SIST EN ISO 20785-3:2017
(Main)Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at aviation altitudes (ISO 20785-3:2015)
Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at aviation altitudes (ISO 20785-3:2015)
The following documents, in whole or in part, are normatively referenced in ISO 20785-3:2015 and are indispensable for its application. 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 measurement (GUM:1995)
ISO 20785‑1, Dosimetry for exposures to cosmic radiation in civilian aircraft ? Part 1: Conceptual basis for measurements
ISO 20785‑2, Dosimetry for exposures to cosmic radiation in civilian aircraft ? Part 2: Characterization of instrument response
Dosimetrie für die Belastung durch kosmische Strahlung in Zivilluftfahrzeugen - Teil 3: Messungen auf Flughöhen (ISO 20785-3:2015)
Dieser Teil von ISO 20785 dient als Grundlage für die Messung der Umgebungs-Äquivalentdosis in Flughöhen zur Bestimmung der Expositionen durch kosmische Strahlung in zivilen Luftfahrzeugen.
Dosimétrie pour les expositions au rayonnement cosmique à bord d'un avion civil - Partie 3: Mesurages à bord d'avions (ISO 20785-3:2015)
L'ISO 20785-3:2015 donne les principes de base permettant de mesurer l'équivalent de dose ambiant aux altitudes de vol pour l'évaluation de l'exposition au rayonnement cosmique à bord d'un avion.
Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem prometu - 3. del: Meritve na višini letenja (ISO 20785-3:2015)
Standard ISO 20785-3:2015 se v celoti ali v delih normativno sklicuje na naslednje dokumente, ki so nepogrešljivi pri njegovi uporabi. Pri datiranih sklicevanjih se uporablja samo navedena izdaja. Pri nedatiranih sklicevanjih se uporablja zadnja izdaja referenčnega dokumenta (vključno z morebitnimi dopolnili).
Vodilo ISO/IEC 98‑1, Merilna negotovost – 1. del: Uvod v izražanje merilne negotovosti Vodilo ISO/IEC 98‑3, Merilna negotovost – 3. del: Vodilo za izražanje merilne negotovosti (GUM:1995) ISO 20785‑1, Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem prometu – 1. del: Konceptualna osnova za meritve ISO 20785‑2, Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem prometu – 2. del: Karakterizacija odziva instrumenta
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 20785-3:2017
01-december-2017
'R]LPHWULMD]DPHUMHQMHL]SRVWDYOMHQRVWLNR]PLþQHPXVHYDQMXYFLYLOQHPOHWDOVNHP
SURPHWXGHO 0HULWYHQDYLãLQLOHWHQMD ,62
Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at
aviation altitudes (ISO 20785-3:2015)
Dosimétrie pour les expositions au rayonnement cosmique à bord d'un avion civil - Partie
3: Mesurages à bord d'avions (ISO 20785-3:2015)
Ta slovenski standard je istoveten z: EN ISO 20785-3:2017
ICS:
17.240 Merjenje sevanja Radiation measurements
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
SIST EN ISO 20785-3:2017 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 20785-3:2017
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SIST EN ISO 20785-3:2017
EN ISO 20785-3
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2017
EUROPÄISCHE NORM
ICS 49.020; 13.280
English Version
Dosimetry for exposures to cosmic radiation in civilian
aircraft - Part 3: Measurements at aviation altitudes (ISO
20785-3:2015)
Dosimétrie pour les expositions au rayonnement
cosmique à bord d'un avion civil - Partie 3: Mesurages
à bord d'avions (ISO 20785-3:2015)
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 20785-3:2017 E
worldwide for CEN national Members.
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SIST EN ISO 20785-3:2017
EN ISO 20785-3:2017 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 20785-3:2017
EN ISO 20785-3:2017 (E)
European foreword
The text of ISO 20785-3:2015 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 20785-3:2017 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 20785-3:2015 has been approved by CEN as EN ISO 20785-3:2017 without any
modification.
3
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SIST EN ISO 20785-3:2017
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SIST EN ISO 20785-3:2017
INTERNATIONAL ISO
STANDARD 20785-3
First edition
2015-11-15
Dosimetry for exposures to cosmic
radiation in civilian aircraft —
Part 3:
Measurements at aviation altitudes
Dosimétrie pour les expositions au rayonnement cosmique à bord
d’un avion civil —
Partie 3: Mesurages à bord d’avions
Reference number
ISO 20785-3:2015(E)
©
ISO 2015
---------------------- Page: 7 ----------------------
SIST EN ISO 20785-3:2017
ISO 20785-3:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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 below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 20785-3:2017
ISO 20785-3:2015(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Quantities and units . 1
3.2 Atmospheric radiation field . 4
4 General considerations . 6
4.1 General description of the cosmic radiation field in the atmosphere . 6
4.2 General considerations concerning the measurements . 8
4.2.1 General. 8
4.2.2 Selection of appropriate instruments . 8
4.2.3 Characterization of the responses of the instruments . 8
4.2.4 Measurements inside an aircraft . 8
4.2.5 Application of appropriate correction factors . 9
4.3 Safety and regulatory requirements for in-flight measurements . 9
5 Measurement at aviation altitude . 9
5.1 Parameters determining the dose rate. 9
5.1.1 Barometric altitude . 9
5.1.2 Geographic coordinates . 9
5.1.3 Solar activity .10
5.2 Possible influence quantities .10
5.2.1 General.10
5.2.2 Cabin air pressure .10
5.2.3 Cabin air temperature .10
5.2.4 Cabin air humidity .10
5.3 Specific considerations for active instruments .10
5.3.1 Power supply . .10
5.3.2 Vibrations and shocks .11
5.3.3 Electromagnetic interferences from the aircraft .11
5.4 Specific considerations for passive measurements .11
5.4.1 Security X-ray scanning .11
5.4.2 Background subtraction .11
6 Uncertainties .11
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 .12
Bibliography .16
© ISO 2015 – All rights reserved iii
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SIST EN ISO 20785-3:2017
ISO 20785-3:2015(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.
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
The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
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
— Part 3: Measurements at aviation altitudes
iv © ISO 2015 – All rights reserved
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SIST EN ISO 20785-3:2017
ISO 20785-3:2015(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 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 to be incorporated into laws and regulations of
EU Member States and has to be 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 effective dose rate, 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, the ICRP in
[4] [5]
Publication 75 and the ICRU in Report 84.
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. Effective dose is not directly
measurable. The operational quantity of interest is ambient dose equivalent, H*(10). Indeed, as
indicated in particular in ICRU Report 84, the ambient dose equivalent is considered to be a conservative
estimator of effective dose if isotropic or superior isotropic irradiation can be assumed. 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 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. Ambient dose equivalent rate as a function of
geographic location, altitude and solar cycle phase is then calculated and folded with flight and staff
roster information.
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 have to be
performed using accurate and reliable methods that ensure the quality of readings provided to workers
and regulatory authorities. This part of ISO 20785 gives procedures for the characterization of the
response of instruments for the determination of ambient dose equivalent in aircraft.
© ISO 2015 – All rights reserved v
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SIST EN ISO 20785-3:2017
ISO 20785-3:2015(E)
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 part of ISO 20785 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.
vi © ISO 2015 – All rights reserved
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SIST EN ISO 20785-3:2017
INTERNATIONAL STANDARD ISO 20785-3:2015(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 3:
Measurements at aviation altitudes
1 Scope
This part of ISO 20785 gives the basis for the measurement of ambient dose equivalent at flight altitudes
for the evaluation of the exposures to cosmic radiation in civilian aircraft.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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
measurement (GUM:1995)
ISO 20785-1, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 1: Conceptual basis
for measurements
ISO 20785-2, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 2: Characterization of
instrument response
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Quantities and units
3.1.1
particle fluence
fluence
Φ
at a given point of space, number dN 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 .
© ISO 2015 – All rights reserved 1
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SIST EN ISO 20785-3:2017
ISO 20785-3:2015(E)
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 the energy E = E is written as
0
Φ (E ). If no special values are indicated, the brackets may be omitted.
E 0
3.1.2
particle fluence rate
fluence rate
Φ
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 .
3.1.3
unrestricted linear energy transfer
linear energy transfer
LET
L
∞
for an ionizing charged particle, mean energy dE imparted locally to matter along a small path through
∞
the matter, minus the sum of the kinetic energies of all the electrons released, divided by the length dl
dE
∞
L =
∞
dl
−1 −1
Note 1 to entry: The unit of the linear energy transfer is J m , a frequently used unit is keV μm .
3.1.4
dose equivalent
H
at the point of interest in tissue
HD= Q
where D is the absorbed dose and Q is the mean quality factor at that point
Note 1 to entry: Q is determined by the unrestricted linear energy transfer, L (often denoted as L or LET), of
∞
charged particles passing through a small volume element (domains) at this point (the value of L is given for
∞
charged particles in water, not in tissue; the difference, however, is small). The dose equivalent at a point in tissue
is then given by:
∞
HQ= ()LD dL
L
∫
L−0
where D = dD/dL is the distribution in terms of L of the absorbed dose at the point of interest.
L
Note 2 to entry: The relationship of Q and L is given in Reference [2].
−1
Note 3 to entry: The unit of dose equivalent is J kg , called sievert (Sv).
2 © ISO 2015 – All rights reserved
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SIST EN ISO 20785-3:2017
ISO 20785-3:2015(E)
3.1.5
ambient dose equivalent
H*(10)
dose equivalent at a point in a radiation field, that would be produced by the corresponding expanded and
aligned field, in the ICRU sphere at 10 mm depth on the radius opposing the direction of the aligned field
−1
Note 1 to entry: The unit of ambient dose equivalent is J kg , called sievert (Sv).
3.1.6
particle fluence-to-ambient dose equivalent conversion coefficient
h(10)*
Φ
quotient of the particle ambient dose equivalent, H*(10), and the particle fluence, Φ
H *(10)
h 10 * =
()
Φ
Φ
2 −1
Note 1 to entry: The unit of the particle fluence-to-ambient dose equivalent conversion coefficient is J m kg
2 2
with the special name Sv m , a frequently used unit is pSv cm .
3.1.7
correction factor
K
factor applied to the indication to correct for deviation of the measurement conditions from
reference conditions
3.1.8
atmosphere depth
X
v
mass of a unit-area column of air above a point in the atmosphere
-2 -2
Note 1 to entry: The unit of atmosphere depth is kg m ; a frequently used unit is g cm .
3.1.9
standard barometric altitude
pressure altitude
altitude determined by a barometric altimeter calibrated with reference to the International Standard
Atmosphere (ISA) (ISO, 1975) when the altimeter’s datum is set to 1 013,25 hPa
Note 1 to entry: The flight level is sometimes given as FL 350, where the number represents multiples of 100 feet
of pressure altitude, based on the ISA and a datum setting of 1 013,25 hPa. However, in some countries flight
levels are expressed in meters, in which case appropriate conversions should be made before applying the data
given in this part of ISO 20785.
3.1.10
magnetic rigidity
P
momentum per charge (of a particle in a magnetic field), given by:
p
P=
Ze
where p is the particle momentum, Z the number of charges on the particle and e the charge on the proton
–1
Note 1 to entry: The base unit of magnetic rigidity is the tesla metre (T m) (= V m s). A frequently used unit is V
(or GV) in a system of units where the values of the speed of light, c, and the charge on the proton, e, are both 1,
and the magnetic rigidity is given by pc/Ze.
Note 2 to entry: Magnetic rigidity characterizes charged-particle trajectories in magnetic fields. All particles having
the same magnetic rigidity have identical trajectories in a magnetic field, independent of particle mass or charge.
© ISO 2015 – All rights reserved 3
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SIST EN ISO 20785-3:2017
ISO 20785-3:2015(E)
3.1.11
geomagnetic cut-off rigidity
cut-off rigidity
r
c
minimum magnetic rigidity an incident particle can have and still penetrate the geomagnetic field to
reach a given location above the Earth
Note 1 to entry: Geomagnetic cut-off rigidity depends on angle of incidence. Often, vertical incidence to the
Earth’s surface is assumed, in which case, the vertical geomagnetic cut-off rigidity is the minimum magnetic
rigidity a vertically incident particle can have and still reach a given location above the Earth.
3.1.12
vertical geomagnetic cut-off rigidity
vertical cut-off
cut-off
minimum magnetic rigidity a vertically incident particle can have and still reach a given location
above the Earth
3.1.13
deceleration potential
ϕ
cosmic ray modulation parameter deduced from space observations of the abundance variation of the
different species in function of the solar cycle epoch
Note 1 to entry: The deceleration potential could be deduced either from the sunspot index or from Climax
neutron monitor output, using simple linear formula depending upon the phase of the solar cycle.
3.2 Atmospheric radiation field
3.2.1
cosmic radiation
cosmic rays
cosmic particles
ionizing radiation consisting of high-energy particles, primarily completely ionized atoms, of extra-
terrestrial origin and the particles they generate by interaction with the atmosphere and other matter
3.2.2
primary cosmic radiation
primary cosmic rays
cosmic radiation incident from space at the Earth’s orbit
3.2.3
secondary cosmic radiation
secondary cosmic rays
cosmogenic particles
particles which are created directly or in a cascade of reactions by primary cosmic rays interacting
with the atmosphere or other matter
Note 1 to entry: Important particles with respec
...
SLOVENSKI STANDARD
oSIST prEN ISO 20785-3:2017
01-junij-2017
'R]LPHWULMDL]SRVWDYOMHQRVWLNR]PLþQHPXVHYDQMXYFLYLOQHPOHWDOVNHPSURPHWX
GHO 0HULWYHOHWDOQDYLãLQL ,62
Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 3: Measurements at
aviation altitudes (ISO 20785-3:2015)
Dosimétrie pour les expositions au rayonnement cosmique à bord d'un avion civil - Partie
3: Mesurages à bord d'avions (ISO 20785-3:2015)
Ta slovenski standard je istoveten z: prEN ISO 20785-3
ICS:
17.240 Merjenje sevanja Radiation measurements
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
oSIST prEN ISO 20785-3:2017 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN ISO 20785-3:2017
---------------------- Page: 2 ----------------------
oSIST prEN ISO 20785-3:2017
INTERNATIONAL ISO
STANDARD 20785-3
First edition
2015-11-15
Dosimetry for exposures to cosmic
radiation in civilian aircraft —
Part 3:
Measurements at aviation altitudes
Dosimétrie pour les expositions au rayonnement cosmique à bord
d’un avion civil —
Partie 3: Mesurages à bord d’avions
Reference number
ISO 20785-3:2015(E)
©
ISO 2015
---------------------- Page: 3 ----------------------
oSIST prEN ISO 20785-3:2017
ISO 20785-3:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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 below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 20785-3:2017
ISO 20785-3:2015(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Quantities and units . 1
3.2 Atmospheric radiation field . 4
4 General considerations . 6
4.1 General description of the cosmic radiation field in the atmosphere . 6
4.2 General considerations concerning the measurements . 8
4.2.1 General. 8
4.2.2 Selection of appropriate instruments . 8
4.2.3 Characterization of the responses of the instruments . 8
4.2.4 Measurements inside an aircraft . 8
4.2.5 Application of appropriate correction factors . 9
4.3 Safety and regulatory requirements for in-flight measurements . 9
5 Measurement at aviation altitude . 9
5.1 Parameters determining the dose rate. 9
5.1.1 Barometric altitude . 9
5.1.2 Geographic coordinates . 9
5.1.3 Solar activity .10
5.2 Possible influence quantities .10
5.2.1 General.10
5.2.2 Cabin air pressure .10
5.2.3 Cabin air temperature .10
5.2.4 Cabin air humidity .10
5.3 Specific considerations for active instruments .10
5.3.1 Power supply . .10
5.3.2 Vibrations and shocks .11
5.3.3 Electromagnetic interferences from the aircraft .11
5.4 Specific considerations for passive measurements .11
5.4.1 Security X-ray scanning .11
5.4.2 Background subtraction .11
6 Uncertainties .11
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 .12
Bibliography .16
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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
The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
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
— Part 3: Measurements at aviation altitudes
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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 to be incorporated into laws and regulations of
EU Member States and has to be 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 effective dose rate, 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, the ICRP in
[4] [5]
Publication 75 and the ICRU in Report 84.
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. Effective dose is not directly
measurable. The operational quantity of interest is ambient dose equivalent, H*(10). Indeed, as
indicated in particular in ICRU Report 84, the ambient dose equivalent is considered to be a conservative
estimator of effective dose if isotropic or superior isotropic irradiation can be assumed. 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 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. Ambient dose equivalent rate as a function of
geographic location, altitude and solar cycle phase is then calculated and folded with flight and staff
roster information.
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 have to be
performed using accurate and reliable methods that ensure the quality of readings provided to workers
and regulatory authorities. This part of ISO 20785 gives procedures for the characterization of the
response of instruments for the determination of ambient dose equivalent in aircraft.
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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 part of ISO 20785 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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INTERNATIONAL STANDARD ISO 20785-3:2015(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 3:
Measurements at aviation altitudes
1 Scope
This part of ISO 20785 gives the basis for the measurement of ambient dose equivalent at flight altitudes
for the evaluation of the exposures to cosmic radiation in civilian aircraft.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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
measurement (GUM:1995)
ISO 20785-1, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 1: Conceptual basis
for measurements
ISO 20785-2, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 2: Characterization of
instrument response
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Quantities and units
3.1.1
particle fluence
fluence
Φ
at a given point of space, number dN 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 .
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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 the energy E = E is written as
0
Φ (E ). If no special values are indicated, the brackets may be omitted.
E 0
3.1.2
particle fluence rate
fluence rate
Φ
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 .
3.1.3
unrestricted linear energy transfer
linear energy transfer
LET
L
∞
for an ionizing charged particle, mean energy dE imparted locally to matter along a small path through
∞
the matter, minus the sum of the kinetic energies of all the electrons released, divided by the length dl
dE
∞
L =
∞
dl
−1 −1
Note 1 to entry: The unit of the linear energy transfer is J m , a frequently used unit is keV μm .
3.1.4
dose equivalent
H
at the point of interest in tissue
HD= Q
where D is the absorbed dose and Q is the mean quality factor at that point
Note 1 to entry: Q is determined by the unrestricted linear energy transfer, L (often denoted as L or LET), of
∞
charged particles passing through a small volume element (domains) at this point (the value of L is given for
∞
charged particles in water, not in tissue; the difference, however, is small). The dose equivalent at a point in tissue
is then given by:
∞
HQ= ()LD dL
L
∫
L−0
where D = dD/dL is the distribution in terms of L of the absorbed dose at the point of interest.
L
Note 2 to entry: The relationship of Q and L is given in Reference [2].
−1
Note 3 to entry: The unit of dose equivalent is J kg , called sievert (Sv).
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3.1.5
ambient dose equivalent
H*(10)
dose equivalent at a point in a radiation field, that would be produced by the corresponding expanded and
aligned field, in the ICRU sphere at 10 mm depth on the radius opposing the direction of the aligned field
−1
Note 1 to entry: The unit of ambient dose equivalent is J kg , called sievert (Sv).
3.1.6
particle fluence-to-ambient dose equivalent conversion coefficient
h(10)*
Φ
quotient of the particle ambient dose equivalent, H*(10), and the particle fluence, Φ
H *(10)
h 10 * =
()
Φ
Φ
2 −1
Note 1 to entry: The unit of the particle fluence-to-ambient dose equivalent conversion coefficient is J m kg
2 2
with the special name Sv m , a frequently used unit is pSv cm .
3.1.7
correction factor
K
factor applied to the indication to correct for deviation of the measurement conditions from
reference conditions
3.1.8
atmosphere depth
X
v
mass of a unit-area column of air above a point in the atmosphere
-2 -2
Note 1 to entry: The unit of atmosphere depth is kg m ; a frequently used unit is g cm .
3.1.9
standard barometric altitude
pressure altitude
altitude determined by a barometric altimeter calibrated with reference to the International Standard
Atmosphere (ISA) (ISO, 1975) when the altimeter’s datum is set to 1 013,25 hPa
Note 1 to entry: The flight level is sometimes given as FL 350, where the number represents multiples of 100 feet
of pressure altitude, based on the ISA and a datum setting of 1 013,25 hPa. However, in some countries flight
levels are expressed in meters, in which case appropriate conversions should be made before applying the data
given in this part of ISO 20785.
3.1.10
magnetic rigidity
P
momentum per charge (of a particle in a magnetic field), given by:
p
P=
Ze
where p is the particle momentum, Z the number of charges on the particle and e the charge on the proton
–1
Note 1 to entry: The base unit of magnetic rigidity is the tesla metre (T m) (= V m s). A frequently used unit is V
(or GV) in a system of units where the values of the speed of light, c, and the charge on the proton, e, are both 1,
and the magnetic rigidity is given by pc/Ze.
Note 2 to entry: Magnetic rigidity characterizes charged-particle trajectories in magnetic fields. All particles having
the same magnetic rigidity have identical trajectories in a magnetic field, independent of particle mass or charge.
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3.1.11
geomagnetic cut-off rigidity
cut-off rigidity
r
c
minimum magnetic rigidity an incident particle can have and still penetrate the geomagnetic field to
reach a given location above the Earth
Note 1 to entry: Geomagnetic cut-off rigidity depends on angle of incidence. Often, vertical incidence to the
Earth’s surface is assumed, in which case, the vertical geomagnetic cut-off rigidity is the minimum magnetic
rigidity a vertically incident particle can have and still reach a given location above the Earth.
3.1.12
vertical geomagnetic cut-off rigidity
vertical cut-off
cut-off
minimum magnetic rigidity a vertically incident particle can have and still reach a given location
above the Earth
3.1.13
deceleration potential
ϕ
cosmic ray modulation parameter deduced from space observations of the abundance variation of the
different species in function of the solar cycle epoch
Note 1 to entry: The deceleration potential could be deduced either from the sunspot index or from Climax
neutron monitor output, using simple linear formula depending upon the phase of the solar cycle.
3.2 Atmospheric radiation field
3.2.1
cosmic radiation
cosmic rays
cosmic particles
ionizing radiation consisting of high-energy particles, primarily completely ionized atoms, of extra-
terrestrial origin and the particles they generate by interaction with the atmosphere and other matter
3.2.2
primary cosmic radiation
primary cosmic rays
cosmic radiation incident from space at the Earth’s orbit
3.2.3
secondary cosmic radiation
secondary cosmic rays
cosmogenic particles
particles which are created directly or in a cascade of reactions by primary cosmic rays interacting
with the atmosphere or other matter
Note 1 to entry: Important particles with respect to radiation protection and radiation measurements in aircraft
are: neutrons, protons, photons, electrons, positrons, muons, and to a lesser extent, pions and nuclear ions
heavier than protons.
3.2.4
galactic cosmic radiation
galactic cosmic rays
GCR
cosmic radiation originating outside the solar system
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3.2.5
solar cosmic radiation
solar cosmic rays
solar particles
cosmic radiation originating from the sun
3.2.6
solar particle event
SPE
large fluence rate of energetic solar particles ejected into space by a solar eruption
Note 1 to entry: Solar particle events are directional.
3.2.7
ground level enhancement
GLE
sudden increase of cosmic radiation observed on the ground by at least two neutron monitor stations
recording simultaneously a greater than 3 % increase in the five-minute-averaged count rate associated
with solar energetic particles
Note 1 to entry: A GLE is associated with a solar-particle event having a high fluence rate of particles with high
energy (greater than 500 MeV).
Note 2 to entry: GLEs are relatively rare, occurring on average about once per year.
3.2.8
solar modulation
change of the GCR field (outside the Earth’s magnetosphere) caused by change of solar activity and
consequent change of the magnetic field of the heliosphere
3.2.9
solar cycle
period during which the solar activity varies with successive maxima separated by an average interval
of about 11 years
Note 1 to entry: If the reversal of the Sun’s magnetic field polarity in successive 11 year periods is taken into
account, the complete solar cycle may be considered to average some 22 years, the Hale cycle.
Note 2 to entry: The sunspot cycle as measured by the relative sunspot number, known as the Wolf number, has
an approximate length of 11 years, but this varies between about 7 and 17 years. An approximate 11-year cycle
has been found or suggested in geomagnetism, frequency of aurora, and other ionospheric characteristics.
3.2.10
relative sunspot number
Wolf number
measure of sunspot activity, computed from the expression k(10g + f ), where f the number of individual
spots, g the number of groups of spots, and k a factor that varies with the observer’s personal experience
of recognition and with observatory (location and instrumentation)
3.2.11
solar maximum
time period of maximum solar activity during a solar cycle, usually defined in terms of relative
sunspot number
3.2.12
solar minimum
time period of minimum solar activity during a solar cycle, usually defined in terms of relative
sunspot number
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3.2.13
cosmic ray neutron monitor
ground level neutron monitor
GLNM
large detector used to measure the time-dependent relative fluence rate of high-energy cosmic
radiation, in particular the secondary neutrons generated in the atmosphere
Note 1 to entry: Protons, other hadrons, and muons, may also be detected.
Note 2 to entry: Installed worldwide at different locations and altitudes on the ground (and occasionally placed
on ships or aircraft), cosmic radiation neutron monitors are used for various cosmic radiation studies and to
determine solar modulation.
4 General considerations
4.1 General description of the cosmic radiation field in the atmosphere
The primary galactic cosmic radiation (and energetic solar particles) interact with the atomic nuclei of
atmospheric constituents, producing a cascade of interactions and secondary reaction products that
contribute to cosmic radiation exposures that decrease in intensity with depth in the atmosphere from
[6] 20
aviation altitudes to sea level . Galactic cosmic radiation (GCR) can have energies up to 10 eV, but
lower-energy particles are the most frequent. After the GCR penetrates the magnetic field of the solar
sy
...
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