SIST EN ISO 16641:2016

SLOVENSKI STANDARD
SIST EN ISO 16641:2016
01-junij-2016
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Measurement of radioactivity in the environment - Air - Radon 220: Integrated
measurement methods for the determination of the average activity concentration using
passive solid-state nuclear track detectors (ISO 16641:2014)
Ermittlung der Radioaktivität in der Umwelt - Luft - Radon-220: Integrierende
Messmethoden für die Bestimmung der mittleren Aktivitätskonzentration mit passiven
Festkörperspurdetektoren (ISO 16641:2014)
Mesurage de la radioactivité dans l'environnement - Air - Radon 220: Méthode de
mesure intégrée pour la détermination de l'activité volumique moyenne avec des
détecteurs passifs solides de traces nucléaires (ISO 16641:2014)
Ta slovenski standard je istoveten z: EN ISO 16641:2016
ICS:
13.040.99 Drugi standardi v zvezi s Other standards related to air
kakovostjo zraka quality
17.240 Merjenje sevanja Radiation measurements
SIST EN ISO 16641:2016 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 16641:2016

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SIST EN ISO 16641:2016


EN ISO 16641
EUROPEAN STANDARD

NORME EUROPÉENNE

April 2016
EUROPÄISCHE NORM
ICS 17.240
English Version

Measurement of radioactivity in the environment - Air -
Radon 220: Integrated measurement methods for the
determination of the average activity concentration using
passive solid-state nuclear track detectors (ISO
16641:2014)
Mesurage de la radioactivité dans l'environnement - Ermittlung der Radioaktivität in der Umwelt - Luft -
Air - Radon 220: Méthode de mesure intégrée pour la Radon-220: Integrierende Messmethoden für die
détermination de l'activité volumique moyenne avec Bestimmung der mittleren Aktivitätskonzentration mit
des détecteurs passifs solides de traces nucléaires (ISO passiven Festkörperspurdetektoren (ISO 16641:2014)
16641:2014)
This European Standard was approved by CEN on 21 February 2016.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16641:2016 E
worldwide for CEN national Members.

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SIST EN ISO 16641:2016
EN ISO 16641:2016 (E)
Contents Page
European foreword . 3
2

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SIST EN ISO 16641:2016
EN ISO 16641:2016 (E)
European foreword
The text of ISO 16641:2014 has been prepared by Technical Committee ISO/TC 85 “Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 16641:2016 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2016, and conflicting national standards shall
be withdrawn at the latest by October 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] 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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16641:2014 has been approved by CEN as EN ISO 16641:2016 without any modification.

3

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SIST EN ISO 16641:2016

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SIST EN ISO 16641:2016
INTERNATIONAL ISO
STANDARD 16641
First edition
2014-10-01
Measurement of radioactivity in the
environment — Air — Radon 220:
Integrated measurement methods
for the determination of the average
activity concentration using passive
solid-state nuclear track detectors
Mesurage de la radioactivité dans l’environnement — Air — Radon
220: Méthode de mesure intégrée pour la détermination de l’activité
volumique moyenne avec des détecteurs passifs solides de traces
nucléaires
Reference number
ISO 16641:2014(E)
©
ISO 2014

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SIST EN ISO 16641:2016
ISO 16641:2014(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
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 2014 – All rights reserved

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SIST EN ISO 16641:2016
ISO 16641:2014(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 3
4 Principle of the measurement method . 4
5 Equipment . 5
6 Sampling . 6
6.1 Sampling objective . 6
6.2 Sampling characteristics . . 6
6.3 Sampling conditions . 6
7 Detection method with solid-state nuclear track detectors (SSNTD) .7
8 Measurement procedure . 7
8.1 General . 7
8.2 Influencing variables . 8
8.3 Calibration . 8
9 Expression of results . 9
9.1 Average thoron activity concentration . 9
9.2 Standard uncertainty . 9
9.3 Decision threshold .10
9.4 Detection limit .10
9.5 Confidence limits.11
9.6 Example .11
10 Test report .12
Annex A (informative) Radon-220 and its decay products .14
Bibliography .16
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ISO 16641:2014(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.
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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
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Introduction
Radon isotopes 222, 220, and 219 are radioactive gases produced by the disintegration of radium
isotopes 226, 224, and 223, which are decay products of uranium-238, thorium-232, and uranium-235,
respectively, are all found in the earth’s crust. Solid elements, also radioactive, followed by stable lead
[1]
are produced by radon disintegration.
Radon is considered to be the main source of human exposure to natural radiation. The UNSCEAR (2006)
[2]
report suggests that, at the international level, radon accounts for around 52 % of the global average
exposure to natural radiation. Isotope 222 (48 %) is far more significant than isotope 220 (4 %), while
isotope 219 is considered negligible.
Recent studies on indoor radon-222 and lung cancer in Europe, North America, and Asia provide strong
evidence that radon-222 causes a substantial number of lung cancers in the general population. Current
estimates of the proportion of lung cancers attributable to radon-222 range from 3 % to 14 %, depending
[3]
on the average radon-222 concentration in the country concerned and the calculation methods.
Indoor radon-222 concentration is mainly measured by passive detectors that can measure both
[4]
radon-222 and radon-220 signals. If the readings are overestimated, the lung cancer risk is given
as a biased estimate when epidemiological studies are carried out. Radon-222 and radon-220 parallel
[4]-[11]
measurements have been carried out in several countries (See Table A.1). Experiences from field
work indicate that there is no correlation among radon-222 and radon-220 and its decay products’
concentrations. This implies that one parameter cannot be estimated from the other. Unless radon-220
activity concentration is measured, a correct radon-222 concentration cannot be given with a single use
of radon-222 measuring device. Therefore, a specific measurement of radon-220 is justified.
Due to its short half-life, radon-220 disappears very rapidly in the atmosphere. An activity concentration
gradient is observed from the walls or grounds to the inner space of the room. Depending on the
objective of the measurement (building characteristics, construction material characterization, etc.),
the sampling location is to be chosen after taking into account this gradient.
Due to a highest level of radon-222 in air, radon-220 is very difficult to measure alone. This International
Standard proposes a measuring method of radon-220 activity concentration using a dual system
considering radon-222 and radon-220.
There are many ways of measuring the activity concentration of radon-220 and its decay products. The
measuring technique proposed is an integrated measurement method for radon-220 only.
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SIST EN ISO 16641:2016
INTERNATIONAL STANDARD ISO 16641:2014(E)
Measurement of radioactivity in the environment — Air
— Radon 220: Integrated measurement methods for the
determination of the average activity concentration using
passive solid-state nuclear track detectors
1 Scope
This International Standard covers integrated measurement techniques for radon-220 with passive
sampling only. It provides information on measuring the average activity concentration of radon-220 in
the air, based on easy-to-use and low-cost passive sampling, and the conditions of use for the measuring
devices.
This International Standard covers samples taken without interruption over periods varying from a few
months to one year.
This type of measurement is also applicable for determination of radon-222 activity concentration.
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 11665-1:2012, Measurement of radioactivity in the environment — Air: radon-222 — Part 1: Origins of
radon and its short-lived decay products and associated measurement methods
ISO 11929, 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 17025:2005, General requirements for the competence of testing and calibration laboratories
IEC 61577-1, Radiation protection instrumentation — Radon and radon decay product measuring
instruments — Part 1: General principles
3 Terms, definitions, and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
activity
number of spontaneous nuclear disintegrations occurring in a given quantity of material over a
reasonably short time interval, divided by this time interval
[SOURCE: ISO 921:1997, 23]
Note 1 to entry: Activity is expressed by the relationship:
AN=×λ
The decay constant is linked to the radioactive half-life (T) by the relationship:
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ISO 16641:2014(E)

ln2
λ=
T
3.1.2
activity concentration
activity per unit volume
[SOURCE: IEC 61577-1]
3.1.3
average activity concentration
exposure to activity concentration divided by the sampling duration
3.1.4
radon exposure
integral with respect to time of radon activity concentration accumulated during the exposure time
Note 1 to entry: Exposure to radon is expressed by:
t
e= Ctd
∫
0
3.1.5
integrated measurement
measurement obtained by accumulating over time physical variables (number of nuclear tracks, number
of electric charges, etc.) linked to the disintegration of radon and/or its decay products, followed by
analysis at the end of the accumulation period
3.1.6
measurand
particular quantity subject to measurement
[SOURCE: ISO/IEC Guide 99]
3.1.7
passive sampling
sampling using no active device like pumps for sampling the atmosphere
[SOURCE: IEC 61577-1]
Note 1 to entry: In this case, the sampling is in most instruments mainly made by diffusion.
3.1.8
primary standard
standard designed or widely acknowledged as having the highest metrological qualities and whose
value is accepted without reference to other standards of the same quantity
[SOURCE: IEC 61577-1]
Note 1 to entry: The concept of primary standard is equally valid for base quantities and derived quantities.
3.1.9
reference atmosphere
radioactive atmosphere in which the influencing parameters (aerosols, radioactivity, climatic conditions,
etc.) are sufficiently well-known or controlled to allow its use in a testing procedure for thoron or its
decay products’ measuring instruments
[SOURCE: IEC 61577-1]
Note 1 to entry: The parameter values concerned shall be traceable to recognized standards.
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3.1.10
reference source
radioactive secondary standard source for use in the calibration of the measuring instruments
[SOURCE: IEC 61577-1]
3.1.11
sampling duration
time interval between the installation and removal of the sampling device at a given point
3.1.12
sampling plan
precise protocol that, depending on the application of the principles of the strategy adopted, defines the
spatial and temporal dimensions of sampling, the frequency, the sample number, the quantities sampled,
etc., and the human resources to be used for the sampling operation
3.1.13
sampling strategy
set of technical principles that aim to resolve, depending on the objectives and site considered, the two
main issues which are the sampling density and the spatial distribution of the sampling areas
Note 1 to entry: The sampling strategy provides the set of technical options that are required in the sampling
plan.
3.1.14
radon-220 decay products
216 212 212 212
polonium-216 ( Po), lead-212 ( Pb), bismuth-212 ( Bi), polonium-212 ( Po), and thallium-208
208
( Tl)
Note 1 to entry: See Figure A.1.
3.2 Symbols
For the purposes of this document, the following symbols apply.
λ decay constant of the nuclide i, in per second
C
average activity concentration, in becquerel per cubic metre (e.g. C radon-220 activity concentra-
Tn
tion)

true value of the average activity concentration
C
t sampling duration, in hours
e exposure to radon, in becquerel per cubic metre hour

u 
standard uncertainty of the estimator of the true value C
u() standard uncertainty associated with the measurement result
U expanded uncertainty calculated by U = k × u() with k = 2
*
decision threshold of the average activity concentration, in becquerel per cubic metre
C
#
detection limit of the average activity concentration, in becquerel per cubic metre
C

lower and upper limit of the confidence interval, respectively, of the average activity concentration, in
CC,
becquerel per cubic metre
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ISO 16641:2014(E)

ω factor linked to the calibration factor f and the sampling duration
1 Tn2
ω factor linked to the calibration factor f and the sampling duration
2 Tn1
ω factor linked to the calibration factor f and the sampling duration
3 Rn1
ω factor linked to the calibration factor f and the sampling duration
4 Rn2
d track density for low air-exchange rate chamber in tracks per square centimetre
L
d track density for high air-exchange rate chamber in tracks per square centimetre
H
track density due to background in tracks per square centimetre
b
f calibration factor for radon-220 in a low air-exchange rate chamber in (tracks per square centimetre per
Tn1
hour) per (becquerel per cubic metre)
f calibration factor for radon-220 in a high air-exchange rate chamber in (tracks per square centimetre
Tn2
per hour) per (becquerel per cubic metre)
f calibration factor for radon-222 in a low air-exchange rate chamber in (tracks per square centimetre per
Rn1
hour) per (becquerel per cubic metre)
f calibration factor for radon-222 in a high air-exchange rate chamber in (tracks per square centimetre
Rn2
per hour) per (becquerel per cubic metre)
4 Principle of the measurement method
The integrated measurement of the average radon-220 activity concentration using a solid-state nuclear
[12]
track detector (SSNTD) is based on the following:
— passive sampling using two chambers with different air-exchange rates during which the alpha
particles, including those produced by the disintegration of radon-220, radon-222, and their decay
products, transfer their energy by ionizing or exciting the atoms in the polymer or plastic. This
energy transferred to the medium leaves areas of damage called “latent tracks”. Because of their
different half-lives, radon-222 and radon-220 can be separated using these two chambers. In the
high air-exchange rate chamber, both isotopes are detected. In the low air-exchange rate chamber,
however, radon–222 is mainly detected with only a small quantity of radon-220 (see Figure 1);
The high air-exchange rate should be set as high as possible so that the calibration factor of radon-220
is ideally the same as that of radon-222. On the contrary, the low air-exchange rate should be set as
low as possible with a high diffusion barrier.
— transport of the exposed detectors to the laboratory for the appropriate chemical processing which
transforms the latent tracks into “visible tracks” counted via an optical system. The number of these
visible tracks per unit surface area is linked to the exposure value of the radon-220 and its decay
products by the calibration factor defined for detectors in the same batch processed chemically and
counted under the same conditions;
— determination of the radon-220 average activity concentration from the exposure value of both
chambers and the sampling period.
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Figure 1 — Principle of radon-thoron separation technique
5 Equipment
The apparatus includes the following.
5.1 A device composed of two closed accumulation chambers with different air-exchange rates.
Each of them is associated with a solid state nuclear track detector. Each closed accumulation chamber
has a filter through which the radon-220 and radon-222 diffuse. This filter is set to prevent access of the
aerosols present in the air at the time of sampling, especially the solid radon-220 and radon-222 decay
products (see Figure 2).
The SSNTD shall come from the same sheet of plastic to avoid different results. Nevertheless each SSNTD
batch is calibrated.
5.2 The equipment and suitable chemical reagents for etching the detector.
See ISO 11665-4.
5.3 An optical microscope and associated equipment, for scanning and counting the etched tracks.
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Key
1 solid state nuclear track detector (SSNTD)
2 support
3 filter or diffusion barrier
4 accumulation chamber
Figure 2 — Example of the design of a radon-222/radon-220 discriminative measuring device
6 Sampling
6.1 Sampling objective
The sampling objective is to place the measuring device, without interruption, in an air sample
representative of the atmospheric medium under investigation.
6.2 Sampling characteristics
The sampling is passive and is performed through a filtering medium. Depending on the air-exchange
rate of the accumulation chamber, one or two radon isotopes can diffuse into the chamber. If the air-
exchange rate is low, only radon-222 can diffuse into the chamber. If the air-exchange is high, both
radon-222 and radon-220 can diffuse into the chamber. The sampling shall be performed in conditions
that preclude clogging of the filtering medium, which would result in modified measuring conditions. If
the filtering medium clogs there is a risk of the air in the chamber not being renewed.
6.3 Sampling conditions
6.3.1 Installation of sampling device
The installation of the measuring device shall be carried out as specified in ISO 11665-1.
In the specific case of an indoor measurement, the measuring device is installed as follows:
— in an area not directly exposed to solar radiation;
— away from a heat source (radiator, picture windows, electrical equipment, chimney, etc.);
— away from traffic areas, doors and windows, and natural ventilation sources (it could, for example,
be sited on an item of furniture like a shelf or sideboard);
6 © I
...