EN ISO 20045:2024

SLOVENSKI STANDARD
01-maj-2024
Merjenje radioaktivnosti v okolju - Zrak: tritij - Preskusna metoda z vzorčenjem z
mehurčki (ISO 20045:2023)
Measurement of the radioactivity in the environment - Air: tritium - Test method using
bubbler sampling (ISO 20045:2023)
Mesurage de la radioactivité dans l’environnement - Air : tritium - Méthode d’essai à
l’aide d’un prélèvement par barbotage (ISO 20045:2023)
Ta slovenski standard je istoveten z: prEN ISO 20045
ICS:
13.040.01 Kakovost zraka na splošno Air quality in general
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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 20045:2023(E)
© ISO 2023
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Published in Switzerland
ii
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
iii
ISO 20045:2023(E)
Foreword
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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, SC 2, Radiological protection.
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iv
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
...