IEC TR 62461:2015

Radiation protection instrumentation - Determination of uncertainty in measurement

IEC TR 62461:2015(E) gives guidelines for the application of the uncertainty analysis according to ISO/IEC Guide 98-3:2008 and its Supplement 1:2008 for measurements covered by standards in the field of radiation protection instrumentation. It does not include the uncertainty associated with the concept of the measuring quantity. This Technical Report explains the principles of the ISO/IEC Guide 98-3:2008 (GUM), its Supplement 1:2008 (GUM S1) and the special considerations necessary for radiation protection at an example taken from individual dosimetry of external radiation. This Technical Report is intended to assist the understanding of the ISO/IEC Guide 98-3:2008 (GUM), its Supplement 1: 2008 (GUM S1). The main changes with respect to the previous edition are as follows:
- add to the analytical method for the determination of uncertainty the Monte Carlo method for the determination of uncertainty according to supplement 1 of the Guide to the Expression of uncertainty in measurement (GUM S1), and
- add a very simple method to judge whether a measured result is significantly different from zero based on ISO 11929.

General Information

• Status: Published
• Publication Date: 22-Jan-2015
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 13.280 - Radiation protection
• Technical Committee: SC 45B - Radiation protection instrumentation
• Drafting Committee: PT 62461 - TC 45/SC 45B/PT 62461
• Current Stage: PPUB - Publication issued
• Start Date: 30-Apr-2015
• Completion Date: 23-Jan-2015

Relations

• Revises: IEC TR 62461:2006 - Radiation protection instrumentation - Determination of uncertainty in measurement
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TR 62461 ®
Edition 2.0 2015-01
TECHNICAL
REPORT
colour
inside
Radiation protection instrumentation – Determination of uncertainty in
measurement
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IEC TR 62461 ®
Edition 2.0 2015-01
TECHNICAL
REPORT
colour
inside
Radiation protection instrumentation – Determination of uncertainty in

measurement
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.280 ISBN 978-2-8322-2216-4

– 2 – IEC TR 62461:2015 © IEC 2015
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 List of symbols . 12
5 The GUM and the GUM S1 concept . 14
5.1 General concept of uncertainty determination . 14
5.1.1 Overview in four steps . 14
5.1.2 Summary of the analytical method for steps 3 and 4 . 15
5.1.3 Summary of the Monte Carlo method for steps 3 and 4 . 15
5.1.4 Which method to use: Analytical or Monte Carlo? . 16
5.2 Example of a model function . 16
5.3 Collection of data and existing knowledge for the example . 18
5.3.1 General . 18
5.3.2 Calibration factor for the example . 19
5.3.3 Zero reading for the example . 20
5.3.4 Reading for the example . 21
5.3.5 Relative response or correction factor for the example . 21
5.3.6 Comparison of probability density distributions for input quantities . 23
5.4 Calculation of the result of a measurement and its standard uncertainty
(uncertainty budget) . 25
5.4.1 General . 25
5.4.2 Analytical method . 25
5.4.3 Monte Carlo method . 26
5.4.4 Uncertainty budgets . 26
5.5 Statement of the measurement result and its expanded uncertainty . 27
5.5.1 General . 27
5.5.2 Analytical method . 28
5.5.3 Monte Carlo method . 28
5.5.4 Representation of the output distribution function in a simple form
(Monte Carlo method) . 31
6 Results below the decision threshold of the measuring device . 31
7 Overview of the annexes . 32
Annex A (informative) Example of an uncertainty analysis for a measurement with an
electronic ambient dose equivalent rate meter according to IEC 60846-1:2009 . 33
A.1 General . 33
A.2 Model function . 33
A.3 Calculation of the complete result of the measurement (measured value,
probability density distribution, associated standard uncertainty, and the
coverage interval) . 34
A.3.1 General . 34
A.3.2 Low level of consideration of measuring conditions . 35
A.3.3 High level of consideration of measuring conditions . 37
Annex B (informative) Example of an uncertainty analysis for a measurement with a
passive integrating dosimetry system according to IEC 62387:2012 . 40

B.1 General . 40
B.2 Model function . 40
B.3 Calculation of the complete result of the measurement (measured value,
probability density distribution, associated standard uncertainty, and the
coverage interval) . 41
B.3.1 General . 41
B.3.2 Low level of consideration of workplace conditions . 41
B.3.3 High level of consideration of workplace conditions . 43
Annex C (informative) Example of an uncertainty analysis for a measurement with an
electronic direct reading neutron ambient dose equivalent meter according to
IEC 61005:2003 . 46
C.1 General . 46
C.2 Model function . 46
C.3 Calculation of the complete result of the measurement (measured value,
probability density distribution, associated standard uncertainty, and the
coverage interval) . 47
C.3.1 General . 47
C.3.2 Analytical method . 47
C.3.3 Monte Carlo method . 48
C.3.4 Comparison of the result of the analytical and the Monte Carlo method . 49
Annex D (informative) Example of an uncertainty analysis for a calibration of radon
activity monitor according to the IEC 61577 series . 51
D.1 General . 51
D.2 Model function . 51
D.3 Calculation of the complete result of the measurement (measured value,
probability density distribution, associated standard uncertainty, and the
coverage interval) . 51
Annex E (informative) Example of an uncertainty analysis for a measurement of
surface emission rate with a contamination meter according to IEC 60325:2002 . 54
E.1 General . 54
E.2 Model function . 54
E.3 Calculation of the complete result of the measurement (measured value,
probability density distribution, associated standard uncertainty, and the
coverage interval) . 54
E.3.1 General . 54
E.3.2 Effects of distance . 55
E.3.3 Contamination non-uniformity . 55
E.3.4 Surface absorption . 56
E.3.5 Other influence quantities . 56
E.3.6 Uncertainty budget . 56
Bibliography . 59

Figure 1 – Triangular probability density distribution of possible values n for the
calibration factor N . 20
Figure 2 – Rectangular probability density distribution of possible values g for the
zero reading G . 21
Figure 3 – Gaussian probability density distribution of possible values g for the
reading G . 21
Figure 4 – Comparison of different probability density distributions of possible values:
rectangular (broken line), triangular (dotted line) and Gaussian (solid line) distribution . 24
Figure 5 – Distribution function Q of the measured value . 29

– 4 – IEC TR 62461:2015 © IEC 2015
Figure 6 – Probability density distribution (PDF) of the measured value . 30
Figure C.1 – Results of the analytical (red dashed lines) and the Monte Carlo method

(grey histogram and blue dotted and solid lines) for H * (10) . 50
Figure D.1 – Result of the analytical (red dashed lines) and the Monte Carlo method
(grey histogram and blue dotted lines) for K . 53
T
Table 1 – Symbols (and abbreviated terms) used in the main text (
...