DIN ISO 12789-2-2013 Reference radiation fields - Simulated workplace neutron fields - Part 2 Calibration fundamentals related to the basic quantities (ISO 12789-2 2008)《参考辐射区域 模拟工.pdf

1、January 2013 Translation by DIN-Sprachendienst.English price group 11No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).IC

2、S 17.240!$LW“1934152www.din.deDDIN ISO 12789-2Reference radiation fields Simulated workplace neutron fields Part 2: Calibration fundamentals related to the basic quantities(ISO 12789-2:2008),English translation of DIN ISO 12789-2:2013-01Referenzstrahlungsfelder Simulierte Arbeitsplatz-Neutronenfelde

3、r Teil 2: Grundlagen der Kalibrierung mit Bezug auf Grundgren (ISO 12789-2:2008),Englische bersetzung von DIN ISO 12789-2:2013-01Champs de rayonnement de rfrence Champs de neutrons simulant ceux de postes de travail Partie 2: Concepts dtalonnage en relation avec les grandeurs fondamentales(ISO 12789

4、-2:2008),Traduction anglaise de DIN ISO 12789-2:2013-01www.beuth.deDocument comprises pagesIn case of doubt, the German-language original shall be considered authoritative.1912.12 DIN ISO 12789-2:2013-01 A comma is used as the decimal marker. Contents Page National foreword .3 National Annex NA (inf

5、ormative) Bibliography 3 Introduction .4 1 Scope 5 2 Terms and definitions .5 3 List of symbols .8 4 Properties of simulated workplace neutron field facilities .9 5 Characterization of simulated workplace neutron fields 9 6 Uncertainties . 13 Annex A (normative) Conversion coefficients 16 Bibliograp

6、hy . 18 2 Tables Table A.1 . 16 DIN ISO 12789-2:2013-01 National foreword This standard has been prepared by Technical Committee ISO/TC 85 “Nuclear energy”, Subcommittee SC 2 “Radiation protection” (Secretariat: AFNOR, France). The responsible German body involved in its preparation was the Normenau

7、sschuss Radiologie (Radiology Standards Committee), Working Committee NA 080-00-01 AA Dosimetrie, in collaboration with the Deutsche Rntgengesellschaft (German Radiological Society), the Deutsche Gesellschaft fr Nuklearmedizin e. V. (DGN) (German Society of Nuclear Medicine), the Deutsche Gesellscha

8、ft fr Medizinische Physik e. V. (DGMP) (German Society for Medical Physics) and the Deutsche Gesellschaft fr Radioonkologie e. V. (DEGRO) (German Society for Radio Oncology). The text of ISO 12789-2:2008 “Reference radiation fields Simulated workplace neutron fields Part 2: Calibration fundamentals

9、related to the basic quantities” has been adopted in this standard without any modification. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. DIN shall not be held responsible for identifying any or all such patent rights. DIN ISO

10、12789 consists of the following parts, under the general title Reference radiation fields Simulated workplace neutron fields: Part 1: Characteristics and methods of production Part 2: Calibration fundamentals related to the basic quantities National Annex NA (informative) Bibliography DIN 6802-1:199

11、1-11, Neutron dosimetry Part 1: Special terms and definitions DIN 6814-2:2000-07, Terms in the field of radiological technique Part 2: Radiation physics DIN 6814-3:2001-01, Terms and definitions in the field of radiological technique Part 3: Dose quantities and units 3 Introduction Neutron fields co

12、mmonly encountered in radiation workplaces are, in most cases, quite different from routinely used calibration fields produced using standard radionuclide sources in low-scatter calibration facilities. The dose equivalent response of personal neutron dosemeters and neutron area survey meters depends

13、 upon the energy distributions of the neutron fields in which they are used, and, in the case of personal dosemeters in particular, the angle of incidence of the neutrons. Calibrations of such devices in reference neutron fields as described in ISO 8529 (all parts) do not thus provide appropriate ca

14、libration factors in most cases. For this reason, several laboratories have developed simulated workplace neutron fields that are intended to simulate the characteristics of particular types of fields in which it is necessary to make personal dosemeter and area survey instrument measurements. These

15、provide facilities in which the performance of these devices in workplace fields can be investigate, and that, in some circumstances, can act as calibration facilities. Because workplace neutron fields depend upon the physical structure of each workplace, this part of ISO 12789 has been written to s

16、pecify the methods of producing and characterizing simulated workplace neutron fields rather than standardizing reference fields as is the philosophy in the companion standard, ISO 8529 (all parts). This part of ISO 12789 is closely related to ISO 12789-1, which describes the facilities and methods

17、currently used to produce simulated workplace neutron radiation fields. These fields have been constructed specifically to moderate source neutrons and include neutrons scattered from the surrounding structure and equipment for the simulation of workplace environments. This part of ISO 12789 describ

18、es the methods used to determine conventional values of the operational quantities characterizing the realistic workplace neutron fields. The operational quantities used in this part of ISO 12789 are ambient dose equivalent, H*(10), and personal dose equivalent, Hp(10). For reference radiation field

19、s, it is recommended to determine their conventional values from the neutron fluence or fluence rate as a function of neutron energy and, for the case of Hp(10), the direction using the conversion coefficients listed in Annex A. In some cases, the use of conversion coefficients is not feasible for d

20、etermining Hp(10), necessitating its direct calculation. At present, no simple methods exist to provide traceability of the operational quantities from a national standards institute to the simulated workplace neutron fields. The process of determining operational quantities from fluence described i

21、n this part of ISO 12789 introduces additional uncertainty. values of the operational quantities and gives new information regarding the uncertainty associated with the inference of energy distributions of neutron fluence using accepted unfolding techniques. The uncertainties in determining Hp(10) u

22、sing information from the direction distribution of the neutron fluence can be large but, at present, the quantification of the uncertainty from this source is not addressed. Reference radiation fields Simulated workplace neutron fields Part 2: Calibration fundamentals related to the basic quantitie

23、s 4 This part of ISO 12789 incorporates accepted methods for determining the uncertaintyN1)associated with the DIN ISO 12789-2:2013-01 N1) National footnote: This standard uses the term “uncertainty in measurement” 8 (Messunsicherheit) even if the quantity to be determined is obtained by way of calc

24、ulation. 1 Scope This part of ISO 12789 describes the characterization of simulated workplace neutron fields produced by methods described in ISO 12789-1. It specifies the procedures used for establishing the calibration conditions of radiation protection devices in neutron fields produced by these

25、facilities, with particular emphasis on the scattered neutrons. The diversity of workplace neutron fields is such that several special facilities have been built in order to simulate them in the laboratory. In this part of ISO 12789, the neutron radiation field specifications are classified by opera

26、tional quantities. General methods for characterizing simulated workplace neutron fields are recommended. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 indication reading M quantity value provided by a measuring instrument or a measuring sy

27、stem NOTE 1 An indication may be presented in visual or acoustic form or may be transferred to another device. An indication is often given by the position of a pointer on the display for analog outputs, a displayed or printed number for digital outputs, a code pattern for code outputs, or an assign

28、ed quantity value for material measures. NOTE 2 An indication and a corresponding value of the quantity being measured are not necessarily values of quantities of the same kind. ISO/IEC Guide 99:2007, 4.1 2.2 conventional quantity value conventional value of a quantity quantity value attributed by a

29、greement to a quantity for a given purpose EXAMPLE 1 Standard acceleration of free fall (formerly called “standard acceleration due to gravity”) gn= 9,806 65 ms2. EXAMPLE 2 Conventional quantity value of the Josephson constant, KJ-90= 483 597,9 GHz V1. EXAMPLE 3 Conventional quantity value of given

30、mass standard, m = 100,003 47 g. NOTE 1 The term “conventional true quantity value” is sometimes used for this concept, but its use is discouraged. 5 N2)N2) National footnote: The definitions also comply with DIN 6802-1:1991-11, DIN 6814-2:2000-07 and DIN 6814-3:2001-01. DIN ISO 12789-2:2013-01 NOTE

31、 2 Sometimes a conventional quantity value is an estimate of a true quantity value. NOTE 3 A conventional quantity value is generally accepted as being associated with a suitably small measurement uncertainty, which might be zero. ISO/IEC Guide 99:2007, 2.12 2.3 neutron fluence quotient of dN by da,

32、 where dN is the number of neutrons incident on a sphere of cross-sectional area da, as given in Equation (1): ddNa = (1) NOTE The unit of the neutron fluence is metres to the negative 2 (m2). 2.4 neutron fluence rate quotient of d by dt, where d is the increment of neutron fluence in the time inter

33、val dt, as given in Equation (2): 2dddddNtat = (2) NOTE 1 The unit of neutron fluence rate is metres to the negative 2 times reciprocal seconds (m2s1). NOTE 2 This quantity is also termed neutron flux density. 2.5 energy distribution of the neutron fluence Equotient of d by dE, where d is the increm

34、ent of neutron fluence in the energy interval between E and E + dE, as given in Equation (3): ddEE = (3) NOTE The unit of the energy distribution of the neutron fluence is metres to the negative 2 times reciprocal joules (m2J1) 2.6 energy and direction distribution of the neutron fluence E,quotient

35、of d by dE and d, where d is the increment of neutron fluence in the energy interval between E and E + dE and the solid angle interval between and + d, as given in Equation (4): 2,dddEE= (4) NOTE The unit of the energy and direction distribution of the neutron fluence is metres to the negative 2 tim

36、es reciprocal joules times reciprocal steradians (m2J1sr1). 6 DIN ISO 12789-2:2013-01 2.7 ambient dose equivalent at 10 mm depth (10) dose equivalent at a point in the radiation field that would be produced by the corresponding expanded and aligned field, in the ICRU sphere at a depth of 10 mm on th

37、e radius opposite the direction of the aligned field NOTE The unit of ambient dose equivalent is joules times reciprocal kilograms (J kg1) with the special name of sievert (Sv). 2.8 personal dose equivalent at 10 mm depth Hp(10) dose equivalent in soft tissue at a depth of 10 mm below a specified po

38、int on the body NOTE 1 The unit of personal dose equivalent is joules times reciprocal kilograms (J kg1) with the special name of sievert (Sv). NOTE 2 In ICRU Report 4712, the ICRU considers the definition of the personal dose equivalent to include the dose equivalent at a depth, d, in a phantom hav

39、ing the composition of ICRU tissue. Then, Hp(10) for the calibration of personal dosemeters is the dose equivalent at a depth of 10 mm in a phantom composed of ICRU tissue, but of the size and shape of the phantom used for calibration (30 cm 30 cm 15 cm parallelepiped) and the conversion coefficient

40、s, hp,slab(10), are calculated for this configuration. 2.9 neutron fluence-to-dose-equivalent conversion coefficient hquotient of the neutron dose equivalent, H, by the neutron fluence, , at a point in the radiation field, as given in Equation (5): Hh= (5) NOTE Any statement of a fluence-to-dose-equ

41、ivalent conversion coefficient requires a statement of the type of dose equivalent, e.g. ambient dose equivalent hor personal dose equivalent hp,slab . 2.10 response R of a measuring instrument indication or reading divided by the conventional value of the quantity causing it NOTE The type of respon

42、se should be specified, e.g., “fluence response”, as given in Equation (6): MR= (6) or “dose equivalent response”, as given in Equation (7): HMRH= (7) If M is a measurement of a rate, then the quantities fluence, , and dose equivalent, H, are replaced by fluence rate, , and dose equivalent rate, Hh(

43、E) is the fluence-to-ambient-dose-equivalent conversion coefficient as a function of the neutron energy, E, given in Annex A. It is necessary to interpolate the energy for the tabulated coefficients, using a log-log four-point Lagrange interpolation technique. 5.4 Determination of Hp,slab(10) 5.4.1

44、General The determination of Hp,slab(10) requires knowledge of both the energy and the direction distribution of the neutron fluence. These distributions should be determined in the presence of the phantom, which can disturb the incident neutron field. The method for determining the conventional val

45、ue of Hp,slab(10) depends on the homogeneity of the radiation field and whether it is incident only on the phantom front face. Calculations and/or measurements are recommended in order to assess the degree of homogeneity, according to the required uncertainty level. Two methods are proposed, the fir

46、st of which (see 5.4.2) is general and applicable to all neutron fields. The second (see 5.4.3) is applicable to the special case of a uniform field (broad and parallel or superposition of a number of such fields) incident on the phantom front face. In this case, the conversion coefficients given in

47、 Annex A can be used. 5.4.2 Non-uniform neutron fields The neutron source and the irradiation geometry shall be simulated by transport calculations. The energy distributions of the neutron and photon fluences are determined at the point at which the quantity is defined, i.e. at 10 mm depth inside th

48、e ICRU slab. For example, using the kerma approximation and the LET-dependent quality factor of neutron-induced secondary charged particles, the operational quantity is calculated as indicated in Equation (10)6: nnnnntrp,slab n f()(1 )(10) ()()d dEEEgH QE kE E E=+(10)11 DIN ISO 12789-2:2013-01 where Enis the energy distribution of the neutron fluence at the point at which the quantity is defined; Qnis the average quality factor for neutron-induced se