EN ISO 20785-1:2017

SLOVENSKI STANDARD
01-december-2017
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Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 1: Conceptual basis
for measurements (ISO 20785-1:2012)
Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 1:
Fondement théorique des mesurages (ISO 20785-1:2012)
Ta slovenski standard je istoveten z: EN ISO 20785-1:2017
ICS:
17.240 Merjenje sevanja Radiation measurements
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20785-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2017
EUROPÄISCHE NORM
ICS 13.280; 49.020
English Version
Dosimetry for exposures to cosmic radiation in civilian
aircraft - Part 1: Conceptual basis for measurements (ISO
20785-1:2012)
Dosimétrie pour l'exposition au rayonnement
cosmique à bord d'un avion civil - Partie 1: Fondement
théorique des mesurages (ISO 20785-1:2012)
This European Standard was approved by CEN on 13 September 2017.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20785-1:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 20785-1:2012 has been prepared by Technical Committee ISO/TC 85 “Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 20785-1:2017 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2018, and conflicting national standards shall be
withdrawn at the latest by April 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 20785-1:2012 has been approved by CEN as EN ISO 20785-1:2017 without any
modification.
INTERNATIONAL ISO
STANDARD 20785-1
Second edition
2012-12-15
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
Reference number
ISO 20785-1:2012(E)
©
ISO 2012
ISO 20785-1:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
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Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 20785-1:2012(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Terms and definitions . 1
2.1 General . 1
2.2 Quantities and units . 2
2.3 Atmospheric radiation field . 8
3 General considerations .10
3.1 General description of the cosmic radiation field in the atmosphere .10
3.2 General calibration considerations for the dosimetry of cosmic radiation fields
in aircraft .11
3.3 Conversion coefficients .13
4 Dosimetric devices .13
4.1 Introduction .13
4.2 Active devices .14
4.3 Passive devices .17
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
[80]
minimum and maximum vertical cut-off rigidity .20
Bibliography .24
ISO 20785-1:2012(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 20785-1 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 20785-1:2006), which has been
technically revised.
ISO 20785 consists of the following parts, under the general title Dosimetry for exposures to cosmic
radiation in civilian aircraft:
— Part 1: Conceptual basis for measurements
— Part 2: Characterization of instrument response
Measurements at aviation altitudes is to form the subject of a future Part 3.
iv © ISO 2012 – All rights reserved

ISO 20785-1:2012(E)
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 fold 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
accepted that the calculated doses should be validated by measurement. The effective dose is not
directly measurable. The operational quantity of interest is ambient d
...