Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 4: Validation of codes (ISO 20785-4:2019)

This document is intended for the validation of codes used for the calculation of doses received by individuals on board aircraft. It gives guidance to radiation protection authorities and code developers on the basic functional requirements which the code fulfils.
Depending on any formal approval by a radiation protection authority, additional requirements concerning the software testing can apply.

(ISO 20785-4:2019)

Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 4: Validation des codes (ISO 20785-4:2019)

Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem prometu - 4. del: Kode za preverjanje veljavnosti (ISO 20785-4:2019)

General Information

Status
Published
Public Enquiry End Date
23-Jun-2021
Publication Date
22-Aug-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
16-Aug-2021
Due Date
21-Oct-2021
Completion Date
23-Aug-2021

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SLOVENSKI STANDARD
SIST EN ISO 20785-4:2021
01-oktober-2021
Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem
prometu - 4. del: Kode za preverjanje veljavnosti (ISO 20785-4:2019)

Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 4: Validation of

codes (ISO 20785-4:2019)

Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 4:

Validation des codes (ISO 20785-4:2019)
Ta slovenski standard je istoveten z: EN ISO 20785-4:2021
ICS:
13.280 Varstvo pred sevanjem Radiation protection
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
SIST EN ISO 20785-4:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 20785-4:2021
---------------------- Page: 2 ----------------------
SIST EN ISO 20785-4:2021
EN ISO 20785-4
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2021
EUROPÄISCHE NORM
ICS 13.280; 49.020
English Version
Dosimetry for exposures to cosmic radiation in civilian
aircraft - Part 4: Validation of codes (ISO 20785-4:2019)
Dosimétrie pour l'exposition au rayonnement (ISO 20785-4:2019)
cosmique à bord d'un avion civil - Partie 4: Validation
des codes (ISO 20785-4:2019)
This European Standard was approved by CEN on 25 July 2021.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, 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: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20785-4:2021 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 20785-4:2021
EN ISO 20785-4:2021 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 20785-4:2021
EN ISO 20785-4:2021 (E)
European foreword

The text of ISO 20785-4:2019 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 20785-4:2021 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 February 2022, and conflicting national standards

shall be withdrawn at the latest by February 2022.

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.

Any feedback and questions on this document should be directed to the users’ national standards body.

A complete listing of these bodies can be found on the CEN website.

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, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 20785-4:2019 has been approved by CEN as EN ISO 20785-4:2021 without any

modification.
---------------------- Page: 5 ----------------------
SIST EN ISO 20785-4:2021
---------------------- Page: 6 ----------------------
SIST EN ISO 20785-4:2021
INTERNATIONAL ISO
STANDARD 20785-4
First edition
2019-05
Dosimetry for exposures to cosmic
radiation in civilian aircraft —
Part 4:
Validation of codes
Dosimétrie pour les expositions au rayonnement cosmique à bord
d'un avion civil —
Partie 4: Validation des codes
Reference number
ISO 20785-4:2019(E)
ISO 2019
---------------------- Page: 7 ----------------------
SIST EN ISO 20785-4:2021
ISO 20785-4:2019(E)
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

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 20785-4:2021
ISO 20785-4:2019(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

3.3 Software terms ........................................................................................................................................................................................ 5

4 General considerations .................................................................................................................................................................................. 5

5 Functionality ............................................................................................................................................................................................................. 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Measured data ......................................................................................................................................................................................... 6

5.3 ICRU reference data ............................................................................................................................................................................ 6

5.4 Code validation using measurements or reference data .................................................................................... 6

5.5 Considerations for the routine dose assessment ...................................................................................................... 6

Bibliography ................................................................................................................................................................................................................................ 8

© ISO 2019 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 20785-4:2021
ISO 20785-4:2019(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 of 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 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, Radiological protection.
A list of all the parts in the ISO 20785 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 20785-4:2021
ISO 20785-4:2019(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

recommendations of the International Commission on Radiological Protection (ICRP) in Publication

[1] [2]

60, the European Union (EU) introduced a Basic Safety Standards Directive (BSS) which included

exposure to natural sources of ionizing radiation, including cosmic radiation, as occupational exposure

[3]

for aircrew. International guidance was also provided by the IAEA Safety Standards Series . This

[4] [5] [6]

action was confirmed by ICRP Publications 103 and 132 , and the EU BSS was revised. 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 organising working schedules with a view to

reducing the doses of highly exposed crew;

iii) to inform workers concerned with the health risks involved in their work; 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 fetus) and effective dose. The cosmic radiation exposure of the body is essentially uniform

and the maternal abdomen provides no effective shielding to the fetus. As a result, the magnitude of

equivalent dose to the fetus 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 thus not needed nor practical,

The preferred approach for the assessment of doses of aircraft crew, where necessary, is to calculate

directly the 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

[7]

individuals. This approach is supported by guidance from the ICRP in Publication 75 and Publication

[5] [8]
132 , 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 irradiation can be assumed. The operational quantity ambient dose

equivalent is a good estimator of effective dose and equivalent dose to the fetus 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. 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 the results can be compared to 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 code.

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 fetus 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 route dose is the best estimate of ambient dose equivalent for the actual route recorded for the

aircrew. However, the actual route flown for that specific flight may vary due to weather, scheduling, etc.

© ISO 2019 – All rights reserved v
---------------------- Page: 11 ----------------------
SIST EN ISO 20785-4:2021
ISO 20785-4:2019(E)

It should be noted that this document addresses galactic cosmic radiation (GCR) only. First discovered

by Victor Hess more than 100 years ago, GCR is a well understood and permanent source of ionizing

radiation both on Earth and in flight. GCR can be modelled with reasonable precision and accuracy.

It should be recognized that there are other sources of radiation that are intermittent. These sources

cannot currently be modelled prior to their occurrence, and are not a subject of this document. These

sources include solar proton events (often called solar particle events), solar neutron events, solar

gamma events, solar magnetic storms that alter the magnetic shielding and terrestrial gamma flashes

which are associated with some lightning. Exposures can also occur from shipments of radioactive

material and also from any medical procedures required as a condition of employment for aircrew.

These intermittent sources can produce radiation exposures that exceed limits for both aircrew and

members of the public.

In order to adequately address the total radiation exposure for occupational workers and for members

of the public who fly, radiation exposure to intermittent sources needs to be addressed after an event

occurs with either radiation monitor
...

SLOVENSKI STANDARD
oSIST prEN ISO 20785-4:2021
01-junij-2021
Dozimetrija za merjenje izpostavljenosti kozmičnemu sevanju v civilnem letalskem
prometu - 4. del: Kode za preverjanje veljavnosti (ISO 20785-4:2019)

Dosimetry for exposures to cosmic radiation in civilian aircraft - Part 4: Validation of

codes (ISO 20785-4:2019)

Dosimétrie pour l'exposition au rayonnement cosmique à bord d'un avion civil - Partie 4:

Validation des codes (ISO 20785-4:2019)
Ta slovenski standard je istoveten z: prEN ISO 20785-4
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 20785-4:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 20785-4:2021
---------------------- Page: 2 ----------------------
oSIST prEN ISO 20785-4:2021
INTERNATIONAL ISO
STANDARD 20785-4
First edition
2019-05
Dosimetry for exposures to cosmic
radiation in civilian aircraft —
Part 4:
Validation of codes
Dosimétrie pour les expositions au rayonnement cosmique à bord
d'un avion civil —
Partie 4: Validation des codes
Reference number
ISO 20785-4:2019(E)
ISO 2019
---------------------- Page: 3 ----------------------
oSIST prEN ISO 20785-4:2021
ISO 20785-4:2019(E)
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

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 20785-4:2021
ISO 20785-4:2019(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

3.3 Software terms ........................................................................................................................................................................................ 5

4 General considerations .................................................................................................................................................................................. 5

5 Functionality ............................................................................................................................................................................................................. 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Measured data ......................................................................................................................................................................................... 6

5.3 ICRU reference data ............................................................................................................................................................................ 6

5.4 Code validation using measurements or reference data .................................................................................... 6

5.5 Considerations for the routine dose assessment ...................................................................................................... 6

Bibliography ................................................................................................................................................................................................................................ 8

© ISO 2019 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 20785-4:2021
ISO 20785-4:2019(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 of 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 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, Radiological protection.
A list of all the parts in the ISO 20785 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 20785-4:2021
ISO 20785-4:2019(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

recommendations of the International Commission on Radiological Protection (ICRP) in Publication

[1] [2]

60, the European Union (EU) introduced a Basic Safety Standards Directive (BSS) which included

exposure to natural sources of ionizing radiation, including cosmic radiation, as occupational exposure

[3]

for aircrew. International guidance was also provided by the IAEA Safety Standards Series . This

[4] [5] [6]

action was confirmed by ICRP Publications 103 and 132 , and the EU BSS was revised. 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 organising working schedules with a view to

reducing the doses of highly exposed crew;

iii) to inform workers concerned with the health risks involved in their work; 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 fetus) and effective dose. The cosmic radiation exposure of the body is essentially uniform

and the maternal abdomen provides no effective shielding to the fetus. As a result, the magnitude of

equivalent dose to the fetus 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 thus not needed nor practical,

The preferred approach for the assessment of doses of aircraft crew, where necessary, is to calculate

directly the 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

[7]

individuals. This approach is supported by guidance from the ICRP in Publication 75 and Publication

[5] [8]
132 , 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 irradiation can be assumed. The operational quantity ambient dose

equivalent is a good estimator of effective dose and equivalent dose to the fetus 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. 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 the results can be compared to 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 code.

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 fetus 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 route dose is the best estimate of ambient dose equivalent for the actual route recorded for the

aircrew. However, the actual route flown for that specific flight may vary due to weather, scheduling, etc.

© ISO 2019 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST prEN ISO 20785-4:2021
ISO 20785-4:2019(E)

It should be noted that this document addresses galactic cosmic radiation (GCR) only. First discovered

by Victor Hess more than 100 years ago, GCR is a well understood and permanent source of ionizing

radiation both on Earth and in flight. GCR can be modelled with reasonable precision and accuracy.

It should be recognized that there are other sources of radiation that are intermittent. These sources

cannot currently be modelled prior to their occurrence, and are not a subject of this document. These

sources include solar proton events (often called solar particle events), solar neutron events, solar

gamma events, solar magnetic storms that alter the magnetic shielding and terrestrial gamma flashes

which are associated with some lightning. Exposures can also occur from shipments of radioactive

material and also from any medical procedures required as a condition of employment for aircrew.

These intermittent sources can produce radiation exposures that exceed limits for both aircrew and

members of the public.

In order to adequately address the total radiation exposure for occupational workers and for members

of the public who fly, radiation exposure to intermittent sources needs to be addressed after an event

occurs with either radiation monitoring or with modelling.
vi © ISO 2019 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST prEN ISO 20785-4:2021
INTERNATIONAL STANDARD ISO 20785-4:2019(E)
Dosimetry for exposures to cosmic radiation in civilian
aircraft —
Part 4:
Validation of codes
1 Scope

This document is intended for the validation of codes used for the calculation of doses received by

individuals on board aircraft. It gives guidance to radiation protection authorities and code developers

on the basic functional requirements which the code fulfils.

Depending on any formal approval by a radiation protection authority, additional requirements

concerning the software testing can apply.
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 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

ISO 20785-3, Dosimetry for exposures to cosmic radiation in civilian aircraft — Part 3: Measurements at

aviation altitudes
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20785-1, ISO 20785-2,

ISO 20785-3 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1 Quantities and units
3.1.1
particle fluence
fluence

quotient of dN by da, where dN is the mean number of particles incident on a sphere of cross sectional

area da, thus
Φ =
© ISO 2019 – All rights reserved 1
---------------------- Page: 9 ---------------------
...

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