1、BSI Standards PublicationBS ISO 20785-3:2015Dosimetry for exposures tocosmic radiation in civilianaircraftPart 3: Measurements at aviation altitudesBS ISO 20785-3:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 20785-3:2015.The UK participation in its prep
2、aration was entrusted to TechnicalCommittee NCE/2, Radiation protection and measurement. A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for
3、its correctapplication. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 81938 4ICS 13.280; 49.020Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy
4、 and Strategy Committee on 30 November 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 20785-3:2015 ISO 2015Dosimetry for exposures to cosmic radiation in civilian aircraft Part 3: Measurements at aviation altitudesDosimtrie pour les expositions au rayonnement c
5、osmique bord dun avion civil Partie 3: Mesurages bord davionsINTERNATIONAL STANDARDISO20785-3First edition2015-11-15Reference numberISO 20785-3:2015(E)BS ISO 20785-3:2015ISO 20785-3:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserv
6、ed. 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
7、at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 20785-3:2015ISO 20785-3:2015(E)Foreword ivIntroduction v1 Scope . 12 N
8、ormative references 13 Terms and definitions . 13.1 Quantities and units . 13.2 Atmospheric radiation field . 44 General considerations 64.1 General description of the cosmic radiation field in the atmosphere . 64.2 General considerations concerning the measurements 84.2.1 General 84.2.2 Selection o
9、f appropriate instruments 84.2.3 Characterization of the responses of the instruments 84.2.4 Measurements inside an aircraft . 84.2.5 Application of appropriate correction factors 94.3 Safety and regulatory requirements for in-flight measurements . 95 Measurement at aviation altitude 95.1 Parameters
10、 determining the dose rate. 95.1.1 Barometric altitude . 95.1.2 Geographic coordinates . 95.1.3 Solar activity . 105.2 Possible influence quantities . 105.2.1 General. 105.2.2 Cabin air pressure 105.2.3 Cabin air temperature 105.2.4 Cabin air humidity .105.3 Specific considerations for active instru
11、ments 105.3.1 Power supply 105.3.2 Vibrations and shocks 115.3.3 Electromagnetic interferences from the aircraft .115.4 Specific considerations for passive measurements 115.4.1 Security X-ray scanning . 115.4.2 Background subtraction . 116 Uncertainties .11Annex A (informative) Representative partic
12、le 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 12Bibliography .16 ISO 2015 All rights reserved iiiContents PageBS ISO 20785-3:2015ISO 20785-3:2015(E)ForewordISO (the Int
13、ernational 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 ha
14、s 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
15、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 acc
16、ordance 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. Detai
17、ls 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 end
18、orsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee respo
19、nsible 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
20、 basis for measurements Part 2: Characterization of instrument response Part 3: Measurements at aviation altitudesiv ISO 2015 All rights reservedBS ISO 20785-3:2015ISO 20785-3:2015(E)IntroductionAircraft crews are exposed to elevated levels of cosmic radiation of galactic and solar origin and second
21、ary radiation produced in the atmosphere, the aircraft structure and its contents. Following recommendations of the International Commission on Radiological Protection in Publication 60,1confirmed by Publication 103,2the European Union (EU) introduced a revised Basic Safety Standards Directive3which
22、 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
23、 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 pr
24、otection 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 Authoriti
25、es 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 effecti
26、ve 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
27、 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
28、 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
29、. This approach is supported by guidance from the European Commission, the ICRP in Publication 754and the ICRU in Report 84.5The 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. Ef
30、fective 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 irradi
31、ation 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
32、 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 operation
33、al 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 wor
34、kers. 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
35、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
36、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 acc
37、urate 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 vB
38、S ISO 20785-3:2015ISO 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 an
39、d 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 a
40、gencies, and by industrial corporations concerned with the determination of ambient dose equivalent for aircraft crew.vi ISO 2015 All rights reservedBS ISO 20785-3:2015INTERNATIONAL STANDARD ISO 20785-3:2015(E)Dosimetry for exposures to cosmic radiation in civilian aircraft Part 3: Measurements at a
41、viation altitudes1 ScopeThis 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 referencesThe following documents, in whole or in part, are normatively reference
42、d 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 expr
43、ession of uncertainty in measurementISO/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 measurementsISO 20785-2, Dosimetry for
44、 exposures to cosmic radiation in civilian aircraft Part 2: Characterization of instrument response3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1 Quantities and units3.1.1particle fluencefluenceat a given point of space, number dN of particles
45、 incident on a small spherical domain divided by the cross-sectional area da of that domain: =ddNaNote 1 to entry: The unit of the fluence is m-2, a frequently used unit is cm-2. ISO 2015 All rights reserved 1BS ISO 20785-3:2015ISO 20785-3:2015(E)Note 2 to entry: The energy distribution of the parti
46、cle fluence, E, is the quotient d by dE, where d is the fluence of particles of energy between E and E+dE. There is an analogous definition for the direction distribution, , of the particle fluence. The complete representation of the double differential particle fluence can be written (with argument
47、s) E,(E,), where the subscripts characterize the variables (quantities) for differentiation and 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 energ
48、y E = E0is written as E(E0). If no special values are indicated, the brackets may be omitted.3.1.2particle fluence ratefluence ratedotnospdotnosp=dddddtNat2where d is the increment of the particle fluence during an infinitesimal time interval with duration dt:Note 1 to entry: The unit of the fluence
49、 rate is m-2s1, a frequently used unit is cm-2s1.3.1.3unrestricted linear energy transferlinear energy transferLETLfor an ionizing charged particle, mean energy dEimparted 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 dlLEl=ddNote 1 to entry: The unit of the linear energy transfer is J m1, a frequently used unit is keV m1.3.1.4dose equivalentHat the point of interest in tissueHDQ=where D is the absorbed dos
