1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 20785-2:2011Dosimetry for exposures to cosmic radiation in civilian aircraftPart 2: Characterization of instrument responseBS ISO 20785-2:2011 BRITISH STANDARDNational for
2、ewordThis British Standard is the UK implementation of ISO 20785-2:2011. 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 pub
3、lication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 54582 5 ICS 13.280; 49.020 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published
4、under the authority of the Standards Policy and Strategy Committee on 30 June 2011.Amendments issued since publicationDate T e x t a f f e c t e dBS ISO 20785-2:2011Reference numberISO 20785-2:2011(E)ISO 2011INTERNATIONAL STANDARD ISO20785-2First edition2011-06-01Dosimetry for exposures to cosmic ra
5、diation in civilian aircraft Part 2: Characterization of instrument response Dosimtrie de lexposition au rayonnement cosmique dans laviation civile Partie 2: Caractrisation de la rponse des instruments BS ISO 20785-2:2011ISO 20785-2:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2011 All rights reserved.
6、Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. I
7、SO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedBS ISO 20785-2:2011ISO 20785-2:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv Introduc
8、tion.v 1 Scope1 2 Normative references1 3 Terms and definitions .2 3.1 General terms 2 3.2 Terms related to quantities and units .7 3.3 Terms related to the atmospheric radiation field.11 4 General considerations.12 4.1 The cosmic radiation field in the atmosphere12 4.2 General considerations for th
9、e dosimetry of the cosmic radiation field in aircraft and requirements for the characterization of instrument response .14 4.3 General considerations for measurements at aviation altitudes .15 5 Calibration fields and procedures .16 5.1 General considerations.16 5.2 Characterization of an instrument
10、 .18 5.3 Instrument-related software .21 6 Uncertainties22 7 Remarks on performance tests22 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-
11、off rigidity 23 Annex B (informative) Radiation fields recommended for use in calibrations.25 Annex C (informative) Comparison measurements 29 Annex D (informative) Charged-particle irradiation facilities31 Bibliography32 BS ISO 20785-2:2011ISO 20785-2:2011(E) iv ISO 2011 All rights reservedForeword
12、 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
13、 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 elec
14、trotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the
15、 member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for iden
16、tifying any or all such patent rights. ISO 20785-2 was prepared by Technical Committee 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
17、to cosmic radiation in civilian aircraft: Part 1: Conceptual basis for measurements Part 2: Characterization of instrument response A Part 3 dealing with measurements at aviation altitudes is in preparation. BS ISO 20785-2:2011ISO 20785-2:2011(E) ISO 2011 All rights reserved vIntroduction Aircraft c
18、rews 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 in Publication 601, confirmed by Publ
19、ication 1032, the European Union (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 crew liable to re
20、ceive 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
21、 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 already been incorporated into laws and regulations of EU member sta
22、tes and is being included in the aviation safety standards and procedures of the Joint Aviation Authorities and the European Air Safety Agency. Other countries, such as Canada and Japan, have issued advisories to their airline industries to manage aircraft crew exposure. For regulatory and legislati
23、ve 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
24、 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 sol
25、ar 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 the effective dose per unit time, as a function of geographic location, altitude and solar cycle phase
26、, and to combine 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 and the ICRP in Publication 754. The role of calculations in this procedure is unique in routine radiatio
27、n protection, and it is widely accepted that the calculated doses should be validated by measurement5. Effective dose is not directly measurable. The operational quantity of interest is the ambient dose equivalent, H*(10). In order to validate the assessed doses obtained in terms of effective dose,
28、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 t
29、aken as a validation of the calculation of effective dose by the same computer code, but this step in the process might 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
30、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. The radiation field in aircraft at altitude is complex, with many types of ionizing radiati
31、on 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 resear
32、ch 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 equival
33、ent need to be performed using accurate and reliable methods that ensure the quality of readings provided to workers and regulatory authorities. The purpose of this part of ISO 20785 is to specify procedures for the determination of the responses of instruments in different reference radiation field
34、s, as a basis for proper characterization of instruments used for the determination of ambient dose equivalent in aircraft at altitude. Requirements for the determination and recording of the cosmic radiation exposure of aircraft crew have been introduced into the national legislation of EU member s
35、tates and other countries. Harmonization of methods BS ISO 20785-2:2011ISO 20785-2:2011(E) vi ISO 2011 All rights reservedused for determining ambient dose equivalent and for calibrating instruments is desirable to ensure the compatibility of measurements performed with such instruments. This part o
36、f 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. BS ISO 2078
37、5-2:2011INTERNATIONAL STANDARD ISO 20785-2:2011(E) ISO 2011 All rights reserved 1Dosimetry for exposures to cosmic radiation in civilian aircraft Part 2: Characterization of instrument response 1 Scope This part of ISO 20785 specifies methods and procedures for characterizing the responses of device
38、s used for the determination of ambient dose equivalent for the evaluation of exposure to cosmic radiation in civilian aircraft. The methods and procedures are intended to be understood as minimum requirements. 2 Normative references The following referenced documents are indispensable for the appli
39、cation 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/IEC Guide 98-1, Uncertainty of measurement Part 1: Introduction to the expression of uncertainty in measurement
40、 ISO/IEC Guide 98-3, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) ISO 4037-1, X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy Part 1: Radiation char
41、acteristics and production methods ISO 6980-1, Nuclear energy Reference beta-particle radiation Part 1: Methods of production ISO 8529-1:2001, Reference neutron radiations Part 1: Characteristics and methods of production ISO 12789-1, Reference radiation fields Simulated workplace neutron fields Par
42、t 1: Characteristics and methods of production ISO 12789-2, Reference radiation fields Simulated workplace neutron fields Part 2: Calibration fundamentals related to the basic quantities ISO 20785-1, Dosimetry for exposures to cosmic radiation in civilian aircraft Part 1: Conceptual basis for measur
43、ements ISO 29661, Reference radiation fields for radiation protection Definitions and fundamental concepts BS ISO 20785-2:2011ISO 20785-2:2011(E) 2 ISO 2011 All rights reserved3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 General terms 3.1.
44、1 angle of radiation incidence angle between the direction of radiation incidence and the reference direction of the instrument 3.1.2 calibration operation that, under specified conditions, establishes a relation between the conventional quantity, H0, and the indication, G NOTE 1 A calibration can b
45、e expressed by a statement, calibration function, calibration diagram, calibration curve or calibration table. In some cases, it can consist of an additive or multiplicative correction of the indication with associated measurement uncertainty. NOTE 2 It is important not to confuse calibration with a
46、djustment of a measuring system, often mistakenly called “self-calibration”, or with verification of calibration. 3.1.3 calibration coefficient Ncoeffquotient of the conventional quantity value to be measured and the corrected indication of the instrument NOTE 1 The calibration coefficient is equiva
47、lent to the calibration factor multiplied by the instrument constant. NOTE 2 The reciprocal of the calibration coefficient, Ncoeff, is the response. NOTE 3 For the calibration of some instruments, e.g. ionization chambers, the instrument constant and the calibration factor are not identified separat
48、ely but are applied together as the calibration coefficient. NOTE 4 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 coeffici
49、ent with respect to absorbed dose, ND. 3.1.4 calibration conditions conditions, within the range of standard test conditions, actually prevailing during the calibration 3.1.5 calibration factor Nfactfactor by which the product of the corrected indication and the associated instrument constant of the instrument is multiplied to obtain the conventional quantity value to be measured under reference conditions NOTE 1 The calibration factor is dimensionless. NOTE 2 The corrected indication is the indication of
