prEN ISO 11704

SLOVENSKI STANDARD
01-oktober-2025
Kakovost vode - Skupna alfa in skupna beta aktivnost - Preskusna metoda s
štetjem s tekočinskim scintilatorjem (ISO/DIS 11704:2025)
Water quality - Gross alpha and gross beta activity - Test method using liquid scintillation
counting (ISO/DIS 11704:2025)
Wasserbeschaffenheit - Gesamt-Alpha- und Gesamt-Beta-Aktivität - Verfahren mit dem
Flüssigszintillationszähler (ISO/DIS 11704:2025)
Qualité de l'eau - Activités alpha globale et bêta globale - Méthode d'essai par comptage
des scintillations en milieu liquide (ISO/DIS 11704:2025)
Ta slovenski standard je istoveten z: prEN ISO 11704
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 11704
ISO/TC 147/SC 3
Water quality — Gross alpha and
Secretariat: AFNOR
gross beta activity — Test method
Voting begins on:
using liquid scintillation counting
2025-09-03
Qualité de l'eau — Activités alpha globale et bêta globale —
Voting terminates on:
Méthode d'essai par comptage des scintillations en milieu liquide
2025-11-26
ICS: 13.060.60; 17.240
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
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Reference number
ISO/DIS 11704:2025(en)
DRAFT
ISO/DIS 11704:2025(en)
International
Standard
ISO/DIS 11704
ISO/TC 147/SC 3
Water quality — Gross alpha and
Secretariat: AFNOR
gross beta activity — Test method
Voting begins on:
using liquid scintillation counting
Qualité de l'eau — Activités alpha globale et bêta globale —
Voting terminates on:
Méthode d'essai par comptage des scintillations en milieu liquide
ICS: 13.060.60; 17.240
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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NOTIFICATION OF ANY RELEVANT PATENT
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Published in Switzerland Reference number
ISO/DIS 11704:2025(en)
ii
ISO/DIS 11704:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and units . 2
4 Principle . 3
5 Sampling . 4
6 Chemical reagents and equipment . 4
6.1 Chemical reagents .4
6.2 Certified reference solutions. .5
6.2.1 General .5
6.2.2 Alpha emitting certified reference solution .5
6.2.3 Beta emitting certified reference solution .5
6.3 Equipment .5
7 Procedure . 6
7.1 Direct counting .6
7.2 Thermal preconcentration .6
7.3 Sample preparation .6
7.4 Liquid scintillation measurement .7
7.4.1 Preparation of alpha and beta calibration sources.7
7.4.2 Optimization of counting conditions .7
7.4.3 Blank sample preparation and measurement .8
7.4.4 Alpha and beta efficiencies .8
7.4.5 Sample measurement .8
8 Expression of results . 9
8.1 Calculation of activity per mass .9
8.2 Standard uncertainty .9
8.3 Decision threshold .11
8.4 Detection limit .11
8.5 Limits of the coverage intervals . 12
8.5.1 Limits of the probabilistically symmetric coverage interval . 12
8.5.2 The shortest coverage interval . 12
9 Quality control .13
10 Interference control .13
10.1 Contamination . 13
10.2 Ingrowth of radon. 13
10.3 Loss of polonium . 13
11 Test report .13
Annex A (informative) Set-up parameters and validation data .15
Annex B (informative) Method performances under different conditions .18
Bibliography . 19

iii
ISO/DIS 11704:2025(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.
This third edition cancels and replaces the second edition (ISO 11704:2018), which has been technically
revised.
The main changes are as follows:
— Modification of the introduction
— Clause 8 : updating of the expression of results
— Updating of the Bibliography
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
ISO/DIS 11704:2025(en)
Introduction
Radionuclides are present throughout the environment, thus, water bodies (e.g. surface waters, ground
waters, sea waters) contain them, 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, fertilizers).
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 -1
the WHO guidance level in drinking water is 0,5 Bq·l for gross alpha activity and 1 Bq·l for gross beta
[4]
activity see NOTES 1 and 2. Compliance with these limits is assessed by measuring radioactivity in
water samples and by comparing the results obtained, with their associated uncertainties, as specified by
[5]
ISO/IEC Guide 98-3 and 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 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 method(s) to support laboratories, which need to determine the Gross alpha and
beta 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, 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.
v
DRAFT International Standard ISO/DIS 11704:2025(en)
Water quality — Gross alpha and gross beta activity — Test
method using 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 essential that tests conducted according to this document be carried out by
suitably qualified staff.
1 Scope
This document specifies a method to measure gross alpha and gross beta activity concentration for alpha-
and beta-emitting radionuclides using Liquid Scintillation Counting (LSC).
-1
The method is applicable to all types of waters with a dry residue of less than 5 g·l and when no correction
for colour quenching is necessary.
The method is applicable to test samples non-saline waters following proper sampling, handling and
preparation.
Gross alpha and beta measurements do not provide the exact radioactive content of a sample but estimate
activity based on standard calibration sources. These measurements, known as the alpha and beta index,
serve as screening tools for an initial assessment of total radioactivity.
The method covers non-volatile radionuclides below 80 °C, since some gaseous or volatile radionuclides (e.g.
radon and radioiodine) can be lost during the source preparation.
The method is applicable to test samples of drinking water, rain water, surface and ground water as well as
cooling water, industrial water, domestic and industrial waste water after proper sampling and test sample
preparation (filtration when necessary and taking into account the amount of dissolved material in the water).
The detection limit depends on the sample volume, the instrument used, the background count rate, the
detection efficiency and the counting time. The detection limit of the method described in this document,
-1 -
using currently available liquid scintillation apparatus, is approximately 20 mBq·kg (α) and 100 mBq·kg
1 -1
(β), which is lower than the WHO criteria for safe consumption of drinking water 500 mBq·kg (α) and
-1 [4]
1 000 mBq·kg (β). This value can typically be achieved with a counting time of 500 min for a test sample
volume of 0,08 l.
The method described in this document is applicable in the event of an emergency situation, because the
results can be obtained in less than 4 h by directly measuring water test samples without any treatment.
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: Guidance on the 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/DIS 11704:2025(en)
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO 11929 (all parts), Determination of the characteristic limits (decision threshold, detection limit and limits of
the confidence interval) for measurements of ionizing radiation — Fundamentals and application
ISO/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, definitions, symbols and units
For the purposes of this document, the terms and definitions given in ISO 80000-10, ISO 11929 series and
ISO/IEC Guide 98-3 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/
−1
a , a Alpha and beta activity per mass Bq·g
α β
−1
 
a , a Possible or assumed true values of the gross alpha and beta mass activity Bq·g
α β
respectively
−1
* *
Gross alpha and gross beta decision threshold respectively Bq·g
a , a
α β
−1
# #
Gross alpha and gross beta detection limit respectively Bq·g
a , a
α β
−1

Lower and upper limits of the probabilistically symmetric coverage interval Bq·g
aa,
αα
for gross alpha mass activity
−1

Lower and upper limits of the probabilistically symmetric coverage interval Bq·g
aa,
ββ
for gross beta mass activity
−1
<>
Lower and upper limits of the shortest coverage interval for gross alpha Bq·g
aa,
αα
mass activity
−1
<>
Lower and upper limits of the shortest coverage interval for gross beta mass Bq·g
aa,
ββ
activity
A , A Activity of the alpha and beta emitter certified reference solution used for Bq
α β
the α and β calibration sources
m Mass of the test sample g
m Mass of initial sample subject to heating or possibly concentration g
m Mass of heated or concentrated sample g
m Mass of heated or concentrated sample transferred in the vial g
m , m Mass of alpha and beta emitters certified reference solutions, respectively g
Sα Sβ
−1
r , r Sample gross count rate, from the alpha and beta windows, respectively s
gα gβ
−1
r , r , r Background or blank or count rate, from the alpha, beta and total windows, s
0α 0β 0T
respectively (background is indicate calibration, blank for measurement)

ISO/DIS 11704:2025(en)
−1
r , r , r Count rate of the alpha calibration source in the alpha, beta and total win- s
Sα,α Sα,β Sα,T
dow
−1
r , r , r Count rate of the beta calibration source in the alpha, beta and total window s
Sβ,α Sβ,β Sβ,T
t Sample counting time s
g
t Blank counting time s
t , t Counting time of α and β calibration sources s
Sα Sβ
−1
u (a) Standard uncertainty associated with the measurement result Bq·g
u Relative standard uncertainty -
rel
−1
U Expanded uncertainty, calculated from U = k·u (a), where k = 1, 2 … Bq·g
−1
 
ua() Standard uncertainty of a as a function of its true value Bq·g
α α
−1
Standard uncertainty of a as a function of its true value Bq·g
ua 
β
()
β
Standard uncertainty associated with the beta interference correction
T χ
()
βα→
Standard uncertainty associated with the alpha interference correction
T χ
()
αβ→
ε , ε Counting efficiency for alpha and beta, respectively —
α β
Φ Distribution function of the standardized normal distribution
α, β False positive and false negative probability respectively
χ Alpha interference — Fraction of counts observed in the beta window with —
αβ→
respect to the total number of counts measured by the counter when an
alpha emitter is measured
χ Beta interference — Fraction of counts observed in the alpha window with —
βα→
respect to the total number of counts measured by the counter when a beta
emitter is measured
k Quantiles of the standardized normal distribution for the probabilities p (for
p
instance p = 1 − α, 1 − β or 1 − γ/2)
k Quantiles of the standardized normal distribution for the probabilities q (for
q
instance q = 1−α, 1− β or 1−γ/2)
s Standard deviation of the efficiency in a repeatability condition
rep
4 Principle
Gross alpha and beta activity concentrations are determined by using liquid scintillation counting of a water
sample mixed with a scintillation cocktail.
Gross alpha and beta determinations are not absolute determinations of the sample radioactive contents,
but relative determinations referred to a specific alpha or beta emitter which constitutes the standard
calibration sources. These types of determinations are also known as the alpha and beta index and are
usually employed as screening parameters for first assessment of total radioactive content.
The sample is acidified using nitric acid and heated., water samples with low salt content can be thermally
concentrated by slow evaporation to improve the method sensitivity. An aliquot of the sample is transferred
into a liquid scintillation vial and a scintillation cocktail is added; scintillations from the vial are then
measured with a liquid scintillation counter having an alpha and beta discrimination device.

ISO/DIS 11704:2025(en)
The counter is previously optimized with respect to an alpha and beta discriminator setting and then
calibrated against alpha and beta emitter certified reference solutions. In data evaluation, no correction for
chemical quenching is applied, since the procedure is designed to provide samples with a relatively constant
quench level.
222 3
The method does not account for Rn and its short lived progeny and it is not suitable for H measurement.
When suspended matter is present in significant quantities, a filtration step is required before acidification.
5 Sampling
Sampling, handling, and storage of the water shall be done as specified in ISO 5667-1, ISO 5667-3, and
ISO 5667-10 and guidance is given for the different types of waters in References [8] to.[14] It is important
that the laboratory receives a sample that is truly representative and has neither been damaged nor modified
during transportation or storage.
Collect 0,1 l to 1 l of water in a plastic bottle (6.3.4) in accordance with ISO 5667-1 and ISO 5667-3. If necessary,
filter the sample immediately after collection and before acidification. If possible, acidify immediately with
nitric acid (6.1.1) to a value not lower than pH 1,7 ± 0,2 (7.1) or pH 2,7 ± 0,2 if thermal preconcentration is
desired (7.2). Verify the acidity by using a pH meter (6.3.3).
NOTE Acidification of the water sample minimizes the loss of radioactive material from solution by adsorption. If
carried out before filtration, it desorbs radioactive material already adsorbed on to the particulate material.
The relatively low acidification of the sample does not ensure long-term preservation. Prepare the test
sample preferably within seven days from collection. Groundwater is usually more stable than raw waters
(see ISO 5667-3).
6 Chemical reagents and equipment
6.1 Chemical reagents
Use only reagents of recognised analytical grade, except for the scintillation cocktail.
It is recommended to use acids and bases of trace metal grade or equivalent (a better purity grade can also
be employed).
6.1.1 Nitric acid, c(HNO ) = commercially available acid with mass fraction w(HNO ) = (65 to 70) %.
3 3
6.1.2 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
Water can contain detectable amounts of Rn and short lived progeny. It is therefore strongly recommended
to boil water under vigorous stirring and let it stand for one day before use. Alternatively, use nitrogen
flushing for about 1 h for a 2 l sample.
6.1.3 Scintillation cocktail, commercially available scintillation cocktails suitable for alpha and beta
discrimination (e.g. diisopropylnaphthalene-based cocktails), water miscible.
6.1.4 Volatile organic solvents, methanol or ethanol

ISO/DIS 11704:2025(en)
6.2 Certified reference solutions.
6.2.1 General
In general, the instrumental parameters (efficiency, alpha and beta optimum discrimination) depend on
alpha and beta energies, thus the choice of alpha and beta emitter certified reference solutions depends
on knowledge of the type of radioactive contaminant likely to be present in the waters being tested
[15]
(see ISO 9696 and Reference [16]).
NOTE More information on metrological traceability can be found in ISO/IEC 17025.
6.2.2 Alpha emitting certified reference solution
The alpha emitting certified reference solution shall not contain any unexpected (e.g. decay products of
short half-life) detectable alpha and beta activity.
U is a convenient choice when waters are checked for their natural radioactivity content, as its energy
is close to the most widespread natural radionuclides (e.g. uranium and thorium isotopes, Ra) and it
is commercially available without decay products of short half-life. The supplier can supply details of the
absence of any decay product.
241 239
Am is commonly used when artificial radionuclide co
...