SIST EN ISO 11665-1:2019

SLOVENSKI STANDARD
01-december-2019
Nadomešča:
SIST EN ISO 11665-1:2015
Merjenje radioaktivnosti v okolju - Zrak: radon Rn-222 - 1. del: Radon in njegovi
kratkoživi razpadni produkti: izvori in merilne metode (ISO 11665-1:2019)
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
11665-1:2019)
Ermittlung der Radioaktivität in der Umwelt - Luft: Radon-222 - Teil 1: Radon und seine
kurzlebigen Folgeprodukte: Quellen und Messverfahren (ISO 11665-1:2019)
Mesurage de la radioactivité dans l'environnement - Air: radon 222 - Partie 1: Origine du
radon et de ses descendants à vie courte, et méthodes de mesure associées (ISO
11665-1:2019)
Ta slovenski standard je istoveten z: EN ISO 11665-1:2019
ICS:
13.040.99 Drugi standardi v zvezi s Other standards related to air
kakovostjo zraka quality
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 11665-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 13.040.01; 17.240 Supersedes EN ISO 11665-1:2015
English Version
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 11665-1:2019)
Mesurage de la radioactivité dans l'environnement - Ermittlung der Radioaktivität in der Umwelt - Luft:
Air: radon 222 - Partie 1: Origine du radon et de ses Radon-222 - Teil 1: Radon und seine kurzlebigen
descendants à vie courte, et méthodes de mesure Folgeprodukte: Quellen und Messverfahren (ISO
associées (ISO 11665-1:2019) 11665-1:2019)
This European Standard was approved by CEN on 6 September 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
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11665-1:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 11665-1:2019) has been prepared by Technical Committee ISO/TC 85 "Nuclear
energy, nuclear technologies, and radiological protection" in collaboration with 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 April 2020, and conflicting national standards shall be
withdrawn at the latest by April 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.
This document supersedes EN ISO 11665-1:2015.
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 11665-1:2019 has been approved by CEN as EN ISO 11665-1:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 11665-1
Second edition
2019-09
Measurement of radioactivity in the
environment — Air: radon-222 —
Part 1:
Origins of radon and its short-lived
decay products and associated
measurement methods
Mesurage de la radioactivité dans l'environnement — Air: radon 222 —
Partie 1: Origine du radon et de ses descendants à vie courte, et
méthodes de mesure associées
Reference number
ISO 11665-1:2019(E)
©
ISO 2019
ISO 11665-1:2019(E)
© ISO 2019
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 11665-1:2019(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 . 8
4 Principle .10
5 Equipment .10
6 Sampling .10
6.1 General .10
6.2 Sampling objective .11
6.3 Sampling characteristics . .11
6.4 Sampling conditions .11
6.4.1 Installation of sampling device .11
6.4.2 Sampling duration .12
6.4.3 Volume of air sampled . . .13
7 Detection .13
7.1 Silver-activated zinc sulphide ZnS(Ag) scintillation .13
7.2 Gamma-ray spectrometry.13
7.3 Liquid scintillation .13
7.4 Air ionization .14
7.5 Semi-conductor (alpha detection) .14
7.6 Solid-state nuclear track detectors (SSNTD) .14
7.7 Discharge of polarised surface inside an ionization chamber .14
8 Measurement .14
8.1 Methods .14
8.2 Influence quantities .15
8.3 Calibration .16
8.4 Quality control .16
9 Expression of results .16
10 Test report .16
Annex A (informative) Radon and its decay products — General information .18
Annex B (informative) Example of results of spot, integrated and continuous
measurements of radon-222 activity concentration .28
Annex C (informative) Example of a test report .30
Bibliography .31
ISO 11665-1:2019(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 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 2, Radiological protection.
This second edition cancels and replaces the first edition (ISO 11665-1:2012), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— update of the Introduction;
— in A.2.4, details added for change in radon activities concentration in time and space in buildings;
— update of the Bibliography.
A list of all the parts in the ISO 11665 series can be found on the ISO website.
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 2019 – All rights reserved

ISO 11665-1:2019(E)
Introduction
Radon isotopes 222, 219 and 220 are radioactive gases produced by the disintegration of radium
isotopes 226, 223 and 224, which are decay products of uranium-238, uranium-235 and thorium-232
respectively, and are all found in the earth's crust (see Annex A for further information). Solid elements,
[1]
also radioactive, followed by stable lead are produced by radon disintegration .
When disintegrating, radon emits alpha particles and generates solid decay products, which are also
radioactive (polonium, bismuth, lead, etc.). The potential effects on human health of radon lie in its solid
decay products rather than the gas itself. Whether or not they are attached to atmospheric aerosols,
radon decay products can be inhaled and deposited in the bronchopulmonary tree to varying depths
[2][3][4][5]
according to their size .
[6]
Radon is today considered to be the main source of human exposure to natural radiation. UNSCEAR
suggests that, at the worldwide level, radon accounts for around 52 % of global average exposure to
natural radiation. The radiological impact of isotope 222 (48 %) is far more significant than isotope
220 (4 %), while isotope 219 is considered negligible (see Annex A). For this reason, references to radon
in this document refer only to radon-222.
Radon activity concentration can vary from one to more orders of magnitude over time and space.
Exposure to radon and its decay products varies tremendously from one area to another, as it depends
on the amount of radon emitted by the soil and building materials, weather conditions, and on the
degree of containment in the areas where individuals are exposed.
As radon tends to concentrate in enclosed spaces like houses, the main part of the population exposure
is due to indoor radon. Soil gas is recognized as the most important source of residential radon through
infiltration pathways. Other sources are described in other parts of ISO 11665 and ISO 13164 series for
[59]
water .
Radon enters into buildings via diffusion mechanism caused by the all-time existing difference between
radon activity concentrations in the underlying soil and inside the building, and via convection
mechanism inconstantly generated by a difference in pressure between the air in the building and the
air contained in the underlying soil. Indoor radon activity concentration depends on radon activity
concentration in the underlying soil, the building structure, the equipment (chimney, ventilation
systems, among others), the environmental parameters of the building (temperature, pressure, etc.)
and the occupants’ lifestyle.
-3
To limit the risk to individuals, a national reference level of 100 Bq·m is recommended by the World
[5] -3
Health Organization . Wherever this is not possible, this reference level should not exceed 300 Bq·m .
This recommendation was endorsed by the European Community Member States that shall establish
national reference levels for indoor radon activity concentrations. The reference levels for the annual
-3[5]
average activity concentration in air shall not be higher than 300 Bq·m .
To reduce the risk to the overall population, building codes should be implemented that require radon
prevention measures in buildings under construction and radon mitigating measures in existing
buildings. Radon measurements are needed because building codes alone cannot guarantee that radon
concentrations are below the reference level.
ISO 11665 consists of several parts (see Figure 1) dealing with:
— measurement methods for radon-222 and its short-lived decay products (see ISO 11665-2,
ISO 11665-3, ISO 11665-4, ISO 11665-5 and ISO 11665-6);
NOTE 1 There are many methods for measuring the radon-222 activity concentration and the potential
alpha energy concentration of its short-lived decay products. The choice of measurement method depends
on the expected level of concentration and on the intended use of the data, such as scientific research and
[8][9]
health-related assessments .
— measurement methods for the radon-222 exhalation rate (see ISO 11665-7 and ISO 11665-9);
ISO 11665-1:2019(E)
NOTE 2 ISO 11665-7 refers back to ISO 11665-5 and ISO 11665-6.
— measurement methods for the radon-222 in the soil (see ISO 11665-11);
— methodologies for radon-222 measurements in buildings (see ISO 11665-8);
— measurement methods for the radon-222 diffusion coefficient (see ISO/TS 11665-12 and
ISO/TS 11665-13)
NOTE 3 ISO 11665-8 refers back to ISO 11665-4 for radon measurements for initial investigation
purposes in a building and to ISO 11665-5, ISO 11665-6 and ISO 11665-7 for measurements for any additional
investigation.
vi © ISO 2019 – All rights reserved

ISO 11665-1:2019(E)
Figure 1 — Structure of the ISO 11665 series
INTERNATIONAL STANDARD ISO 11665-1:2019(E)
Measurement of radioactivity in the environment — Air:
radon-222 —
Part 1:
Origins of radon and its short-lived decay products and
associated measurement methods
1 Scope
This document outlines guidance for measuring radon-222 activity concentration and the potential
alpha energy concentration of its short-lived decay products in the air.
The measurement methods fall into three categories:
a) spot measurement methods;
b) continuous measurement methods;
c) integrated measurement methods.
This document provides several methods commonly used for measuring radon-222 and its short-lived
decay products in air.
This document also provides guidance on the determination of the inherent uncertainty linked to the
measurement methods described in its different parts.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 17025, 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
IEC 61577-2, Radiation protection instrumentation — Radon and radon decay product measuring
222 220
instruments — Part 2: Specific requirements for  Rn and Rn measuring instruments
IEC 61577-3, Radiation protection instrumentation — Radon and radon decay product measuring
instruments — Part 3: Specific requirements for radon decay product measuring instruments
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
ISO 11665-1:2019(E)
— IEC Electropedia: available at http: //www .electropedia .org/
3.1.1
active sampling
sampling using active devices like pumps for sampling the atmosphere
[SOURCE: IEC 61577-1:2006, 3.2.22]
3.1.2
activity
disintegration rate
number of spontaneous nuclear disintegrations occurring in a given quantity of material during a
suitably small interval of time divided by that interval of time
Note 1 to entry: Activity, A, is expressed by the relationship given in Formula (1):
A= λ⋅N
where
λ is the decay constant per second;
N is the number of atoms.
Note 2 to entry: The decay constant is linked to the radioactive half-life by the relationship:
ln 2
λ =
T
1/2
where
T is the radioactive half-life, in seconds.
1/2
3.1.3
activity concentration
activity per unit volume
[SOURCE: IEC 61577-1:2006, 3.1.2]
3.1.4
attached fraction
fraction of the potential alpha energy concentration of short-lived decay products that is attached to the
ambient aerosol
[SOURCE: IEC 61577-1:2006, 3.2.15, modified]
Note 1 to entry: The sizes of the carrier aerosol to which most of the short-lived decay products are attached are
generally in the 0,1 μm to 0,3 μm range of median values.
3.1.5
average activity concentration
exposure to activity concentration divided by the sampling duration
3.1.6
average potential alpha energy concentration
exposure to potential alpha energy concentration divided by the sampling duration
2 © ISO 2019 – All rights reserved

ISO 11665-1:2019(E)
3.1.7
background noise
signals caused by something other than the radiation to be detected
Note 1 to entry: A distinction can be made between signals caused by radiation from sources inside or outside the
detector other than those targeted for the measurements and signals caused by defects in the detection system
electronic circuits and their electrical power supply.
3.1.8
continuous measurement
measurement obtained by taking a sample continuously (or at integration intervals typically in range of
1 min to 120 min) with simultaneous or slightly delayed analysis
Note 1 to entry: The sampling duration shall be adapted to the dynamics of the phenomenon studied to monitor
the evolution of radon activity concentration over time.
Note 2 to entry: See Annex B for further information.
3.1.9
diffusion length
distance crossed by an atom due to diffusion forces before decaying
Note 1 to entry: Diffusion length, l, is expressed by the relationship given in Formula (3):
D 
l=
 
λ
 
where
D is the diffusion coefficient, in square metres per second;
λ is the decay constant per second.
3.1.10
equilibrium factor
ratio of the potential alpha energy concentration of short-lived radon decay products in a given volume
of air to the potential alpha energy concentration of these decay products if these are in radioactive
equilibrium with radon in the same volume of air
Note 1 to entry: The short-lived Rn decay products present in an atmosphere are very rarely in radioactive
equilibrium with their parent (through being trapped on the walls or eliminated by an air renewal system, for
example) and the equilibrium factor is used to qualify this state of "non-equilibrium".
Note 2 to entry: The equilibrium factor is between 0 and 1. The equilibrium factor in buildings typically varies
[4][6]
between 0,1 and 0,9, with an average value equal to 0,4 .
Note 3 to entry: The equilibrium factor, F , is expressed by Formula (4):
eq
E
PAEC,222
Rn
F =
eq
-9
5,57⋅×10 C
Rn
where
is the potential alpha energy concentration of Rn, in joules per cubic metre;
E
PAEC,222
Rn
222 222
is the potential alpha energy concentration of the short-lived Rn decay products for 1 Bq of Rn
-9
5,57×10 in equilibrium with its short-lived decay products, in joules per becquerel;

is the activity concentration of Rn, in becquerels per cubic metre.
C
Rn
ISO 11665-1:2019(E)
3.1.11
grab sampling
collection of a sample (i.e of air containing radon or aerosol particles) during a period considered short
compared with the fluctuations of the quantity under study (i.e volume activity of air)
[SOURCE: IEC 61577-1:2006, 3.2.18]
3.1.12
guideline value
value which corresponds to scientific, legal or other requirements with regard to the detection
capability and which is intended to be assessed by the measurement procedure by comparison with the
detection limit
Note 1 to entry: The guideline value can be given, for example, as an activity, a specific activity or an activity
concentration, a surface activity or a dose rate.
Note 2 to entry: The comparison of the detection limit with a guideline value allows a decision on whether or not
the measurement procedure satisfies the requirements set forth by the guideline value and is therefore suitable
for the intended measurement purpose. The measurement procedure satisfies the requirement if the detection
limit is smaller than the guideline value.
Note 3 to entry: The guideline value shall not be confused with other values stipulated as conformity requests or
as regulatory limits.
[SOURCE: ISO 11929-2:2019, 3.18]
3.1.13
integrated measurement
measurement performed by continuous sampling of a volume of air which, over time, is accumulating
physical quantities (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
Note 1 to entry: See Annex B for further information.
3.1.14
long-term measurement
measurement based on an air sample collected within a period greater than one month
3.1.15
measurand
quantity intended to be measured
[SOURCE: ISO/IEC Guide 99:2007, 2.3]
3.1.16
measuring system
set of one or more measuring instruments and often other devices, including any reagent and supply,
assembled and adapted to give information used to generate measured quantity values within specified
intervals for quantities of specified kinds
[SOURCE: ISO/IEC Guide 99:2007, 3.2]
3.1.17
passive sampling
sampling using no active devices such as pumps for sampling the atmosphere, whereby in most
instruments sampling is performed mainly by diffusion
[SOURCE: IEC 61577-1:2006, 3.2.21 modified]
4 © ISO 2019 – All rights reserved

ISO 11665-1:2019(E)
3.1.18
potential alpha energy of short-lived radon decay products
total alpha energy emitted during the decay of atoms of short-lived radon decay products along the
210 222
decay chain through to Pb for the decay chains of the Rn
Note 1 to entry: The potential alpha energy of short-lived Rn decay products, E , is expressed by
PAE,222
Rn
Formula (5):
 
EE+ ⋅ N
() ()
AE,218 AE,214 218
Po Po Po
 
E =
PAE,222
 
Rn
+EN⋅ +++NE ⋅ N
 
() ()
AE,214 214 214 AE,214 214
Po Pb Bi Po Po
 
where
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,218
Po
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,214
Po
is the number of atoms of Po;
N
Po
is the number of atoms of Pb;
N
Pb
is the number of atoms of Bi;
N
Bi
is the number of atoms of Po.
N
Po
Note 2 to entry: The total alpha energy emitted during the decay of atoms of short-lived radon decay products
208 220
along the decay chain through to Pb for the decay chains of the Rn is expressed by Formula (6):
 
EE+0,36+⋅⋅0,64 EN⋅
() ()
AE,216 AE,212 AE,212 216
Po Bi Po Poo
 
E =
PAE,220
 
Rn
+0,36+⋅⋅EE0,64 ⋅ NN++E ⋅ N
 () () ()
AE,212 AE,212 212 212 AE,2112 212
Bi Po Pb Bi Po Po
 
where
is the potential alpha energy of Rn, in joules;
E
PAE,220
Rn
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,216
Po
is the alpha particle energy produced by the disintegration of Bi, in joules;
E
AE,212
Bi
is the alpha particle energy produced by the disintegration of Po, in joules;
E
AE,212
Po
is the number of atoms of Pb;
N
Pb
is the number of atoms of Bi;
N
Bi
is the number of atoms of Po.
N
Po
3.1.19
potential alpha energy concentration of short-lived radon decay products
concentration of any mixture of short-lived radon decay products in air in terms of the alpha energy
210 208
released during complete decay through Pb and/or Pb respectively
ISO 11665-1:2019(E)
[SOURCE: IEC 61577-1:2006, 3.2.2, modified]
Note 1 to entry: The potential alpha energy concentration of the nuclide i, E , is expressed by Formula (7):
PAEC,i
E
PAE,i
E =
PAEC,i
V
where
is the potential alpha energy of the nuclide i, in joules;
E
PAE,i
V is the sampled volume, in cubic metres.
3.1.20
potential alpha energy concentration exposure
integral with respect to time of potential alpha energy concentration accumulated during the
exposure time
Note 1 to entry: Exposure to potential alpha energy concentration, X , is expressed by Formula (8):
PAEC
t
XE=d⋅ t
PAEC PAEC
∫
where
is the potential alpha energy concentration, in joules per cubic metre;
E
PAEC
t is the sampling duration, in seconds.
3.1.21
primary standard
standard designed with, or widely acknowledged as having, the highest metrological qualities and
whose value is accepted without reference to other standards of the same quantity
Note 1 to entry: The concept of a primary standard is equally valid for base quantities and derived quantities.
[SOURCE: IEC 61577-1:2006, 3.1.3]
3.1.22
radioactive equilibrium of radon-222 with its short-lived decay products
state of radon and its short-lived decay products whereby the activity of each radionuclide is equal
Note 1 to entry: In radioactive equilibrium, the activity of each short-lived decay product decreases over time
like the radon activity.
3.1.23
radon emanation
mechanism whereby a radon atom leaves the individual particle of solid material in which it has been
formed and reaches the free space of pores
3.1.24
radon exhalation
mechanism whereby a radon atom produced by emanation and transported (by diffusion or convection)
towards the material surface is released from the material into the surrounding medium (air)
3.1.25
radon exhalation rate
value of the activity concentration of radon atoms that leave a material per unit time
Note 1 to entry: The radon exhalation rate under conditions whereby the radon activity concentration at the
surface of the material equals zero is called free radon exhalation rate.
6 © ISO 2019 – All rights reserved

ISO 11665-1:2019(E)
Note 2 to entry: The free radon exhalation rate is approximated from the radon exhalation rate if the radon
activity at the surface of the material has a sufficiently low value.
3.1.26
radon surface exhalation rate
value of the activity concentration of radon atoms that leave a material per unit surface of the material
per unit time
3.1.27
radon mass exhalation rate
value of the activity concentration of radon atoms that leave a material per unit mass of the material
per unit time
3.1.28
radon exposure
integral with respect to time of radon activity concentration accumulated during the exposure time
Note 1 to entry: Exposure to radon, X, is expressed by Formula (9):
t
XC=dt
∫
where
C is the activity concentration, in becquerels per cubic metre;
t is the sampling duration, in seconds.
3.1.29
reference atmosphere
radioactive atmosphere in which the influence quantities (aerosols, radioactivity, climatic conditions,
etc.) are sufficiently well-known or controlled to allow its use in a testing procedure for measuring
instruments for radon or short-lived decay products
Note 1 to entry: The parameter values concerned shall be traceable to recognized standards.
[SOURCE: IEC 61577-1:2006, 3.2.26 modified – Last sentence of the definition changed to note 1 to entry.]
3.1.30
reference source
radioactive secondary standard source for use in the calibration of the measuring instruments
[SOURCE: IEC 61577-1:2006, 3.2.25]
3.1.31
sampling duration
time interval during which the sampling is performed at a given point
3.1.32
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
Note 1 to entry: See ISO/IEC 17025:2017, 7.3, for further information on sampling plans.
3.1.33
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.
ISO 11665-1:2019(E)
3.1.34
sensor
element of a measuring system that is directly affected by a phenomenon body, or substance carrying a
quantity to be measured
[SOURCE: ISO/IEC Guide 99:2007, 3.8]
Note 1 to entry: The term "detector" is also used for this concept.
3.1.35
short-lived decay products
radionuclides with a half-life of less than one hour produced by radon-222 disintegration ( Rn):
218 214 214 214
polonium-218 ( Po), lead-214 ( Pb), bismuth-214 ( Bi) and polonium-214 ( Po)
Note 1 to entry: See Figure A.1.
216 212
Note 2 to entry: Decay products of radon-220 disintegration such as polonium-216 ( Po), lead-212 ( Pb),
212 212 208
bismuth-212 ( Bi), polonium-212 ( Po) and thallium-208 ( Tl) can interfere with the radon-222
measurement (see Figure A.2).
3.1.36
short-term measurement
measurement based on an air sample collected within a period comparable to the duration of the
half-life of radon
3.1.37
spot measurement
measurement based on a grab sample taken within a period of less than one hour, at a given point in
space, together with an analysis (e.g. count) carried out simultaneously or after a set period of time
Note 1 to entry: See Annex B for further information.
3.1.38
unattached fraction of E
PAEC,222
Rn
fraction of the potential alpha energy concentration of short-lived decay products that is not attached
to the ambient aerosol
Note 1 to entry: The particle size concerned is in the order of magnitude of nanometres.
220 212 220
Note 2 to entry: In the case of Rn, the relatively long half-life of Pb can lead to cases where Rn completely
disappears before Bi; in this case, the unattached fraction of short-lived radon-220 decay products cannot be
defined.
[SOURCE: IEC 61577-1:2006, 3.2.14]
3.2 Symbols
For the purposes of this document the following symbols apply.
activity of the nuclide i, in becquerels
A
i
activity concentration of the nuclide i, in becquerels per cubic metre
C
i
average activity concentration of the nuclide i, in becquerels per cubic metre
C
i
diffusion coefficient, in square metres per second
D
alpha particle energy produced by the disintegration of the nuclide i, in joules
E
AE,i
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ISO 11665-1:2019(E)
potential alpha energy of the nuclide i, in joules
E
PAE,i
potential alpha energy concentration of the nuclide i, in joules per cubic metre
E
PAEC,i
average potential alpha energy of the nuclide i, in joules
E
PAE,i
average potential alpha energy concentration of the nuclide i, in joules per cubic metre
E
PAEC,i
equilibrium factor (dimensionless)
F
eq
diffusion length, in metres
l
number of atoms of the nuclide i
N
i
radioactive half-life of the nuclide i, in seconds
T
1/2,i
sampling duration, in seconds
t
U
expanded uncertainty calculated by U=ku⋅ with k= 2
()
standard uncertainty associated with the measurement result
u
()
V sampled volume, in cubic metres
exposure to radon, in becquerel-hours per cubic metre
X
potential alpha energy concentration exposure, in joule-hours per cubic metre
X
PAEC
Y primary measurement result of the measurand
*
decision threshold of the measurand
y
#
detection limit of the measurand
y
 lower limit of the confidence interval of the measurand
y

upper limit of the confidence interval of the measurand
y
exhalation rate, in becquerels per square metre per second
φ
free exhalation rate, in becquerels per square metre per second
φ
f
mass exhalation rate, in becquerels per square metre per second
φ
m
surface exhalation rate, in becquerels per square metre per second
φ
s
decay constant of the nuclide i, per second
λ
i
ISO 11665-1:2019(E)
4 Principle
The measurement methods presented in this document are based on the following elements:
a) sampling a volume of air representative of the atmosphere under investigation;
b) detecting radiations produced by successive radioactive disintegrations of the radon isotopes and
their decay products.
NOTE Examples of results for radon activity concentration measurements are given in Annex B.
5 Equipment
Equipment is specific to the different measurement methods and is described in the various parts of
ISO 11665. Equipment shall be in accordance with IEC 61577-1, IEC 61577-2 and IEC 61577-3.
6 Sampling
6.1 General
Selection of the appropriate sampling method depends on the site under investigation (mines, outdoors,
houses, buildings open to the public, workplaces, etc.), the intended use of the data and the anticipated
level of radon activity concentration.
The radon activity concentration and the potential alpha energy concentration of its decay products
vary tremendously over time (see Annex A). More than one order of magnitude in variation can be
observed over time at the same place and thus measurement results depend on the sampling duration,
[10]
which can extend from a few minutes to a few hours or several months and on the sampling date (see
Figure B.2).
The extrapolation from an average activity concentration obtained from a measurement performed
during a given sampling duration at a given sampling time to an average activity concentration
representative of a different sampling duration and/or sampling time requires knowledge of the radon
activity concentration variability over the inferred period. In some cases, the uncertainty attached to
this variability can be so large that such an extrapolation becomes meaningless for the objective of the
measurement.
It is therefore important that the choice of sampling method and duration and time of sampling is
compatible with the measurement objective and its required uncertainty. For these reasons, the
measurement results following screening of an area over a short sampling period need to be interpreted
with caution.
The sampling process is performed using different approaches or sampling strategies depending on
the objective pursued. Whatever this objective might be, the sampling strategy should be carefully
selected, as it determines a large number of decisions and can generate important and costly activities.
Radon activity concentration measurement results and the potential alpha energy concentration
measurement results can only be correctly interpreted if the sample is representative of the air that is
being characterized.
The definition of the sampling strategy shall follow, as far as possible, the following stages:
a) analysis of records to enable an historic study of the previous use of the sampling site;
b) site reconnaissance (in some cases, analytic investigation techniques using portable radioactivity
detectors, may be used to identify the areas to be studied in detail);
c) identification of preferential migration pathways and/or accumulation areas;
d) site reconnaissance with respect to the sampling to be undertaken.
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ISO 11665-1:2019(E)
The implementation of this strategy, which also includes the definition of the data quality objectives
accord
...