or detection limit in a statistically consistent way. The clause also allows reporting either probabilistically symmetric coverage intervals or the shortest coverage interval.

Test report content

Clause 12 requires the test report to follow ISO/IEC 17025 and to include the reference to ISO 13169, sample identification, units, result expression, relevant dates, and where needed the decision threshold and limit of detection.

For users, this means the report is structured so that a regulator, buyer or technical reviewer can see what was tested, when, by which method, and how the result should be interpreted.

What terms does ISO/FDIS 13169 define?

• Alpha efficiency (ε) - the combined extraction and counting efficiency for the alpha measurement; it tells the laboratory how much of the uranium activity is effectively counted.
• Decision threshold (a*) - the level used to decide whether the measured activity is distinguishable from zero with the chosen false positive probability.
• Limit of detection (a#) - the smallest activity the method can detect under the stated conditions with the chosen false negative probability.
• Coverage interval - the interval reported around the result to express uncertainty; the document uses both probabilistically symmetric and shortest coverage intervals.
• Spillover parameter (τα, τβ) - a measure of alpha-beta cross-talk in the discriminator settings; it shows how well the instrument separates alpha and beta events.
• Total activity concentration (cA) - the activity of uranium isotopes per litre of water, obtained from the activity per unit mass and the sample density.
• Standard uncertainty u(a) - the uncertainty attached to the activity result before expansion to a broader coverage interval.

Who uses ISO/FDIS 13169?

ISO/FDIS 13169 is used by water-testing laboratories that measure radioactivity in drinking water, surface water, groundwater, wastewater and other non-saline waters. It is also relevant to environmental monitoring teams, radiological laboratories, and quality managers who need a documented method for uranium measurement.

The method is especially useful where decisions depend on low-level activity concentrations, for example routine monitoring, compliance checks, emergency response, and comparison with national or WHO guidance levels. Buyers and lab managers use it to judge whether a laboratory can deliver uranium results with the required detection limit and uncertainty.

What changed in ISO/FDIS 13169 from the previous edition?

This second edition cancels and replaces ISO 13169:2018. The foreword states that the introduction was modified, the expression of results was updated, and the bibliography was updated.

Which standards are used with ISO/FDIS 13169?

• ISO/IEC Guide 98-3 - provides the framework for expressing measurement uncertainty.
• ISO 5667-1 - gives guidance on designing sampling programmes and sampling techniques.
• ISO 5667-3 - covers preservation and handling of water samples.
• ISO 5667-10 - gives guidance on sampling waste water.
• ISO 80000-10 - supplies quantities and units for atomic and nuclear physics used in the method.
• ISO 11929-1 - provides the basis for decision threshold, detection limit and coverage interval calculations.
• ISO/IEC 17025 - sets the competence and quality system expectations for testing laboratories.

What does the ISO/FDIS 13169 document contain?

The document contains the full laboratory method, including the principle of extraction followed by liquid scintillation counting, the sampling instructions, reagent and equipment lists, and the calibration and blank preparation steps. It also includes the procedure for direct analysis and pre-concentration by evaporation, so a laboratory can match the method to the sample and the required sensitivity.

It contains the calculation framework for spillover, efficiency, activity, uncertainty, decision threshold, detection limit and coverage intervals. The test report clause shows what must be stated when results are reported against the decision threshold or detection limit.

Annex A adds practical validation material. It shows example spectra, a spillover diagram, calibration parameters, characteristic limits for different sample masses, and validation data for linearity, precision, accuracy, detection limit and uncertainty.

FINAL DRAFT
International
Standard
ISO/TC 147/SC 3
Water quality — Uranium —
Secretariat: AFNOR
Test method using alpha liquid
Voting begins on:
scintillation counting
2026-10-02
Qualité de l'eau — Uranium — Méthode d'essai par comptage des
Voting terminates on:
scintillations alpha en milieu liquide
2026-11-27
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 SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 147/SC 3
Water quality — Uranium —
Secretariat: AFNOR
Test method using alpha liquid
Voting begins on:
scintillation counting
Qualité de l'eau — Uranium — Méthode d'essai par comptage des
Voting terminates on:
scintillations alpha en milieu liquide
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 SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
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Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Principle . 3
6 Sampling . 4
7 Chemical reagents and equipment . 4
7.1 Chemical reagents .4
7.2 Equipment and apparatus .5
8 Instrument set up and calibration . 5
8.1 Preparation of extractant scintillation cocktail .5
8.2 Preparation of alpha emitter calibration source .6
8.3 Preparation of beta emitter calibration source .6
8.4 Optimization of counting conditions .6
8.5 Detection efficiency .6
8.6 Blank sample preparation and measurement.7
9 Procedure . 7
9.1 Without pre-concentration .7
9.2 Pre-concentration by evaporation .7
9.3 Sample preparation .8
9.4 Sample measurement .8
10 Quality assurance and quality control program . 8
10.1 Interference control .8
10.2 Quality control .8
11 Expression of results . 8
11.1 Calculation of activity per unit of mass .8
11.2 Standard uncertainty .8
11.3 Decision threshold .9
11.4 Limit of detection .9
11.5 Limits of the coverage intervals .9
11.5.1 Limits of the probabilistically symmetric coverage interval .9
11.5.2 Shortest coverage interval .10
11.6 Calculations using the activity concentration .10
12 Test report .11
Annex A (informative) Set-up parameters and validation data .12
Bibliography .16

iii
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).
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 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 second edition cancels and replaces the first edition (ISO 13169:2018), which has been technically
revised.
The main changes are as follows:
— the introduction has been modified;
— the expression of results has been updated in Clause 8;
— the Bibliography has been updated.
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.

iv
Introduction
Radionuclides are present throughout the environment, thus, water bodies (e.g. surface waters, ground
waters and sea waters) contain radionuclides, which can be of either natural or anthropogenic origin.
3 14 40
— Naturally-occurring radionuclides, including H, C, K and those originating from the thorium and
210 210 222 226 228 227 232 231 234 238
uranium decay series, in particular Pb, Po, Rn, Ra, Ra, Ac, Th, Pa, U and U,
can be found in water bodies due to either natural processes (e.g. desorption from the soil and runoff by
rain water) or released from technological processes involving naturally occurring radioactive materials
(e.g. mining, mineral processing, oil, gas and coal production, water treatment, and production and use
of phosphate fertilisers).
55 59 63 90 99
— Anthropogenic radionuclides such as Fe, Ni, Ni, Sr, Tc, transuranic elements (e.g. Np, Pu, Am,
60 137
and Cm) and some gamma emitting radionuclides such as Co and Cs can also be found in natural
waters. Small quantities of anthropogenic radionuclides can be discharged from nuclear facilities into
the environment as a result of authorized routine releases. The radionuclides present in liquid effluents
[1]
are usually controlled before being discharged to the environment and water bodies. Anthropogenic
radionuclides used for medical and industrial applications can be released into the environment after
use. Anthropogenic radionuclides are also found in waters due to contamination fallout resulting from
above-ground nuclear detonations and accidents such as those that have occurred at the Chornobyl and
Fukushima nuclear facilities.
Radionuclide activity concentrations in water bodies can vary according to local geological characteristics
and climatic conditions and can be locally and temporally enhanced by releases from nuclear facilities
[2][3]
during planned, existing and emergency exposure situations . Some drinking-water sources can thus
contain radionuclides at activity concentrations that can present a human health risk. The World Health
[4]
Organization (WHO) recommends to routinely monitor radioactivity in drinking waters and to take
proper actions when needed to minimize the health risk.
National regulations usually specify the activity concentration limits that are authorized in drinking waters,
water bodies and liquid effluents to be discharged to the environment. These limits can vary for planned,
existing and emergency exposure situations. As an example, during either a planned or existing situation,
−1 238 −1 324 [4]
the WHO guidance level in drinking water is 10 Bq·l for U and 1 Bq·l for U , see NOTES 1 and 2.
Conformity to these limits is assessed by measuring radioactivity in water samples and by comparing the
[5]
results obtained, with their associated uncertainties, as specified by ISO/IEC Guide 98-3 and ISO 5667-20 .
−1
The provisional guideline value for total content of uranium in drinking water is 30 µg·l based on its
chemical toxicity, which is predominant compared with its radiological toxicity.
NOTE 1 If the value is not specified in Annex 6 of Reference [4], the value has been calculated using the formula
provided in Reference [4] and the dose coefficient data from References [6] and [7].
NOTE 2 The guidance level calculated in Reference [4] is the activity concentration that results in an effective dose
−1 −1
of 0,1 mSv·a to members of the public for an intake of 2 l·d of drinking water for one year. This is an effective
dose that represents a very low level of risk to human health and which is not expected to give rise to any detectable
[4]
adverse health effects .
This document contains a test method to support laboratories which need to determine uranium isotopes
activity in water samples. The method described in this document can be used for various types of waters
(see Clause 1). Minor modifications such as sample volume and counting time can be made if needed to
ensure that the decision threshold, limit of detection and uncertainties are below the required limits. This
can be done for several reasons such as emergency situations, lower national guidance limits and operational
requirements.
v
FINAL DRAFT International Standard ISO/FDIS 13169:2026(en)
Water quality — Uranium — Test method using alpha liquid
scintillation counting
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.
IMPORTANT — Tests conducted according to this document shall be carried out by suitably trained
staff.
1 Scope
This document specifies a method to measure uranium isotopes in non-saline waters by extraction and
liquid scintillation counting. This document covers the measurement of soluble uranium isotopes in water
−3 −1 −1
in activity concentrations between approximately 2·10 Bq·kg and 10 Bq·kg when analysing a 1 l test
sample volume with a 60 000 s counting time using a liquid scintillation counting instrument with α/β
234 238
discrimination function. This method can be used to determine the ratio of U/ U.
NOTE This method has not been tested for the measurement of other uranium isotopes.
This document applies to test samples of non-saline waters after proper sampling, handling and preparation.
This document is also applicable in the event of an emergency situation.
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 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 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/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/IEC Guide 98-3, ISO 11929-1 and
ISO 80000-10 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/
4 Symbols
236 −1
A activity concentration of U, the standard solution Bq·g
S
−1
a total massic activity of uranium isotopes Bq·g
−1

a
possible or assumed true quantity values of the activity per mass Bq·g
−1
a* decision threshold of the measurand Bq·g
# −1
a limit of detection of the measurand Bq·g
−1

Bq·g
lower and upper limits of the probabilistically symmetric coverage interval
aa,
−1

lower and upper limits of the shortest coverage interval Bq·g
aa,
−1
c total activity concentration of the uranium isotopes Bq·l
A
ε alpha efficiency —
φ
distribution function of the standardized normal distribution, Φ(k ) = p applies —
p
α false positive probability —
β false negative probability —
m sample mass g
standard solution mass g
m
S
m mass of U standard solution used for the preparation of the calibration sample g
S(U)
m mass of Sr standard solution used for the preparation of the calibration sample g
S(Sr)
−1
r sample count rate in the alpha window s
g
−1
r count rate of the calibration sample in the alpha window s
S
−1
r blank sample count rate in the alpha window s
−1
background count rate from the alpha window s
r
0,α
−1
background count rate of the beta window s
r
0,β
−1
background count rate from the total window s
r
0,T
−1
r alpha emitter count rate in beta window when measuring alpha standard s
Sα,β
−1
r alpha emitter count rate in total (alpha+beta) window when measuring alpha standard s
Sα,T
−1
r beta emitter count rate in alpha window when measuring beta standard s
Sβ,α
−1
r beta emitter count rate in total (alpha+beta) window when measuring beta standard s
Sβ,T
t blank sample counting time s
t sample counting time s
g
t calibration or sample counting time s
s
−1
u(a) standard uncertainty associated with the measurand Bq·g
—
u relative standard uncertainty
rel
−1
ua  standard uncertainty of a as a function of its true value Bq·g

−1
#
standard uncertainty of a when the true value is the detection limit Bq·g

ua

−1
U(a) expanded uncertainty of the measurand, calculated by U = k u(a) with k = 2, …, Bq·g
τ alpha spillover parameter —
α
τ beta spillover parameter —
β
quantiles of the standardized normal distribution for the probabilities p (for instance —
k
p
p = 1 − α, 1 − β or 1 − γ/2)
k quantiles of the standardized normal distribution for the probabilities q (for instance —
q
q = 1−α, 1− β or 1−γ/2)
ρ −1
density of water samples g·l
s(ε) standard deviation of the alpha efficiency —
−1
s
s  standard deviation of alpha net count rate
 cps
ω auxiliary quantity —
V volume of test sample l
−1
w calibration factor l
5 Principle
5.1 The limit of detection depends on the sample volume, the instrument used, the background count
rate, the detection efficiency, the counting time and the chemical yield. The limit of detection of the method
described in this document, using currently available liquid scintillation apparatus, is approximately
−1 −1
0,002 Bq·l , which is lower than the WHO criteria for safe consumption of drinking water (10 Bq·l for
238 −1 234 [4]
U and 1 Bq·l for U) . This value can typically be achieved with a counting time of 60 000 s for a test
sample volume of 1 l, as shown in Table A.2.
234 235 238
5.2 Uranium has three natural isotopes, which are all radioactive: U, U and U. Details of these are
reported in Table 1.
Human activity can modify the natural ratio of uranium isotopes. As well, dissolved uranium in natural
waters can show isotope ratios different from natural ones due to leaching mechanisms.

Table 1 — Uranium isotopes features
Isotope Natural mass Half-life Specific activity concen-
abundance tration per gram of isotope
−1
% year Bq·g
238 9 4
U 99,27 4,468·10 1,235·10
235 8 2
U 0,72 7,04·10 5,579·10
234 5 4
U 0,005 4 2,455 ·10 1,243·10
The water sample is first acidified with a fixed amount of nitric acid and then, if a lower detection limit is
required, concentrated by evaporation. Uranium isotopes are then separated by a liquid-liquid extraction
using a scintillation cocktail containing a complexing agent such as bis(2-ethylhexyl) hydrogen phosphate
(HDEHP) and measured by liquid scintillation. The total activity of uranium isotopes can be thus determined.
U standard solution is used for calibration (external standard).
234 238
Spectral deconvolution can be performed using a suitable software to assess the U/ U ratio.
6 Sampling
Sampling, handling and storage of the water shall be done as specified in ISO 5667-1, ISO 5667-3 and
ISO 5667-10. guidance is given for the different types of waters in References [8] to [14]. The laboratory
must receive a sample that is truly representative and has neither been damaged or modified during
transportation or storage.
Store the water sample (from 0,1 l to 1 l) in a plastic bottle in accordance with ISO 5667-3. Acidify the sample
with HNO : if the sample is not supposed to be concentrated by evaporation, add 5 ml of HNO (7.1.1) to 95 g
3 3
of sample; if pre-concentration has to be carried out, add 5 ml of HNO (7.1.1) to 1 000 g of sample (see 9.1
and 9.2). The sample is filtered to remove suspended matter using a 0,45 μm filter. A smaller pore size filter
can also be used, but the filtration can take longer.
The sample shall be a
...

ISO/DISFDIS 13169:2026(en)
ISO/TC 147/SC 3
Secretariat: AFNOR
ISO TC 147/SC 3/WG 15
Date: 2026-09-18
Water quality — Uranium — Test method using alpha liquid
scintillation counting
Second edition
Date: 2026-07-01
Qualité de l'eau — Uranium — Méthode d'essai par comptage des scintillations alpha en milieu liquide
TThhiiss d drraft iaft iss su subbmmiitted tted to to a pa parallearallel vl vote ote iinn IS ISOO, CE, CENN.

FDIS stage
ISO/DISFDIS 13169:2026(en)
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
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
iii
ISO/DISFDIS 13169:2025(E2026(en)
Contents
Foreword . Error! Bookmark not defined.
Introduction . Error! Bookmark not defined.
1 Scope . Error! Bookmark not defined.
2 Normative references . Error! Bookmark not defined.
3 Terms and definitions . Error! Bookmark not defined.
4 Symbols . Error! Bookmark not defined.
5 Principle. Error! Bookmark not defined.
6 Sampling . Error! Bookmark not defined.
7 Chemical reagents and equipment . Error! Bookmark not defined.
7.1 Chemical reagents . Error! Bookmark not defined.
7.2 Equipment and apparatus . Error! Bookmark not defined.
8 Instrument set up and calibration . Error! Bookmark not defined.
8.1 Preparation of extractant scintillation cocktail . Error! Bookmark not defined.
8.2 Preparation of alpha emitter calibration source . Error! Bookmark not defined.
8.3 Preparation of beta emitter calibration source . Error! Bookmark not defined.
8.4 Optimization of counting conditions . Error! Bookmark not defined.
8.5 Detection efficiency . Error! Bookmark not defined.
8.6 Blank sample preparation and measurement . Error! Bookmark not defined.
9 Procedure . Error! Bookmark not defined.
9.1 Without pre-concentration . Error! Bookmark not defined.
9.2 Pre-concentration by evaporation . Error! Bookmark not defined.
9.3 Sample preparation . Error! Bookmark not defined.
9.4 Sample measurement . Error! Bookmark not defined.
10 Quality assurance and quality control program . Error! Bookmark not defined.
10.1 Interference control . Error! Bookmark not defined.
10.2 Quality control . Error! Bookmark not defined.
11 Expression of results . Error! Bookmark not defined.
11.1 Calculation of activity per unit of mass . Error! Bookmark not defined.
11.2 Standard uncertainty. Error! Bookmark not defined.
11.3 Decision threshold . Error! Bookmark not defined.
11.4 Limit of detection . Error! Bookmark not defined.
11.5 Limits of the coverage intervals . Error! Bookmark not defined.
11.6 Calculations using the activity concentration . Error! Bookmark not defined.
12 Test report . Error! Bookmark not defined.
(informative) Set-up parameters and validation data . Error! Bookmark not defined.
Bibliography . Error! Bookmark not defined.

iv
ISO/DISFDIS 13169:2026(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 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).
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 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 second edition cancels and replaces the first edition (ISO 13169:2018), which has been technically
revised.
The main changes are as follows:
— — the introduction has been modified;
— — the expression of results has been updated in 8Clause 8;;
— — the Bibliography has been updated.
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/DISFDIS 13169:2025(E2026(en)
Introduction
Radionuclides are present throughout the environment, thus, water bodies (e.g. surface waters, ground waters
and sea waters) contain radionuclides, which can be of either natural or anthropogenic origin.
3 14 40
— — Naturally-occurring radionuclides, including H, C, K and those originating from the thorium and
210 210 222 226 228 227 232 231 234 238
uranium decay series, in particular Pb, Po, Rn, Ra, Ra, Ac, Th, Pa, U and U, can be
found in water bodies due to either natural processes (e.g. desorption from the soil and runoff by rain
water) or released from technological processes involving naturally occurring radioactive materials (e.g.
mining, mineral processing, oil, gas and coal production, water treatment, and production and use of
phosphate fertilisers).
55 59 63 90 99
— — Anthropogenic radionuclides such as Fe, Ni, Ni, Sr, Tc, transuranic elements (e.g. Np, Pu, Am,
60 137
and Cm) and some gamma emitting radionuclides such as Co and Cs can also be found in natural
waters. Small quantities of anthropogenic radionuclides can be discharged from nuclear facilities into the
environment as a result of authorized routine releases. The radionuclides present in liquid effluents are
[1]
usually controlled before being discharged to the environment[1] and water bodies. Anthropogenic
radionuclides used for medical and industrial applications can be released into the environment after use.
Anthropogenic radionuclides are also found in waters due to contamination fallout resulting from above-
ground nuclear detonations and accidents such as those that have occurred at the Chornobyl and
Fukushima nuclear facilities.
Radionuclide activity concentrations in water bodies can vary according to local geological characteristics and
climatic conditions and can be locally and temporally enhanced by releases from nuclear facilities during
[2][3]
planned, existing and emergency exposure situations[2][3]. . Some drinking-water sources can thus
contain radionuclides at activity concentrations that can present a human health risk. The World Health
[4]
Organization (WHO) recommends to routinely monitor radioactivity in drinking waters[4] and to take
proper actions when needed to minimize the health risk.
National regulations usually specify the activity concentration limits that are authorized in drinking waters,
water bodies and liquid effluents to be discharged to the environment. These limits can vary for planned,
existing and emergency exposure situations. As an example, during either a planned or existing situation, the
-−1 238 -−1 324 [4]
WHO guidance level in drinking water is 10 Bq·l for U and 1 Bq·l for U[4], , see NOTES 1 and 2.
Conformity withto these limits is assessed by measuring radioactivity in water samples and by comparing the
results obtained, with their associated uncertainties, as specified by ISO/IEC Guide 98-3 and ISO 5667-
[5]
20[5] .
-−1
The provisional guideline value for total content of uranium in drinking water is 30 µg·l based on its
chemical toxicity, which is predominant compared with its radiological toxicity.
NOTE 1 If the value is not specified in Annex 6 of Reference [4][4],, the value has been calculated using the formula
provided in Reference [4][4] and the dose coefficient data from References [6][6] and[7] [7].
NOTE 2 The guidance level calculated in Reference [4][4] is the activity concentration that results in an effective dose
-−1 −1
of 0,1 mSv·a to members of the public for an intake of 2 l·d of drinking water for one year. This is an effective dose
that represents a very low level of risk to human health and which is not expected to give rise to any detectable adverse
[4]
health effects[4] .
This document contains a test method to support laboratories which need to determine uranium isotopes
activity in water samples. The method described in this document can be used for various types of waters (see
1Clause 1).). Minor modifications such as sample volume and counting time can be made if needed to ensure
that the decision threshold, limit of detection and uncertainties are below the required limits. This can be done
for several reasons such as emergency situations, lower national guidance limits and operational
requirements.
vi
DRAFT International Standard ISO/DIS 13169:2026(en)

Water quality — Uranium — Test method using alpha liquid
scintillation counting
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.
IMPORTANT — It is absolutely essential that testsTests conducted in accordance withaccording to this
document shall be carried out by suitably qualifiedtrained staff.
1 Scope
This document specifies a method to measure uranium isotopes in non-saline waters by extraction and liquid
scintillation counting. This methoddocument covers the measurement of soluble uranium isotopes in water
−3 -−1 -−1
in activity concentrations between approximately 2·10 Bq·kg and 10 Bq·kg when analysing a 1 l test
sample volume with a 60 000 s counting time using a Liquid Scintillation Countingliquid scintillation counting
234 238
instrument with α/β discrimination function. This method can be used to determine the ratio of U/ U.
NOTE This method has not been tested for the measurement of other uranium isotopes.
This document applies to test samples of non-saline waters after proper sampling, handling and preparation.
This document is also applicable in the event of an emergency situation.
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
measurement (GUM:1995)
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: Guidance on the preservationPreservation and
handling of water samples
ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste water
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO 11929-1Determination1, Determination of the characteristic limits (decision threshold, detection limit and
limits of the confidencecoverage interval) for measurements of ionizing radiation — Fundamentals and
application — Part 1: Elementary applications
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO/DISFDIS 13169:2025(E2026(en)
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
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/IEC Guide 98-3, ISO
11929-1 and ISO/IEC Guide 98-3 80000-10 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/
4 Symbols
236 −1
A activity concentration of U, the standard solution Bq·g
S
−1
a total massic activity of uranium isotopes Bq·g
−1
𝑎˜ possible or assumed true quantity values of the activity per mass Bq·g
−1
a* decision threshold of the measurand Bq·g
# −1
a limit of detection of the measurand Bq·g
⊲ ⊳
−1
𝑎 , 𝑎 lower and upper limits of the probabilistically symmetric coverage interval Bq·g
< >
−1
𝑎 , 𝑎 lower and upper limits of the shortest coverage interval Bq·g
−1
c total activity concentration of the uranium isotopes Bq·l
A
ε alpha efficiency —
𝜙 distribution function of the standardized normal distribution, Φ(k ) = = p applies —
p
α false positive probability —
β false negative probability —
m sample mass g
𝑚 standard solution mass g
S
m mass of U standard solution used for the preparation of the calibration sample g
S(U)
m mass of Sr standard solution used for the preparation of the calibration sample g
S(Sr)
-−1
r sample count rate in the alpha window s
g
−1
r count rate of the calibration sample in the alpha window s
S
−1
r blank sample count rate in the alpha window s
−1
𝑟 background count rate from the alpha window s
0,𝛼
−1
𝑟 background count rate of the beta window s
0,𝛽
−1
𝑟 background count rate from the total window s
0,T
−1
r alpha emitter count rate in beta window when measuring alpha standard s
Sα,β
−1
r alpha emitter count rate in total (alpha+beta) window when measuring alpha standard s
Sα,T
−1
r beta emitter count rate in alpha window when measuring beta standard s
Sβ,α
ISO/DISFDIS 13169:2026(en)
−1
r beta emitter count rate in total (alpha+beta) window when measuring beta standard s
Sβ,T
t blank sample counting time s
t sample counting time s
g
t calibration or sample counting time s
s
−1
u(a) standard uncertainty associated with the measurand Bq·g
𝑢 relative standard uncertainty —
rel
−1
𝑢˜ (𝑎˜) standard uncertainty of a as a function of its true value Bq·g
#
−1
standard uncertainty of a when the true value is the detection limit Bq·g
𝑢˜ (𝑎 )
−1
U(a) expanded uncertainty of the measurand, calculated by U = = k u(a) with k= = 2, …, Bq·g
τα alpha spillover parameter —
τ beta spillover parameter —
β
quantiles of the standardized normal distribution for the probabilities p (for instance p —
k
p
= = 1 − α, 1 − β or 1 − γ/2)
k quantiles of the standardized normal distribution for the probabilities q (for instance —
q
q = 1−α, 1− β or 1−γ/2)
−1
𝜌 density of water samples g·l
s(ε) standard deviation of the alpha efficiency —
-−1
s s
α
standard deviation of alpha net count rate
𝑠
cps
𝛼 cps
ω auxiliary quantity —
V volume of test sample l
−1
w calibration factor l
5 Principle
5.1 The limit of detection depends on the sample volume, the instrument used, the background count rate,
the detection efficiency, the counting time, and the chemical yield. The limit of detection of the method
described in this document, using currently available liquid scintillation apparatus, is approximately
-−1 -−1 238
0,002 Bq·l , which is lower than the WHO criteria for safe consumption of drinking water (10 Bq·l for U
-−1 234 [4]
and 1 Bq·l for U)[4]). . This value can typically be achieved with a counting time of 60 000 s for a test
sample volume of 1 l, as shown in Table A.2 Table A2.
234 235 238
5.2 Uranium has three natural isotopes, which are all radioactive: U, U and U. Details of these are
reported in Table 1 Table 1 below. .
Human activity can modify the natural ratio of uranium isotopes. As well, dissolved uranium in natural waters
can show isotope ratios different from natural ones due to leaching mechanisms.
Table 1 — Uranium isotopes features
Isotope Natural mass Half-life, yr Specific activity
abundance concentration per
gram of isotope
-−1
% year Bq·g
238 9 4
U 99,27 4,468·10 1,235·10
ISO/DISFDIS 13169:2025(E2026(en)
Isotope Natural mass Half-life, yr Specific activity
abundance concentration per
gram of isotope
-−1
% year Bq·g
235 8 2
U 0,72 7,04·10 5,579·10
234 5 4
U 0,0054005 4 2,455 ·10 1,243·10
The water sample is first acidified with a fixed amount of nitric acid and then, if a lower detection limit is
required, concentrated by evaporation. Uranium isotopes are then separated by a liquid-liquid extraction
using a scintillation cocktail containing a complexing agent such as bis(2-ethylhexyl) hydrogen phosphate
(HDEHP) and measured by liquid scintillation. The total activity of uranium isotopes can be thus determined.
U standard solution is used for calibration (external standard).
234 238
Spectral deconvolution can be performed using a suitable software to assess the U/ U ratio.
6 Sampling
Sampling, handling and storage of the water shall be done as specified in ISO 5667-1, ISO 5667-3 and
ISO 5667-10. guidance is given for the different types of waters in References [8][8] to[14] [14]. The
laboratory must receive a sample that is truly representative and has neither been damaged or modified
during transportation or storage.
Store the water sample (from 0,1 l to 1 l) in a plastic bottle in accordance with ISO 5667--3. Acidify the sample
with HNO : if the sample is not supposed to be concentrated by evaporation, add 5 ml of HNO (7.1.1(7.1.1))
3 3
to 95 g of sample; if pre-concentration has to be carried out, add 5 ml of HNO3 (7.1.1(7.1.1)) to 1 000 g of
sample (see 9.19.1 and 9.29.2).). The sample is filtered to remove suspended matter using a 0,45 μm filter. A
smaller pore size filter can also be used, but the filtration can take longer.
The sample shall be acidified after filtration to pH less than 2 with HNO (7.1.1(7.1.1).). The water test sample
should be stored at 3± ± 2 °C if not immediately analysed.
7 Chemical reagents and equipment
7.1 Chemical reagents
Use only reagents of recognisedrecognized analytical grade.
It is recommended to use acids and bases of trace metal grade or equivalent (a better purity grade can also be
employed).
-−1 -−1
7.1.1 7.1.1 Nitric acid, c(HNO ) = = 15,8 mol·l , ρ = 1,42 g·ml , mass fraction w(HNO ) = 70 %.
3 3
-−1
7.1.2 7.1.2 Nitric acid, c(HNO3) = 0,7 mol·l .
-−1
7.1.3 7.1.3 Hydrochloric acid, c(HCl) = 0,1 mol·l .
7.1.4 7.1.4 Ultrapure water with a resistivity of more than 18,2 MΩ cm at 25 °C and total organic carbon
−1
less than 1 μg∙l .
Unless otherwise stated, water refers to ultrapure water.
Water can contain detectable amounts of Rn and short-lived progeny. It is therefore strongly recommended
to boil it under vigorous stirring and let it stand for one day before its use. An alternative option is to purge it
with nitrogen for about 1 h for 2 l volume.
ISO/DISFDIS 13169:2026(en)
7.1.5 7.1.5 Scintillation cocktail, to be prepared (see 7.17.1).).
7.1.6 7.1.6 Ethanol, 95 %.
7.1.7 7.1.7 p-xylene, 99 %, for spectroscopy or scintillation grade.
7.1.8 7.1.8 Bis(2-ethylhexyl) hydrogen phosphate, 95 %.
7.1.9 7.1.9 Naphthalene, 99 %, scintillation grade.
7.1.10 7.1.10 2-(4-biphenylyl)-6-phenyl benzoxazole (PBBO), scintillation grade.
7.1.11 7.1.11 Radioactive standard solution.
236 90 90
Alpha and beta emitter standard solutions (respectively U and Sr/ Y or others suitable uranium isotopes
and beta emitting radionuclides) shall be provided with either calibration certificates containing at least the
activity concentration and measurement uncertainty, or statement of conformity with an identified
metrological specification, or both.
7.2 Equipment and apparatus
7.2.1 7.2.1 Balance.
7.2.2 7.2.2 Hot plate with magnetic stirrer and stirring bar.
7.2.3 7.2.3 Liquid scintillation counter, with α/β discrimination option, with preferably thermostated
counting chamber and preferably a commercially available low background counter to achieve better
detection limits.
7.2.4 7.2.4 Polyethylene scintillation vials, PTFE coated, 20 ml.
PTFE coated polyethylene vials are the best choice of scintillation vials because they prevent both the diffusion
of the cocktail into the wall of the vial and the absorption of radon from the outer environment. Glass vials
exhibit a considerably higher background and generally degrade both α/β discrimination and α peaks
resolution.
8 Instrument set up and calibration
8.1 Preparation of extractant scintillation cocktail
To prepare 500 ml of cocktail, weigh in a beaker:
— naphthalene (7.1.9Naphthalene (7.1.9):): 90,0 g;
— PBBO (7.1.10(7.1.10):): 2,0 g;
— HDEHP (7.1.8(7.1.8):): 25,0 g.
Add approximately 450 ml of p-xylene (7.1.7(7.1.7)) and stir for about 1 h with a magnetic stirrer. Transfer to
a 500 ml tared flask, coarsely filtering (e.g. with glass wool), and bring to volume
...

PROJET FINAL
Norme
internationale
ISO/TC 147/SC 3
Qualité de l'eau — Uranium —
Secrétariat: AFNOR
Méthode d'essai par comptage
Début de vote:
des scintillations alpha en milieu
2026-10-02
liquide
Vote clos le:
2026-11-27
Water quality — Uranium — Test method using alpha liquid
scintillation counting
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
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Numéro de référence
PROJET FINAL
Norme
internationale
ISO/TC 147/SC 3
Qualité de l'eau — Uranium —
Secrétariat: AFNOR
Méthode d'essai par comptage
Début de vote:
des scintillations alpha en milieu
2026-10-02
liquide
Vote clos le:
2026-11-27
Water quality — Uranium — Test method using alpha liquid
scintillation counting
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2026
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Publié en Suisse
Numéro de référence
ii
Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 2
4 Symboles . 2
5 Principe. 3
6 Échantillonnage . 4
7 Réactifs chimiques et appareillage . 4
7.1 Réactifs chimiques .4
7.2 Équipement et appareillage .5
8 Réglage et étalonnage du compteur . 5
8.1 Préparation du cocktail scintillant d’extraction .5
8.2 Préparation de la source d’étalonnage d’émetteur alpha .6
8.3 Préparation de la source d’étalonnage d’émetteur bêta .6
8.4 Optimisation des conditions de comptage .6
8.5 Rendement de détection .7
8.6 Préparation et mesurage de l’échantillon de l’essai à blanc .7
9 Mode opératoire . 7
9.1 Sans préconcentration .7
9.2 Préconcentration par évaporation .8
9.3 Préparation de l’échantillon .8
9.4 Mesurage de l’échantillon .8
10 Programme d’assurance qualité et de contrôle qualité . 8
10.1 Contrôle des interférences .8
10.2 Contrôle qualité .8
11 Expression des résultats . 8
11.1 Calcul de l’activité massique .8
11.2 Incertitude-type .9
11.3 Seuil de décision .9
11.4 Limite de détection .9
11.5 Limites des intervalles élargis .10
11.5.1 Limites de l’intervalle élargi probabilistiquement symétrique .10
11.5.2 Intervalle élargi le plus court .10
11.6 Calculs à l’aide de l’activité volumique .11
12 Rapport d’essai .11
Annexe A (informative) Paramètres de réglage et données de validation .13
Bibliographie . 17

iii
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes nationaux
de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est en général
confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude a le droit de faire
partie du comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l’ISO participent également aux travaux. L’ISO collabore étroitement avec
la Commission électrotechnique internationale (IEC) en ce qui concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document
a été rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2
(voir www.iso.org/directives).
L’ISO attire l’attention sur le fait que la mise en application du présent document peut entraîner l’utilisation
d’un ou de plusieurs brevets. L’ISO ne prend pas position quant à la preuve, à la validité et à l’applicabilité de
tout droit de brevet revendiqué à cet égard. À la date de publication du présent document, l’ISO n’avait pas
reçu notification qu’un ou plusieurs brevets pouvaient être nécessaires à sa mise en application. Toutefois,
il y a lieu d’avertir les responsables de la mise en application du présent document que des informations
plus récentes sont susceptibles de figurer dans la base de données de brevets, disponible à l’adresse
www.iso.org/brevets. L’ISO ne saurait être tenue pour responsable de ne pas avoir identifié tout ou partie de
tels droits de brevet.
Les appellations commerciales éventuellement mentionnées dans le présent document sont données pour
information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de
l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles techniques au
commerce (OTC), voir www.iso.org/avant-propos.
Le présent document a été élaboré par le comité technique ISO/TC 147, Qualité de l’eau, sous-comité SC 3,
Mesurages de la radioactivité, en collaboration avec le comité technique CEN/TC 230, Analyse de l’eau, du
Comité européen de normalisation (CEN), conformément à l’Accord de coopération technique entre l’ISO et
le CEN (Accord de Vienne).
Cette deuxième édition annule et remplace la première édition (ISO 13169:2018), qui a fait l’objet d’une
révision technique.
Les principales modifications sont les suivantes:
— l’Introduction a été modifiée;
— l’expression des résultats a été mise à jour à l’Article 8;
— la Bibliographie a été mise à jour.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes se
trouve à l’adresse www.iso.org/fr/members.html.

iv
Introduction
Les radionucléides sont présents partout dans l’environnement. Dès lors, les masses d’eau (par exemple les
eaux de surface, les eaux souterraines et les eaux de mer) contiennent des radionucléides d’origine naturelle
ou anthropique.
3 14 40
— Les radionucléides naturels, y compris H, C, K et ceux provenant des chaînes de désintégration du
210 210 222 226 228 227 232 231 234 238
thorium et de l’uranium, notamment Pb, Po, Rn, Ra, Ra, Ac, Th, Pa, U ou U,
peuvent se trouver dans les masses d’eau en raison de processus naturels (par exemple, la désorption par
le sol ou le lessivage par les eaux pluviales) ou bien ils peuvent être libérés par des procédés technologiques
mettant en œuvre des matières radioactives existant à l’état naturel (par exemple, l’extraction minière,
le traitement de sables minéraux, la production de carburant, de gaz ou de charbon, le traitement des
eaux et la production et l’utilisation d’engrais phosphatés).
55 59 63 90 99
— Les radionucléides engendrés par l’activité humaine, tels que Fe, Ni, Ni, Sr, Tc, mais aussi
des éléments transuraniens (américium, plutonium, neptunium et curium, par exemple) et certains
60 137
radionucléides émetteurs gamma tels que Co et Cs peuvent également être présents dans les
eaux naturelles. De petites quantités de radionucléides sont rejetées dans l’environnement par les
installations du cycle du combustible lors des rejets périodiques autorisés. Les radionucléides présents
[1]
dans les effluents liquides sont habituellement contrôlés avant d’être déversés dans l’environnement
et les masses d’eau. Des radionucléides, utilisés dans le cadre d’applications médicales et industrielles,
sont également libérés dans l’environnement après usage. Les radionucléides d’origine anthropique sont
aussi présents dans les eaux du fait de contaminations par retombées d’éléments radioactifs rejetés dans
l’atmosphère lors de l’explosion de dispositifs nucléaires ou lors d’accidents nucléaires, tels que ceux de
Tchernobyl et de Fukushima.
— Les activités volumiques des radionucléides dans les masses d’eau sont variables en fonction des
caractéristiques géologiques et des conditions climatiques locales, et peuvent être renforcées localement
et dans le temps par les rejets d’installations nucléaires dans des situations d’exposition planifiée,
[2][3]
d’exposition d’urgence et d’exposition existante . Certaines sources d’eau potable peuvent donc
contenir des radionucléides à des activités volumiques susceptibles de présenter un risque sanitaire
pour l’Homme. L’Organisation mondiale de la santé (OMS) recommande une surveillance régulière de la
[4]
radioactivité des eaux potables et la mise en place d’actions adéquates si besoin est afin de limiter le
plus possible le risque pour la santé humaine.
Les législations nationales spécifient généralement les limites autorisées d’activité volumique dans les eaux
potables, les masses d’eau et les effluents liquides rejetés dans l’environnement. Ces limites sont susceptibles
de varier dans le cas de situations d’exposition planifiée, existante ou d’urgence. À titre d’exemple, lors d’une
situation planifiée ou existante, la limite indicative donnée par l’OMS pour l’uranium dans l’eau potable est
−1 238 −1 324 [4]
de 10 Bq·l pour U et de 1 Bq·l pour U , voir les NOTES 1 et 2. La conformité à ces limites peut être
évaluée à partir des résultats de mesure d’échantillons d’eau et des incertitudes qui y sont associées, tel que
[5]
précisé par le Guide 98-3 de l’ISO/IEC et l’ISO 5667-20 .
−1
La limite indicative provisoire concernant la teneur totale en uranium dans l’eau potable est de 30 µg·l ,
laquelle a été fixée sur la base de sa toxicité chimique, qui est plus importante que sa toxicité radiologique.
NOTE 1 Si cette valeur n’est pas précisée dans l’Annexe 6 de la Référence [4], elle est calculée à l’aide de l’équation
donnée dans la Référence [4] et du coefficient de dose des Références [6] et [7].
NOTE 2 La limite indicative calculée par la Référence [4] correspond à l’activité volumique pour une consommation
−1 −1
de 2 l·j d’eau potable pendant un an, aboutissant à une dose effective de 0,1 mSv·a pour un individu moyen. Cette
dose effective présente un niveau de risque très faible qui ne devrait pas entraîner d’effets indésirables et détectables
[4]
pour la santé .
Le présent document décrit une méthode d’essai pour répondre aux besoins des laboratoires qui déterminent
l’activité des isotopes de l’uranium dans les échantillons d’eau. La méthode décrite dans le présent document
peut être appliquée à divers types d’eaux (voir l’Article 1). Il est possible d’apporter des modifications
mineures, par exemple au volume d’un échantillon ou à la durée de comptage, afin de s’assurer que le seuil
de décision, la limite de détection et les incertitudes sont inférieures aux limites requises. Ces modifications

v
peuvent être effectuées dans le cadre d’une situation d’urgence, de limites indicatives nationales inférieures
et d’obligations opérationnelles, etc.

vi
PROJET FINAL Norme internationale ISO/FDIS 13169:2026(fr)
Qualité de l'eau — Uranium — Méthode d'essai par comptage
des scintillations alpha en milieu liquide
AVERTISSEMENT — Il convient que les utilisateurs du présent document maîtrisent les pratiques
courantes de laboratoire. Le présent document ne prétend pas aborder la totalité des aspects liés à la
sécurité qui pourraient découler de son utilisation. Il incombe à l’utilisateur d’établir des pratiques
appropriées en matière d’hygiène et de sécurité.
IMPORTANT — Les essais réalisés conformément au présent document doivent être effectués par du
personnel ayant reçu une formation adéquate.
1 Domaine d’application
Le présent document spécifie une méthode de mesure des isotopes de l’uranium dans des eaux non salines
par extraction et comptage des scintillations en milieu liquide. Le présent document couvre le mesurage
des isotopes de l’uranium solubles présents dans l’eau à des activités volumiques comprises entre
−3 −1 −1
environ 2·10 Bq·kg et 10 Bq·kg lors de l’analyse d’un échantillon d’essai d’un volume de 1 l avec une
durée de comptage de 60 000 s au moyen d’un instrument de comptage des scintillations en milieu liquide
disposant d’une fonction de séparation α/β. Cette méthode peut être utilisée pour déterminer le rapport
234 238
de U/ U.
NOTE Cette méthode n’a pas été validée pour le mesurage des autres isotopes de l’uranium.
Le présent document s’applique à des échantillons d’eaux non salines soumis à l’essai après échantillonnage,
manipulation et préparation convenables.
Le présent document est également applicable en situation d’urgence.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour
les références non datées, la dernière édition du document de référence s’applique (y compris les éventuels
amendements).
Guide ISO/IEC 98-3, Incertitude de mesure — Partie 3: Guide pour l’expression de l’incertitude de mesure (GUM:
1995)
ISO 5667-1, Qualité de l’eau — Échantillonnage — Partie 1: Recommandations relatives à la conception des
programmes et des techniques d’échantillonnage
ISO 5667-3, Qualité de l’eau — Échantillonnage — Partie 3: Conservation et manipulation des échantillons d’eau
ISO 5667-10, Qualité de l’eau — Échantillonnage — Partie 10: Lignes directrices pour l’échantillonnage des eaux
résiduaires
ISO 11929-1, Détermination des limites caractéristiques (seuil de décision, limite de détection et limites de
l’intervalle élargi) pour mesurages de rayonnements ionisants — Principes fondamentaux et applications —
Partie 1: Applications élémentaires
ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d'étalonnages et d'essais
ISO 80000-10, Grandeurs et unités — Partie 10: Physique atomique et nucléaire

3 Termes et définitions
Pour les besoins du présent document, les termes et définitions de le Guide ISO/IEC 98-3, de l’ISO 11929-1 et
de l’ISO 80000-10 s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en normalisation,
consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp
— IEC Electropedia: disponible à l’adresse https:// www .electropedia .org/
4 Symboles
236 −1
A activité volumique de U, solution étalon Bq·g
S
−1
a activité massique totale des isotopes de l’uranium Bq·g
−1

a
valeurs vraies possibles ou présumées de l’activité massique Bq·g
−1
a* seuil de décision du mesurande Bq·g
# −1
a limite de détection du mesurande Bq·g
−1

Bq·g
limites inférieure et supérieure de l’intervalle élargi probabilistiquement symétrique
aa,
−1

limites inférieure et supérieure de l’intervalle élargi le plus court Bq·g
aa,
−1
c activité volumique totale des isotopes de l’uranium Bq·l
A
ε rendement alpha —
φ
fonction de répartition de la loi normale centrée réduite, Φ(k ) = p s’applique —
p
α probabilité de faux positif —
β probabilité de faux négatif —
m masse de l’échantillon g
g
masse de la solution étalon
m
S
m masse de la solution étalon de U utilisée pour la préparation de l’échantillon étalon g
S(U)
m masse de la solution étalon de Sr utilisée pour la préparation de l’échantillon étalon g
S(Sr)
−1
r taux de comptage de l’échantillon dans la fenêtre alpha s
g
−1
r taux de comptage de l’échantillon étalon dans la fenêtre alpha s
S
−1
r taux de comptage de l’échantillon de l’essai à blanc dans la fenêtre alpha s
−1
taux de comptage du bruit de fond de la fenêtre alpha s
r
0,α
−1
taux de comptage du bruit de fond de la fenêtre bêta s
r
0,β
−1
taux de comptage du bruit de fond de la fenêtre totale s
r
0,T
−1
r taux de comptage de l’émetteur alpha dans la fenêtre bêta lors du mesurage de l’étalon alpha s
Sα,β
−1
taux de comptage de l’émetteur alpha dans la fenêtre totale (alpha+bêta) lors du mesurage s
r
Sα,T
de l’étalon alpha
−1
r taux de comptage de l’émetteur bêta dans la fenêtre alpha lors du mesurage de l’étalon bêta s
Sβ,α
−1
taux de comptage de l’émetteur bêta dans la fenêtre totale (alpha+bêta) lors du mesurage s
r
Sβ,T
de l’étalon bêta
t durée de comptage de l’échantillon de l’essai à blanc s
t durée de comptage de l’échantillon s
g
t durée de comptage de l’échantillon ou de l’étalonnage s
s
−1
u(a) incertitude-type associée au mesurande Bq·g
—
incertitude-type relative
u
rel
−1
incertitude-type de a en fonction de sa valeur vraie Bq·g
 
ua

−1
#
incertitude-type de a lorsque la valeur vraie est la limite de détection Bq·g

ua

−1
U(a) incertitude élargie du mesurande, calculée par U = k u(a) avec k = 2, …, Bq·g
τ paramètre d’interférence alpha —
α
τ paramètre d’interférence bêta —
β
quantile de la loi normale centrée réduite pour les probabilités p (par exemple p = 1 − α, —
k
p
1 − β ou 1 − γ/2)
k quantile de la loi normale centrée réduite pour les probabilités q (par exemple q = 1−α, —
q
1− β ou 1−γ/2)
−1
ρ
masse volumique des échantillons d’eau g·l
s(ε) écart-type du rendement alpha —
−1
s
écart-type du taux de comptage net alpha
s �
α cps
ω grandeur auxiliaire —
V volume de l’échantillon d’essai l
−1
w facteur d’étalonnage l
5 Principe
5.1 La limite de détection dépend du volume de l’échantillon, de l’instrument utilisé, du taux de comptage
du bruit de fond, du rendement de détection, de la durée de comptage et du rendement chimique. La limite de
détection de la méthode décrite dans le présent document, en utilisant un appareil de scintillation en milieu
−1
liquide actuellement disponible, est d’environ·0,002 Bq·l , cette valeur étant inférieure aux critères de
−1 238 −1 234 [4]
l’OMS pour une consommation en toute sécurité d’eau potable (10 Bq·l pour U et 1 Bq·l pour U) .
Cette valeur peut généralement être obtenue par le mesurage d’un échantillon d’essai de 1 l avec une durée
de comptage de 60 000 s, comme indiqué dans le Tableau A.2.

234 235 238
5.2 L’uranium possède trois isotopes naturels, tous radioactifs: U, U et U. Les détails de ceux-ci
sont présentés dans le Tableau 1.
L’activité humaine peut modifier le rapport naturel des isotopes de l’uranium. De plus, l’uranium dissous
dans les eaux naturelles peut présenter des rapports isotopiques différents des rapports naturels en raison
des mécanismes de lixiviation.
Tableau 1 — Caractéristiques des isotopes de l’uranium
Isotope Abondance mas- Demi-vie Activité volumique spéci-
sique naturelle fique par gramme d’isotope
−1
% an Bq·g
238 9 4
U 99,27 4,468·10 1,235·10
235 8 2
U 0,72 7,04·10 5,579·10
234 5 4
U 0,005 4 2,455 ·10 1,243·10
L’échantillon d’eau est tout d’abord acidifié avec une quantité connue d’acide nitrique puis, si une limite
de détection inférieure est requise, concentré par évaporation. Les isotopes de l’uranium sont ensuite
séparés par extraction liquide-liquide à l’aide d’un cocktail scintillant contenant un complexant tel que
l’hydrogénophosphate de bis(2-éthylhexyle) (HDEHP) et sont mesurés par comptage des scintillations en
milieu liquide. L’activité totale des isotopes de l’uranium peut ainsi être déterminée. La solution étalon
de U est utilisée pour l’étalonnage (étalon externe).
234 238
Une déconvolution spectrale peut être réalisée à l’aide d’un logiciel adéquat pour évaluer le rapport U/ U.
6 Échantillonnage
L’échantillonnage, la manipulation et le stockage de l’eau doivent être effectués comme cela est spécifié dans
l’ISO 5667-1, l’ISO 5667-3 et l’ISO 5667-10. Des recommandations sont données pour les différents types
d’eaux dans les Références [8] à [14]. Le laboratoire doit recevoir un échantillon réellement représentatif qui
n’a pas été altéré ou modifié lors du transport et du stockage.
Conserver l’échantillon d’eau (de volume compris entre 0,1 l et 1 l) dans un flacon en plastique conformément
à l’ISO 5667-3. Acidifier l’échantillon avec du HNO : s’il est présumé qu’il ne nécessite pas d’être concentré
par évaporation, ajouter 5 ml de HNO (7.1.1) à 95 g d’échantillon; s’il doit être préconcentré, ajouter 5 ml
de HNO (7.1.1) à 1 000 g d’échantillon (voir 9.1 et 9.2). Filtrer l’échantillon au moyen d’un filtre de porosité
0,45 μm afin d’éliminer les matières en suspension. Un filtre de plus petite porosité peut également être
utilisé, mais la filtration peut prendre plus de temps.
L’échantillon doit être acidifié après filtration à l’aide de HNO (7.1.1) jusqu’à obtenir un pH inférieur à 2.
Si l’échantillon d’eau pour essai n’est pas immédiatement analysé, il convient de le conserver à (3 ± 2) °C.
7 Réactifs chimiques et appareillage
7.1 Réactifs chimiqu
...