ASTM E170-2017 red 1250 Standard Terminology Relating to Radiation Measurements and Dosimetry《辐射测量和剂量相关标准术语》.pdf

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1、Designation: E170 16aE170 17Standard Terminology Relating toRadiation Measurements and Dosimetry1This standard is issued under the fixed designation E170; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A

2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis terminology generally covers terms that apply to radiation measurements and dosimetryassociated with energy deposition and radiat

3、ion effects, or damage, in materials caused by interactionsby high-energy radiation fields. The common radiation fields considered are X-rays, gamma rays,electrons, alpha particles, neutrons, and mixtures of these fields. This treatment is not intended to beexhaustive but reflects special and common

4、 terms used in technology and applications of interest toCommittee E10, as for example, in areas of radiation effects on components of nuclear power reactors,radiation hardness testing of electronics, and radiation processing of materials.This terminology uses recommended definitions and concepts of

5、 quantities, with units, for radiationmeasurements as contained in the International Commission on Radiation Units and Measurements(ICRU) Report 85a on “Fundamental Quantities and Units for Ionizing Radiation,” October 2011.2Those terms that are defined essentially according to the terminology of IC

6、RU Report 85a will befollowed by ICRU in parentheses. It should also be noted that the units for quantities used are the latestadopted according to the International System of Units (SI) which are contained in Appendix X1 astaken from a table in ICRU Report 85a.2 This terminology also uses recommend

7、ed definitions of twoJCGM documents,3 namely “International vocabulary of metrology” (VIM, 2012, unless indicatedotherwise) and “Guide to the expression of uncertainty in measurement” (GUM, 2008). Those termsthat are defined essentially according to the terminology of these documents will be followe

8、d by eitherVIM or GUM in parentheses.A term is boldfaced when it is defined in this standard. For some terms, text in italics is used justbefore the definition to limit its field of application, for example, see activity.1. Referenced Documents1.1 ASTM Standards:4E380 Practice for Use of the Interna

9、tional System of Units (SI) (the Modernized Metric System) (Withdrawn 1997)5E722 Practice for Characterizing Neutron Fluence Spectra in Terms of an Equivalent Monoenergetic Neutron Fluence forRadiation-Hardness Testing of ElectronicsE910 Test Method for Application and Analysis of Helium Accumulatio

10、n Fluence Monitors for Reactor Vessel Surveillance,E706 (IIIC)1.2 Joint Committee for Guides in Metrology (JCGM) Reports:3JCGM 100:2008, GUM 1995 , with minor corrections, Evaluation of measurement data Guide to the expression of uncertaintyin measurementJCGM 200:2012, VIM International vocabulary o

11、f metrology Basic and general concepts and associated terms1 This terminology is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applications and is the direct responsibility of Subcommittee E10.93on Editorial.Current edition approved Oct. 1, 2016June 1, 2017. Published Novemb

12、er 2016June 2017. Originally approved in 1963. Last previous edition approved in 2016 asE170 16.E170 16a. DOI: 10.1520/E0170-16A.10.1520/E0170-17.2 ICRU Report 60 has been superseded by ICRU Report 85a on “Fundamental Quantities and Units for Ionizing Radiation,” October 2011. Both of these document

13、s areavailable from International Commission on Radiation Units and Measurements (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.3 Document produced by Working Groups of the Joint Committee for Guides in Metrology (JCGM). Available free of charge at BIPM website (http:/www.bipm.org).4 For

14、referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.5 The last approved version of this historical standard is referenc

15、ed on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that user

16、s consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.3 ICRU Documents:2ICRU 60 F

17、undamental Quantities and Units for Ionizing Radiation, December 30, 1998ICRU 85a Fundamental Quantities and Units for Ionizing Radiation, October, 20111.4 NIST Document:6NIST Technical Note 1297 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results, 19941.5 ISO Standa

18、rd:7ISO 10012 Measurement management systems Requirements for measurement processes and measuring equipment2. Terminologyabsorbed dose (D)quotient of d by dm, where d is the mean incremental energy imparted by ionizing radiation to matterof incremental mass dm. (ICRU), thusD 5d/dm (1)DISCUSSIONThe S

19、I unit of absorbed dose is the gray (Gy), where 1 gray is equivalent to the absorption of 1 joule per kilogram of the specified material (1 Gy= 1 J/kg). The unit rad (1 rad = 100 erg/g = 0.01 Gy) is still widely used in the nuclear community; however, its continued use is not encouraged. Fora photon

20、 source under conditions of charged particle equilibrium, the absorbed dose, D, may be expressed as follows:D 5Een/, (2)where: = fluence (m2),E = energy of the ionizing radiation (J), anden/ = mass energy absorption coefficient (m2/kg).If bremsstrahlung production within the specified material is ne

21、gligible, the mass energy absorption coefficient (en/) is equal to the mass energytransfer coefficient (tr/), and absorbed dose is equal to kerma if, in addition, charged particle equilibrium exists.absorbed dose rate (D)quotient of dD by dt where dD is the increment of absorbed dose in the time int

22、erval dt (ICRU), thusD 5dD/dt (3)SI unit: Gys1.DISCUSSIONThe absorbed-dose rate is often specified as an average value over a longer time interval, for example, in units of Gymin1 or Gyh1.accuracycloseness of agreement between a measured quantity value and a true quantity value of a measurand (VIM).

23、DISCUSSION(1) The concept “accuracy” is not a quantity and is not given a numerical quantity value. A measurement is said to be moreaccurate when it offers a smaller measurement error.(2) The term “accuracy” should not be used for measurement trueness and the term “precision” should not be used for“

24、accuracy,” which, however, is related to both these concepts.(3) “Accuracy” is sometimes understood as closeness of agreement between measured quantity values that are being attributedto the measurand.activation cross sectioncross section for a specific direct or compound nuclear interaction in whic

25、h the product nucleus isradioactive.DISCUSSIONFission and spallation processes produce a statistical ensemble of outgoing nuclear channels, but they are not considered to be activation reactions.activity (A)of an amount of radionuclide in a particular energy state at a given time, quotient of dN by

26、dt, where dN is themean change in the number of nuclei in that energy state due to spontaneous nuclear transformations in the time interval dt(ICRU), thus6 Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, USA, http:/www.nis

27、t.gov7 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.E170 172A 52dN/dt (4)Unit: s1The special name for the unit of activity is the becquerel (Bq), where1Bq51s2

28、1 (5)DISCUSSIONThe former special unit of activity was the curie (Ci), where1Ci53.731010 s21 exactly!. (6)The negative sign in Eq 4 is an indication that the activity is decreasing with time. The “particular energy state” is the ground state of the nuclideunless otherwise specified. The activity of

29、an amount of radionuclide in a particular energy state is equal to the product of the decay constant forthat state and the number of nuclei in that state (that is, A = N). (See decay constant.)aleatory uncertaintyuncertainty representing random uncertainty contributors where there is little possibil

30、ity of reducing thisuncertainty contributor by consideration of a more controlled scenario.DISCUSSION(1) One paradigm decomposes uncertainty into epistemic and aleatory components. This division of uncertainty categories isvery dependent upon what question is being posed in a given application.Aleat

31、ory uncertainties can be transformed into epistemicuncertainties depending upon the application. The uncertainties underlying a quantity may be classified as aleatory or epistemicaccording to the goals of the process.(2) Aleatory uncertainty, also referred to as variability, stochastic uncertainty o

32、r irreducible uncertainty, is used to describeinherent variation associated with a quantity or phenomenon of interest. The determination of material properties or operatingconditions of a physical system typically leads to aleatory uncertainties; additional experimental characterization might provid

33、emore conclusive description of the variability but cannot eliminate it completely. Aleatory uncertainty is normally characterizedusing probabilistic approaches.analysis bandwidthspectral band used in an instrument, such as a densitometer, for a measurement.analysis wavelengthwavelength used in a sp

34、ectrophotometric instrument for the measurement of optical absorbance orreflectance.annihilation radiationgamma radiation produced by the annihilation of a positron and an electron.DISCUSSIONFor particles at rest, two photons are produced, each having an energy corresponding to the rest mass of an e

35、lectron (511 keV).backscatter peakpeak in the observed photon spectrum resulting from large-angle (110) Compton scattering of gamma raysfrom materials near the detector.DISCUSSIONThis peak is normally below about 0.25 MeV. Also, it will not have the same shape as the full-energy peaks (being wider a

36、nd skewed toward lowerenergy).benchmark neutron fieldwell-characterized irradiation environment which provides a fluence or fluence rate of neutronssuitable for the validation or calibration of experimental techniques and methods as well as for validation of cross sections andother nuclear data, whe

37、re following classification for reactor dosimetry has been made:8controlled neutron fieldneutron field physically well-defined, and with some spectrum definition, employed for a restricted setof validation experiments.reference neutron fieldpermanent and reproducible neutron field less well characte

38、rized than a standard field but accepted asa measurement reference by a community of users.standard neutron fieldpermanent and reproducible neutron field that is characterized to state-of-the-art accuracy in terms ofneutron fluence rate and energy spectra, and their associated spatial and angular di

39、stributions, where important field quantities needto be verified by interlaboratory measurements.DISCUSSION8 The following three definitions are derived from: Neutron Cross Sections for Reactor Dosimetry, International Atomic Energy Agency, Laboratory Activities, Vienna,Vol 1, 1978, p. 62 and Vlasov

40、, M., IAEA Program on Benchmark Neutron Fields Applications for Reactor Dosimetry, Report INDC(SEC)-54/L+Dos, IAEA, Vienna, 1976.E170 173A type of neutron field is considered to be a “standard” over a specified energy range and there is only one type of “standard neutron field” for a givenenergy ran

41、ge. Currently, the 252Cf spontaneous fission field is a “standard neutron field” from 0.5 MeV to 8 MeV. The deuterium-tritium (DT)accelerator field is considered to be the “standard neutron field” from 13.5 to 15 MeV. The thermal Maxwellian and epithermal 1/E slowing-down fieldare also considered to

42、 be “standard neutron fields.”bremsstrahlungbroad-spectrum electromagnetic radiation emitted when an energetic charged particle is influenced by a strongelectric field, such as the Coulomb field of an atomic nucleus.DISCUSSIONIn radiation processing, bremsstrahlung photons are generated by the decel

43、eration or deflection of energetic electrons in a target material. When anelectron passes close to an atomic nucleus, the strong Coulomb field causes the electron to deviate from its original motion. This interaction resultsin a loss of kinetic energy by the electron with the emission of electromagn

44、etic radiation; the photon energy distribution extends up to the maximumkinetic energy of the incident electron. This bremsstrahlung spectrum depends on the electron energy, the composition and thickness of the target, andthe angle of emission with respect to the incident electron.buildupfactorfor r

45、adiation passing through a medium, ratio of the total value of a specified radiation quantity (such as absorbeddose) at any point in that medium to the contribution to that quantity from the incident uncollided radiation reaching that point.cadmium ratioratio of the neutron reaction rate measured wi

46、th a given bare neutron detector to the neutron reaction ratemeasured with an identical neutron detector enclosed by a particular cadmium cover and exposed in the same neutron field atthe same or an equivalent spatial location.DISCUSSIONIn practice, meaningful experimental values can be obtained in

47、an isotropic neutron field by using a cadmium filter approximately 1 mm thick.calibrated instrumentinstrument that has been through a calibration process at established time intervals.DISCUSSIONMeasurements carried out by this instrument have metrological traceability to the reference standard if ca

48、libration is properly carried out.calibrationset of operations that establish, under specified conditions, the relationship between values of quantities indicated bya measuring instrument or measuring system, or values represented by a material measure or a reference material, and thecorresponding v

49、alues realized by standards (VIM: 1993).DISCUSSION(1) Calibration conditions include environmental and irradiation conditions present during calibration.(2) These standards should have metrological traceability to a national or international standard.(3) To be reliable, calibration should be carried out at regular time intervals frequency may depend on the final use of thedata. Often, the frequency is specified by regulatory authorities.calibration source or fieldsee electron standard field, gamma-ray