ISO/TS 11665-12:2018

TECHNICAL ISO/TS
SPECIFICATION 11665-12
First edition
2018-10
Measurement of radioactivity in the
environment — Air: radon-222 —
Part 12:
Determination of the diffusion
coefficient in waterproof materials:
membrane one-side activity
concentration measurement method
Mesurage de la radioactivité dans l'environnement — Air : radon
222 —
Partie 12: Détermination du coefficient de diffusion des matériaux
imperméables: méthode de mesure de l'activité volumique d'un côté
de la membrane
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

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 . 3
5 Equipment . 5
6 Sample preparation . 6
6.1 General consideration . 6
6.2 Fixing the sample in the holder . 7
6.3 Connection of the holder (cap) with the chamber . 7
7 Control measurements . 8
7.1 Verification of radon-tightness . 8
7.2 Calibration . 9
7.3 Detector background . 9
7.4 Instrument statistical fluctuation . 9
8 Measurement of radon activity concentration .10
9 Processing and expression of the results for the sample .11
9.1 Determination of the radon diffusion coefficient in the sample .11
9.2 Characteristics of measurement limits .11
9.3 Estimation of confidence interval and uncertainty .13
9.4 Expression of the results .13
10 Requirements for the test .14
11 Influencing factors .15
12 Expression of the results and assessment of the standard uncertainty for the material .16
13 Quality management and calibration of the test device .17
14 Test report .17
14.1 The test report for material .17
14.2 The test report for each sample .18
14.3 Archived material .18
Annex A (informative) Determination of the radon diffusion coefficient of the sample .19
Bibliography .27
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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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
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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 2, Radiological protection.
A list of all parts in the ISO 11665 series can be found on the ISO website.
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iv © ISO 2018 – All rights reserved

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. Solid elements, also radioactive, followed by stable
[4]
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
according to their size.
[5]
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. 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, 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
[2]
water .
Radon enters into buildings via a diffusion mechanism caused by the all-time existing difference
between radon activity concentrations in the underlying soil and inside the building, and via a
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
[6]
World Health Organization . Wherever this is not possible, this reference level should not exceed
-3
300 Bq·m . This recommendation that was endorsed by the European community member states
establishes national reference levels for indoor radon activity concentrations. The reference levels for
-3[8]
the annual average activity concentration in air cannot be higher than 300 Bq·m .
To reduce the risk to the overall population, building codes which require radon prevention measures
in buildings under construction and radon mitigating measures in existing buildings should be
implemented. Radon measurements are needed because building codes alone cannot guarantee that
radon concentrations are below the reference level.
When a building requires protection against radon from the soil, radon-proof insulation (based on
membranes, coatings or paints) placed between the soil and the indoors may be used as a stand-alone
radon prevention/remediation strategy or in combination with other techniques such as passive or
active soil depressurization. Radon-proof insulation functions at the same time as the waterproof
insulation.
The radon diffusion coefficient is a parameter that determines the barrier properties of waterproof
materials against the diffusive transport of radon. Applicability of the radon diffusion coefficient for
radon-proof insulation can be prescribed by national building standards and codes. Requirements for
radon-proof insulation as regards the durability, mechanical and physical properties and the maximum
design of value of the radon diffusion coefficient can also be prescribed by national building standards
and codes.
As no reference standards and no reference materials are currently available for these types of
mate
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