SIST EN ISO 11665-3:2020

SLOVENSKI STANDARD
oSIST prEN ISO 11665-3:2019
01-december-2019
Merjenje radioaktivnosti v okolju - Zrak: radon Rn-222 - 3. del: Točkovna metoda za
merjenje potencialne koncentracije alfa energije njegovih kratkoživih razpadnih
produktov (ISO/FDIS 11665-3:2019)
Measurement of radioactivity in the environment - Air: radon-222 - Part 3: Spot
measurement method of the potential alpha energy concentration of its short-lived decay
products (ISO/FDIS 11665-3:2019)
Ermittlung der Radioaktivität in der Umwelt - Luft: Radon-222 - Teil 3:
Punktmessverfahren der potenziellen Alpha-Energiekonzentration der kurzlebigen
Radon-Folgeprodukte (ISO/FDIS 11665-3:2019)
Mesurage de la radioactivité dans l'environnement - Air: radon 222 - Partie 3: Méthode
de mesure ponctuelle de l'énergie alpha potentielle volumique de ses descendants à vie
courte (ISO/FDIS 11665-3:2019)
Ta slovenski standard je istoveten z: prEN ISO 11665-3
ICS:
13.040.99 Drugi standardi v zvezi s Other standards related to air
kakovostjo zraka quality
17.240 Merjenje sevanja Radiation measurements
oSIST prEN ISO 11665-3:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 11665-3:2019

---------------------- Page: 2 ----------------------
oSIST prEN ISO 11665-3:2019
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 11665-3
ISO/TC 85/SC 2
Measurement of radioactivity in the
Secretariat: AFNOR
environment — Air: radon-222 —
Voting begins on:
2019-09-25
Part 3:
Voting terminates on:
Spot measurement method of the
2019-12-18
potential alpha energy concentration
of its short-lived decay products
Mesurage de la radioactivité dans l'environnement — Air: radon 222 —
Partie 3: Méthode de mesure ponctuelle de l'énergie alpha potentielle
volumique de ses descendants à vie courte
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 11665-3:2019(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2019

---------------------- Page: 3 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© 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

---------------------- Page: 4 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(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 . 2
4 Principle of the measurement method . 3
5 Equipment . 3
6 Sampling . 4
6.1 General . 4
6.2 Sampling objective . 4
6.3 Sampling characteristics . . 4
6.4 Sampling conditions . 5
6.4.1 General. 5
6.4.2 Installation of sampling system . 5
6.4.3 Sampling duration . 5
6.4.4 Volume of air sampled . . . 5
7 Detection method . 5
8 Measurement . 5
8.1 Procedure . 5
8.2 Influence quantities . 6
8.3 Calibration . 6
9 Expression of results . 7
9.1 General . 7
9.2 Potential alpha energy concentration . 7
9.3 Standard uncertainty . 7
9.4 Decision threshold . 8
9.5 Detection limit . 9
9.6 Limits of the confidence interval . 9
10 Test report . 9
Annex A (informative) Examples of gross alpha counting protocols .11
Annex B (informative) Calculation of the coefficients k , k and k .12
218 ,j 214 ,j 214 ,j
Po Pb Bi
Annex C (informative) Measurement method using gross alpha counting according to the
Thomas protocol .16
Bibliography .19
© ISO 2019 – All rights reserved iii

---------------------- Page: 5 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see 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 11665-3:2012), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— update of the Introduction;
— 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

---------------------- Page: 6 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(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 ISO 11665-1:2019, Annex A for further information). Solid
[1]
elements, 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 ISO 11665-1:2019, 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
[7]
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 should establish
national reference levels for indoor radon activity concentrations. The reference levels for the annual
-3[5]
average activity concentration in air should 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.
Variations of a few nanojoules per cubic metre to several thousand nanojoules per cubic metre are
observed in the potential alpha energy concentration of short-lived radon decay products.
The potential alpha energy concentration of short-lived radon-222 decay products in the atmosphere
can be measured by spot and integrated measurement methods (see ISO 11665-1). This document deals
with spot measurement methods. A spot measurement of the potential alpha energy concentration
relates to the time when the measurement is taken and has no significance in annual exposure. This
type of measurement does not therefore apply when assessing the annual exposure.
NOTE The origin of radon-222 and its short-lived decay products in the atmospheric environment are
described generally in ISO 11665-1 together with measurement methods.
© ISO 2019 – All rights reserved v

---------------------- Page: 7 ----------------------
oSIST prEN ISO 11665-3:2019

---------------------- Page: 8 ----------------------
oSIST prEN ISO 11665-3:2019
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 11665-3:2019(E)
Measurement of radioactivity in the environment — Air:
radon-222 —
Part 3:
Spot measurement method of the potential alpha energy
concentration of its short-lived decay products
1 Scope
This document describes spot measurement methods for determining the activity concentration
of short-lived radon-222 decay products in the air and for calculating the potential alpha energy
concentration.
This document gives indications for performing a spot measurement of the potential alpha energy
concentration, after sampling at a given place for several minutes, and the conditions of use for the
measuring devices.
The measurement method described is applicable for a rapid assessment of the potential alpha energy
concentration. The result obtained cannot be extrapolated to an annual estimate potential alpha energy
concentration of short-lived radon-222 decay products. Thus, this type of measurement is not applicable
for the assessment of annual exposure or for determining whether or not to mitigate citizen exposures
to radon or radon decay products.
This measurement method is applicable to air samples with potential alpha energy concentration
3
greater than 5 nJ/m .
NOTE This document does not address the potential contribution of radon-220 decay products.
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 11665-1, 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/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 61577-3, 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 terms and definitions given in ISO 11665-1 apply.
© ISO 2019 – All rights reserved 1

---------------------- Page: 9 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(E)

3.2 Symbols
For the purposes of this document, the symbols given in ISO 11665-1 and the following apply.
C activity concentration of the nuclide i, in becquerels per cubic metre
i
alpha particle energy produced by the disintegration of the nuclide i, in joules
E
AE,i
total alpha particle energy potentially produced by the nuclide i, in joules
E
AEt,i
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
decision threshold of the potential alpha energy concentration of the nuclide i, in joules per
*
E
PAEC,i
cubic metre
detection limit of the of the potential alpha energy concentration of the nuclide i, in joules
#
E
PAEC,i
per cubic metre
lower limit of the confidence interval of the potential alpha energy concentration of the nu-

E
PAEC,i
clide i, in joules per cubic metre
upper limit of the confidence interval of the potential alpha energy concentration of the

E
PAEC,i nuclide i, in joules per cubic metre
th
I j number of gross counts obtained between times t and t
j j cj
th
I j number of background counts obtained between times t and t
0,j j cj
th
k coefficient related to the j number of gross count for radon decay product i, depending on
i,j
the decay constants of the radon decay products, the sampling duration, t , and the times t
s j
and t , per square second
cj
N number of atoms of the nuclide i
i
n counting number depending on the gross alpha counting protocol used
Q sampling flowrate, in cubic metres per second
t end time of counting j, in seconds
cj
t start time of counting j, in seconds
j
t sampling duration, in seconds
s
U expanded uncertainty calculated by U = k⋅u( ) with k = 2
u( ) standard uncertainty associated with the measurement result
u ( ) relative standard uncertainty
rel
V sampled volume, in cubic metres
ε counting efficiency, in pulses per disintegration
c
λ decay constant of the nuclide i, per second
i
2 © ISO 2019 – All rights reserved

---------------------- Page: 10 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(E)

4 Principle of the measurement method
Spot measurement of the potential alpha energy concentration of short-lived radon-222 decay products
is based on the following elements:
a) grab sampling, at time t, of short-lived radon decay products contained in a volume of air
representative of the atmosphere under investigation, using a high-efficiency filtering membrane;
b) repeated gross alpha measurements of the collected decay products using a detector sensitive to
alpha particles; the counting stage starts after sampling has stopped;
c) calculation of the activity concentrations of the radon decay products using the laws of radioactive
decay and the counting results from a preset duration, repeated at given times.
The gross alpha measurement method quantifies alpha particles emitted by short-lived radon decay
222 218
products. The Rn decay product chain shows that 99,98 % of the decays of Po result in the emission
214 214
of alpha particles. It can, therefore, be considered as a pure alpha emitter. Pb and Bi are not alpha
214
emitters, but they contribute to the appearance of alpha particles from the decay of Po.
After collecting the air sample, the gross alpha activity is measured for various counting durations.
Because of the fast decay of radon decay products, the isotopic composition of a sample rapidly changes
during collection as well as during the counting durations. Repeated measurements of the gross alpha
activity are necessary in order to describe the decay of the sample and thereby calculate the amounts of
the various decay products which were originally collected in the air sample.
222
NOTE Although Rn and its decay products are usually found in higher quantity, environmental air
220
samples can also contain significant activity of radonuclides of the Rn decay chain as well as other airborne
long-lived radionuclides. In such cases, the formulas and procedures given in this document need to be adapted
to take into account these additional radionuclides.
5 Equipment
The apparatus shall include a sampling system and a detection system composed of a detector
connected to a counting system (see Figure 1). The measuring devices used shall be in accordance with
IEC 61577-1 and IEC 61577-3.
The sampling system shall include the following components:
a) an open filter holder allowing fast and easy removal of the filter after sampling;
b) a pump;
c) a high-efficiency particulate air filter (HEPA filter with a minimum efficiency of 99,97 % for a
particle size of 0,3 µm);
d) a flowmeter and a chronometer;
Possible detectors include the following:
— a photomultiplier associated with a sensitive scintillation surface [for example ZnS(Ag)];
— a silicon semi-conductor that is sensitive to alpha particles.
The detector, connected to a pulse counting system, shall have a sensitive detection surface at least
equal in diameter to the filtering membrane.
© ISO 2019 – All rights reserved 3

---------------------- Page: 11 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(E)

a)  Sampling system b) Detection system
Key
1 filtering membrane
2 filter holder
3 support
4 flowmeter and chronometer
5 pump
6 counting system
7 detector
Figure 1 — Functional diagram of a spot measuring system for potential alpha energy
concentration of short-lived radon decay products
6 Sampling
6.1 General
Grab sampling is representative of the potential alpha energy concentration of short-lived radon-222
decay products at a given time and a given place.
6.2 Sampling objective
The sampling objective is to collect, without interruption, all the aerosols, regardless of their size
(unattached and attached fractions), carrying short lived radon decay products and contained in the
ambient air during a given sampling duration (<1 h).
6.3 Sampling characteristics
The unattached and attached fractions of short-lived radon decay products shall be sampled without
interruption from the atmosphere under investigation by pumping and filtering a known volume of air
through a high-efficiency collection membrane located in an open filter holder. The air sampling shall
be omni-directional.
In order to count the emitted alpha particles correctly, the sampling system shall conduct to the surface
deposit of the radionuclides on the filter and shall prevent the aerosols from being buried.
The sampling system shall be used in conditions that preclude clogging of the filtering membrane, which
would cause self-absorption of the alpha emissions of particles collected on the filter or a reduction in
the sampling flowrate over time.
4 © ISO 2019 – All rights reserved

---------------------- Page: 12 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(E)

6.4 Sampling conditions
6.4.1 General
Sampling shall be carried out as specified in ISO 11665-1. The sampling location, date and time shall be
recorded.
6.4.2 Installation of sampling system
Installation of the sampling system shall be carried out as specified in ISO 11665-1.
6.4.3 Sampling duration
218
Given the short half-lives of the radon-222 decay products, particularly Po, the sampling duration
should normally be less than or equal to 20 min. A longer sampling duration would not improve the
detection limit of the method.
6.4.4 Volume of air sampled
The volume of air sampled shall be ascertained by continuous measurement of the flowrate during
sampling with a calibrated system (for example a sonic nozzle) (see IEC 61577-3).
7 Detection method
Detection shall be performed using silver-activated zinc sulphide ZnS(Ag) scintillation or a
semi-conductor (alpha detection), as described in ISO 11665-1.
8 Measurement
8.1 Procedure
Measurement shall be carried out as follows.
a) Select the sampling duration, t .
s
b) Plan the counting stage, with n countings, and choose start time t and end time t for each number
j cj
of counts I . The different sets are organized from j = 1 to j = n. Before a set of counting, a specific
j
waiting time can be required.
NOTE Examples of gross alpha counting protocols are given in Annex A. The measurement method
using gross alpha counting according to the Thomas protocol is detailed in Annex C.
c) Install the detection system (detector and pulse counting system).
d) Determine the background level of the filtering membrane. Before carrying out sampling, position
the virgin membrane opposite the detector, in accordance with manufacturer recommendations.
Measure the virgin membrane by means of n successive gross alpha countings during specific
counting durations t − t according to the counting stage selected:
cj j
1) t = 0 to t = t         standby, there is no count if t > 0;
1 1
2) t = t to t = t        count I is performed;
1 c1 0,1
3) t = t to t = t       standby, there is no count if t > t ;
cj−1 j j cj−1
4) t = t to t = t         count I is performed.
j cj 0,j
© ISO 2019 – All rights reserved 5

---------------------- Page: 13 ----------------------
oSIST prEN ISO 11665-3:2019
ISO/FDIS 11665-3:2019(E)

If n > 1, repeat stages 3) and 4) until j = n.
e) Record values of I for j = 1 to j = n.
0,j
f) Select and locate the measuring point.
g) Install the sampling system.
h) Using grab sampling, obtain an air sample representative of
...