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IEC TR 61577-5
Edition 1.0 2019-07
TECHNICAL
REPORT
colour
inside
Radiation protection instrumentation – Radon and radon decay product
measuring instruments –
Part 5: General properties of radon and radon decay products and their
measurement methods
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IEC TR 61577-5
Edition 1.0 2019-07
TECHNICAL
REPORT
colour
inside
Radiation protection instrumentation – Radon and radon decay product
measuring instruments –
Part 5: General properties of radon and radon decay products and their
measurement methods
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.280 ISBN 978-2-8322-7123-0
– 2 – IEC TR 61577-5:2019 IEC:2019
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Symbols, quantities and units . 8
3.1 Symbols . 8
3.2 Quantities and units . 9
4 Radon in the environment . 9
4.1 Origin, genesis and decay . 9
4.2 Radon in the rocks and soils and its transport towards the atmosphere . 10
4.3 Radon concentration in the outdoor air. 11
4.4 Radon concentration in houses and at workplaces . 11
5 Radon decay products in the atmosphere . 12
5.1 Physical processes of decay products in gaseous media . 12
5.2 Aerosol characteristics and ventilation . 13
6 Physical and chemical properties of radon and radon decay products . 14
6.1 Physical and chemical properties . 14
6.2 Solubility of radon in liquids . 14
6.3 Radiological properties and radioactive equilibrium . 15
6.4 Interaction of alpha particles with matter and energy deposition . 17
222 220
7 Measurement of Rn and Rn and their decay products . 18
7.1 Relevant measurement quantities and units . 18
7.1.1 Activity concentration (C) . 18
7.1.2 Equilibrium equivalent activity concentration (EEC, C ) . 18
eq
7.1.3 Equilibrium factor (F) . 19
7.1.4 Exposure to radon (P ) . 19
Rn
7.1.5 Potential alpha energy (ε ) . 20
p
7.1.6 Potential alpha energy concentration (C ) . 20
p
7.1.7 Potential alpha energy exposure (P ) . 22
p
7.1.8 The unattached and attached fraction of potential alpha energy
concentration . 22
7.2 Instruments measuring airborne radon activity concentration . 22
7.3 Measurement of radon decay products . 23
7.3.1 General overview of instruments . 23
7.3.2 Sampling of the unattached radon decay products . 24
7.3.3 Counting methods for the measurement of the activity concentrations
and the potential alpha-energy concentration . 25
8 Quality assurance . 30
8.1 Definition and purpose . 30
8.2 Quality control . 31
8.3 Validation and traceability of measurements . 31
8.3.1 Validation of methods . 31
8.3.2 Type test of radon instruments . 31
8.3.3 Interlaboratory comparison . 31
8.3.4 Measurement traceability and calibration . 32
9 Determination of the measurement uncertainty, detection threshold, detection limit . 32
9.1 General . 32
9.2 Procedure for the determination . 33
Annex A (informative) Tables and Figures . 35
Annex B (informative) Radioactive decay formulae . 40
B.1 General . 40
B.2 Symbols . 40
B.3 Preliminary considerations and assumptions . 40
B.4 Build-up of filter activity during sampling . 41
B.5 Decay of the filter activity after cessation of sampling . 43
B.6 Number of alpha disintegrations registered after sampling . 44
Annex C (informative) Uncertainty analysis for the method of multiple successive
countings to determine the activity concentrations of radon and thoron decay products . 46
C.1 Symbols . 46
C.2 Uncertainties of the parameter of the model function . 46
C.3 Decision threshold . 50
C.4 Detection limit . 51
C.5 Confidence limits . 51
C.6 Best estimate and its uncertainty . 52
Bibliography . 53
st
Figure 1 – Diurnal variations of the radon activity concentration in the cellar, 1 and
nd
2 floor of a detached house measured over 12 days . 12
Figure 2 – Decay of Rn after injection of 1 000 Bq at the start time and generation
of decay products . 16
Figure 3 – Decay of Rn (Thoron) after injection of 1 000 Bq at the start time and
generation of decay products . 16
Figure 4 – Activity build-up of Rn and its decay products for a continuous supply of
Rn with a rate of 1 Bq/s (in the absence of initial activities) . 16
Figure 5 – Activity build-up of Rn (Thoron) and its decay products for a continuous
supply of Rn with a rate of 1 Bq/s (in the absence of initial activities) . 16
Figure 6 – Total stopping power of alpha particles penetrating different materials, the
graphs use data from [38] . 17
Figure 7 – Contributions of the deposition processes to the total efficiency (calculated
exemplarily for a wire screen) . 24
Figure 8 – Variation of deposition efficiency of a wire screen in dependence on air flow
velocity (calculated exemplarily for a wire screen) . 24
Figure 9 – Measurement error of the method of MARKOV given in percent for different
ratios of decay products in the air sampled . 27
Figure 10 – Method of multiple successive countings . 28
Figure A.1 – Sampling and measurement procedures commonly used for radon
instruments . 35
Figure A.2 – Sampling and measurement procedures commonly used for radon
progeny instruments . 35
Figure B.1 – Scheme for sampling and counting . 44
Table 1 – Coefficients for the calculation of the equilibrium equivalent concentration
from measured activity concentrations of radon progeny . 19
Table 2 – Potential alpha energy per atom for Rn progeny including standard
uncertainty . 21
– 4 – IEC TR 61577-5:2019 IEC:2019
Table 3 – Potential alpha energy per atom for Rn progeny including standard
uncertainty . 21
Table 4 – Time scheme for the method of Thomas [57] . 26
Table 5 – Time scheme for the method of MARKOV [63] . 27
Table A.1 – Physical and chemical characteristics [29] . 36
226 222 222
Table A.2 – Ra, Rn and radionuclides of the Rn decay chain [37] . 36
224 220 220
Table A.3 – Ra, Rn and radionuclides of the Rn decay chain [37] . 37
Table A.4 – CSDA-Range of alpha particles emitted by Radon-222 and Radon-220
decay products in different materials [38] .
...