1、BRITISH STANDARD BS ISO 6980-1:2006 Nuclear energy Reference beta-particle radiation Part 1: Methods of production ICS 17.240 BS ISO 6980-1:2006 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 September 2006 BSI 2006 ISBN 0 580 48884 5 Nat
2、ional foreword This British Standard reproduces verbatim ISO 6980-1:2006 and implements it as the UK national standard. Together with BS ISO 6980-2:2004 and BS ISO 6980-3, it partially supersedes BS ISO 6980:1996 which will be withdrawn upon publication of all three parts. The UK participation in it
3、s preparation was entrusted to Technical Committee NCE/2, Radiation protection and measurement. A list of organizations represented on NCE/2 can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for
4、 its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. Date Comments Reference number ISO 6980-1:2006(E)INTERNATIONAL STANDARD ISO 6980-1 First edition 2006-08-01 Nuclear energy Reference beta-particle
5、radiation Part 1: Methods of production nergie nuclaire Rayonnement bta de rfrence Partie 1: Mthodes de production BS ISO 6980-1:2006ii iii Contents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 2 4 Requirements for reference beta-particle radiation fields at the c
6、alibration distance 4 4.1 Energy of the reference radiation fields. 4 4.2 Shape of the beta-particle spectrum. 4 4.3 Uniformity of the dose rate 4 4.4 Photon contamination 4 4.5 Variation of the beta-particle emission with time 4 5 Radionuclides suitable for reference beta-particle radiation fields
7、4 6 Source characteristics and their measurement 5 6.1 Fundamental characteristics of reference sources 5 6.2 Characteristics of the two series of reference beta-particle radiation fields . 8 7 Source calibration. 10 Annex A (informative) Tissue equivalent materials 11 Annex B (informative) Characte
8、ristics of the recommended sources Examples of source construction 12 Bibliography . 13 BS ISO 6980-1:2006iv 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
9、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
10、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. The main task of technical committees is to pre
11、pare 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 vote. Attention is drawn to the possibility that
12、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 6980-1 was prepared by Technical Committee ISO/TC 85, Nuclear energy, Subcommittee SC 2, Radiation protection. This first edition of ISO 698
13、0-1, together with the first edition of ISO 6980-2 and the first edition of ISO 6980-3 cancels and replaces ISO 6980:1996, which has been technically revised ISO 6980 consists of the following parts, under the general title Nuclear energy Reference beta-particle radiations: Part 1: Methods of produc
14、tion Part 2: Calibration fundamentals related to basic quantities characterizing the radiation field Part 3: Calibration of area and personal dosemeters and the determination of their response as a function of beta radiation energy and angle of incidence BS ISO 6980-1:20061 Nuclear energy Reference
15、beta-particle radiation Part 1: Methods of production 1 Scope This part of ISO 6980 specifies the requirements for reference beta radiation fields produced by radionuclide sources to be used for the calibration of personal and area dosemeters and dose-rate meters to be used for the determination of
16、the quantities H p (0,07) and H (0,07), and for the determination of their response as a function of beta particle energy and angle of incidence. It gives the characteristics of radionuclides that have been used to produce reference beta radiation fields, gives examples of suitable source constructi
17、ons and describes methods for the measurement of the residual maximum beta particle energy and the dose equivalent rate at a depth of 0,07 mm in the International Commission on radiation units and measurements (ICRU) sphere. The energy range involved lies between 66 keV 1)and 3,6 MeV and the dose eq
18、uivalent rates are in the range from about 10 Sv h 1to at least 10 Sv h 1 . In addition, for some sources variations of the dose equivalent rate as a function of the angle of incidence are given. This part of ISO 6980 proposes two series of beta reference radiation fields, from which the radiation n
19、ecessary for determining the characteristics (calibration and energy and angular dependence of response) of an instrument can be selected. Series 1 reference radiation fields are produced by radionuclide sources used with beam flattening filters designed to give uniform dose equivalent rates over a
20、large area at a specified distance. The proposed sources of 90 Sr + 90 Y, 85 Kr, 204 Tl and 147 Pm produce maximum dose equivalent rates of approximately 200 mSv h 1 . Series 2 reference radiation fields are produced without the use of beam-flattening filters, which allows large area planar sources
21、and a range of source-to-calibration plane distances to be used. Close to the sources, only relatively small areas of uniform dose rate are produced, but this series has the advantage of extending the energy and dose rate ranges beyond those of Series 1. The radionuclides used are those of series 1
22、with the addition of the radionuclides 14 C and 106 Ru + 106 Rh; these sources produce dose equivalent rates of up to 10 Sv h 1 . 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. Fo
23、r undated references, the latest edition of the referenced document (including any amendments) applies. International vocabulary of basic and general terms in metrology, (VIM), BIPM/IEC/IFCC/ISO/IUPAC/IUPAP/ OIML ICRU 51:1993, Quantities and Units in Radiation Protection Dosimetry ISO 6980-3, Nuclea
24、r energy Reference beta-particle radiations Part 3: Calibration of area and personal dosemeters and determination of their response as a function of beta radiation energy and angle of incidence 1) The lower limit of the energies being considered is the energy of an electron that can just penetrate t
25、o the depth of interest, 0,07 mm 1 . BS ISO 6980-1:20062 3 Terms and definitions For the purposes of this document, the terms and definitions given in ICRU Report 51, VIM and ISO 6980-3 and the following apply. 3.1 absorbed dose D quotient of d by dm, where d is the mean energy imparted by ionizing
26、radiation to matter of mass dm d/ d D m = (1) NOTE The unit of the absorbed dose is joule per kilogram (J kg 1 ) with the special name of gray (Gy). 3.2 absorbed dose rate D quotient of dD by dt, where dD is the increment of absorbed dose in the time interval, dt d/ d D Dt = (2) NOTE The SI unit of
27、absorbed dose rate is gray per second (Gy s 1 ). Units of absorbed dose rate are any quotient of the gray or its decimal multiples or submultiples by an appropriate unit of time (e.g. mGy h 1 ). 3.3 dose equivalent H product of the absorbed dose, D, and the quality factor, Q, at a point in an irradi
28、ated medium H DQ = (3) NOTE 1 For beta, X and gamma radiation, Q can be taken as equal to unity for external radiation 1 . NOTE 2 The SI unit of dose equivalent is joule per kilogram (J kg 1 ) with the special name of sievert (Sv). 3.4 dose equivalent rate H quotient of dH by dt, where dH is the inc
29、rement of dose equivalent in the time interval, dt dd H Ht = (4) NOTE The SI unit of dose equivalent rate is the sievert per second (Sv s 1 ). Units of dose equivalent rate are any quotient of the sievert or its decimal multiples and a suitable unit of time (e.g. mSv h 1 ). 3.5 directional dose equi
30、valent for weakly penetrating radiation (0,07; ) H dose equivalent that, at a point in a radiation field, is produced by the corresponding expanded field in the ICRU sphere at a depth of 0,07 mm on a radius in a specified direction, NOTE 1 The unit of the directional dose equivalent is joule per kil
31、ogram (J kg 1 ) with the special name sievert (Sv). NOTE 2 In the expanded field, the fluence and its angular and energy distributions have the same value over the volume of interest as in the actual field at the point of measurement. NOTE 3 See ICRU 56 2 . BS ISO 6980-1:20063 3.6 personal dose equi
32、valent for weakly penetrating radiation H p (0,07) dose equivalent in soft tissue below a specified point on the body at a depth of 0,07 mm NOTE 1 The unit of the personal dose equivalent is joule per kilogram (J kg 1 ) with the special name sievert (Sv). NOTE 2 In a unidirectional field, the direct
33、ion can be specified in terms of the angle, , between the direction opposing the incident field and a specified normal on the phantom surface. 3.7 total mass stopping power S/ the quotient of dE by dl, where dE is the energy lost by a charged particle in traversing a distance, dl, in a material of m
34、ass density, 1d d SE l = (5) NOTE 1 The SI unit of mass stopping power is joule per square metre (J m 2kg 1 ). E can be expressed in electronvolts (eV) and hence S/ can be expressed in eV m 2kg 1 . NOTE 2 S is the total linear stopping power. NOTE 3 For energies at which nuclear interactions can be
35、neglected, the total mass stopping power is col rad 1d 1d dd SEE ll =+ (6) where col col (d /d ) ElS = is the linear collision stopping power; rad rad (d /d ) ElS = is the linear radiative stopping power. 3.8 ICRU tissue material with a density of 1 g cm 3and a mass composition of 76,2 % oxygen, 10,
36、1 % hydrogen, 11,1 % carbon, and 2,6 % nitrogen NOTE See ICRU report 39 10 . 3.9 tissue equivalence property of a material that approximates the radiation attenuation and scattering properties ICRU tissue NOTE See Annex A; more tissue substitutes are given by ICRU report 44 3 . 3.10 maximum beta ene
37、rgy E maxhighest value of the energy of beta particles emitted by a particular nuclide that can emit one or several continuous spectra of beta particles with different maximum energies BS ISO 6980-1:20064 3.11 residual maximum beta energy E reshighest value of the energy of a beta-particle spectrum
38、at the calibration distance after having been modified by scattering and absorption 3.12 residual maximum beta particle range R resrange in an absorbing material of a beta-particle spectrum of residual maximum energy, E res4 Requirements for reference beta-particle radiation fields at the calibratio
39、n distance 4.1 Energy of the reference radiation fields The energy of the reference radiation field is defined to be equal to E res(see 3.11 and 6.1.2). 4.2 Shape of the beta-particle spectrum The beta-particle spectrum of the reference radiation should ideally result from one beta decay branch from
40、 one radionuclide. In practice, the emission of more than one branch is acceptable provided that all the main branches have similar energies, E max , within 20 % In other cases, the lower energy branches shall be attenuated by the source encapsulation or by additional filtration to reduce their beta
41、 emission rates to less than 10 % of the emission rate from the main branch. 4.3 Uniformity of the dose rate The dose rate at the calibration distance should be as uniform as possible over the area of the detector. Since available sources for series 1 reference radiation fields (see 6.2.2) cannot at
42、 present produce high absorbed dose rates with satisfactory uniformity for large radiation field diameters, a further series (series 2) of reference beta-particle radiation fields is proposed (see 6.2.3). A beta-particle radiation field is considered to be uniform over a certain radiation field diam
43、eter if the dose rate does not vary by more than 5 % for E resW 300 keV and by not more than 10 % for E res 300 keV (see 6.2.2). 4.4 Photon contamination The photon dose rate contributing to H p (0,07) due to contamination of the reference radiation by gamma, X-ray and bremsstrahlung radiation shoul
44、d be less than 5 % of the beta particle dose rate recorded by the detector under calibration. 4.5 Variation of the beta-particle emission with time The beta-particle emission rate decreases with time due to the radioactive decay of the beta particle source. The half-life of a radionuclide should be
45、as long as possible, preferably longer than one year. The half-lives of the recommended sources are given in Table 1. 5 Radionuclides suitable for reference beta-particle radiation fields Table 1 gives the characteristics of beta-particle-emitting radionuclides of a suitable energy range. Beta- part
46、icle-emitting radionuclides should be selected from those listed in this table. These radionuclides emit a continuous spectrum of beta particles with energies ranging from zero up to a maximum value, E max , characteristic of the particular nuclide. Note that a radionuclide normally requires encapsu
47、lation to be a practical source and that the encapsulating material produces bremsstrahlung and characteristic X-rays. BS ISO 6980-1:20065 Table 1 Beta particle radionuclide data Radionuclide Half life adays Maximum energy emitted b E maxMeV Photon radiation 14 C 2 093 000 0,156 None 147 Pm 958,2 0,
48、225 : 0,121 MeV (0,01 %) Sm X-rays: 5,6 to 7,2 keV 39,5 to 46,6 keV 85 Kr 3 915 0,687 : 0,514 MeV (0,4 %) 204 Tl 1 381 0,763 Hg X-rays: 9,9 to 13,8 keV 68,9 to 82,5 keV 90 Sr + 90 Y 10 523 2,274 None 106 Ru + 106 Rh 373,6 3,54 106 Rh : 0,121 MeV (0,01 %) 0,622 MeV (11 % doublet) 1,05 MeV (1,5 % doub
49、let) 1,13 MeV (0,5 % doublet) 1,55 MeV (0,2 %) a The values in this column taken from ISO 6980-2:2004 Table C.4 11 . b The values given in this column are for information purposes only. 6 Source characteristics and their measurement 6.1 Fundamental characteristics of reference sources 6.1.1 Construction of reference sources The construction of the reference sources sh
