SIST EN ISO 20785-2:2020

SLOVENSKI STANDARD
oSIST prEN ISO 20785-2:2019
01-april-2019
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Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 2: Characterization
of instrument response (ISO/DIS 20785-2:2019)
Dosimetrie zu Expositionen durch kosmische Strahlung in Flugzeugen der zivilen
Luftfahrt - Teil 2: Charakterisierung des Antwortverhaltens von Messinstrumenten
(ISO/DIS 20785-2:2019)
Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 2:
Caractérisation de la réponse des instruments (ISO/DIS 20785-2:2019)
Ta slovenski standard je istoveten z: prEN ISO 20785-2
ICS:
17.240 Merjenje sevanja Radiation measurements
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
oSIST prEN ISO 20785-2:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 20785-2:2019

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oSIST prEN ISO 20785-2:2019
DRAFT INTERNATIONAL STANDARD
ISO/DIS 20785-2
ISO/TC 85/SC 2 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2019-02-15 2019-05-10
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 2:
Characterization of instrument response
Dosimétrie de l'exposition au rayonnement cosmique dans l'aviation civile —
Partie 2: Caractérisation de la réponse des instruments
ICS: 49.020; 13.280
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 20785-2:2019(E)
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 SUPPORTING DOCUMENTATION. ISO 2019

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COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
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Published in Switzerland
ii © ISO 2019 – All rights reserved

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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 2
3.2 Terms related to quantities and units . 7
3.3 Atmospheric radiation field .11
4 General considerations .13
4.1 The cosmic radiation field in the atmosphere .13
4.2 General considerations for the dosimetry of the cosmic radiation field in aircraft
and requirements for the characterization of instrument response .14
4.3 General considerations for measurements at aviation altitudes .16
5 Calibration fields and procedures .17
5.1 General considerations .17
5.2 Characterization of an instrument .19
5.2.1 Determination of the dosimetric characteristics of an instrument .19
5.2.2 Reference radiation fields .21
5.2.3 Scattered radiation . .21
5.2.4 Effect of other types of radiation .21
5.2.5 Requirements for characterization in non-reference conditions .22
5.2.6 Use of numerical simulations .22
5.3 Instrument-related software .22
5.3.1 Software development procedures .22
5.3.2 Software testing .23
5.3.3 Data analysis using spreadsheets .23
6 Uncertainties .23
7 Remarks on performance tests .23
Annex A (informative) Representative particle fluence energy distributions for the cosmic
radiation field at flight altitudes for solar minimum and maximum conditions and
for minimum and maximum vertical cut-off rigidity .24
Annex B (informative) Radiation fields recommended for use in calibrations .26
Annex C (informative) Comparison measurements .30
Annex D (informative) Charged-particle irradiation facilities .32
Bibliography .33
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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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO's adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 2, Radiological protection.
This second edition cancels and replaces the first edition (ISO 20785-2:2011), which has been technically
revised. The main changes compared to the previous edition are as follows:
A list of all the parts in the ISO 20785 series can be found on the ISO website.
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Introduction
Aircraft crews are exposed to elevated levels of cosmic radiation of galactic and solar origin and
secondary radiation produced in the atmosphere, the aircraft structure and its contents. Following
[1]
recommendations of the International Commission on Radiological Protection in Publication 60,
[2]
confirmed by Publication 103, the European Union (EU) introduced a revised Basic Safety Standards
[3]
Directive which included exposure to natural sources of ionizing radiation, including cosmic
radiation, as occupational exposure. The Directive requires account to be taken of the exposure of
aircraft crew liable to receive more than 1 mSv per year. It then identifies the following four protection
measures: (i) to assess the exposure of the crew concerned; (ii) to take into account the assessed
exposure when organizing working schedules with a view to reducing the doses of highly exposed
crew; (iii) to inform the workers concerned of the health risks their work involves; and (iv) to apply the
same special protection during pregnancy to female crew in respect of the “child to be born” as to other
female workers. The EU Council Directive has already been incorporated into laws and regulations of
EU member states and is being included in the aviation safety standards and procedures of the Joint
Aviation Authorities and the European Air Safety Agency. Other countries, such as Canada and Japan,
have issued advisories to their airline industries to manage aircraft crew exposure.
For regulatory and legislative purposes, the radiation protection quantities of interest are equivalent
dose (to the foetus) and effective dose. The cosmic radiation exposure of the body is essentially uniform,
and the maternal abdomen provides no effective shielding to the foetus. As a result, the magnitude of
equivalent dose to the foetus can be put equal to that of the effective dose received by the mother.
Doses on board aircraft are generally predictable, and events comparable to unplanned exposure in
other radiological workplaces cannot normally occur (with the rare exceptions of extremely intense
and energetic solar particle events). Personal dosemeters for routine use are not considered necessary.
The preferred approach for the assessment of doses of aircraft crew, where necessary, is to calculate
directly the effective dose per unit time, as a function of geographic location, altitude and solar cycle
phase, and to combine these values with flight and staff roster information to obtain estimates of
effective doses for individuals. This approach is supported by guidance from the European Commission
[4]
and the ICRP in Publication 75 .
The role of calculations in this procedure is unique in routine radiation protection, and it is widely
[5]
accepted that the calculated doses should be validated by measurement. Effective dose is not directly
measurable. The operational quantity of interest is the ambient dose equivalent, H*(10). In order to
validate the assessed doses obtained in terms of effective dose, calculations can be made of ambient
dose equivalent rates or route doses in terms of ambient dose equivalent, and values of this quantity
determined by measurements traceable to national standards. The validation of calculations of ambient
dose equivalent for a particular calculation method may be taken as a validation of the calculation of
effective dose by the same computer code, but this step in the process might need to be confirmed.
The alternative is to establish, a priori, that the operational quantity ambient dose equivalent is a good
estimator of effective dose and equivalent dose to the foetus for the radiation fields being considered,
in the same way that the use of the operational quantity personal dose equivalent is justified for the
estimation of effective dose for radiation workers.
The radiation field in aircraft at altitude is complex, with many types of ionizing radiation present, with
energies ranging up to many GeV. The determination of ambient dose equivalent for such a complex
radiation field is difficult. In many cases, the methods used for the determination of ambient dose
equivalent in aircraft are similar to those used at high-energy accelerators in research laboratories.
Therefore, it is possible to recommend dosimetric methods and methods for the calibration of dosimetric
devices, as well as the techniques for maintaining the traceability of dosimetric measurements to
national standards. Dosimetric measurements made to evaluate ambient dose equivalent need to
be performed using accurate and reliable methods that ensure the quality of readings provided to
workers and regulatory authorities. The purpose of this document is to specify procedures for the
determination of the responses of instruments in different reference radiation fields, as a basis for
proper characterization of instruments used for the determination of ambient dose equivalent in
aircraft at altitude.
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Requirements for the determination and recording of the cosmic radiation exposure of aircraft crew have
been introduced into the national legislation of EU member states and other countries. Harmonization
of methods used for determining ambient dose equivalent and for calibrating instruments is desirable
to ensure the compatibility of measurements performed with such instruments.
This document is intended for the use of primary and secondary calibration laboratories for ionizing
radiation, by radiation protection personnel employed by governmental agencies, and by industrial
corporations concerned with the determination of ambient dose equivalent for aircraft crew.
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oSIST prEN ISO 20785-2:2019
DRAFT INTERNATIONAL STANDARD ISO/DIS 20785-2:2019(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 2:
Characterization of instrument response
1 Scope
This document specifies methods and procedures for characterizing the responses of devices used
for the determination of ambient dose equivalent for the evaluation of exposure to cosmic radiation in
civilian aircraft. The methods and procedures are intended to be understood as minimum requirements.
2 Normative references
The following referenced documents are indispensable for the application 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/IEC Guide 98-1, Uncertainty of measurement — Part 1: Introduction to the expression of uncertainty
in measurement
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 4037-1, X and gamma reference radiation for calibrating dosemeters and doserate meters and for
determining their response as a function of photon energy — Part 1: Radiation characteristics and
production methods
ISO 6980-1, Nuclear energy — Reference beta-particle radiation — Part 1: Methods of production
ISO 8529-1:2001, Reference neutron radiations — Part 1: Characteristics and methods of production
ISO 12789-1, Reference radiation fields — Simulated workplace neutron fields — Part 1: Characteristics
and methods of production
ISO 12789-2, Reference radiation fields — Simulated workplace neutron fields — Part 2: Calibration
fundamentals related to the basic quantities
ISO 20785-1, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 1: Conceptual basis for
measurements
ISO 29661, Reference radiation fields for radiation protection — Definitions and fundamental concepts
3 Terms and definitions
For the purposes of this document, the terms and definitions following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at http: //www .iso .org/obp
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3.1 General terms
3.1.1
angle of radiation incidence
α
angle between the direction of radiation incidence and the reference direction of the instrument
3.1.2
calibration
operation that, under specified conditions, establishes a relation between the conventional quantity,
H , and the indication, G
0
Note 1 to entry: A calibration can be expressed by a statement, calibration function, calibration diagram,
calibration curve or calibration table. In some cases, it can consist of an additive or multiplicative correction of
the indication with associated measurement uncertainty.
Note 2 to entry: It is important not to confuse calibration with adjustment of a measuring system, often
mistakenly called “self-calibration”, or with verification of calibration.
3.1.3
calibration coefficient
N
coeff
quotient of the conventional quantity value to be measured and the corrected indication of the
instrument
Note 1 to entry: The calibration coefficient is equivalent to the calibration factor multiplied by the instrument
constant.
Note 2 to entry: The reciprocal of the calibration coefficient, N , is the response.
coeff
Note 3 to entry: For the calibration of some instruments, e.g. ionization chambers, the instrument constant and
the calibration factor are not identified separately but are applied together as the calibration coefficient.
Note 4 to entry: It is necessary, in order to avoid confusion, to state the quantity to be measured, for example:
the calibration coefficient with respect to fluence, N , the calibration coefficient with respect to kerma, N , the
Φ K
calibration coefficient with respect to absorbed dose, N .
D
3.1.4
calibration conditions
conditions, within the range of standard test conditions, actually prevailing during the calibration
3.1.5
calibration factor
N
fact
factor by which the product of the corrected indication and the associated instrument constant of the
instrument is multiplied to obtain the conventional quantity value to be measured under reference
conditions
Note 1 to entry: The calibration factor is dimensionless.
Note 2 to entry: The corrected indication is the indication of the instrument corrected for the effect of influence
quantities, where applicable.
Note 3 to entry: The value of the calibration factor can vary with the magnitude of the quantity to be measured.
In such cases, a detector assembly is said to have a non-constant response.
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3.1.6
measured quantity value
measured value of a quantity
measured value
M
quantity value representing a measurement result
Note 1 to entry: For a measurement involving replicate indications, each indication can be used to provide a
corresponding measured quantity value. This set of measured quantity values can be used to calculate a
resulting measured quantity value, such as an average or a median value, usually with a decreased associated
measurement uncertainty.
Note 2 to entry: When the range of the true quantity values believed to represent the measurand is small
compared with the measurement uncertainty, a measured quantity value can be considered to be an estimate
of an essentially unique true quantity value and is often an average or a median of individual measured quantity
values obtained through replicate measurements.
Note 3 to entry: In the case where the range of the true quantity values believed to represent the measurand is
not small compared with the measurement uncertainty, a measured value is often an estimate of an average or a
median of the set of true quantity values.
Note 4 to entry: In ISO/IEC Guide 98-3:2008, the terms “result of measurement” and “estimate of the value of the
measurand” or just “estimate of the measurand” are used for “measured quantity value”.
3.1.7
conventional quantity value
conventional value of a quantity
conventional value
H
0
quantity value attributed by agreement to a quantity for a given purpose
Note 1 to entry: The term “conventional true quantity value” is sometimes used for this concept, but its use is
discouraged.
Note 2 to entry: Sometimes, a conventional quantity value is an estimate of a true quantity value.
Note 3 to entry: A conventional quantity value is generally accepted as being associated with a suitably small
measurement uncertainty, which might be zero.
Note 4 to entry: In ISO 20785 series, the conventional quantity value is the best estimate of the value of the
quantity to be measured, determined by a primary or a secondary standard which is traceable to a primary
standard.
3.1.8
correction factor
k
factor applied to the indication to correct for deviation of measurement conditions from reference
conditions
Note 1 to entry: If the correction of the effect of the deviation of an influence quantity requires a factor, the
influence quantity is of type F.
3.1.9
correction summand
G
S
summand applied to the indication to correct for the zero indication or the deviation of the measurement
conditions from the reference conditions
Note 1 to entry: If the correction of the effect of the deviation of an influence quantity requires a summand, the
influence quantity is of type S.
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3.1.10
indication
G
quantity value provided by a measuring instrument or a measuring system
Note 1 to entry: An indication can be presented in visual or acoustic form or can be transferred to another device.
An indication is often given by the position of a pointer on the display for analogue outputs, a displayed or printed
number for digital outputs, a code pattern for code outputs, or an assigned quantity value for material measures.
Note 2 to entry: An indication and a corresponding value of the quantity being measured are not necessarily
values of quantities of the same kind.
3.1.11
influence quantity
quantity that, in a direct measurement, does not affect the quantity that is actually measured, but
affects the relation between the indication and the measurement result
Note 1 to entry: An indirect measurement involves a combination of direct measurements, each of which may be
affected by influence quantities.
Note 2 to entry: In ISO/IEC Guide 98-3:2008, the concept “influence quantity” is defined as in ISO/
IEC Guide 99:2007, covering not only the quantities affecting the measuring system, as in the definition above,
but also those quantities that affect the quantities actually measured. Also, in ISO/IEC Guide 98-3, this concept is
not restricted to direct measurements.
Note 3 to entry: The correction of the effect of the influence quantity can require a correction factor (for an
influence quantity of type F) and/or a correction summand (for an influence quantity of type S) to be applied to
the indication of the detector assembly, e.g. in the case of microphonic or electromagnetic disturbance.
EXAMPLE The indication given by an unsealed ionization chamber is influenced by the temperature
and pressure of the surrounding atmosphere. Although needed for determining the value of the dose, the
measurement of these two quantities is not the primary objective.
3.1.12
instrument constant
c
i
quantity value by which the indication of the instrument, G (or, if corrections or normalization were
carried out, G ), is multiplied to give the value of the measurand or of a quantity to be used to
corr
calculate the value of the measurand
Note 1 to entry: If the instrument's indication is already expressed in the same units as the measurand, as is
the case with area dosemeters, for instance, the instrument constant, c , is dimensionless. In such cases, the
i
calibration factor and the calibration coefficient can be the same. Otherwise, if the indication of the instrument
has to be converted to the same units as the measurand, the instrument constant has a dimension.
3.1.13
measurand
quantity intended to be measured
3.1.14
point of test
point in the radiation field at which the conventional quantity value is known
Note 1 to entry: The reference point of a detector assembly is placed at the point of test for calibration purposes
or for the determination of the response.
3.1.15
primary measurement standard
primary standard
measurement standard established using a primary reference measurement procedure or created as
an artifact, chosen by convention
Note 1 to entry: A primary standard has the highest metrological quality in a given field.
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3.1.16
quantity value
number and reference together expressing the magnitude of a quantity
Note 1 to entry: A quantity value is either a product of a number and a measurement unit (the unit “one” is
generally not indicated for quantities of dimension “one”) or a number and a reference to a measurement
procedure.
3.1.17
reference conditions
conditions of use prescribed for testing the performance of a detector assembly or for comparing the
results of measurements
Note 1 to entry: The reference conditions represent the values of the set of influence quantities for which the
calibration result is valid without any correction.
Note 2 to entry: The value of the measurand can be chosen freely in agreement with the properties of the
detector assembly to be calibrated. The quantity to be measured is not an influence quantity but can influence
the calibration result and the response (see also Note 1).
3.1.18
reference direction
direction, in the coordinate system
...