ISO 20045:2023
(Main)Measurement of the radioactivity in the environment — Air: tritium — Test method using bubbler sampling
Measurement of the radioactivity in the environment — Air: tritium — Test method using bubbler sampling
This document describes a test method to determine the activity concentration of atmospheric tritium by trapping tritium in air by bubbling through a water solution. Atmospheric tritium activity concentration levels are expressed in becquerel per cubic metre (Bq∙m-3). The formulae are given for a sampling system with four bubblers. They can also be applied to trapping systems with only one trapping module consisting of two bubblers if only tritiated water vapour (HTO) is in the atmosphere to be sampled. This document does not cover laboratory test sample results, in becquerel per litre of trapping solution, according to ISO 9698 or ISO 13168. The test method detection limit result is between 0,2 Bq∙m-3 and 0,5 Bq∙m-3 when the sampling duration is about one week.
Mesurage de la radioactivité dans l’environnement — Air : tritium — Méthode d’essai à l’aide d’un prélèvement par barbotage
Le présent document décrit une méthode d’essai pour déterminer l’activité volumique du tritium atmosphérique en piégeant du tritium dans l’air par barbotage à travers une solution aqueuse. Les niveaux d’activité volumique du tritium atmosphérique sont exprimés en becquerels par mètre cube (Bq∙m−3). Les formules données sont valables pour un système de prélèvement à quatre barboteurs. Elles sont également applicables aux systèmes de piégeage avec un seul module de piégeage constitué de deux barboteurs, à la condition que l’atmosphère dans laquelle a lieu le prélèvement ne contienne que de la vapeur d'eau tritiée (HTO). Le présent document ne traite pas des résultats pour les échantillons d’essai de laboratoire, en becquerels par litre de solution de piégeage, conformément à l’ISO 9698 ou l’ISO 13168. Le résultat de la limite détection de la méthode d’essai est compris entre 0,2 Bq∙m−3 et 0,5 Bq∙m−3 pour une durée de prélèvement d’environ une semaine.
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INTERNATIONAL ISO
STANDARD 20045
First edition
2023-05
Measurement of the radioactivity in
the environment — Air: tritium — Test
method using bubbler sampling
Mesurage de la radioactivité dans l’environnement — Air : tritium —
Méthode d’essai à l’aide d’un prélèvement par barbotage
Reference number
ISO 20045:2023(E)
© ISO 2023
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ISO 20045:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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
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Published in Switzerland
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ISO 20045:2023(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 . 2
3.2 Symbols, definitions and units . 3
4 Principle . 4
5 Influence quantities . 6
6 Equipment . 6
6.1 Description and requirements of the sampling system . 6
6.2 Location of sampling head . 7
6.3 Air flow rate, sampling duration and air volume sampling . 7
6.4 Trapping water solution . 7
6.5 Specifications for use . 7
7 Procedure .8
7.1 Sampling . 8
7.2 Sample collection and transportation . 9
7.3 Receipt. 9
7.4 Conservation . 9
7.5 Tritium activity concentration measurement . 9
8 Expression of results . 9
8.1 General . 9
8.2 Calculations for tritiated water vapour . 10
8.2.1 Activity concentration . . 10
8.2.2 Decision threshold . 10
8.2.3 Detection limit . 11
8.2.4 Coverage intervals limits . 11
8.2.5 Conditions of use .12
8.3 Calculation for tritiated gas compounds .12
8.3.1 Tritiated gas without significant HTO level .13
8.3.2 Tritiated gas compounds with significant HTO level . 14
8.3.3 Coverage intervals limits . 16
8.3.4 Conditions of use . 16
9 Test report .17
Annex A (informative) Technical data for tritium .19
Annex B (informative) Determination of trapping efficiency .21
Annex C (informative) Preserving of tritiated water solutions .25
Annex D (informative) Example of sampling and calculations forms .26
Annex E (informative) Examples of calculations of air tritium activity concentrations .29
Bibliography .35
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ISO 20045:2023(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, SC 2, Radiological protection.
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.
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ISO 20045:2023(E)
Introduction
Everyone is exposed to natural radiation. The natural sources of radiation include cosmic rays and
naturally occurring radioactive substances which exist on Earth such as flora, fauna or the human body.
Human activities involving the use of radiation and radioactive substances add to the radiation exposure
from this natural exposure. Some of those activities, such as the mining and use of ores containing
naturally-occurring radioactive materials (NORM) and the production of energy by burning coal that
contains such substances, simply enhance the exposure from natural radiation sources. Nuclear power
plants and other nuclear installations use radioactive materials and produce radioactive effluents and
waste during operation and decommissioning. The use of radioactive materials in industry, medicine,
agriculture and research is expanding around the globe.
All these human activities give rise to radiation exposures that are only a small fraction of the global
average level of natural exposure. The medical use of radiation is the largest and a growing man-made
source of radiation exposure in developed countries. It includes diagnostic radiology, radiotherapy,
nuclear medicine and interventional radiology.
Radiation exposure also occurs as a result of occupational activities. It is incurred by workers in
industry, medicine and research using radiation or radioactive substances, as well as by passengers
and crew during air travel. The average level of occupational exposures is generally below the global
average level of natural radiation exposure (see Reference [2]).
As uses of radiation increase, so do the potential health risk and the public's concerns. Thus, all these
exposures are regularly assessed in order to
a) improve the understanding of global levels and temporal trends of public and worker exposure,
b) evaluate the components of exposure so as to provide a measure of their relative impact, and
c) identify emerging issues that may warrant more attention and study. While doses to workers
are mostly directly measured, doses to the public are usually assessed by indirect methods
using the results of radioactivity measurements of waste, liquid and/or gaseous effluents and/or
environmental samples.
Radioactivity from several naturally-occurring and anthropogenic sources is present throughout the
environment. Thus, atmosphere can contain radionuclides of natural, human-made, or both origins.
40 3 14
— Natural radionuclides including K, H, C and those originating from the thorium and uranium
226 228 234 238 210
decay series, in particular Ra, Ra, U, U and Pb which can be found in materials from
natural sources or can be released from technological processes involving naturally occurring
radioactive materials (e.g. the mining and processing of mineral sands or phosphate fertilizer
production and use).
— Human-made radionuclides, such as transuranic elements (americium, plutonium, neptunium, and
3 14 90
curium), H, C, Sr and gamma-ray emitting radionuclides can also be found gaseous effluent
discharges, in environmental matrices (water, air, soil and biota), in food and in animal feed as a
result of authorized releases into the environment, fallout from the explosion in the atmosphere of
nuclear devices and radionuclides releases from accidents of nuclear reactors, such as those that
occurred in Chernobyl and Fukushima.
To ensure that the data obtained from radioactivity monitoring programs support their intended use, it
is essential that the stakeholders (for example nuclear site operators, regulatory and local authorities)
agree on appropriate methods and procedures for obtaining representative samples and for sampling,
handling, storing, preparing and measuring the test samples. An assessment of the overall measurement
uncertainty also needs to be carried out systematically. As reliable, comparable and ‘fit for purpose’
data are an essential requirement for any public health decision based on radioactivity measurements,
international standards of tested and validated radionuclide test methods are an important tool for
the production of such measurement results. The application of standards serves also to guarantee
comparability of the test results over time and between different testing laboratories. Laboratories
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ISO 20045:2023(E)
apply them to demonstrate their technical competencies and to complete proficiency tests successfully
during interlaboratory comparisons, two prerequisites for obtaining national accreditation.
Today, over a hundred International standards, prepared by Technical Committees of the International
Organization for Standardization, including those produced by ISO/TC 85, and the International
Electrotechnical Commission (IEC), are available to testing laboratories for measuring radionuclides in
different matrices.
3
Tritium ( H) is a radioactive isotope of hydrogen. It is a pure beta emitting radionuclide, with a
maximum energy equal to 18,591 ± 1 keV and a radiological half-life equal to 12,312 (0,025) years
(see Reference [3]). It is naturally occurring and continuously produced in the upper atmosphere by
interaction of cosmic rays with nitrogen and oxygen nuclei (see Reference [4]).
Two main chemical species of both natural and anthropogenic tritium are present in the environment.
The most abundant chemical form is tritiated water (HTO) (see Reference [5]). Tritium can also be
present in the form of tritiated gas (HT or T ) usually present in the vicinity of tritium-emitting facilities
2
(see Reference [6]), tritiated methane (CH T), or in other various organic forms of tritium commonly
3
observed in terrestrial, aquatic continental, and marine ecosystems (see References [7], [8] and [9]).
Anthropogenic tritium compounds come from radioactive releases of nuclear facilities i.e., nuclear
power plants, irradiated fuel reprocessing and recycling plants, military defence, medical research
applications, and past atmospheric testing of nuclear devices (see Annex A).
This document describes the method to assess the activity concentration of atmospheric tritium via air
sampling by bubbler devices which trap tritiated water vapour and tritiated gas in a water solution. The
method can be used for any type of environmental study or monitoring.
The test method is used in the context of a quality assurance management system (ISO/IEC 17025). It
can be adapted so that the characteristic limits, decision threshold, detection limit and uncertainties
ensure that the test results of the atmospheric tritium activity concentrations can be verified to be
below guidance levels required by a national authority for either planned or existing situations or for
an emergency situation.
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INTERNATIONAL STANDARD ISO 20045:2023(E)
Measurement of the radioactivity in the environment —
Air: tritium — Test method using bubbler sampling
1 Scope
This document describes a test method to determine the activity concentration of atmospheric
tritium by trapping tritium in air by bubbling through a water solution. Atmospheric tritium activity
-3
concentration levels are expressed in becquerel per cubic metre (Bq∙m ).
The formulae are given for a sampling system with four bubblers. They can also be applied to trapping
systems with only one trapping module consisting of two bubblers if only HTO is in the atmosphere to
be sampled.
This document does not cover laboratory test sample results, in becquerel per litre of trapping solution,
according to ISO 9698 or ISO 13168.
-3 -3
The test method detection limit result is between 0,2 Bq∙m and 0,5 Bq∙m when the sampling duration
is about one week.
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 4788, Laboratory glassware — Graduated measuring cylinders
ISO 9698, Water quality — Tritium — Test method using liquid scintillation counting
ISO 13168, Water quality — Simultaneous determination of tritium and carbon 14 activities — Test method
using liquid scintillation counting
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
3 Terms, definitions and symbols
For the purposes of this document, the definitions, symbols and abbreviations given in,
ISO/IEC Guide 98-3, ISO/IEC Guide 99, 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 https:// www .electropedia .org/
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ISO 20045:2023(E)
3.1 Terms and definitions
3.1.1
aerosol
dispersion of very fine solid particles or liquid droplets in air or gases
3.1.2
air sample
representative part of the atmosphere sampled routinely, intermittently or continuously to examine its
various characteristics
3.1.3
bubbler
glass container that holds the trapping water solution (3.1.11)
3.1.4
bubbler sample
bubbler (3.1.3) which an air sample (3.1.2) bubbled through
3.1.5
oxidizing efficiency
ratio of atmospheric tritium gas compounds converted into tritiated water vapour (3.1.13), oxidized
with a catalytic converter furnace, to tritium gas compounds in the atmosphere during the sampling
period
3.1.6
sampling module
module composed of two bubblers (3.1.3) connected in series to trap tritium species HTO (3.1.13) or no-
HTO (3.1.12)
3.1.7
sampling system
device for sampling atmospheric tritium by bubbling through a water solution that consists of a
sampling head which is the air inlet, a transport line, collector, and flow conditioning system
Note 1 to entry: Recorded samples are analysed off-line in a testing laboratory.
3.1.8
standard conditions
temperature of 273,13 K (0 °C) and a pressure of 101 325 Pa
Note 1 to entry: Used to convert air densities into a common basis. Other temperature and pressure conditions
may be used and should be applied consistently.
3.1.9
test sample
representative volume taken from the bubbler sample (3.1.4) to analyse the tritium activity
concentration by a testing laboratory
3.1.10
trapping efficiency
ratio of tritiated water vapour (3.1.13) activity concentration collected, during the sampling period, to
atmospheric tritiated water vapour (3.1.13) activity concentration
3.1.11
trapping water solution
any types of colourless water with no apparent biological activities to trap atmospheric tritium by
molecular and/or isotopic exchange between the tritium atoms in water vapour of the air and the
hydrogen atoms of the water molecules in solution
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ISO 20045:2023(E)
3.1.12
tritiated gas
no-HTO
tritium gas compounds where HT and CH T molecules are predominant chemical gas species in
3
atmosphere
3.1.13
tritiated water vapour
HTO
water vapour where one hydrogen atom of a water molecule is substituted by one tritium atom
3.2 Symbols, definitions and units
Table 1 — Symbols, definitions and units
Symbol Definition and unit
A tritium activity of the bubbler sample, B , in becquerel (Bq) where i =1, 2, 3 or 4
i i
A reference tritium activity of tritiated water vapour (HTO) in the atmosphere in becquerel (Bq)
ref
−1
c tritium activity concentration of the test sample, i, in becquerel per litre (Bq·l )
i
decision threshold of the tritium activity concentration of the test sample, i, in becquerel per litre
*
c
−1
i
(Bq·l )
detection limit of the tritium activity concentration of the test sample, i, in becquerel per
#
c
−1
i
litre (Bq·l )
reference tritium activity concentration of tritiated water vapour (HTO) in the atmosphere in
c
ref −3
becquerel per cubic metre (Bq·m ) at standard conditions
tritium activity concentration of tritiated water vapour (HTO) in the atmosphere in becquerel per
c
w
−3
cubic metre (Bq·m ) at standard conditions
tritium activity concentration of tritiated gas compounds (no-HTO) in the atmosphere in becquer-
c
g
−3
el per cubic metre (Bq·m ) at standard conditions
decision threshold of the tritium activity concentration of HTO and no-HTO respectively in the
* *
c and c
−3
w g
atmosphere in becquerel per cubic metre (Bq·m ) at standard conditions
detection limit of the tritium activity concentration of HTO and no-HTO respectively in the atmos-
# #
c and c
−3
w g
phere in becquerel per cubic metre (Bq·m ) at standard conditions
cc,
ww
lower and upper limits of the probabilistically symmetric coverage interval of HTO and no-HTO
and
−3
respectively in the atmosphere in becquerel per cubic metre (Bq·m ) at standard conditions
cc,
gg
<>
cc,
ww
lower and upper limits of the shortest coverage interval of HTO and no-HTO respectively in the
and
−3
atmosphere in becquerel per cubic metre (Bq·m ) at standard conditions
<>
cc,
gg
ε trapping efficiency of each bubbler sample, i
Bi
ε oxidizing efficiency of the catalytic converter furnace
F
coverage factor with k = 1, 2, 3, .
k
3 −1
q
air flow rate of sampling system in cubic metre per hour (m ·h ) at standard conditions
p
t counting duration of the test sample, i, in seconds (s)
i
t
sampling duration in hour (h)
p
standard uncertainty of the tritium activity concentration of the test sample, i, in becquerel per
uc()
i −1
litre (Bq·l )
uy() standard uncertainty associated with parameter, y, result (k = 1)
Uy expanded uncertainty calculated by Uy =⋅ku y with k > 1
() () ()
3
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ISO 20045:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Definition and unit
relative standard uncertainty associated with parameter, y, result calculated by
uy()
rel −1
uy =uy ⋅ y
() ()
rel
Uy() relative expanded uncertainty calculated by Uy()=⋅ku ()ykwith >1
rel relrel
3
sampled air volume in cubic metre (m ) at standard conditions
V
where Vq=⋅t
pp
V water volume of bubbler sample, B , at the end of sampling duration in litre (l)
Bi i
V initial same volume of water in each bubbler, B , in litre (l)
Bref i
−1
w correction factor for the tritium activity concentration of the test sample, i, in per litre (l )
i
4 Principle
The bubbler sampling method consists of trapping airborne tritium compounds in water solution.
The sampled air is continuously pumped through a series of bubblers containing trapping water and
transformed as micro-bubbles in the water. The micro bubbles allow for the efficient capture of airborne
tritium water vapour in the trapping solution by molecular and isotopic exchanges.
After filtering of solid aerosol particles by the dust filter, the sampled air passes through a first sampling
module of two bubblers. This unit collects tritiated water vapour from the air. A second module,
specifically for no-HTO compounds, can also be connected in series. In this case, the sampled air shall
pass through a catalytic converter furnace which converts no-HTO compounds into HTO. This second
module collects residual HTO not trapped by the first module and no-HTO compounds that have been
converted into HTO.
The flow of air through the sampling system is controlled by a mass flow metre.
The Figure 1 shows a diagram of an example of a sample system. Other air flow control and injection
configurations can be used.
4
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ISO 20045:2023(E)
Key
1 atmospheric air to monitor at temperature, T, and relative humidity RH in %
2 sampling head
3 connection pipe
4 anti-dust filter
5 hydrophobic filter
6 mass flow meter
7 bubbler with trapping water solution
8 micro-bubbles generator
9 catalytic converter furnace
10 pump
11 cooling module
12 first module for HTO trapping (bubblers B1 and B2)
13 second module for no-HTO and residual HTO trapping (bubblers B3 and B4)
Figure 1 — Example of an atmospheric air sampling system diagram with two sampling
modules
At the end of the sampling period, trapping solutions shall be collected separately and transported as
soon as possible to the testing laboratory.
Tritium activity concentration of water from each bubbler sample, in becquerel per litre of bubbler
sample, shall be estimated by liquid scintillation in accordance with ISO 9698 or ISO 13168.
Activity concentrations of atmospheric tritium shall be calculated taking into account:
— air volume sampled;
— water volume of each bubbler sample at the start and end of sampling period;
— activity concentration of each bubbler sample;
— HTO trapping efficiency and if required;
— oxidizing efficiency of the catalytic converter furnace.
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ISO 20045:2023(E)
5 Influence quantities
Numerous parameters can affect the sampling of atmospheric air. These influencing quantities may be
categorized as controllable or uncontrollable parameters. Controllable parameters can be monitored
by applying the requirements of this document. Uncontrollable parameters are closely linked with
environmental conditions such as atmospheric air temperature and humidity or ambient temperature
at the sampling location.
Controllable quantities are:
— air flow rate;
— height of trapping solution into each bubbler;
— micro-bubbling into each bubbler;
— temperature of the bubbler sample during sampling;
— oxidizing efficiency of the catalytic converter furnace during heating;
— hermetically sealing of sampling system;
— conditions of sampling and filtration of atmospheric air upstream of sampling device.
6 Equipment
6.1 Description and requirements of the sampling system
The sampling system shall include:
— a sampling head equipped with protection against direct rainfall or splashing;
— a connection pipe as short as possible, between the sam
...
NORME ISO
INTERNATIONALE 20045
Première édition
2023-05
Mesurage de la radioactivité dans
l’environnement — Air : tritium
— Méthode d’essai à l’aide d’un
prélèvement par barbotage
Measurement of the radioactivity in the environment — Air: tritium
— Test method using bubbler sampling
Numéro de référence
ISO 20045:2023(F)
© ISO 2023
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ISO 20045:2023(F)
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Publié en Suisse
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ISO 20045:2023(F)
Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives .1
3 Termes, définitions et symboles . 1
3.1 Termes et définitions . 2
3.2 Symboles, définitions et unités . 3
4 Principe. 4
5 Grandeurs d’influence. 6
6 Équipement . 6
6.1 Description et exigences du système de prélèvement . 6
6.2 Emplacement de la tête de prélèvement . 7
6.3 Débit d’air, durée de prélèvement et volume d’air prélevé . 7
6.4 Eau de piégeage . 7
6.5 Spécifications d’utilisation. 7
7 Mode opératoire . 8
7.1 Échantillonnage . 8
7.2 Collecte et transport des échantillons. 9
7.3 Réception . 9
7.4 Conservation . 9
7.5 Mesurage de l’activité volumique du tritium . 9
8 Expression des résultats .10
8.1 Généralités . 10
8.2 Calculs pour la vapeur d’eau tritiée . 10
8.2.1 Activité volumique . 10
8.2.2 Seuil de décision . 10
8.2.3 Limite de détection . 11
8.2.4 Limites des intervalles élargis . 11
8.2.5 Conditions d’utilisation .12
8.3 Calculs des composés gazeux de tritium .12
8.3.1 Gaz tritié sans niveau important de HTO .13
8.3.2 Composés gazeux de tritium avec un niveau important de HTO . 14
8.3.3 Limites de l’intervalle élargi . 16
8.3.4 Conditions d’utilisation . 16
9 Rapport d’essai .17
Annexe A (informative) Caractéristiques techniques du tritium .19
Annexe B (informative) Détermination du rendement de piégeage .21
Annexe C (informative) Préservation des solutions aqueuses tritiées .26
Annexe D (informative) Exemple de fiches de prélèvement et de calcul .27
Annexe E (informative) Exemples de calculs des activités volumiques du tritium dans l’air .30
Bibliographie .36
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ISO 20045:2023(F)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document
a été rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2
(voir www.iso.org/directives.
L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www.iso.org/brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion
de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir le lien suivant: www.iso.org/iso/fr/avant-propos.
Le présent document a été élaboré par le comité technique ISO/TC 85, Énergie nucléaire, technologies
nucléaires, et radioprotection, sous-comité SC 2, Radioprotection.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www.iso.org/members.html.
iv
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ISO 20045:2023(F)
Introduction
Tout individu est exposé à des rayonnements naturels. Parmi les sources de ces rayonnements, on
compte les rayons cosmiques et les substances radioactives naturellement présentes sur Terre telles
que la faune, la flore ou le corps humain. À cette exposition naturelle aux rayonnements s’ajoute celle
issue des activités anthropiques mettant en œuvre des rayonnements et des substances radioactives.
Certaines de ces activités, dont l’exploitation minière et l’utilisation de minerais contenant des matières
radioactives naturelles (MRN), ainsi que la production d’énergie par combustion de charbon contenant
ces substances, ne font qu’augmenter l’exposition aux sources naturelles de rayonnement. Les centrales
électriques nucléaires et autres installations nucléaires emploient des matières radioactives et génèrent
des effluents et des déchets radioactifs dans le cadre de leur exploitation puis de leur déclassement.
L’utilisation de matières radioactives dans les secteurs de l’industrie, de la médecine, de l’agriculture et
de la recherche connaît un essor mondial.
Toutes ces activités anthropiques provoquent des expositions aux rayonnements qui ne représentent
qu’une petite fraction du niveau moyen mondial des expositions naturelles aux rayonnements. Dans
les pays développés, la plus importante source anthropique d’exposition aux rayonnements, qui ne
cesse d’augmenter, vient de l’utilisation des rayonnements à des fins médicales. Ces applications
médicales englobent la radiologie diagnostique, la radiothérapie, la médecine nucléaire et la radiologie
interventionnelle.
L’exposition aux rayonnements découle également d’activités professionnelles. C’est le cas des employés
des secteurs de l’industrie, de la médecine et de la recherche qui utilisent des rayonnements ou des
substances radioactives, ou encore des passagers et du personnel navigant pendant les voyages aériens.
Le niveau moyen des expositions professionnelles est généralement inférieur au niveau moyen mondial
des expositions naturelles aux rayonnements (voir la Référence [2]).
Du fait de l’utilisation croissante des rayonnements, le risque pour la santé et les préoccupations
du public augmentent. Par conséquent, toutes ces expositions sont régulièrement évaluées afin:
a) d’améliorer la compréhension des niveaux mondiaux et des tendances temporelles de l’exposition
du public et des travailleurs;
b) d’évaluer les composantes de l’exposition de manière à chiffrer leur impact relatif et ;
c) d’identifier les problèmes émergents qui peuvent nécessiter une attention plus soutenue et une
étude complémentaire. Alors que les doses reçues par les travailleurs sont le plus souvent mesurées
directement, celles reçues par le public sont habituellement évaluées par des méthodes indirectes
qui consistent à exploiter les résultats des mesurages de la radioactivité de déchets, d’effluents
liquides, gazeux ou les deux, ou d’échantillons environnementaux.
La radioactivité provenant de sources d’origine naturelle et anthropique est présente partout dans
l’environnement. Dès lors, l’atmosphère aussi peut contenir des radionucléides d’origine naturelle,
anthropique ou les deux.
40 3 14
— Les radionucléides naturels comprenant le K, le H, le C et les radionucléides des familles
226 228 234 238 210
radioactives du thorium et de l’uranium, notamment le Ra, le Ra, le U, le U et le Pb qui
peuvent être retrouvés dans des matériaux issus de sources naturelles ou qui peuvent être émis par
des procédés technologiques mettant en œuvre des matières radioactives naturelles (par exemple
l’exploitation minière et le traitement des sables minéraux ou la production et l’utilisation d’engrais
phosphatés).
— Les radionucléides anthropiques, tels que les éléments transuraniens (américium, plutonium,
3 14 90
neptunium, curium), le H, le C, le Sr et les radionucléides émetteurs gamma qui peuvent également
être retrouvés dans les rejets gazeux, dans les matrices environnementales (telles que l’eau, l’air, le
sol, le biote), dans l’alimentation et dans les aliments pour animaux à la suite de rejets autorisés
dans l’environnement, les retombées radioactives engendrées par l’explosion dans l’atmosphère de
dispositifs nucléaires et les retombées radioactives résultant d’accidents de réacteurs nucléaires
tels que ceux qui se sont produits à Tchernobyl et à Fukushima.
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ISO 20045:2023(F)
Afin de garantir que les données obtenues dans le cadre de programmes de surveillance de la
radioactivité permettent de répondre à l’objectif de l’évaluation, il est primordial que les parties
prenantes (les exploitants de site nucléaire, les organismes de réglementation, les autorités locales,
etc.) conviennent des méthodes et des modes opératoires appropriés pour obtenir des échantillons
représentatifs ainsi que pour le prélèvement, la manipulation, le stockage, la préparation et le mesurage
des échantillons pour essai. Il est également nécessaire de procéder systématiquement à une évaluation
de l’incertitude globale de mesure. Pour toute décision en matière de santé publique s’appuyant sur
des mesures de la radioactivité, il est capital que les données soient fiables, comparables et adéquates
par rapport à l’objectif de l’évaluation. C’est pourquoi les Normes internationales, qui spécifient des
méthodes d’essai des radionucléides vérifiées par des essais puis validées, constituent des outils
fondamentaux dans l’obtention de tels résultats de mesure. L’application de normes permet également
de garantir la comparabilité des résultats d’essai dans le temps et entre différents laboratoires d’essai.
Les laboratoires les appliquent pour démontrer leurs compétences techniques et pour passer les essais
d’aptitude lors d’études interlaboratoires, deux conditions préalables à l’obtention d’une accréditation
nationale.
À l’heure actuelle, plus d’une centaine de Normes internationales, élaborées par les comités techniques
de l’Organisation internationale de normalisation, dont celles élaborées par le comité technique
ISO/TC 85, et la Commission électrotechnique internationale (IEC), sont disponibles pour permettre
aux laboratoires d’essai de mesurer les radionucléides dans différentes matrices.
3
Le tritium ( H) est un isotope radioactif de l’hydrogène. Radionucléide émetteur bêta pur, le tritium a
une énergie maximale égale à 18,591± 1 keV et une demi-vie radiologique égale à 12,312 (0,025) ans
(voir la Référence [3]). C’est également un radionucléide naturel qui est produit continuellement dans
la haute atmosphère par interaction des rayons cosmiques avec les noyaux d’azote et d’oxygène (voir la
Référence [4]).
On retrouve deux espèces chimiques principales du tritium naturel et anthropique dans
l’environnement. La forme chimique la plus abondante est l’eau tritiée (HTO) (voir la Référence [5]).
Le tritium peut également exister sous forme de gaz tritié (HT ou T ), généralement au voisinage des
2
[6]
installations émettrices de tritium (voir la Référence ) et de méthane tritié (CH T), ou sous diverses
3
formes organiques tritiées communément observées dans les écosystèmes terrestres, aquatiques
continentaux, et marins (voir les Références [7],[8] et [9]).
Les composés de tritium anthropique proviennent des émissions radioactives des installations
nucléaires, soit des centrales électriques nucléaires, des usines de retraitement et de recyclage du
combustible irradié, de la défense militaire, des applications de recherche médicale, et des essais
atmosphériques passés d’engins nucléaires (voir l’Annexe A).
Le présent document décrit la méthode d’évaluation de l’activité volumique du tritium atmosphérique
par prélèvement d’air à l’aide de barboteurs qui piègent de la vapeur d’eau tritiée et du gaz tritié
en solution aqueuse. La méthode est utilisable dans le cadre de tout type d’étude ou de contrôle de
l’environnement.
La méthode d’essai est utilisée dans le cadre d’un système de management de l’assurance qualité
(ISO/IEC 17025). Elle peut être adaptée de façon que les limites caractéristiques, le seuil de décision, la
limite de détection et les incertitudes garantissent qu’il soit possible de vérifier que les résultats d’essai
relatifs à l’activité volumique du tritium atmosphérique sont inférieurs aux limites indicatives requises
par une autorité nationale soit pour des situations existantes ou planifiées, soit pour une situation
d’urgence.
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NORME INTERNATIONALE ISO 20045:2023(F)
Mesurage de la radioactivité dans l’environnement — Air
: tritium — Méthode d’essai à l’aide d’un prélèvement par
barbotage
1 Domaine d’application
Le présent document décrit une méthode d’essai pour déterminer l’activité volumique du tritium
atmosphérique en piégeant du tritium dans l’air par barbotage à travers une solution aqueuse. Les
niveaux d’activité volumique du tritium atmosphérique sont exprimés en becquerels par mètre cube
−3
(Bq∙m ).
Les formules données sont valables pour un système de prélèvement à quatre barboteurs. Elles
sont également applicables aux systèmes de piégeage avec un seul module de piégeage constitué de
deux barboteurs, à la condition que l’atmosphère dans laquelle a lieu le prélèvement ne contienne que
du HTO.
Le présent document ne traite pas des résultats pour les échantillons d’essai de laboratoire, en
becquerels par litre de solution de piégeage, conformément à l’ISO 9698 ou l’ISO 13168.
−3 −3
Le résultat de la limite détection de la méthode d’essai est compris entre 0,2 Bq∙m et 0,5 Bq∙m pour
une durée de prélèvement d’environ une semaine.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s’applique (y compris les
éventuels amendements).
ISO 4788, Verrerie de laboratoire — Éprouvettes graduées cylindriques
ISO 9698, Qualité de l'eau — Tritium — Méthode d'essai par comptage des scintillations en milieu liquide
ISO 13168, Qualité de l’eau — Détermination simultanée des activités volumiques du tritium et du
carbone 14 — Méthode par comptage des scintillations en milieu liquide
Guide ISO/IEC 98-3, Incertitude de mesure — Partie 3: Guide pour l’expression de l’incertitude de mesure
(GUM: 1995)
Guide ISO/IEC 99, Vocabulaire international de métrologie — Concepts fondamentaux et généraux et
termes associés (VIM)
ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d'étalonnages et d'essais
ISO 80000-10, Grandeurs et unités — Partie 10: Physique atomique et nucléaire
3 Termes, définitions et symboles
Pour les besoins du présent document, les définitions, les symboles et les abréviations donnés dans le
Guide ISO/IEC 98-3, le Guide ISO/IEC 99, l’ISO 80000-10 ainsi que les suivants s’appliquent.
1
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ISO 20045:2023(F)
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l’adresse https ://www .iso .org/ obp
— IEC Electropedia: disponible à l’adresse https ://www .electropedia .org/
3.1 Termes et définitions
3.1.1
aérosols
dispersion de particules solides très fines ou de gouttelettes de liquide dans l’air ou dans les gaz
3.1.2
échantillon d’air
partie représentative prélevée dans l’atmosphère de façon ponctuelle, intermittente ou continue afin
d’en examiner diverses caractéristiques
3.1.3
barboteur
récipient en verre qui contient l’eau de piégeage (3.1.11)
3.1.4
échantillon de barbotage
barboteur (3.1.3) dans lequel un échantillon d’air (3.1.2) a barboté
3.1.5
rendement d’oxydation
rapport des composés gazeux de tritium atmosphériques convertis en vapeur d’eau tritiée (3.1.13), par
oxydation avec un four catalytique de conversion, sur les composés gazeux de tritium dans l’atmosphère
pendant la période de prélèvement
3.1.6
module de prélèvement
module constitué de deux barboteurs (3.1.3) raccordés en série pour piéger les espèces de tritium HTO
(3.1.13) ou non HTO (3.1.12)
3.1.7
système de prélèvement
dispositif de prélèvement du tritium atmosphérique par barbotage à travers une solution aqueuse,
constitué d’une tête de prélèvement qui est l’entrée d’air, d’une ligne de transport, d’un collecteur et
d’un système de refroidissement du flux
Note 1 à l'article: Les échantillons enregistrés sont analysés en différé dans un laboratoire d’essai.
3.1.8
conditions normales
273,13 K (0°C) pour la température et 101 325 Pa pour la pression
Note 1 à l'article: Utilisées pour convertir les masses volumiques de l’air normalement. Il est autorisé d’utiliser
d’autres conditions de température et de pression mais il convient de les appliquer de manière homogène.
3.1.9
échantillon pour essai
volume représentatif prélevé dans l’échantillon de barbotage (3.1.4) pour l’analyse de l’activité volumique
du tritium par un laboratoire d’essai
3.1.10
rendement de piégeage
rapport de l’activité volumique de la vapeur d’eau tritiée (3.1.13) collectée, pendant la période de
prélèvement, sur l’activité volumique de vapeur d’eau tritiée (3.1.13) atmosphérique
2
© ISO 2023 – Tous droits réservés
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ISO 20045:2023(F)
3.1.11
eau de piégeage
tout type d’eau incolore sans activités biologiques apparentes pour piéger du tritium atmosphérique
par échange moléculaire, isotopique, ou les deux, entre les atomes de tritium présents dans la vapeur
d’eau de l’air et les atomes d’hydrogène des molécules d’eau de la solution
3.1.12
gaz tritiés
non HTO
composés gazeux de tritium où les molécules HT et CH T sont les espèces chimiques gazeuses
3
prédominantes dans l’atmosphère
3.1.13
vapeur d’eau tritiée
HTO
vapeur d’eau atmosphérique dans laquelle un atome d’hydrogène d’une molécule d’eau est remplacé
par un atome de tritium
3.2 Symboles, définitions et unités
Tableau 1 — Symboles, définitions et unités
Symbole Définition et unité
A activité du tritium de l’échantillon de barbotage B , en becquerels (Bq), pour i = 1, 2, 3 ou 4
i i
activité de référence du tritium de la vapeur d’eau tritiée (HTO) dans l’air atmosphérique, en bec-
A
ref
querel (Bq)
−1
c activité volumique du tritium de l’échantillon pour essai i, en becquerel par litre (Bq·l )
i
*
−1
seuil de décision de l’activité volumique de l’échantillon pour essai i, en becquerel par litre (Bq·l )
c
i
limite de détection de l’activité volumique du tritium de l’échantillon pour essai i, en becquerel par
#
c
−1
i
litre (Bq·l )
activité de référence du tritium de la vapeur d’eau tritiée (HTO) dans l’air atmosphérique, en bec-
c
ref −3
querel par mètre cube (Bq·m ) dans les conditions normales
activité volumique du tritium de la vapeur d’eau tritiée (HTO) dans l’air atmosphérique, dans les
c
w −3
conditions normales, en becquerel par mètre cube (Bq·m )
activité volumique du tritium des composés gazeux titriés (non-HTO) dans l’air atmosphérique,
c
g
−3
dans les conditions normales, en becquerel par mètre cube (Bq·m )
seuil de décision de l’activité volumique du tritium du HTO et du non HTO respectivement dans
* *
c et c
−3
w g
l’air atmosphérique, dans les conditions normales, en becquerel par mètre cube (Bq·m )
limite de détection de l’activité volumique du tritium du HTO et du non HTO respectivement dans
# #
c et c
−3
w g
l’air atmosphérique, dans les conditions normales, en becquerel par mètre cube (Bq·m )
cc,
ww
limites inférieure et supérieure de l’intervalle élargi probabilistiquement symétrique du HTO et
et
du non HTO respectivement dans l’air atmosphérique, dans les conditions normales, en becquerel
−3
par mètre cube (Bq·m )
cc,
gg
<>
cc,
ww
limites inférieure et supérieure de l’intervalle élargi le plus court du HTO et du non HTO respec-
et
tivement dans l’air atmosphérique, dans les conditions normales, en becquerel par mètre cube
−3
(Bq·m )
<>
cc,
gg
ε rendement de piégeage de chaque échantillon de barbotage i
Bi
ε rendement d’oxydation du four catalytique de conversion
F
k facteur d’élargissement pour k = 1, 2, 3.
débit d’air du système de prélèvement dans les conditions normales, en mètres cubes par
q
p
3 −1
heure (m ·h )
3
© ISO 2023 – Tous droits réservés
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ISO 20045:2023(F)
TTabableleaauu 1 1 ((ssuuiitte)e)
Symbole Définition et unité
t durée de comptage de l’échantillon pour essai i en secondes (s)
i
t
durée de prélèvement en heures (h)
p
incertitude-type de l’activité volumique du tritium de l’échantillon d’essai i, en becquerel par
uc()
i −3
mètre cube (Bq·m )
uy incertitude-type associée au résultat du paramètre y, pour (k = 1)
()
Uy() incertitude élargie calculée par Uy() =⋅ku()y pour k > 1
−1
uy()
incertitude-type relative associée au résultat du paramètre y calculé par uy =uy ⋅ y
rel () ()
rel
Uy() incertitude élargie relative calculée avec Uy()=⋅ku ()ykwith >1
rel relrel
3
volume d’air prélevé en mètres cubes (m ) dans les conditions normales
V
où Vq=⋅t
pp
V volume d’eau de l’échantillon de barbotage B à la fin de la période de prélèvement, en litre (l)
Bi i
V volume d’eau initial identique, dans chaque barboteur B , en litre (l)
Bref i
−1
w facteur de correction de l’activité volumique du titrium de l’échantillon pour essai, i, par litre (l )
i
4 Principe
La méthode de prélèvement par barbotage consiste à piéger les composés tritiés en suspension dans
l’air dans une solution aqueuse. L’air prélevé est pompé en continu à travers une série de barboteurs
contenant l’eau de piégeage et transformé en micro-bulles dans l’eau. Les micro-bulles permettent
une capture efficace de la vapeur d’eau tritiée dans la solution de piégeage par échange moléculaire et
isotopique.
Après filtration des particules solides d’aérosols par le filtre antipoussière, l’air prélevé traverse un
premier module de prélèvement de deux barboteurs. Cette
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 20045
ISO/TC 85/SC 2
Measurement of the radioactivity in
Secretariat: AFNOR
the environment – Air: tritium – Test
Voting begins on:
2023-02-24 Method using bubbler sampling
Voting terminates on:
Mesurage de la radioactivité dans l’environnement — Air : tritium —
2023-04-21
Méthode d’essai à l’aide d’un prélèvement par barbotage
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 20045:2023(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 2023
---------------------- Page: 1 ----------------------
ISO/FDIS 20045:2023(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 20045
ISO/TC 85/SC 2
Measurement of the radioactivity in
Secretariat: AFNOR
the environment – Air: tritium – Test
Voting begins on:
Method using bubbler sampling
Voting terminates on:
Mesurage de la radioactivité dans l’environnement — Air : tritium —
Méthode d’essai à l’aide d’un prélèvement par barbotage
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
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OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 2 ----------------------
ISO/FDIS 20045:2023(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 . 2
3.2 Symbols, definitions and units . 3
4 Principle . 4
5 Influence quantities . 6
6 Equipment . 6
6.1 Description and requirements of the sampling system . 6
6.2 Location of sampling head . 7
6.3 Air flow rate, sampling duration and air volume sampling . 7
6.4 Trapping water solution . 7
6.5 Specifications for use . 7
7 Procedure .8
7.1 Sampling . 8
7.2 Sample collection and transportation . 9
7.3 Receipt. 9
7.4 Conservation . 9
7.5 Tritium activity concentration measurement . 9
8 Expression of results . 9
8.1 General . 9
8.2 Calculations for tritied water vapour . 10
8.2.1 Activity concentration . . 10
8.2.2 Decision threshold . 10
8.2.3 Detection limit . 11
8.2.4 Coverage intervals limits . 11
8.2.5 Conditions of use .12
8.3 Calculation for tritied gas compounds .12
8.3.1 Tritiated gas without significant HTO level .13
8.3.2 Tritiated gas compounds with significant HTO level . 14
8.3.3 Coverage intervals limits . 16
8.3.4 Conditions of use . 16
9 Test report .17
Annex A (informative) Technical data for tritium .19
Annex B (informative) Determination of trapping efficiency.21
Annex C (informative) Preserving of tritiated water solutions .25
Annex D (informative) Example of sampling and calculations forms .26
Annex E (informative) Examples of calculations of air tritium activity concentrations .29
Bibliography .35
iii
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ISO/FDIS 20045:2023(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 nongovernmental, 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, SC 2, Radiological protection.
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
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---------------------- Page: 4 ----------------------
ISO/FDIS 20045:2023(E)
Introduction
Everyone is exposed to natural radiation. The natural sources of radiation include cosmic rays and
naturally occurring radioactive substances which exist on Earth such as flora, fauna or the human body.
Human activities involving the use of radiation and radioactive substances add to the radiation exposure
from this natural exposure. Some of those activities, such as the mining and use of ores containing
naturally-occurring radioactive materials (NORM) and the production of energy by burning coal that
contains such substances, simply enhance the exposure from natural radiation sources. Nuclear power
plants and other nuclear installations use radioactive materials and produce radioactive effluents and
waste during operation and decommissioning. The use of radioactive materials in industry, agriculture
and research is expanding around the globe.
All these human activities give rise to radiation exposures that are only a small fraction of the global
average level of natural exposure. The medical use of radiation is the largest and a growing man-made
source of radiation exposure in developed countries. It includes diagnostic radiology, radiotherapy,
nuclear medicine and interventional radiology.
Radiation exposure also occurs as a result of occupational activities. It is incurred by workers in
industry, medicine and research using radiation or radioactive substances, as well as by passengers
and crew during air travel. The average level of occupational exposures is generally below the global
average level of natural radiation exposure (see Reference [2])
As uses of radiation increase, so do the potential health risk and the public's concerns. Thus, all these
exposures are regularly assessed in order to
a) improve the understanding of global levels and temporal trends of public and worker exposure,
b) evaluate the components of exposure so as to provide a measure of their relative impact, and
c) identify emerging issues that may warrant more attention and study. While doses to workers
are mostly directly measured, doses to the public are usually assessed by indirect methods
using the results of radioactivity measurements of waste, liquid and/or gaseous effluents and/or
environmental samples.
Radioactivity from several naturally-occurring and anthropogenic sources is present throughout the
environment. Thus, atmosphere can contain radionuclides of natural, humanmade, or both origins.
40 3 14
— Natural radionuclides including K, H, C and those originating from the thorium and uranium
226 228 234 238 210
decay series, in particular Ra, Ra, U, U and Pb which can be found in materials from
natural sources or can be released from technological processes involving naturally occurring
radioactive materials (e.g. the mining and processing of mineral sands or phosphate fertilizer
production and use).
— Humanmade radionuclides, such as transuranic elements (americium, plutonium, neptunium, and
3 14 90
curium), H, C, Sr and gamma-ray emitting radionuclides can also be found gaseous effluent
discharges, in environmental matrices (water, air, soil and biota), in food and in animal feed as a
result of authorized releases into the environment, fallout from the explosion in the atmosphere of
nuclear devices and fallout from accidents, such as those that occurred in Chernobyl and Fukushima.
To ensure that the data obtained from radioactivity monitoring programs support their intended use, it
is essential that the stakeholders (for example nuclear site operators, regulatory and local authorities)
agree on appropriate methods and procedures for obtaining representative samples and for sampling,
handling, storing, preparing and measuring the test samples. An assessment of the overall measurement
uncertainty also needs to be carried out systematically. As reliable, comparable and ‘fit for purpose’
data are an essential requirement for any public health decision based on radioactivity measurements,
international standards of tested and validated radionuclide test methods are an important tool for
the production of such measurement results. The application of standards serves also to guarantee
comparability of the test results over time and between different testing laboratories. Laboratories
apply them to demonstrate their technical competencies and to complete proficiency tests successfully
during interlaboratory comparisons, two prerequisites for obtaining national accreditation.
v
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ISO/FDIS 20045:2023(E)
Today, over a hundred International standards, prepared by Technical Committees of the International
Organization for Standardization, including those produced by ISO/TC 85, and the International
Electrotechnical Commission (IEC), are available to testing laboratories for measuring radionuclides in
different matrices.
3
Tritium ( H) is a radioactive isotope of hydrogen. It is a pure beta emitting radionuclide, with a
maximum energy equal to 18,591 (1) keV and a radiological half-life equal to 12,312 (0,025) years
(see Reference [3]). It is naturally occurring and continuously produced in the upper atmosphere by
interaction of cosmic rays with nitrogen and oxygen nuclei (see Reference [4]).
Two main chemical species of both natural and anthropogenic tritium are present in the environment.
The most abundant chemical form is tritiated water (HTO) (see Reference [5]). Tritium can also be
present in the form of tritiated gas (HT or T ) usually present in the vicinity of tritium-emitting facilities
2
(see Reference [6]), tritiated methane (CH T), or in other various organic forms of tritium commonly
3
observed in terrestrial, aquatic continental, and marine ecosystems (see References [7], [8] and [9]).
Anthropogenic tritium compounds come from radioactive releases of nuclear facilities i.e., nuclear
power plants, irradiated fuel reprocessing and recycling plants, military defence, medical research
applications, and past atmospheric testing of nuclear devices (see Annex A).
This document describes the method to assess the activity concentration of atmospheric tritium via air
sampling by bubbler devices which trap tritiated water vapour and tritiated gas in a water solution. The
method can be used for any type of environmental study or monitoring.
The test method is used in the context of a quality assurance management system (ISO/IEC 17025). It
can be adapted so that the characteristic limits, decision threshold, detection limit and uncertainties
ensure that the test results of the atmospheric tritium activity concentrations can be verified to be
below guidance levels required by a national authority for either planned or existing situations or for
an emergency situation.
vi
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 20045:2023(E)
Measurement of the radioactivity in the environment – Air:
tritium – Test Method using bubbler sampling
1 Scope
This document describes a test method to determine the activity concentration of atmospheric
tritium by trapping tritium in air by bubbling through a water solution. Atmospheric tritium activity
3
concentration levels are expressed in becquerel per cubic metre (Bq∙m ).
The formulae are given for a sampling system with four bubblers. They can also be applied to trapping
systems with only one trapping module consisting of two bubblers if only HTO is in the atmosphere to
be sampled.
This document does not cover laboratory test sample results, in becquerel per litre of trapping solution,
according to ISO 9698 or ISO 13168.
3 3
The test method detection limit result is between 0,2 Bq∙m and 0,5 Bq∙m when the sampling duration
is about one week.
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 4788, Laboratory glassware — Graduated measuring cylinders
ISO 9698, Water quality — Tritium — Test method using liquid scintillation counting
ISO 13168, Water quality — Simultaneous determination of tritium and carbon 14 activities — Test method
using liquid scintillation counting
ISO/IEC Guide 983, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 8000010, Quantities and units — Part 10: Atomic and nuclear physics
3 Terms, definitions and symbols
For the purposes of this document, the definitions, symbols and abbreviations given in,
ISO/IEC Guide 98-3, ISO/IEC Guide 99, 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 https:// www .electropedia .org/
1
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ISO/FDIS 20045:2023(E)
3.1 Terms and definitions
3.1.1
aerosol
dispersion of very fine solid particles or liquid droplets in air or gases
3.1.2
air sample
representative part of the atmosphere sampled routinely, intermittently or continuously to examine its
various characteristics
3.1.3
bubbler
glass container that holds the trapping water solution (3.1.11)
3.1.4
bubbler sample
bubbler (3.1.3) which an air sample (3.1.2) bubbled through
3.1.5
oxidizing efficiency
ratio of atmospheric tritium gas compounds converted into tritiated water vapour (3.1.13), oxidized
with a catalytic converter furnace, to tritium gas compounds in the atmosphere during the sampling
period
3.1.6
sampling module
composed of two bubblers (3.1.3) connected in series to trap tritium species HTO (3.1.13) or no-HTO
(3.1.12)
3.1.7
sampling system
device for sampling atmospheric tritium by bubbling through a water solution that consists of a
sampling head which is the air inlet, a transport line, collector, and flow conditioning system
Note 1 to entry: Recorded samples are analysed off-line in a testing laboratory.
3.1.8
standard conditions
temperature of 273,13 K (0 °C) and a pressure of 101 325 Pa
Note 1 to entry: Used to convert air densities into a common basis. Other temperature and pressure conditions
may be used and should be applied consistently.
3.1.9
test sample
representative volume taken from the bubbler sample (3.1.4) to analyse the tritium activity
concentration by a testing laboratory
3.1.10
trapping efficiency
ratio of tritiated water vapour (3.1.13) activity concentration collected, during the sampling period, to
atmospheric tritiated water vapour (3.1.13) activity concentration
3.1.11
trapping water solution
Any types of colourless water with no apparent biological activities to trap atmospheric tritium by
molecular and/or isotopic exchange between the tritium atoms in water vapour of the air and the
hydrogen atoms of the water molecules in solution
2
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ISO/FDIS 20045:2023(E)
3.1.12
tritiated gas
noHTO
tritium gas compounds where HT and CH T molecules are predominant chemical gas species in
3
atmosphere
3.1.13
tritiated water vapour
HTO
water vapour where one hydrogen atom of a water molecule is substituted by one tritium atom
3.2 Symbols, definitions and units
Table 1 — Symbols, definitions and units
Symbol Definition and unit
A tritium activity of the bubbler sample, B , in becquerel (Bq) where i =1, 2, 3 or 4
i i
A reference tritium activity of tritiated water vapour (HTO) in the atmosphere in becquerel (Bq)
ref
−1
c tritium activity concentration of the test sample, i, in becquerel per litre (Bq·l )
i
decision threshold of the tritium activity concentration of the test sample, i, in becquerel per litre
*
c
−1
i
(Bq·l )
detection limit of the tritium activity concentration of the test sample, i, in becquerel per
#
c
−1
i
litre (Bq·l )
reference tritium activity concentration of tritiated water vapour (HTO) in the atmosphere in
c
ref −3
becquerel per cubic metre (Bq·m ) at standard conditions
tritium activity concentration of tritiated water vapour (HTO) in the atmosphere in becquerel per
c
w
−3
cubic metre (Bq·m ) at standard conditions
tritium activity concentration of tritiated gas compounds (no-HTO) in the atmosphere in becquer
c
g
−3
el per cubic metre (Bq·m ) at standard conditions
decision threshold of the tritium activity concentration of HTO and no-HTO respectively in the
* *
c and c
−3
w g
atmosphere in becquerel per cubic metre (Bq·m ) at standard conditions
detection limit of the tritium activity concentration of HTO and no-HTO respectively in the atmos
# #
c and c
−3
w g
phere in becquerel per cubic metre (Bq·m ) at standard conditions
cc,
ww
lower and upper limits of the probabilistically symmetric coverage interval of HTO and no-HTO
and
−3
respectively in the atmosphere in becquerel per cubic metre (Bq·m ) at standard conditions
cc,
gg
<>
cc,
ww
lower and upper limits of the shortest coverage interval of HTO and no-HTO respectively in the
and
−3
atmosphere in becquerel per cubic metre (Bq·m ) at standard conditions
<>
cc,
gg
ε trapping efficiency of each bubbler sample, i
Bi
ε oxidizing efficiency of the catalytic converter furnace
F
coverage factor with k = 1, 2, 3, .
k
3 −1
q
air flow rate of sampling system in cubic metre per hour (m ·h ) at standard conditions
p
t counting duration of the test sample, i, in seconds (s)
i
t
sampling duration in hour (h)
p
standard uncertainty of the tritium activity concentration of the test sample, i, in becquerel per
uc()
i −1
litre (Bq·l )
uy() standard uncertainty associated with parameter, y, result (k = 1)
Uy expanded uncertainty calculated by Uy =⋅ku y with k > 1
() () ()
3
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ISO/FDIS 20045:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Definition and unit
relative standard uncertainty associated with parameter, y, result calculated by
uy
() −1
rel
uy()=uy()⋅ y
rel
Uy relative expanded uncertainty calculated by Uy =⋅ku ykwith >1
() () ()
rel relrel
3
sampled air volume in cubic metre (m ) at standard conditions
V
where Vq=⋅t
pp
V water volume of bubbler sample, B , at the end of sampling duration in litre (l)
Bi i
V initial same volume of water in each bubbler, B , in litre (l)
Bref i
−1
w correction factor for the tritium activity concentration of the test sample, i, in per litre (l )
i
4 Principle
The bubbler sampling method consists of trapping airborne tritium compounds in water solution.
The sampled air is continuously pumped through a series of bubblers containing trapping water and
transformed as micro-bubbles in the water. The micro bubbles allow for the efficient capture of airborne
tritium water vapour in the trapping solution by molecular and isotopic exchanges.
After filtering of solid aerosol particles by the dust filter, the sampled air passes through a first sampling
module of two bubblers. This unit collects tritiated water vapour from the air. A second module,
specifically for no-HTO compounds, can also be connected in series. In this case, the sampled air shall
pass through a catalytic converter furnace which converts no-HTO compounds into HTO. This second
module collects residual HTO not trapped by the first module and no-HTO compounds that have been
converted into HTO.
The flow of air through the sampling system is controlled by a mass flow metre.
The Figure 1 shows a diagram of an example of a sample system. Other air flow control and injection
configurations can be used.
4
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ISO/FDIS 20045:2023(E)
Key
1 atmospheric air to monitor at temperature, T, and relative humidity RH in %
2 sampling head
3 connection pipe
4 anti-dust filter
5 hydrophobic filter
6 mass flow meter
7 bubbler with trapping water solution
8 microbubbles generator
9 catalytic converter furnace
10 pump
11 cooling module
12 first module for HTO trapping (bubblers B1 and B2)
13 second module for noHTO and residual HTO trapping (bubblers B3 and B4)
Figure 1 — Example of an atmospheric air sampling system diagram with two sampling
modules
At the end of the sampling period, trapping solutions shall be collected separately and transported as
soon as possible to the testing laboratory.
Tritium activity concentration of water from each bubbler sample, in becquerel per litre of bubbler
sample, shall be estimated by liquid scintillation in accordance with ISO 9698 or ISO 13168.
Activity concentrations of atmospheric
...
ISO/FDIS 20045:2023(E) Style Definition: Heading 1: Indent: Left: 0 pt, First line:
0 pt, Tab stops: Not at 21.6 pt
Date: 2023-01-24xx Style Definition: Heading 2: Font: Bold, Tab stops: Not at
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Style Definition: Heading 4: Font: Bold
Secretariat: AFNOR
Style Definition: Heading 5: Font: Bold
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Measurement of the radioactivity in the environment – Air –: tritium – Test
Style Definition: ANNEX
method using bubbler sampling
Style Definition: AMEND Terms Heading: Font: Bold
Mesurage de la radioactivité dans l’environnement — Air: tritium— Méthode d’essai avec
Style Definition: AMEND Heading 1 Unnumbered: Font:
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échantillonnage par barbotage
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ISO/FDIS 20045:2023(E)
© ISO 2023 Commented [eXtyles1]: The reference is to a withdrawn
standard which has been replaced
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or
ISO 20344, Personal protective equipment — Test methods
utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or
for footwear
posting on the internet or an intranet, without prior written permission. Permission can be requested
Formatted: Pattern: Clear
from either ISO at the address below or ISO's member body in the country of the requester.
Formatted: Pattern: Clear
ISO Copyright Office
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Fax: + 41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.orgwww.iso.org
Published in Switzerland.
ii © ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 20045:2023(E)
Contents Page
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 2
3.2 Symbols, definitions and units . 3
4 Principle . 4
5 Influence quantities . 6
6 Equipment . 6
6.1 Description and requirements of the sampling system . 6
6.2 Location of sampling head . 7
6.3 Air flow rate, sampling duration and air volume sampling . 7
6.4 Trapping water solution . 7
6.5 Specifications for use . 7
7 Procedure . 8
7.1 Sampling . 8
7.2 Sample collection and transportation . 9
7.3 Receipt . 9
7.4 Conservation . 9
7.5 Tritium activity concentration measurement . 9
8 Expression of results . 9
8.1 General . 9
8.2 Calculations for tritied water vapour . 10
8.2.1 Activity concentration . 10
8.2.2 Decision threshold . 10
8.2.3 Detection limit . 10
8.2.4 Coverage intervals limits . 11
8.2.4.1 Probabilistically symmetric coverage interval . 11
8.2.4.2 Shortest coverage interval . 11
8.2.5 Conditions of use . 12
8.3 Calculation for tritied gas compounds . 12
8.3.1 Tritiated gas without significant HTO level . 12
8.3.1.1 Activity concentration . 12
8.3.1.2 Decision threshold . 13
8.3.1.3 Detection limit . 13
8.3.2 Tritiated gas compounds with significant HTO level . 13
8.3.2.1 Activity concentration . 13
8.3.2.2 Decision threshold . 14
8.3.2.3 Detection limit . 14
8.3.3 Coverage intervals limits . 15
8.3.3.1 Probabilistically symmetric coverage interval . 15
8.3.3.2 Shortest coverage interval . 15
8.3.4 Conditions of use . 15
9 Test report . 16
Annex A (informative) Technical data for tritium . 18
Annex B (informative) Determination of trapping efficiency . 20
B.1 Measurement principle . 20
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ISO/FDIS 20045:2023(E)
B.2 Trapping efficiency of first bubbler sample . 20
B.3 Typical values . 22
Annex C (informative) Preserving of tritiated water solutions . 25
C.1 Tritiated trapping solutions tests . 25
C.2 Tritiated water solution tests . 25
C.3 Conclusion . 25
Annex D (informative) Example of sampling and calculations forms . 26
D.1 Sampling forms . 26
D.2 Calculation forms . 28
Annex E (informative) Examples of calculations of air tritium activity concentrations . 29
E.1 Calculation example without significant HTO level into bubbler samples B3 . 29
E.2 Calculation example with significant HTO level into bubbler samples B3 and B4 . 31
Bibliography
. 33Introdu
ction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 2
3.2 Symbols, definitions and units . 3
4 Principle . 4
5 Influence quantities . 6
6 Equipment . 6
6.1 Description and requirements of the sampling system . 6
6.2 Location of sampling head . 7
6.3 Air flow rate, sampling duration and air volume sampling . 7
6.4 Trapping water solution . 7
6.5 Specifications for use . 7
7 Procedure . 8
7.1 Sampling . 8
7.2 Sample collection and transportation . 9
7.3 Receipt . 9
7.4 Conservation . 9
7.5 Tritium activity concentration measurement . 9
8 Expression of results . 9
8.1 General . 9
8.2 Calculations for tritied water vapour . 10
8.2.1 Activity concentration . 10
8.2.2 Decision threshold . 10
8.2.3 Detection limit . 10
8.2.4 Coverage intervals limits . 11
8.2.4.1 Probabilistically symmetric coverage interval . 11
8.2.4.2 Shortest coverage interval . 11
8.2.5 Conditions of use . 12
8.3 Calculation for tritied gas compounds . 12
8.3.1 Tritiated gas without significant HTO level . 12
8.3.1.1 Activity concentration . 12
8.3.1.2 Decision threshold . 13
8.3.1.3 Detection limit . 13
iv © ISO 2023 – All rights reserved
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ISO/FDIS 20045:2023(E)
8.3.2 Tritiated gas compounds with significant HTO level . 13
8.3.2.1 Activity concentration . 13
8.3.2.2 Decision threshold . 14
8.3.2.3 Detection limit . 14
8.3.3 Coverage intervals limits . 15
8.3.3.1 Probabilistically symmetric coverage interval . 15
8.3.3.2 Shortest coverage interval . 15
8.3.4 Conditions of use . 15
9 Test report . 16
Annex A (informative) Technical data for tritium . 18
Annex B (informative) Determination of trapping efficiency . 20
Annex C (informative) Preserving of tritiated water solutions . 25
Annex D (informative) Example of sampling and calculations forms . 26
Annex E (informative) Examples of calculations of air tritium activity concentrations . 29
Bibliography . 33
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---------------------- Page: 5 ----------------------
ISO/FDIS 20045:2023(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/directiveswww.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/patentswww.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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, SC 2, Radiological protection.
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.
vi © ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/FDIS 20045:2023(E)
Introduction
Everyone is exposed to natural radiation. The natural sources of radiation include cosmic rays and
naturally occurring radioactive substances which exist on Earth such as flora, fauna or the human body.
Human activities involving the use of radiation and radioactive substances add to the radiation exposure
from this natural exposure. Some of those activities, such as the mining and use of ores containing
naturally-occurring radioactive materials (NORM) and the production of energy by burning coal that
contains such substances, simply enhance the exposure from natural radiation sources. Nuclear power
plants and other nuclear installations use radioactive materials and produce radioactive effluents and
waste during operation and decommissioning. The use of radioactive materials in industry, agriculture
and research is expanding around the globe.
All these human activities give rise to radiation exposures that are only a small fraction of the global
average level of natural exposure. The medical use of radiation is the largest and a growing man-made
source of radiation exposure in developed countries. It includes diagnostic radiology, radiotherapy,
nuclear medicine and interventional radiology.
Radiation exposure also occurs as a result of occupational activities. It is incurred by workers in industry,
medicine and research using radiation or radioactive substances, as well as by passengers and crew
during air travel. The average level of occupational exposures is generally below the global average level
of natural radiation exposure (see Reference [12])
As uses of radiation increase, so do the potential health risk and the public's concerns. Thus, all these
exposures are regularly assessed in order to
a) improve the understanding of global levels and temporal trends of public and worker exposure,
b) evaluate the components of exposure so as to provide a measure of their relative impact, and
c) identify emerging issues that may warrant more attention and study. While doses to workers are
mostly directly measured, doses to the public are usually assessed by indirect methods using the
results of radioactivity measurements of waste, liquid and/or gaseous effluents and/or
environmental samples.
Radioactivity from several naturally-occurring and anthropogenic sources is present throughout the
environment. Thus, atmosphere can contain radionuclides of natural, human-made, or both origins.
40 3 14
— Natural radionuclides including K, H, C and those originating from the thorium and uranium
226 228 234 238 210
decay series, in particular Ra, Ra, U, U and Pb which can be found in materials from
natural sources or can be released from technological processes involving naturally occurring
radioactive materials (e.g. the mining and processing of mineral sands or phosphate fertilizer
production and use).
— Human-made radionuclides, such as transuranic elements (americium, plutonium, neptunium, and
3 14 90
curium), H, C, Sr and gamma-ray emitting radionuclides can also be found gaseous effluent
discharges, in environmental matrices (water, air, soil and biota), in food and in animal feed as a
result of authorized releases into the environment, fallout from the explosion in the atmosphere of
nuclear devices and fallout from accidents, such as those that occurred in Chernobyl and Fukushima.
To ensure that the data obtained from radioactivity monitoring programs support their intended use, it
is essential that the stakeholders (for example nuclear site operators, regulatory and local authorities)
agree on appropriate methods and procedures for obtaining representative samples and for sampling,
handling, storing, preparing and measuring the test samples. An assessment of the overall measurement
uncertainty also needs to be carried out systematically. As reliable, comparable and ‘fit for purpose’ data
are an essential requirement for any public health decision based on radioactivity measurements,
international standards of tested and validated radionuclide test methods are an important tool for the
production of such measurement results. The application of standards serves also to guarantee
© ISO 2023 – All rights reserved vii
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ISO/FDIS 20045:2023(E)
comparability of the test results over time and between different testing laboratories. Laboratories apply
them to demonstrate their technical competencies and to complete proficiency tests successfully during
interlaboratory comparisons, two prerequisites for obtaining national accreditation.
Today, over a hundred International standards, prepared by Technical Committees of the International
Organization for Standardization, including those produced by ISO/TC 85, and the International
Electrotechnical Commission (IEC), are available to testing laboratories for measuring radionuclides in
different matrices.
3
Tritium ( H) is a radioactive isotope of hydrogen. It is a pure beta emitting radionuclide, with a maximum
energy equal to 18,591 (1) keV and a radiological half-life equal to 12,312 (0,025) years (see
Reference [23]). It is naturally occurring and continuously produced in the upper atmosphere by
interaction of cosmic rays with nitrogen and oxygen nuclei (see Reference [34]).
Two main chemical species of both natural and anthropogenic tritium are present in the environment.
The most abundant chemical form is tritiated water (HTO) (see Reference [45]). Tritium can also be
present in the form of tritiated gas (HT or T2) usually present in the vicinity of tritium-emitting facilities
(see Reference [56]), tritiated methane (CH T), or in other various organic forms of tritium commonly
3
observed in terrestrial, aquatic continental, and marine ecosystems (see References [6], [7], [8] and [89]). Formatted: Pattern: Clear
Anthropogenic tritium compounds come from radioactive releases of nuclear facilities i.e., nuclear power
plants, irradiated fuel reprocessing and recycling plants, military defence, medical research applications,
and past atmospheric testing of nuclear devices (see Annex A).
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This document describes the method to assess the activity concentration of atmospheric tritium via air
sampling by bubbler devices which trap tritiated water vapour and tritiated gas in a water solution. The
method can be used for any type of environmental study or monitoring.
The test method is used in the context of a quality assurance management system (ISO/IEC 17025). It can
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be adapted so that the characteristic limits, decision threshold, detection limit and uncertainties ensure
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that the test results of the atmospheric tritium activity concentrations can be verified to be below
guidance levels required by a national authority for either planned or existing situations or for an
emergency situation.
viii © ISO 2023 – All rights reserved
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 20045:2023(E)
Measurement of the radioactivity in the environment – Air:
tritium – Test method using bubbler sampling
1 Scope
This document describes a test method to determine the activity concentration of atmospheric tritium by
trapping tritium in air by bubbling through a water solution. Atmospheric tritium activity concentration
-3
levels are expressed in becquerel per cubic metre (Bq∙m ).
The formulae are given for a sampling system with four bubblers. They can also be applied to trapping
systems with only one trapping module consisting of two bubblers if only HTO is in the atmosphere to be
sampled.
This document does not cover laboratory test sample results, in becquerel per litre of trapping solution,
according to ISO 9698 or ISO 13168. Commented [eXtyles2]: ISO 13168: current stage is 40.99
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The test method detection limit result is between 0,2 Bq∙m and 0,5 Bq∙m when the sampling duration
is about one week. Formatted: Pattern: Clear
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2 Normative references
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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.
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ISO 4788, Laboratory glassware — Graduated measuring cylinders
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ISO 4788, Laboratory glassware — Graduated measuring cylinders
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ISO 9698, Water quality — Tritium — Test method using liquid scintillation counting
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ISO 11929-1, Determination of the characteristic limits (decision threshold, detection limit and limits
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of the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part
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1: Elementary applications
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ISO 13168, Water quality — Simultaneous determination of tritium and carbon 14 activities — Test
method using liquid scintillation counting
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ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
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measurement (GUM:1995))
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ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and
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associated terms (VIM))
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ISO/IEC 17025, Genera
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