SIST EN ISO 20785-1:2020

SLOVENSKI STANDARD
oSIST prEN ISO 20785-1:2019
01-april-2019
'R]LPHWULMD]DPHUMHQMHL]SRVWDYOMHQRVWLNR]PLþQHPXVHYDQMXYFLYLOQHPOHWDOVNHP
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Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 1: Conceptual basis
for measurements (ISO/DIS 20785-1:2019)
Dosimetrie zu Expositionen durch kosmische Strahlung in Flugzeugen der zivilen
Luftfahrt - Teil 1: Konzeptionelle Grundlage für Messungen (ISO/DIS 20785-1:2019)
Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 1:
Fondement théorique des mesurages (ISO/DIS 20785-1:2019)
Ta slovenski standard je istoveten z: prEN ISO 20785-1
ICS:
13.280 Varstvo pred sevanjem Radiation protection
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
oSIST prEN ISO 20785-1:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 20785-1:2019

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oSIST prEN ISO 20785-1:2019
DRAFT INTERNATIONAL STANDARD
ISO/DIS 20785-1
ISO/TC 85/SC 2 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2019-01-30 2019-04-24
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 1:
Conceptual basis for measurements
Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil —
Partie 1: Fondement théorique des mesurages
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 20785-1:2019(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
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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 Quantities and units . 3
3.3 Atmospheric radiation field . 8
4 General considerations .10
4.1 The cosmic radiation field in the atmosphere .10
4.2 General calibration considerations for the dosimetry of cosmic radiation fields in
aircraft .11
4.2.1 Approach .11
4.2.2 Considerations concerning the measurement .12
4.2.3 Considerations concerning the radiation field .12
4.2.4 Considerations concerning calibration .13
4.2.5 Simulated aircraft fields .13
4.3 Conversion coefficients .14
5 Dosimetric devices .14
5.1 Introduction .14
5.2 Active devices .14
5.2.1 Devices to determine all field components .14
5.2.2 Devices for low LET/non-neutron .16
5.2.3 Devices for high-LET/neutron component .16
5.3 Passive devices .17
5.3.1 General considerations .17
5.3.2 Etched track detectors .18
5.3.3 Fission foil detectors .18
5.3.4 Superheated emulsion neutron detectors (bubble) detectors .18
5.3.5 Thermoluminescent detectors.19
5.3.6 Photoluminescent detectors .19
Annex A (informative) Representative particle fluence rate 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 .20
Bibliography .26
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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 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, Subcommittee SC 2, Radiation protection.
This second edition cancels and replaces the first edition (ISO 20785-1:2012), which has been technically
revised. The main changes are:
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 crews
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 crews; (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 crews 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 the
equivalent dose (to the foetus) and the 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 crews, 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
[4]
European Commission and the ICRP in Publication 75.
The role of calculations in this procedure is unique in routine radiation protection and it is widely
accepted that the calculated doses should be validated by measurement. The effective dose is not
directly measurable. The operational quantity of interest is 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
the effective dose by the same computer code, but this step in the process may 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 should be
performed using accurate and reliable methods that ensure the quality of readings provided to workers
and regulatory authorities. This document gives a conceptual basis for the characterization of the
response of instruments for the determination of ambient dose equivalent in aircraft.
Requirements for the determination and recording of the cosmic radiation exposure of aircraft
crews have been introduced into the national legislation of EU Member States and other countries.
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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 crews.
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oSIST prEN ISO 20785-1:2019
DRAFT INTERNATIONAL STANDARD ISO/DIS 20785-1:2019(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 1:
Conceptual basis for measurements
1 Scope
This document describes the conceptual basis for the determination of ambient dose equivalent for the
evaluation of exposure to cosmic radiation in civilian aircraft and for the calibration of instruments
used for that purpose.
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/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 20785-2, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 2: Characterization of
instrument response
ISO 20785-3, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 3: Measurements at
aviation altitudes
ISO 20785-4, Dosimetry for exposures to cosmic radiation in civilian aircraft —Part 4: Validation of codes
ISO 29661, Reference radiation fields for radiation protection — Definitions and fundamental concepts
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1 General terms
3.1.1
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 may be expressed by a statement, calibration function, calibration diagram,
calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicative correction of
the indication with associated measurement uncertainty.
Note 2 to entry: : Calibration should not be confused with adjustment of a measuring system, often mistakenly
called "self-calibration", or with verification of calibration.
Note 3 to entry: Often, the first step alone in the above definition is perceived as being calibration.
3.1.2
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
3.1.3
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.
3.1.4
reference conditions
conditions of use prescribed for testing the performance of a detector assembly or for comparison of
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.
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3.1.5
response
R
quotient of the indication, G, or the corrected indication, G , and the conventional quantity value to be
corr
measured
Note 1 to entry: To avoid confusion, it is necessary to specify which of the quotients, given in the definition of
the response (to G or to G ) is applied. Furthermore, it is necessary, in order to avoid confusion, to state the
corr
quantity to be measured, for example: the response with respect to fluence, R , the response with respect to
Φ
kerma, R , the response with respect to absorbed dose, R .
K D
Note 2 to entry: : The reciprocal of the response under the specified conditions is equal to the calibration
coefficient N
coeff.
Note 3 to entry: The value of the response may vary with the magnitude of the quantity to be measured. In such
cases the detector assembly's response is said to be non-constant.
Note 4 to entry: The response usually varies with the energy and direction distribution of the incident
radiation. It is, therefore, useful to consider the response as a function, R(E,Ω), of the radiation energy, E, and
of the direction, Ω of the incident monodirectional radiation. R(E) describes the "energy dependence" and R(Ω)
the "angle dependence" of response; for the latter, Ω may be expressed by the angle, α, between the reference
direction of the detector assembly and the direction of an external monodirectional field.
3.2 Quantities and units
3.2.1
particle fluence
fluence
Φ
number, dN, at a given point in space, of particles incident on a small spherical domain, divided by the
cross-sectional area, da, of that domain:
dN
Φ =
da
−2 −2
Note 1 to entry: The unit of the fluence is m ; a frequently used unit is cm .
Note 2 to entry: The energy distribution of the particle fluence, Φ , is the quotient, dΦ, by dE, where dΦ is the
E
fluence of particles of energy between E and E+dE. There is an analogous definition for the direction distribution,
Φ , of the particle fluence. The complete representation of the double differential particle fluence can be written
Ω
(with arguments) Φ (E,Ω), where the subscripts characterize the variables (quantities) for differentiation and
E,Ω
where the symbols in the brackets describe the values of the variables. The values in the brackets are needed for
special function values, e.g. the energy distribution of the particle fluence at energy E = E is written as Φ (E ). If
0 E 0
no special values are indicated, the brackets may be omitted.
3.2.2
particle fluence rate
fluence rate

Φ
rate of the particle fluence expressed as
2
dΦ d N

Φ ==
dt ddat⋅
where dΦ is the increment of the particle fluence during an infinitesimal time interval with duration dt.
−2 −1 −2 −1
Note 1 to entry: The unit of the fluence rate is m s , a frequently used unit is cm s .
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3.2.3
energy imparted
ε
for ionizing radiation in the matter within a given three-dimensional domain,
εε=
∑
i
where
ε is the energy deposited in a single interaction, i, and given by ε = ε – ε + Q, where
i i in out
ε is the energy of the incident ionizing particle, excluding rest energy;
in
ε is the sum of the energies of all ionizing particles leaving the interaction, excluding rest energy, and
out
Q is the change in the rest energies of the nucleus and of all particles involved in the interaction.
Note 1 to entry: Energy imparted is a stochastic quantity.
Note 2 to entry: The unit of the energy imparted is J.
3.2.4
mean energy imparted
ε
mean energy imparted to the matter in a given domain, expressed as
ε =−RR + Q
∑
in out
where
R is the radiant energy of all those charged and uncharged ionizing particles that enter the domain;
in
R is the radiant energy of all those charged and uncharged ionizing particles that leave the domain, and
out
∑Q is the sum of all changes of the rest energy of nuclei and elementary particles that occur in
that domain.
Note 1 to entry: This quantity has the meaning of expected value of the energy imparted.
Note 2 to entry: The unit of the mean energy imparted is J.
3.2.5
specific energy imparted
specific energy
z
for any ionizing radiation,
ε
z =
m
where
ε is the energy imparted to the irradiated matter;
m is the mass of the irradiated matter.
Note 1 to entry: Specific energy imparted is a stochastic quantity.
Note 2 to entry: In the limit of a small domain, the mean specific energy imparted is equal to the absorbed dose.
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Note 3 to entry: The specific energy imparted can be the result of one or more (energy-deposition) events.
–1
Note 4 to entry: The unit of specific energy is J⋅kg , with the special name gray (Gy).
3.2.6
absorbed dose
D
for any ionizing radiation,
dε
D =
dm
where
   is the mean energy imparted by ionizing radiation to an element of irradiated matter of mass dm.
dε
Note 1 to entry: In the limit of a small domain, the mean specific energy is equal to the absorbed dose.
−1
Note 2 to entry: The unit of absorbed dose is J kg , with the special name gray (Gy).
3.2.7
kerma
K
for indirectly ionizing (uncharged) particles, the mean sum of the initial kinetic energies dE of all the
tr
charged ionizing particles liberated by uncharged ionizing particles in an element of matter, divided by
the mass dm of that element:
dE
tr
K=
dm
Note 1 to entry: Quantity dE includes the kinetic energy of the charged particles emitted in the decay of excited
tr
atoms or molecules or nuclei.
−1
Note 2 to entry: The unit of kerma is J kg , with the special name gray (Gy).
3.2.8
restricted linear energy transfer
linear energy transfer
LET
L
Δ
for an ionizing charged particle, the mean energy, dE , imparted locally to matter along a small path
Δ
through the matter minus the sum of the kinetic energies of all the electrons released with kinetic
energies in excess of Δ, divided by the length, dl:
dE
Δ
L =
Δ
dl
Note 1 to entry: This quantity is not completely defined unless Δ is specified, i.e. the maximum kinetic energy of
secondary electrons whose energy is considered to be “locally deposited”. Δ may be expressed in eV.
Note 2 to entry: Linear energy transfer is often abbreviated LET, but to which should be appended the subscript
Δ or its numerical value.
−1 −1
Note 3 to entry: The unit of the linear energy transfer is J m , a frequently used unit is keV μm .
Note 4 to entry: If no energy cut-off is imposed, the unrestricted linear en
...