Water quality - Radium-226 - Part 1: Test method using liquid scintillation counting (ISO 13165-1:2013)

ISO 13165-1:2013 specifies the determination of radium-226 (226Ra) activity concentration in non-saline water samples by extraction of its daughter radon-222 (222Rn) and its measurement using liquid scintillation counting.
Radium-226 activity concentrations which can be measured by this test method utilizing currently available liquid scintillation counters goes down to 50 mBq l−1. This method is not applicable to the measurement of other radium isotopes.

Wasserbeschaffenheit - Radium-226 - Teil-1: Verfahren mit dem Flüssigszintillationszhler (ISO 13165-1:2013)

Dieser Teil von ISO 13165 legt ein Verfahren für die Bestimmung der Aktivitätskonzentration von Radium 226 (226Ra) in nicht salzhaltigem Wasser durch Extraktion des Tochterisotops Radon 222 (222Rn) und dessen Messung mithilfe eines Flüssigszintillationszählers fest.
Bei Verwendung derzeit erhältlicher Flüssigszintillationszähler ist Radium 226 mit diesem Verfahren in Aktivitätskonzentrationen ab 50 mBq l−1 messbar. Dieses Verfahren eignet sich nicht für die Messung anderer Radiumisotope.

Qualité de l'eau - Radium 226 - Partie 1: Méthode d'essai par comptage des scintillations en milieu liquide (ISO 13165-1:2013)

L'ISO 13165-1:2013 spécifie la détermination de l'activité volumique du radium 226 (226Ra) dans des échantillons d'eau non saline par extraction de son produit, le radon 222 (222Rn), et son mesurage par comptage des scintillations en milieu liquide.
Les activités volumiques du radium 226 qui peuvent être mesurées au moyen de cette méthode d'essai par comptage des scintillations en milieu liquide vont jusqu'à 50 mBq l-1. Cette méthode n'est pas applicable au mesurage d'autres isotopes du radium.

Kakovost vode - Radij Ra-226 - 1. del: Preskusna metoda s štetjem s tekočinskim scintilatorjem (ISO 13165-1:2013)

General Information

Status
Published
Public Enquiry End Date
01-Aug-2019
Publication Date
07-Apr-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
31-Mar-2020
Due Date
05-Jun-2020
Completion Date
08-Apr-2020

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SLOVENSKI STANDARD
SIST EN ISO 13165-1:2020
01-maj-2020
Kakovost vode - Radij Ra-226 - 1. del: Preskusna metoda s štetjem s tekočinskim
scintilatorjem (ISO 13165-1:2013)
Water quality - Radium-226 - Part 1: Test method using liquid scintillation counting (ISO
13165-1:2013)
Wasserbeschaffenheit - Radium-226 - Teil-1: Verfahren mit dem
Flüssigszintillationszhler (ISO 13165-1:2013)
Qualité de l'eau - Radium 226 - Partie 1: Méthode d'essai par comptage des scintillations
en milieu liquide (ISO 13165-1:2013)
Ta slovenski standard je istoveten z: EN ISO 13165-1:2020
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
SIST EN ISO 13165-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 13165-1:2020

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SIST EN ISO 13165-1:2020


EN ISO 13165-1
EUROPEAN STANDARD

NORME EUROPÉENNE

February 2020
EUROPÄISCHE NORM
ICS 13.060.60; 17.240
English Version

Water quality - Radium-226 - Part 1: Test method using
liquid scintillation counting (ISO 13165-1:2013)
Qualité de l'eau - Radium 226 - Partie 1: Méthode Wasserbeschaffenheit - Radium-226 - Teil-1: Verfahren
d'essai par comptage des scintillations en milieu mit dem Flüssigszintillationszhler (ISO 13165-1:2013)
liquide (ISO 13165-1:2013)
This European Standard was approved by CEN on 6 October 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13165-1:2020 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
SIST EN ISO 13165-1:2020
EN ISO 13165-1:2020 (E)
Contents Page
European foreword . 3

2

---------------------- Page: 4 ----------------------
SIST EN ISO 13165-1:2020
EN ISO 13165-1:2020 (E)
European foreword
The text of ISO 13165-1:2013 has been prepared by Technical Committee ISO/TC 147 "Water quality”
of the International Organization for Standardization (ISO) and has been taken over as EN ISO 13165-
1:2020 by Technical Committee CEN/TC 230 “Water analysis” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2020, and conflicting national standards shall
be withdrawn at the latest by August 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 13165-1:2013 has been approved by CEN as EN ISO 13165-1:2020 without any
modification.

3

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SIST EN ISO 13165-1:2020

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SIST EN ISO 13165-1:2020
INTERNATIONAL ISO
STANDARD 13165-1
First edition
2013-04-15
Water quality — Radium-226 —
Part 1:
Test method using liquid scintillation
counting
Qualité de l’eau — Radium 226 —
Partie 1: Méthode d’essai par comptage des scintillations en milieu
liquide
Reference number
ISO 13165-1:2013(E)
©
ISO 2013

---------------------- Page: 7 ----------------------
SIST EN ISO 13165-1:2020
ISO 13165-1:2013(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

---------------------- Page: 8 ----------------------
SIST EN ISO 13165-1:2020
ISO 13165-1:2013(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Symbols, definitions and units . 1
4 Principle . 2
5 Reagents and equipment . 2
5.1 Reagents. 2
5.2 Equipment . 3
6 Sampling . 3
7 Instrument set-up and calibration . 4
7.1 Preparation of calibration sources . 4
7.2 Optimization of counting conditions . 4
7.3 Detection efficiency. 4
7.4 Blank sample preparation and measurement . 5
8 Procedure. 5
8.1 Direct counting. 5
8.2 Thermal preconcentration . 5
8.3 Sample preparation . 6
8.4 Sample measurement . 6
9 Quality control . 6
10 Expression of results . 6
10.1 Calculation of massic activity . 6
10.2 Standard uncertainty . 6
10.3 Decision threshold . 7
10.4 Detection limit . 7
10.5 Confidence limits. 8
10.6 Calculations using the activity concentration . 8
11 Interference control . 8
12 Test report . 9
Annex A (informative) Set-up parameters and validation data .10
Bibliography .14
© ISO 2013 – All rights reserved iii

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SIST EN ISO 13165-1:2020
ISO 13165-1:2013(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 13165-1 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,
Radioactivity measurements.
ISO 13165 consists of the following parts, under the general title Water quality — Radium-226:
— Part 1: Test method using liquid scintillation counting
— Part 2: Test method using emanometry
The following part is under preparation:
— Part 3: Test method using coprecipitation and gamma-spectrometry
iv © ISO 2013 – All rights reserved

---------------------- Page: 10 ----------------------
SIST EN ISO 13165-1:2020
ISO 13165-1:2013(E)

Introduction
Radioactivity from several naturally occurring and human-made sources is present throughout the
environment. Thus, water bodies (surface waters, groundwaters, sea waters) can contain radionuclides
of natural and artificial origin (i.e. human-made).
a) Natural radionuclides, including potassium-40, and those of the thorium and uranium decay series,
in particular radium-226, radium-228, uranium-234, uranium-238, lead-210, can be found in water
for natural reasons (e.g. desorption from the soil and wash-off by rain water) or release from
technological processes involving naturally occurring radioactive materials (e.g. the mining and
processing of mineral sands or phosphate fertilizer production and use).
b) Human-made radionuclides such as transuranium elements (americium, plutonium, neptunium,
curium), tritium, carbon-14, strontium-90 and gamma-emitting radionuclides can also be found in
natural waters as they can be authorized to be routinely released into the environment in small
quantities in the effluent discharged from nuclear fuel cycle facilities and following their use
in unsealed form in medicine or industry. They are also found in water due to fallout from past
explosions in the atmosphere of nuclear devices and the accidents at Chernobyl and Fukushima.
Drinking water can thus contain radionuclides at activity concentrations which present a risk to human
health. In order to assess the quality of drinking-water (including mineral waters and spring waters)
with respect to its radionuclide content and to provide guidance on reducing health risks by taking
measures to decrease radionuclide activity concentrations, water resources (groundwater, river, lake,
sea, etc.) and drinking water are monitored for their radioactivity content as recommended by the World
Health Organization (WHO).
An International Standard on a test method of radium-226 activity concentrations in water samples
is justified for test laboratories carrying out these measurements, which are sometimes required
by national authorities, as laboratories may have to obtain a specific accreditation for radionuclide
measurement in drinking water samples.
Radium-226 activity concentration can vary widely according to local geological and climatic
−1 −1
characteristics and ranges from 0,001 Bq l in surface waters up to 50 Bq l in natural groundwaters;
−1
the guidance level for radium-226 in drinking water as recommended by WHO is 1 Bq l (Reference [7]).
−1
NOTE The guidance level is the activity concentration with an intake of 2 l day of drinking water for 1 year
−1
that results in an effective dose of 0,1 mSv year for members of the public, an effective dose that represents a
very low level of risk that is not expected to give rise to any detectable adverse health effect.
This International Standard is one of a series on determination of the activity concentration of
radionuclides in water samples.
© ISO 2013 – All rights reserved v

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SIST EN ISO 13165-1:2020

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SIST EN ISO 13165-1:2020
INTERNATIONAL STANDARD ISO 13165-1:2013(E)
Water quality — Radium-226 —
Part 1:
Test method using liquid scintillation counting
WARNING — Persons using this part of ISO 13165 should be familiar with normal laboratory
practice. This part of ISO 13165 does not purport to address all of the safety problems, if any,
associated with its use. It is the responsibility of the user to establish appropriate safety and
health practices and to ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this part of
ISO 13165 be carried out by suitably qualified staff.
1 Scope
226
This part of ISO 13165 specifies the determination of radium-226 ( Ra) activity concentration in non-
222
saline water samples by extraction of its daughter radon-222 ( Rn) and its measurement using liquid
scintillation counting.
Radium-226 activity concentrations which can be measured by this test method utilizing currently
−1
available liquid scintillation counters goes down to 50 mBq l . This method is not applicable to the
measurement of other radium isotopes.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Symbols, definitions and units
For the purposes of this document, the definitions, symbols and abbreviations given in ISO 80000-10,
ISO/IEC Guide 98-3, and the following apply.
a massic activity of the sample at the measuring time, in becquerels per gram
226
a massic activity of the Ra standard solution at the measuring time, in becquerels per gram
S
a* decision threshold for the massic alpha-activity, in becquerels per gram
© ISO 2013 – All rights reserved 1

---------------------- Page: 13 ----------------------
SIST EN ISO 13165-1:2020
ISO 13165-1:2013(E)

#
a detection limit for the massic alpha-activity, in becquerels per gram
⊲ ⊳
a , a lower and upper limits of the confidence interval, in becquerels per gram
c activity concentration, in becquerels per litre
A
m mass of the test sample, in grams
m mass of initial sample subject to heating or possibly concentration, in grams
1
m mass of heated or concentrated sample, in grams
2
m mass of heated or concentrated sample transferred in the vial, in grams
3
226
m mass of Ra standard solution used for the preparation of the calibration sample, in grams
S
r blank sample count rate in the alpha-window, in reciprocal seconds
0
r sample gross count rate in the alpha-window, in reciprocal seconds
g
r count rate of the calibration sample in the alpha-window, in reciprocal seconds
S
t blank sample counting time, in seconds
0
t sample counting time, in seconds
g
t calibration sample counting time, in seconds
S
u(a) standard uncertainty associated with the measurement result; in becquerels per gram
U expanded uncertainty, calculated using U = ku(a), with k = 1, 2, … in becquerels per gram
w factor equal to 1/εm
ε alpha-efficiency
ρ density, in grams per litre
4 Principle
226 222
Ra massic activity is determined by liquid scintillation counting of daughter Rn at isotopic
222
equilibrium (99,56 %) reached 30 d after the preparation of the sample. The Rn is extracted from
aqueous solution by means of a scintillation cocktail immiscible with water inside the scintillation vial
(References [1]–[4]).
The aqueous sample is acidified, heated and, if possible, concentrated by slow evaporation in order to
222
desorb Rn and to achieve a better detection limit. The concentrated aqueous sample is transferred
into a radon-tight scintillation vial and a water-immiscible scintillation cocktail is added.
After 30 d, the sample is measured by liquid scintillation counting (LSC) applying alpha and beta
222 218 214
discrimination: only alpha-emiss
...

SLOVENSKI STANDARD
oSIST prEN ISO 13165-1:2019
01-julij-2019
Kakovost vode - Radij Ra-226 - 1. del: Preskusna metoda s štetjem s tekočinskim
scintilatorjem (ISO 13165-1:2013)
Water quality - Radium-226 - Part 1: Test method using liquid scintillation counting (ISO
13165-1:2013)
Wasserbeschaffenheit - Radium-226 - Teil-1: Verfahren mit dem FlüssigszintillationszÃ
¤hler (ISO 13165-1:2013)
Qualité de l'eau - Radium 226 - Partie 1: Méthode d'essai par comptage des scintillations
en milieu liquide (ISO 13165-1:2013)
Ta slovenski standard je istoveten z: prEN ISO 13165-1
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
17.240 Merjenje sevanja Radiation measurements
oSIST prEN ISO 13165-1:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 13165-1:2019

---------------------- Page: 2 ----------------------
oSIST prEN ISO 13165-1:2019
INTERNATIONAL ISO
STANDARD 13165-1
First edition
2013-04-15
Water quality — Radium-226 —
Part 1:
Test method using liquid scintillation
counting
Qualité de l’eau — Radium 226 —
Partie 1: Méthode d’essai par comptage des scintillations en milieu
liquide
Reference number
ISO 13165-1:2013(E)
©
ISO 2013

---------------------- Page: 3 ----------------------
oSIST prEN ISO 13165-1:2019
ISO 13165-1:2013(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

---------------------- Page: 4 ----------------------
oSIST prEN ISO 13165-1:2019
ISO 13165-1:2013(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Symbols, definitions and units . 1
4 Principle . 2
5 Reagents and equipment . 2
5.1 Reagents. 2
5.2 Equipment . 3
6 Sampling . 3
7 Instrument set-up and calibration . 4
7.1 Preparation of calibration sources . 4
7.2 Optimization of counting conditions . 4
7.3 Detection efficiency. 4
7.4 Blank sample preparation and measurement . 5
8 Procedure. 5
8.1 Direct counting. 5
8.2 Thermal preconcentration . 5
8.3 Sample preparation . 6
8.4 Sample measurement . 6
9 Quality control . 6
10 Expression of results . 6
10.1 Calculation of massic activity . 6
10.2 Standard uncertainty . 6
10.3 Decision threshold . 7
10.4 Detection limit . 7
10.5 Confidence limits. 8
10.6 Calculations using the activity concentration . 8
11 Interference control . 8
12 Test report . 9
Annex A (informative) Set-up parameters and validation data .10
Bibliography .14
© ISO 2013 – All rights reserved iii

---------------------- Page: 5 ----------------------
oSIST prEN ISO 13165-1:2019
ISO 13165-1:2013(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 13165-1 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,
Radioactivity measurements.
ISO 13165 consists of the following parts, under the general title Water quality — Radium-226:
— Part 1: Test method using liquid scintillation counting
— Part 2: Test method using emanometry
The following part is under preparation:
— Part 3: Test method using coprecipitation and gamma-spectrometry
iv © ISO 2013 – All rights reserved

---------------------- Page: 6 ----------------------
oSIST prEN ISO 13165-1:2019
ISO 13165-1:2013(E)

Introduction
Radioactivity from several naturally occurring and human-made sources is present throughout the
environment. Thus, water bodies (surface waters, groundwaters, sea waters) can contain radionuclides
of natural and artificial origin (i.e. human-made).
a) Natural radionuclides, including potassium-40, and those of the thorium and uranium decay series,
in particular radium-226, radium-228, uranium-234, uranium-238, lead-210, can be found in water
for natural reasons (e.g. desorption from the soil and wash-off by rain water) or release from
technological processes involving naturally occurring radioactive materials (e.g. the mining and
processing of mineral sands or phosphate fertilizer production and use).
b) Human-made radionuclides such as transuranium elements (americium, plutonium, neptunium,
curium), tritium, carbon-14, strontium-90 and gamma-emitting radionuclides can also be found in
natural waters as they can be authorized to be routinely released into the environment in small
quantities in the effluent discharged from nuclear fuel cycle facilities and following their use
in unsealed form in medicine or industry. They are also found in water due to fallout from past
explosions in the atmosphere of nuclear devices and the accidents at Chernobyl and Fukushima.
Drinking water can thus contain radionuclides at activity concentrations which present a risk to human
health. In order to assess the quality of drinking-water (including mineral waters and spring waters)
with respect to its radionuclide content and to provide guidance on reducing health risks by taking
measures to decrease radionuclide activity concentrations, water resources (groundwater, river, lake,
sea, etc.) and drinking water are monitored for their radioactivity content as recommended by the World
Health Organization (WHO).
An International Standard on a test method of radium-226 activity concentrations in water samples
is justified for test laboratories carrying out these measurements, which are sometimes required
by national authorities, as laboratories may have to obtain a specific accreditation for radionuclide
measurement in drinking water samples.
Radium-226 activity concentration can vary widely according to local geological and climatic
−1 −1
characteristics and ranges from 0,001 Bq l in surface waters up to 50 Bq l in natural groundwaters;
−1
the guidance level for radium-226 in drinking water as recommended by WHO is 1 Bq l (Reference [7]).
−1
NOTE The guidance level is the activity concentration with an intake of 2 l day of drinking water for 1 year
−1
that results in an effective dose of 0,1 mSv year for members of the public, an effective dose that represents a
very low level of risk that is not expected to give rise to any detectable adverse health effect.
This International Standard is one of a series on determination of the activity concentration of
radionuclides in water samples.
© ISO 2013 – All rights reserved v

---------------------- Page: 7 ----------------------
oSIST prEN ISO 13165-1:2019

---------------------- Page: 8 ----------------------
oSIST prEN ISO 13165-1:2019
INTERNATIONAL STANDARD ISO 13165-1:2013(E)
Water quality — Radium-226 —
Part 1:
Test method using liquid scintillation counting
WARNING — Persons using this part of ISO 13165 should be familiar with normal laboratory
practice. This part of ISO 13165 does not purport to address all of the safety problems, if any,
associated with its use. It is the responsibility of the user to establish appropriate safety and
health practices and to ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this part of
ISO 13165 be carried out by suitably qualified staff.
1 Scope
226
This part of ISO 13165 specifies the determination of radium-226 ( Ra) activity concentration in non-
222
saline water samples by extraction of its daughter radon-222 ( Rn) and its measurement using liquid
scintillation counting.
Radium-226 activity concentrations which can be measured by this test method utilizing currently
−1
available liquid scintillation counters goes down to 50 mBq l . This method is not applicable to the
measurement of other radium isotopes.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Symbols, definitions and units
For the purposes of this document, the definitions, symbols and abbreviations given in ISO 80000-10,
ISO/IEC Guide 98-3, and the following apply.
a massic activity of the sample at the measuring time, in becquerels per gram
226
a massic activity of the Ra standard solution at the measuring time, in becquerels per gram
S
a* decision threshold for the massic alpha-activity, in becquerels per gram
© ISO 2013 – All rights reserved 1

---------------------- Page: 9 ----------------------
oSIST prEN ISO 13165-1:2019
ISO 13165-1:2013(E)

#
a detection limit for the massic alpha-activity, in becquerels per gram
⊲ ⊳
a , a lower and upper limits of the confidence interval, in becquerels per gram
c activity concentration, in becquerels per litre
A
m mass of the test sample, in grams
m mass of initial sample subject to heating or possibly concentration, in grams
1
m mass of heated or concentrated sample, in grams
2
m mass of heated or concentrated sample transferred in the vial, in grams
3
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m mass of Ra standard solution used for the preparation of the calibration sample, in grams
S
r blank sample count rate in the alpha-window, in reciprocal seconds
0
r sample gross count rate in the alpha-window, in reciprocal seconds
g
r count rate of the calibration sample in the alpha-window, in reciprocal seconds
S
t blank sample counting time, in seconds
0
t sample counting time, in seconds
g
t calibration sample counting time, in seconds
S
u(a) standard uncertainty associated with the measurement result; in becquerels per gram
U expanded uncertainty, calculated using U = ku(a), with k = 1, 2, … in becquerels per gram
w factor equal to 1/εm
ε alpha-efficiency
ρ density, in grams per litre
4 Principle
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Ra massic activity is determined by liquid scintillation counting of daughter Rn at isotopic
222
equilibrium (99,56 %) reached 30 d after the preparation of the sample. The Rn is extracted from
aqueous solution by means of a scintillation cocktail immiscible with water inside the scintillation vial
(References [1]–[4]).
The aqueous sample is acidified, heated and, if possible, concentrated by slow evaporation in order to
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desorb Rn and to achieve a better detection limit. The concentrated aqueous sample is transferred
into a radon-tight scintillation vial and a water-immiscible scintillation cocktail is added.
After 30 d, the sample is measured by liquid scintillation counting (LSC) applying alpha and beta
222 218 214
discrimination: only alpha-emission of Rn and that of its short lived progeny ( Po, Po) are
considered, as this counting condition ensures a better detection limit.
5 Reagents and equipment
5.1 Reagents
All reagents shall be of recognized analytical grade and, except for 5.1.3 and 5.1.4, shall not contain any
detectable alpha- and beta-activity.
2 © ISO 2013 – All rights reserved

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oSIST prEN ISO 13165-1:2019
ISO 13165-1:2013(E)

5.1.1 Laboratory water, distilled or deionized, complying with ISO 3696, grade 3.
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Deionized water can contain detectable amounts of Rn and short-lived daughters. It is therefore
strongly recommended that water be boiled under vigorous stirring and allowed to stand for 1 day
before use. Otherwise, flux it with nitrogen for about 1 h for 2 l.
−1 −1
5.1.2 Nitric acid, c(HNO ) = 15,8 mol l , ρ = 1,42 g ml , mass fraction w(HNO ) = 70 %.
3 3
5.1.3 Scintillation cocktail, commercially available scintillation cocktails, water immiscible and
suitable for alpha and beta discrimination (e.g. diisopropylnaphthalene-based cocktails).
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5.1.4 Ra standard solution
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Ra standard solutions shall be provided with calibration certificates containing at least the activity
concentration, measurement uncertainty and/or statement of compliance with an identified metrological
specification.
5.2 Equipment
5.2.1 Balance.
5.2.2 Hotplate with magnetic stirrer and stirring bar.
5.2.3 pH-meter.
5.2.4 Wide-mouth HDPE sample bottles, volumes between 100 ml and 500 ml.
5.2.5 Liquid scintillation counter, with alpha and beta discrimination option, with thermostated
counting chamber and preferably an ultra-low level counter to achieve better detection limits.
5.2.6 Polyethylene scintillation vials, PTFE coated, 20 ml.
PTFE-coated polyethylene vials are the best choice, since they prevent both the diffusion of the
cocktail into the wall of the vial and the absorption of radon from the environment. Glass vials ex
...

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