ISO/FDIS 9697

• Abstract:

  This document specifies a test method for the determination of gross beta activity concentration in non-saline waters. The method covers non-volatile radionuclides with maximum beta energies of approximately 0,3 MeV or higher. Measurement of low energy beta emitters (e.g. 3H, 228Ra, 210Pb, 14C, 35S and 241Pu) and some gaseous or volatile radionuclides (e.g. radon and radioiodine) might not be included in the gross beta quantification using the test method described in this document. This test method is applicable to the analysis of raw and drinking waters. The range of application depends on the amount of total soluble salts in the water and on the performance characteristics (background count rate and counting efficiency) of the counter used. It is the laboratory's responsibility to ensure the suitability of this method for the water samples tested.

• Status: Not Published
• ICS: 13.060.60 - Examination of physical properties of water
• ICS: 13.280 - Radiation protection
• Technical Committee: ISO/TC 147/SC 3 - Radioactivity measurements
• Drafting Committee: ISO/TC 147/SC 3 - Radioactivity measurements
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 02-Sep-2026
• Completion Date: 02-Sep-2026

• Consolidates: FprEN ISO 9697 - Water quality - Gross beta activity - Test method using thick source (ISO/FDIS 9697:2026)
• Effective Date: 12-Feb-2026
• Consolidates: ISO 17555:2021 - Plastics — Film and sheeting — Biaxially oriented polypropylene (PP) films
• Effective Date: 29-Jun-2024
• Revises: ISO 9697:2018 - Water quality — Gross beta activity — Test method using thick source
• Effective Date: 22-Jun-2024

Overview

ISO/FDIS 9697:2026 specifies a standardized laboratory method for determining the gross beta activity concentration in non-saline water samples using a thick source technique. Developed by the International Organization for Standardization (ISO), this test method is designed for application in raw and drinking waters, focusing on non-volatile beta-emitting radionuclides with maximum beta energies of approximately 0.3 MeV or higher. It does not cover low-energy beta emitters or certain volatile radionuclides, such as radon or radioiodine.

Ensuring reliable detection of gross beta activity in water is critical for health risk assessments, regulatory compliance, and environmental monitoring. This standard provides structured sampling, preparation, and measurement procedures suitable for qualified laboratories to deliver accurate and comparable results.

Key Topics

• Scope:

  • Applicable to non-saline waters, including raw and drinking water.
  • Focuses on gross beta activity from non-volatile and medium- to high-energy beta emitters.
  • Not suitable for low-energy beta emitters (e.g., tritium, ^14C, ^210Pb) or volatile radionuclides (e.g., radon).

• Method Principle:

  • Water samples are evaporated, converted to sulfate residue, baked, and prepared on a planchet.
  • Residues are measured for beta activity using a calibrated beta counting instrument, typically a gas-flow proportional counter.
  • Results express gross beta activity as an equivalent concentration referenced to a known beta standard, aiding in preliminary screening.

• Quality Assurance:

  • Requires labs to utilize quality control measures as outlined in ISO/IEC 17025.
  • Involves regular checks of contamination, correct calibration procedures, and method verification through reference or spiked materials.
  • Emphasizes the importance of analyst competence and periodic proficiency checks.

• Measurement Limitations:

  • Detection limits depend on both the amount of dissolved solids in the sample and the instrument's performance (background and efficiency).
  • The method is not intended for rapid field use; suitable laboratory facilities and qualified personnel are required.

Applications

• Drinking Water Monitoring: Used by water utilities, environmental labs, and regulatory agencies to monitor compliance with gross beta activity limits set by health guidelines or national regulations.
• Screening for Radioactive Contamination: Efficient for initial screening of water sources potentially impacted by nuclear facilities, incidents, or environmental releases of beta-emitting radionuclides.
• Quality Control in Water Treatment: Offers a reliable method for verifying the effectiveness of water treatment processes in removing radioactivity.
• Regulatory Reporting: Results obtained using this standard support regulatory reporting and decision-making regarding public health and environmental safety.

This standardized approach allows for consistency in testing and harmonization across international borders, supporting global water quality initiatives.

Related Standards

• ISO 5667 Series: Guidance on design, sampling, preservation, and quality assurance for water sampling.
• ISO 80000-10: Definitions and units for atomic and nuclear physics measurements.
• ISO 11929-1: Procedures for determining detection and decision limits in ionizing radiation measurements.
• ISO/IEC Guide 98-3: Guidance on the expression of measurement uncertainty.
• ISO/IEC 17025: General requirements for laboratory competency in testing and calibration.
• ISO 9696: Gross alpha activity measurement in water using similar thick source methods.
• ISO 9698, ISO 13162, ISO 22908: Complementary standards for detecting specific radionuclides or volatile beta emitters not covered by ISO/FDIS 9697.

By adhering to the guidelines and procedures outlined in ISO/FDIS 9697, laboratories and stakeholders can confidently assess water quality in relation to gross beta radioactivity, ensuring public health protection and regulatory compliance.

Keywords: water quality, gross beta activity, test method, radionuclide measurement, drinking water safety, environmental monitoring, ISO standards, beta emitters, laboratory analysis.

FINAL DRAFT
International
Standard
ISO/TC 147/SC 3
Water quality — Gross beta activity
Secretariat: AFNOR
— Test method using thick source
Voting begins on:
Qualité de l'eau — Activité bêta globale — Méthode d'essai par 2026-09-02
source épaisse
Voting terminates on:
2026-10-28
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 — Gross beta activity
Secretariat: AFNOR
— Test method using thick source
Voting begins on:
Qualité de l'eau — Activité bêta globale — Méthode d'essai par
source épaisse
Voting terminates on:
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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
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 Chemical reagents and equipment . 3
6.1 Chemical reagents .3
6.2 Equipment .4
7 Procedure . 4
7.1 Sampling .4
7.2 Pre-treatment .5
7.3 Concentration stage .5
7.4 Sulfation stage.5
7.5 Baking stage . .5
7.6 Source preparation .5
7.7 Measurement .6
7.8 Determination of counting background .6
7.9 Preparation of calibration sources .6
7.10 Sensitivity and bias .7
7.11 Optimization of the determination .7
8 Quality assurance and quality control . 7
8.1 General .7
8.2 Contamination check .7
8.3 Interference control of the contribution of the natural radionuclides .7
8.4 Method verification .8
8.5 Demonstration of analyst capability . .8
9 Expression of results . 9
9.1 Calculation of activity concentration .9
9.2 Standard uncertainty .9
9.3 Decision threshold .10
9.4 Limit of detection .10
9.5 Limits of the coverage intervals .11
9.5.1 Limits of the probabilistically symmetric coverage interval .11
9.5.2 Shortest coverage interval .11
10 Test report .12
Annex A (informative) Example of performance criteria .13
Bibliography . 14

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 fifth edition cancels and replaces the fourth edition (ISO 9697:2018), which has been technically
revised.
The main changes are as follows:
— the normative references have been updated;
— additional symbols for the coverage interval and uncertainty calculations have been added.
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, 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 rainwater) or from technological processes involving naturally occurring radioactive materials
(e.g. mining, mineral processing, oil, gas and coal production, water treatment, 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,
60 137
Am, 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 to 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 to the environment after use.
Anthropogenic radionuclides are also found in waters due to contamination from fallout resulting from
above-ground nuclear detonations and accidents such as those that have occurred at the Chernobyl 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 [ ]
the WHO guidance level for gross beta activity in drinking water is 1,0 Bq·l 4 , see NOTES 1, 2 and 3.
Conformity with these limits is assessed by measuring radioactivity in water samples and by comparing
[12]
the results obtained, with their associated uncertainties, as specified by ISO/IEC Guide 98-3 and
[5]
ISO 5667-20 .
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 Gross alpha and gross beta activity are often measured together; the WHO guidance level for gross alpha
−1 [ ]
activity in drinking water is 0,5 Bq·l 4 .
NOTE 3 The guidance level calculated in Reference [4] is the activity concentration that results in a committed
−1 −1
effective dose 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
[4]
detectable adverse health effects .
This document contains a test method to support laboratories which need to determine the gross beta
activity concentration in water samples. The method(s) 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, detection limit, 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.
3 14 228
NOTE 4 This method does not cover low energy beta emitters, such as H, C and Ra or volatile beta emitters
131 [9] [10] [11]
such as I and radon, which are covered in standards such as ISO 9698 , ISO 13162 and ISO 22908 .

v
FINAL DRAFT International Standard ISO/FDIS 9697:2026(en)
Water quality — Gross beta activity — Test method using
thick source
WARNING — Persons using this document shall be familiar with normal laboratory practice. This
document does not purport to address all of the safety issues, 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 test method for the determination of gross beta activity concentration in non-
saline waters.
This document covers non-volatile radionuclides with maximum beta energies of approximately 0,3 MeV or
higher.
3 228 210 14 35
This document does not apply to the measurement of low-energy beta emitters (e.g. H, Ra, Pb, C, S
and Pu) and some gaseous or volatile radionuclides (e.g. radon and radioiodine).
This document is applicable to the analysis of raw and drinking waters with low amounts of total soluble
salts in the water. The limit of detection depends on the performance characteristics (background count
rate and counting efficiency) of the counter used.
As this method requires sample preparation in laboratory facilities, this method is not suited for rapid, in-
the-field analysis.
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 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 5667-14, Water quality — Sampling — Part 14: Guidance on quality assurance and quality control of
environmental water sampling and handling
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 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 80000-10 and ISO 11929-1 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
A beta activity in calibration source, at the time of calibration Bq
−1
c beta activity concentration, without and with corrections Bq·l
A
−1
*
Bq·l
decision threshold, without and with corrections
c
A
−1
#
Bq·l
detection limit, without and with corrections
c
A
−1
 possible or assumed true quantity values of the measurand Bq·l
c
A
−1

Bq·l
lower limit of the probabilistically symmetric coverage interval
c
A
−1

Bq·l
upper limit of the probabilistically symmetric coverage interval
c
A
−1
<
Bq·l
lower limit of the shortest coverage interval
c
A
−1
>
Bq·l
upper limit of the shortest coverage interval
c
A
quantiles of the standardised normal distribution for the probabilities p (for instance
k
p = 1 , 1 − β or 1− γ / 2 )
p
quantiles of the standardised normal distribution for the probabilities q (for instance
k
q
q = 1 , 1 − β or 1− γ / 2 )
m mass of baked residue from volume, V mg
m mass of the sample residue deposited on the planchet mg
r
−1
r background count rate from the alpha window s
0α
−1
r background count rate from the beta window s
0β
−1
r sample gross count rate from the alpha window s
gα
−1
r sample gross count rate from the beta window s
gβ
−1
r calibration count rate of the alpha source from the alpha window s
sα
−1
r calibration count rate of the beta source from the beta window s
sβ
−1
calibration count rate in the beta window when the alpha calibration source is s
r
sα→β
measured
S surface area of the planchet mm
t background counting time s
t sample counting time s
g
t calibration count time of the alpha and beta sources s
s
−1
u(c ) standard uncertainty associated with the measurement result Bq·l
A
standard uncertainty of the estimator c as a function of an assumed true value c
A
A
 
uc

A
of the measurand
u (y)relative uncertainty of y
rel
−1
U expanded uncertainty calculated from U = ku(c ), with k = 1, 2 … Bq·l
A
V volume of test sample equivalent to the mass of solid on the planchet l
V volume of the water sample l
t
ε counting efficiency for the specified radioactive standard
−2
mg·mm
ρ surface density of the sample residue deposited on the planchet
s
alpha-beta cross-talk correction factor, i.e. percentage of alpha count going into the %
χ
beta window from the alpha calibration source
5 Principle
Gross beta analysis is a screening method intended to ensure that the activity concentration of some beta
emitters does not exceed specified reference levels. This type of determination is also known as gross beta
index. Gross beta analysis is not expected to be as accurate nor as precise as specific radionuclide analysis
after radiochemical separations. Also, it is not an absolute determination of the activity concentration of all
beta-emitting radionuclides in a test sample.
The sample, taken, handled and preserved as specified in ISO 5667-1, ISO 5667-3 and ISO 5667-14, is evaporated
to almost dryness, converted to the sulfate form, and baked at 350 °C. A portion of the residue is transferred
onto a planchet and the beta activity is measured using a beta counter (e.g. a gas flow proportional counter),
which is calibrated against a suitable beta calibration source, such as potassium-40 ( K) or strontium-90/
90 90
yttrium-90 ( Sr + Y) in equilibrium.
If simultaneous gross alpha and beta measurements are required on the same water sample, the procedure
[13]
specified in this document is very similar to that of ISO 9696 . However, the counting surface density shall
-2[12][15]
be less than 0,1 mg·mm .
A performance criteria example is given in Annex A.
6 Chemical reagents and equipment
6.1 Chemical reagents
All reagents shall be of recognized analytical grade and shall not contain any detectable beta activity.
NOTE A method to prepare reagent blanks and to check for the absence of any inherent beta radioactivity or
contamination is given in Clause 8.
6.1.1 Ultrapure water, with a resistivity of more than 18,2 MΩ∙cm at 25 °C and total organic carbon less
−1
than 1 μg∙l .
Unless otherwise stated, water refers to ultrapure water.
6.1.2 Calibration source, the choice of the beta calibration source depends on the knowledge of the type
90 40
of radioactive contaminant likely to be present in the waters being tested; Sr and K are commonly used.
40 −1 −1 [4]
NOTE The beta activity of K in natural potassium is 27,9 Bq·g , i.e. 14,5 Bq·g in potassium chloride .
−1
6.1.3 Nitric acid, c(HNO ) = 8 mol·l .
−1 −1
6.1.4 Sulfuric acid, c(H SO ) = 18 mol·l , ρ = 1,84 g·ml , mass fraction w(H SO ) = 95 %.
2 4 2 4
6.1.5 Volatile organic solvents, methanol or acetone.
6.1.6 Calcium sulfate, CaSO .
6.1.7 Vinyl acetate [(C H O ) ].
4 6 2 n
226 210
CAUTION — As calcium salts can contain trace amounts of either Ra or Pb, or both, checks for
the presence of these radionuclides shall be made.
6.2 Equipment
Usual laboratory equipment and, in particular, the following:
6.2.1 Beta counter, preferably of the gas-flow proportional type, or otherwise using a plastic scintillation
detector or a silicon-charged particle detector.
When using a gas-flow proportional counter, it is advisable to choose the electronic beta window with a
239 241
minimal beta-alpha cross-talk and correct for the alpha-beta cross-talk using a Pu or Am alpha source.
If an e
...

ISO/TC 147/SC 3
Secretariat: AFNOR
Date: 2026-08-18
Water quality — Gross beta activity — Test method using thick
source
Fifth edition
Date: 2026-06-1
Qualité de l'eau — Activité bêta globale — Méthode d'essai par source épaisse
FDIS stage
TThhiiss d drraft iaft iss su subbmmiitted tted to to a pa parallearallel vl vote ote iinn IS ISOO, CE, CENN.
ISO/DISFDIS 9697:20252026(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
ii
iii
ISO/DISFDIS 9697:20252026(en)
Contents
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 2
5 Principle . 3
6 Chemical reagents and equipment . 3
6.1 Chemical reagents . 3
6.2 Equipment . 4
7 Procedure . 4
7.1 Sampling . 5
7.2 Pre-treatment . 5
7.3 Concentration stage . 5
7.4 Sulfation stage . 5
7.5 Baking stage . 6
7.6 Source preparation . 6
7.7 Measurement . 6
7.8 Determination of counting background . 6
7.9 Preparation of calibration sources. 6
7.10 Sensitivity and bias . 7
7.11 Optimization of the determination . 7
8 Quality assurance and quality control . 7
8.1 General. 7
8.2 Contamination check . 8
8.3 Interference control of the contribution of the natural radionuclides . 8
8.4 Method verification . 9
8.5 Demonstration of analyst capability . 9
9 Expression of results . 9
9.1 Calculation of activity concentration . 9
9.2 Standard uncertainty. 10
9.3 Decision threshold . 11
9.4 Limit of detection . 11
9.5 Limits of the coverage intervals . 11
10 Test report . 12
Annex A (informative) Example of performance criteria . 14
Bibliography . 15

iv
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 fifth edition cancels and replaces the fourth edition (ISO 9697:2018), which has been technically
revised.
The main changes are as follows:
— — the normative references have been updated;
— — additional symbols for the coverage interval and uncertainty calculations have been added.
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 9697:20252026(en)
Introduction
Radionuclides are present throughout the environment; thus, water bodies (e.g. surface waters, ground
waters, 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
210 210 222 226 228 227 232 231 234
thorium and 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 rainwater) or 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,
60 137
Pu, Am, 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
to the environment as a result of authorized routine releases. The radionuclides present in liquid
[1]
effluents are usually controlled before being discharged to the environment[1] and water bodies.
Anthropogenic radionuclides used for medical and industrial applications can be released to the
environment after use. Anthropogenic radionuclides are also found in waters due to contamination from
fallout resulting from above-ground nuclear detonations and accidents such as those that have occurred
at the Chernobyl 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 [ [4]
WHO guidance level for gross beta activity in drinking water is 1,0 Bq·l [4] ,, see NOTES 1, 2 and 3.
Conformity with 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[12] and ISO 5667-
[5]
20[5] .
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 Gross alpha and gross beta activity are often measured together:; the WHO guidance level for gross alpha
−1 [ [4]
activity in drinking water is 0,5 Bq·l [4] .
NOTE 3 The guidance level calculated in Reference [4][4] is the activity concentration that results in a committed
−1 −1
effective dose 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
[4]
detectable adverse health effects[4] .
This document contains a test method to support laboratories, which need to determine the gross beta
activity concentration in water samples. The method(s) 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, detection limit, 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
3 14 228
NOTE 4 This method does not cover low energy beta emitters, such as H, C and Ra or volatile beta emitters such
131 [9] [10] [11]
as I and radon, which are covered in standards such as ISO 9698[9], , ISO 13162[10] and ISO 22908[11], .
vii
DRAFT International Standard ISO/DIS 9697:2026(en)

Water quality — Gross beta activity — Test method using thick
source
WARNING — Persons using this document shall be familiar with normal laboratory practice. This
document does not purport to address all of the safety issues, 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 test method for the determination of gross beta activity concentration in non-
saline waters. The method covers non-volatile radionuclides with maximum beta energies of approximately
0,3 MeV or higher.
This document covers non-volatile radionuclides with maximum beta energies of approximately 0,3 MeV or
higher.
3 228 210 14 35
This document does not apply to the measurement of low-energy beta emitters (e.g. H, Ra, Pb, C, S
and Pu) and some gaseous or volatile radionuclides (e.g. radon and radioiodine).
This test methoddocument is applicable to the analysis of raw and drinking waters with low amounts of total
soluble salts in the water. LimitThe limit of detection depends on the performance characteristics
(background count rate and counting efficiency) of the counter used.
It is the laboratory’s responsibility to ensure the suitability of this method for the water samples tested. As
this method requires sample preparation in laboratory facilities, this method is not suited for rapid, in-the-
field analysis.
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 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--14, Water quality — Sampling — Part 14: Guidance on quality assurance and quality control of
environmental water sampling and handling
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 80000--10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/DISFDIS 9697:20252026(en)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 80000-10 and ISO 11929-1 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
A beta activity in calibration source, at the time of calibration Bq
−1
c beta activity concentration, without and with corrections Bq·l
A
−1
Bq·l
decision threshold, without and with corrections

−1
Bq·l
detection limit, without and with corrections

−1
Bq·l
possible or assumed true quantity values of the measurand

−1
Bq·l
lower limit of the probabilistically symmetric coverage interval

−1
Bq·l
upper limit of the probabilistically symmetric coverage interval

−1
Bq·l
lower limit of the shortest coverage interval

−1
Bq·l
upper limit of the shortest coverage interval

quantiles of the standardised normal distribution for the probabilities p (for
instance p = , , 1 − β or 1− ) )

quantiles of the standardised normal distribution for the probabilities q (for

instance q = , 1 − β or 1− )
quantiles of the standardised normal distribution for the probabilities q (for instance
k
q
 /2
q = 1− , 1 − β or 1− )
m mass of baked residue from volume, V mg
m mass of the sample residue deposited on the planchet mg
r
−1
r background count rate from the alpha window s
0α
−1
r background count rate from the beta window s
0β
−1
r sample gross count rate from the alpha window s
gα
−1
r sample gross count rate from the beta window s
gβ
−1
r calibration count rate of the alpha source from the alpha window s
sα
−1
r calibration count rate of the beta source from the beta window s
sβ
−1
calibration count rate in the beta window when the alpha calibration source is s
r
sα→β
measured
S surface area of the planchet mm
t background counting time s
t sample counting time s
g
t calibration count time of the alpha and beta sources s
s
−1
u(c ) standard uncertainty associated with the measurement result Bq·l
A
standard uncertainty of the estimator c as a function of an assumed true value
A
of the measurand
u (y) relative uncertainty of y
rel
−1
U expanded uncertainty calculated from U = ku(c ), with k = 1, 2 … Bq·l
A
V volume of test sample equivalent to the mass of solid on the planchet l
V volume of the water sample l
t
ε counting efficiency for the specified radioactive standard
−2
mg·mm
surface density of the sample residue deposited on the planchet

alpha-beta cross-talk correction factor, i.e. percentage of alpha count going into the %
χ
beta window from the alpha calibration source
5 Principle
Gross beta analysis is a screening method intended to ensure that the activity concentration of some beta
emitters does not exceed specified reference levels. This type of determination is also known as gross beta
index. Gross beta analysis is not expected to be as accurate nor as precise as specific radionuclide analysis
after radiochemical separations. Also, it is not an absolute determination of the activity concentration of all
beta-emitting radionuclides in a test sample.
The sample, taken, handled and preserved as specified in ISO 5667-1, ISO 5667-3 and ISO 5667-14, is
evaporated to almost dryness, converted to the sulfate form, and baked at 350 °C. A portion of the residue is
transferred onto a planchet and the beta activity is measured using a beta counter (e.g. a gas flow
proportional counter), which is calibrated against a suitable beta calibration source, such as potassium-
40 90 90
40 ( K) or strontium-90/yttrium-90 ( Sr + Y) in equilibrium.
If simultaneous gross alpha and beta measurements are required on the same water sample, the procedure
specified in this document is very similar to that of ISO 9696[13][13]. However, the counting surface density
-2[
shall be less than 0,1 mg··mm [12][15][12][15].
A performance criteria example is given in Annex AAnnex A.
6 Chemical reagents and equipment
6.1 Chemical reagents
All reagents shall be of recognisedrecognized analytical grade and shall not contain any detectable beta
activity.
NOTE A method to prepare reagent blanks and to check for the absence of any inherent beta radioactivity or
contamination is given in 8Clause 8.
6.1.1 6.1.1 Ultrapure water, with a resistivity of more than 18,2 MΩ∙cm at 25 °C and total organic
−1
carbon less than 1 μg∙l .
ISO/DISFDIS 9697:20252026(en)
Unless otherwise stated, water refers to ultrapure water.
6.1.2 6.1.2 Calibration source, the choice of the beta calibration source depends on the knowledge of
90 40
the type of radioactive contaminant likely to be present in the waters being tested; Sr and K are
commonly used.
40 −1 −1 [4]
NOTE The beta activity of K in natural potassium is 27,9 Bq·g , i.e. 14,5 Bq·g in potassium chloride[4] .
−1
6.1.3 6.1.3 Nitric acid, c(HNO ) = 8 mol·l .
−1 −1
6.1.4 6.1.4 Sulfuric acid, c(H SO ) = 18 mol·l , ρ = 1,84 g·ml , mass fraction w(H SO ) = 95 %.
2 4 2 4
6.1.5 6.1.5 Volatile organic solvents, methanol or acetone.
6.1.6 6.1.6 Calcium sulfate, CaSO .
6.1.7 6.1.7 Vinyl acetate, [(C H O ) ].
4 6 2 n
226 210
CAUTION — — As calcium salts can contain trace amounts of either Ra or Pb, or both, checks for
the presence of these radionuclides shall be made.
6.2 Equipment
Usual laboratory equipment and, in particular, the following:
6.2.1 6.2.1 Beta counter, preferably of the gas-flow proportional type, or otherwise using a plastic
scintillation detector or a silicon-charged particle detector.
When using a gas-flow proportional counter, it is advisable to choose the electronic beta window with a
239 241
minimal beta-alpha cross-talk and correct for the alpha-beta cross-talk using a Pu or Am alpha source. If
an equipment other than a gas-flow proportional counter is used, then the cross-talk can be insignificant and
ignored.
If a windowless gas-flow proportional counter is used, carry out regular checks for possible contamination of
the counting system by counting blank samples.
NOTE The particulate nature of the source that is intended to be counted can give rise to contamination if operated
in a vacuum (as in the case of silicon-charged particle detector) or gas-flow systems (as used in a proportional counter).
6.2.2 6.2.2 Planchet with counting tray, large enough for a deposited sample of a surface density of at
−2 −2
least 2,5 mg·mm (250 mg·cm ), having a lipped edge and made of stainless steel.
The diameter of the planchet that is intended to be used is determined by the counter requirements, i.e. the
detector diameter and source holder dimensions.
NOTE Even spreading of the prepared solid source material onto the planchet is required and some analysts find it
easier to produce this on a polished metal surface, whereas others prefer to use an etched or roughened planchet (sand
blasting and chemical etching has been applied for this purpose).
6.2.3 6.2.3 Muffle furnace, capable of being maintained at (350 ± 10) °C.
6.2.4 6.2.4 Chromatographic reagent grade silica gel, with 0,1 · ·S ± 1 for contamination check.
7 Procedure
WARNING — The use of this document can involve hazardous materials, operations and equipment.
This document does not purport to address all the safety problems associated with its use. It is the
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