Measurement of radioactivity in the environment -- Air: radon-222

This document specifies the method intended for assessing the radon diffusion coefficient in waterproofing materials such as bitumen or polymeric membranes, coatings or paints, as well as assumptions and boundary conditions which will be met during the test. The test method described in this document allows to estimate the radon diffusion coefficient in the range of 10-5 m2/s to 10-12 m2/s[8][9] with an associated uncertainty from 10 % to 40 %.

Mesurage de la radioactivité dans l'environnement -- Air : radon 222

General Information

Status
Published
Publication Date
18-Oct-2018
Current Stage
6060 - International Standard published
Start Date
11-Aug-2018
Completion Date
19-Oct-2018
Ref Project

RELATIONS

Buy Standard

Technical specification
ISO/TS 11665-12:2018 - Measurement of radioactivity in the environment -- Air: radon-222
English language
27 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

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/TS 11665-12:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO/TS 11665-12:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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 2018 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 11665-12:2018(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 ........................................................................................................................................................................................................................ 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

© ISO 2018 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TS 11665-12:2018(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 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.
A list of all 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 2018 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 11665-12:2018(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. 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.

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

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

© ISO 2018 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/TS 11665-12:2018(E)

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

materials, and related values of the radon diffusion coefficient, the metrological requirement regarding

the determination of the performance of the different methods described in ISO/TS 11665-13 and in

[3]
this document, as required by ISO 17025 , cannot be directly met.

NOTE The origin of radon-222 and its short-lived decay products in the atmospheric environment and the

measurement methods are described in ISO 11665-1.
vi © ISO 2018 – All rights reserved
---------------------- Page: 6 ----------------------
TECHNICAL SPECIFICATION ISO/TS 11665-12:2018(E)
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
1 Scope

This document specifies the method intended for assessing the radon diffusion coefficient in

waterproofing materials such as bitumen or polymeric membranes, coatings or paints, as well as

assumptions and boundary conditions which will be met during the test.

The test method described in this document allows to estimate the radon diffusion coefficient in the

-5 2 -12 2 [8][9]
range of 10 m /s to 10 m /s with an associated uncertainty from 10 % to 40 %.
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 80000-10, Quantities and units — Part 10: Atomic and nuclear physics

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

me a s ur ement (GUM: 1995)
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, ISO 80000-10 and

the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1.1
material

material produced according to certain technical specifications which is the object of the test

3.1.2
sample

certain amount of material (3.1.1) chosen from the production batch for determination of the radon

diffusion coefficient (3.1.3)
© ISO 2018 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/TS 11665-12:2018(E)
3.1.3
radon diffusion coefficient

radon activity permeating due to molecular diffusion through unit area of a monolayer material

of unit thickness per unit time at unit radon activity concentration gradient on the boundaries of this

material (3.1.1)

[SOURCE: ISO/TS 11665-13:2017, 3.1.3, modified — “” has been added as the domain of the

definition.]
3.1.4
decisive measurements
measurement results used to calculate the radon diffusion coefficient (3.1.3)
3.1.5
decisive volume of the chamber
volume of the chamber used to calculate the radon diffusion coefficient (3.1.3)
3.1.6
decisive area of the sample

material (3.1.1) sample (3.1.2) area used to calculate the radon diffusion coefficient (3.1.3)

3.1.7
radon transfer coefficient

radon transport in thin boundary layer of air near the surface of the sample (3.1.2)

Note 1 to entry: The default value of the radon transfer coefficient is 0,001 m/s to 0,1 m/s.

[SOURCE: ISO/TS 11665-13:2017, 3.1.15, modified — Note 1 to entry has been removed. Note 2 to entry

has become Note 1 to entry and has been slightly rephrased.]
3.2 Symbols

For the purposes of this document, the symbols given in ISO 11665-1 and the following apply.

D Radon diffusion coefficient of the sample, in square metre per second

< Lower limit of the confidence interval of the radon diffusion coefficient of the sample, in

square metre per second

> Upper limit of the confidence interval of the radon diffusion coefficient of the sample, in

square metre per second
D Radon diffusion coefficient of the material, in square metre per second
λ Radon decay constant, in per second
λ Radon leakage rate, in per second
Best estimate of the radon leakage rate, in per second
C Radon activity concentration in the sample, in becquerel per cubic metre

C Radon activity concentration in a source-detect chamber, in becquerel per cubic metre

C Radon activity concentration in a source-detect chamber at the initial time after injection of

radon, in becquerel per cubic metre
C Radon activity concentration in the ambient air, in becquerel per cubic metre
amb
2 © ISO 2018 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/TS 11665-12:2018(E)

C Measured radon activity concentration in a source-detect chamber, in becquerel per

cubic metre
d Thickness of the sample, in metre
S Decisive area of the sample, in square metre
V Decisive volume of the source-detect chamber, in cubic metre
h Radon transfer coefficient, in metre per second
t Time, in second
τ Time of start of measurement period, in second (or hour)
i i
r Gross count rate, in counts per second
Gross count rate from alpha-source, in counts per second
r Background count rate, in counts per second

R Measured rate of decrease of radon activity concentration in the chamber (of pulse count rate)

R Calculated rate of decrease of radon activity concentration in the chamber

R Calculated rate of decrease of radon activity concentration in the chamber at verification of

radon-tightness
R Function of the minimum measured rate of decrease in the chamber
min
R Function of the maximum measured rate of decrease in the chamber
max
u(y) Standard uncertainty of the value of y
s(y) Standard deviation of the value of y
u (D) Relative uncertainty of the radon diffusion coefficient in the sample
rel
k Coverage factor
N Number of samples of the test material
4 Principle

The one-side method is based on the measurement of the decrease over time of the radon activity

concentration in a source-detect chamber in contact with one side of the tested membrane. The test

is performed in a non-stationary mode. This test method can be used for single-layer waterproof

materials when testing results are needed rapidly. They are not applicable for multi-layer waterproof

materials that do not meet the requirements of Figure 7.

A sample of the tested material is installed in the sealed end of the cylindrical chamber (Figure 1). The

detector of radon activity is located at the other end of the chamber.

In the beginning of the test, a highly active portion of radon is injected into the chamber through a

special valve. Since then, radon activity concentration in the chamber begins to decline because of

a) diffusion of radon through the sample towards the ambient air,
b) radon decay, and
c) leakage of radon from the chamber.
© ISO 2018 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO/TS 11665-12:2018(E)

The chamber serves as a source radon and also allows to measure radon activity in the chamber.

Key
1 source-detect chamber
2 tested sample
3 ambient air
Figure 1 — Measurement scheme

The process of radon transfer from the chamber through the sample is described by Formulae (1) and (2):

∂Ct() S
sd s
 
=−λ ⋅−Ct() ⋅⋅hC ()tC− (,0 t) (1)
sd 1 sd
 
∂t V
∂Cx(,t)(∂ Cx,)t
= D −⋅λ Cx(,t) , 0≤≤xd , 0≤ with the following boundary conditions in Formulae (3) to (5):
C (t = 0) = C , C(x, 0) = 0 (3)
sd 0
∂Ct(0, )
 
−D =⋅hC ()tC− (0,t) (4)
1sd
 
∂Cd(,t)
 
 
−D =⋅hC(,dt)−C , Ct() =0 (5)
2amb  amb 
 

Formulae (1) to (5) with respect to the values of radon activity concentration in the chamber are solved

as the function expressed by Formula (6):
C (t) = C ·f(t, D, λ, V , S , d) (6)
sd 0 sd s
which is calculated as in Formula (7):
 
λτ ()−t −⋅λ t
 
Ct() =+Ce Fe()ττd (7)
sd 0 ∫
 
 

The calculation by Formula (7) is carried out by the algorithm described in Annex A.

4 © ISO 2018 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/TS 11665-12:2018(E)

During the test, the ratios between current radon activity concentrations in the chamber to radon

activity concentration at the beginning of the decisive measurements are registered. These ratios

determine the rate of radon activity concentration decrease in the chamber (Clause 8).

The radon diffusion coefficient in the sample is calculated according to 9.1, taking into account the

effect of radon leakage from the chamber.
5 Equipment
The scheme of the test installation is shown in Figure 2.
Key
1 chamber 10 computer
2 bolt (with washer) 11 micro-fan
3 holder 12 power supply of the micro-fan
4 sample 13 valve
5 insert 14 syringe
6 scintillation plate 15 radon source
7 light-transmissive window 16 thermometer
8 photomultiplier unit 17 cap
9 signal converter
Figure 2 — The scheme of the test installation

The installation includes an aluminium cylindrical chamber (1). The lower end of the chamber is a

flange with a sealing gasket which is hermetically connected to the aluminium holders (3) with a test

sample (4) by bolts (2).

Aluminium cylindrical inserts (5) are used to reduce the decisive volume of the chamber.

Scintillation plate (6) with sensitive ZnS(Ag) layer and light-transmissive window (7) made of

polymethyl methacrylate are hermetically embedded in the upper end of the chamber.

The alpha radiation of radon and its progeny, interacting with the sensitive layer of the scintillator plate,

causes light flashes (scintillations) which are converted into electrical pulses by the photomultiplier

unit (8). These pulses are converted by the device (9) and transmitted to the computer (10). The

computer software registers the average count rate at predetermined time intervals.

© ISO 2018 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO/TS 11665-12:2018(E)
[8]

The micro-fan (11) provides stability in registering radon activity inside the chamber . The micro-

fan is equipped with a brushless motor and a consumption current of less than 20 mA at a voltage not

exceeding 5 V. The power of the micro-fan is provided by a power supply of stable voltage (12).

The sealed valve (13) for injecting radon inside the chamber with the syringe (14) is located on the

sidewall of the chamber. The radon portion in the syringe is introduced from the radon source (15). The

activity and the volume of the radon source should be 10 kBq to 100 kBq and 0,2 l to 0,5 l, respectively.

The thermometer (16) is connected to the computer.

The test installation is equipped with at least 3 holders and one aluminium cap (17).

To register the activity concentration, a semiconductor or another type of detector, located inside the

chamber and meeting the requirements of Clauses 7 and 10, can be also used.
The installation kit also includes
a) a torque wrench with predetermined torque between 1 Nm and 10 Nm,

b) a measuring instrument capable of determining the thickness of the tested sample with accuracy of

±0,01 mm (maximum standard relative measurement uncertainty of 5 %),
c) an epoxy adhesive,
d) alcohol, acetone, or another degreasing agent.

The chamber is set upright and the flange downwards (Figure 2) to avoid problems for radon exhalation

from the sample.
Light shall not enter the chamber when the photomultiplier is on.
6 Sample preparation
6.1 General consideration

If the condition of Formula (29) is not satisfied after testing 3 samples, additional samples of the

material should be prepared and tested until this condition is fulfilled.

The samples are cut out from the prefabricated membranes at a minimum distance of 20 mm from the

edges of the membrane.

In the case of coatings, paints, sealants or other waterproof materials prepared on site, at least 3

samples are required for testing. Samples can be produced by applying a coating, paint or sealant on a

non-absorbing flexible underlay material (for example wax-paper, cellophane, foil, etc.) that is removed

from the sample after the drying process is completed. The underlay shall not react with the applied

coatings, paints or sealants. Approximately uniform thickness of the samples can be achieved with the

help of guide gibs (paint, coating or sealant is poured or pasted between the gibs of uniform height

and the excessive material is removed by drawing the steel float over the gibs). The samples shall

not be tested until the drying and hardening processes are completed. The time between the sample

preparation and the start of the measurement as well as the storing conditions shall correspond to the

recommendation of the producer.

The thickness of each sample is measured at 4 points per 0,01 m placed uniformly along the surface of

the sample. The resulting thickness of each sample is the arithmetic mean of all measurements on the

sample. If a radon-permeable surface coating is part of the tested material, its thickness is not included

in the thickness of the tested sample. This type of surface coating can be removed from the sample

before performing the test.
6 © ISO 2018 – All rights reserved
---------------------- Page: 12 ----------------------
ISO/TS 11665-12:2018(E)
6.2 Fixing the sample in the holder

The sample is cut into a disk and fixed in the holder (Figure 3) so that the direction of the radon flow

through the sample during the test corresponds to the real flow direction through the material in

operational conditions.

The sample is fixed in the holder without slack via an epoxy adhesive that is first applied to the shelf of

the holder, and then poured into the annular gap (1 mm to 2 mm) between the sample and the sidewall

of the holder.

The surfaces of the sample and the holder to which the adhesive is applied, should be pre-treated by the

degreasing agent.

During the preparation of the epoxy adhesive, the hardener is added to the epoxy resin in an amount

which provides elasticity to the adhesive composition in order to avoid excessive hardness and

brittleness after solidification. The prepared glue fixes the sample holder reliably for at least one week.

Before reuse, the holder is purified from the epoxy adhesive by using a solvent of epoxy resin, or by

immersion in boiling water, or by a lathe.

The holder is attached to the chamber not earlier than 24 h after fixing the sample.

Dimensions in millimetres
Key
1 holder
2 shelf of the holder of 4 mm to 5 mm width
3 sidewall of the holder
4 sample
5 epoxy adhesive
ØА decisive diameter of the sample, equal to the inner diameter of the chamber
ØB diameter of the sample
ØC diameter of the mating part of the holder
Figure
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.