1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 20785-1:2012Dosimetry for exposures to cosmic radiation in civilian aircraftPart 1: Conceptual basis for measurementsBS ISO 20785-1:2012 BRITISH STANDARDNational forewordT
2、his British Standard is the UK implementation of ISO 20785-1:2012. The UK participation in its preparation was entrusted to TechnicalCommittee NCE/2, Radiation protection and measurement. A list of organizations represented on this committee can be obtained on request to its secretary.This publicati
3、on does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013ISBN 978 0 580 70479 6 ICS 13.280; 49.020 Compliance with a British Standard cannot confer immu
4、nity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2013.Amendments issued since publicationDate Text affectedBS ISO 20785-1:2012 ISO 2012Dosimetry for exposures to cosmic radiation in civilian aircraft Part
5、 1: Conceptual basis for measurementsDosimtrie pour lexposition au rayonnement cosmique bord dun avion civil Partie 1: Fondement thorique des mesuragesINTERNATIONAL STANDARDISO20785-1Second edition2012-12-15Reference numberISO 20785-1:2012(E)BS ISO 20785-1:2012ISO 20785-1:2012(E)ii ISO 2012 All righ
6、ts reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
7、 address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 20785-1:2012ISO 20785-1:2012(E) ISO 2012 All rights reserved iiiCont
8、ents PageForeword ivIntroduction v1 Scope . 12 Terms and definitions . 12.1 General . 12.2 Quantities and units . 22.3 Atmospheric radiation field . 83 General considerations .103.1 General description of the cosmic radiation field in the atmosphere 103.2 General calibration considerations for the d
9、osimetry of cosmic radiation fields in aircraft . 113.3 Conversion coefficients . 134 Dosimetric devices 134.1 Introduction . 134.2 Active devices 144.3 Passive devices . 17Annex A (informative) Representative particle fluence rate energy distributions for the cosmic radiation field at flight altitu
10、des for solar minimum and maximum conditions and for minimum and maximum vertical cut-off rigidity 80.20Bibliography .24BS ISO 20785-1:2012ISO 20785-1:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). T
11、he 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-go
12、vernmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.T
13、he main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vot
14、e.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 20785-1 was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and
15、 radiological protection, Subcommittee SC 2, Radiological protection.This second edition cancels and replaces the first edition (ISO 20785-1:2006), which has been technically revised.ISO 20785 consists of the following parts, under the general title Dosimetry for exposures to cosmic radiation in civ
16、ilian aircraft: Part 1: Conceptual basis for measurements Part 2: Characterization of instrument responseMeasurements at aviation altitudes is to form the subject of a future Part 3.iv ISO 2012 All rights reservedBS ISO 20785-1:2012ISO 20785-1:2012(E)IntroductionAircraft crews are exposed to elevate
17、d 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 in Publication 60,1confirmed by Publication 103,2the European Un
18、ion (EU) introduced a revised Basic Safety Standards Directive3which included exposure to natural sources of ionizing radiation, including cosmic radiation, as occupational exposure. The Directive requires account to be taken of the exposure of aircraft crews liable to receive more than 1 mSv per ye
19、ar. It then identifies the following four protection measures: (i) to assess the exposure of the crew concerned; (ii) to take into account the assessed exposure when organizing working schedules with a view to reducing the doses of highly exposed crews; (iii) to inform the workers concerned of the h
20、ealth risks their work involves; and (iv) to apply the same special protection during pregnancy to female crews in respect of the “child to be born” as to other female workers. The EU Council Directive has already been incorporated into laws and regulations of EU Member States and is being included
21、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 pr
22、otection quantities of interest are the equivalent dose (to the foetus) and the effective dose. The cosmic radiation exposure of the body is essentially uniform and the maternal abdomen provides no effective shielding to the foetus. As a result, the magnitude of equivalent dose to the foetus can be
23、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). P
24、ersonal dosemeters for routine use are not considered necessary. The preferred approach for the assessment of doses of aircraft crews, where necessary, is to calculate directly the effective dose per unit time, as a function of geographic location, altitude and solar cycle phase, and to fold these v
25、alues with flight and staff roster information to obtain estimates of effective doses for individuals. This approach is supported by guidance from the European Commission and the ICRP in Publication 75.4The role of calculations in this procedure is unique in routine radiation protection and it is wi
26、dely accepted that the calculated doses should be validated by measurement. The effective dose is not directly measurable. The operational quantity of interest is ambient dose equivalent, H*(10). In order to validate the assessed doses obtained in terms of effective dose, calculations can be made of
27、 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
28、 calculation of the effective dose by the same computer code, but this step in the process may need to be confirmed. The alternative is to establish a priori that the operational quantity ambient dose equivalent is a good estimator of effective dose and equivalent dose to the foetus for the radiatio
29、n 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 a
30、nd 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,
31、 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 fo
32、r maintaining the traceability of dosimetric measurements to national standards. Dosimetric measurements made to evaluate ambient dose equivalent must be performed using accurate and reliable methods that ensure the quality of readings provided to workers and regulatory authorities. This part of ISO
33、 20785 gives a conceptual basis for the characterization of the response of instruments for the determination of ambient dose equivalent in aircraft. ISO 2012 All rights reserved vBS ISO 20785-1:2012ISO 20785-1:2012(E)Requirements for the determination and recording of the cosmic radiation exposure
34、of aircraft crews 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
35、.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 crews
36、.vi ISO 2012 All rights reservedBS ISO 20785-1:2012INTERNATIONAL STANDARD ISO 20785-1:2012(E)Dosimetry for exposures to cosmic radiation in civilian aircraft Part 1: Conceptual basis for measurements1 ScopeThis part of ISO 20785 gives the conceptual basis for the determination of ambient dose equiva
37、lent for the evaluation of exposure to cosmic radiation in civilian aircraft and for the calibration of instruments used for that purpose.2 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.2.1 General2.1.1calibrationoperation that, under specified con
38、ditions, establishes a relation between the conventional quantity, H0, and the indication, GNote 1 to entry: A calibration may be expressed by a statement, calibration function, calibration diagram, calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicati
39、ve correction of the indication with associated measurement uncertainty.Note 2 to entry: Calibration should not be confused with adjustment of a measuring system, often mistakenly called “self-calibration”, or with verification of calibration.Note 3 to entry: Often, the first step alone in the above
40、 definition is perceived as being calibration.2.1.2calibration coefficientNcoeffquotient of the conventional quantity value to be measured and the corrected indication of the instrumentNote 1 to entry: The calibration coefficient is equivalent to the calibration factor multiplied by the instrument c
41、onstant.Note 2 to entry: The reciprocal of the calibration coefficient, Ncoeff, is the response.Note 3 to entry: For the calibration of some instruments, e.g. ionization chambers, the instrument constant and the calibration factor are not identified separately but are applied together as the calibra
42、tion coefficient.Note 4 to entry: It is necessary, in order to avoid confusion, to state the quantity to be measured, for example: the calibration coefficient with respect to fluence, N, the calibration coefficient with respect to kerma, NK, the calibration coefficient with respect to absorbed dose,
43、 ND. ISO 2012 All rights reserved 1BS ISO 20785-1:2012ISO 20785-1:2012(E)2.1.3indicationGquantity value provided by a measuring instrument or a measuring systemNote 1 to entry: An indication can be presented in visual or acoustic form or can be transferred to another device. An indication is often g
44、iven by the position of a pointer on the display for analogue outputs, a displayed or printed number for digital outputs, a code pattern for code outputs, or an assigned quantity value for material measures.Note 2 to entry: An indication and a corresponding value of the quantity being measured are n
45、ot necessarily values of quantities of the same kind.2.1.4reference conditionsconditions of use prescribed for testing the performance of a detector assembly or for comparison of results of measurementsNote 1 to entry: The reference conditions represent the values of the set of influence quantities
46、for which the calibration result is valid without any correction.Note 2 to entry: The value of the measurand may be chosen freely in agreement with the properties of the detector assembly to be calibrated. The quantity to be measured is not an influence quantity but may influence the calibration res
47、ult and the response.2.1.5responseRquotient of the indication, G, or the corrected indication, Gcorr, and the conventional quantity value to be measuredNote 1 to entry: To avoid confusion, it is necessary to specify which of the quotients, given in the definition of the response (to G or to Gcorr) i
48、s applied. Furthermore, it is necessary, in order to avoid confusion, to state the quantity to be measured, for example: the response with respect to fluence, R, the response with respect to kerma, RK, the response with respect to absorbed dose, RD.Note 2 to entry: The reciprocal of the response und
49、er the specified conditions is equal to the calibration coefficient Ncoeff.Note 3 to entry: The value of the response may vary with the magnitude of the quantity to be measured. In such cases the detector assemblys response is said to be non-constant.Note 4 to entry: The response usually varies with the energy and direction distribution of the incident radiation. It is, therefore, useful to consider the response as a function, R(E,), of the radiation energy, E, and of the direction, combarrowextenderarrowrightnospcombarrowextender, of the
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