ASTM E545-2014 red 7511 Standard Test Method for Determining Image Quality in Direct Thermal Neutron Radiographic Examination《测定直接热中子射线照相检验中成像质量的标准试验方法》.pdf

《ASTM E545-2014 red 7511 Standard Test Method for Determining Image Quality in Direct Thermal Neutron Radiographic Examination《测定直接热中子射线照相检验中成像质量的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM E545-2014 red 7511 Standard Test Method for Determining Image Quality in Direct Thermal Neutron Radiographic Examination《测定直接热中子射线照相检验中成像质量的标准试验方法》.pdf（7页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: E545 05 (Reapproved 2010)E545 14Standard Test Method forDetermining Image Quality in Direct Thermal NeutronRadiographic Examination1This standard is issued under the fixed designation E545; the number immediately following the designation indicates the year oforiginal adoption or, in th

2、e case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope Sco

3、pe*1.1 This test method covers the use of an Image Quality Indicator (IQI) system to determine the relative2 quality of radiographicimages produced by direct, thermal neutron radiographic examination. The requirements expressed in this test method are notintended to control the quality level of mate

4、rials and components.1.2 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of theuser of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitationsprior to use.1.3

5、 The values stated in SI units are regarded to be standard.2. Referenced Documents2.1 ASTM Standards:3E543 Specification for Agencies Performing Nondestructive TestingE748 Practices for Thermal Neutron Radiography of MaterialsE803 Test Method for Determining the L/D Ratio of Neutron Radiography Beam

6、sE1316 Terminology for Nondestructive ExaminationsE2003 Practice for Fabrication of the Neutron Radiographic Beam Purity IndicatorsE2023 Practice for Fabrication of Neutron Radiographic Sensitivity Indicators3. Terminology3.1 DefinitionsFor definitions of terms used in this test method, see Terminol

7、ogy E1316, Section H.4. Summary of Test Method4.1 The judgment of the quality of a neutron radiograph is based upon the evaluation of images obtained from indicators thatare exposed along with the test object. In cases of limited film size or extended object size, the indicators may be exposed onano

8、ther film immediately prior to or following exposure of the test object under exactly the same conditions (refer to ProcessControl Radiographs, Section 10). The IQI values must be determined from films with an optical density between 2.0 to 3.0. Twotypes of IQIs are used.4.1.1 Beam Purity Indicator

9、(BPI)The BPI is a device used for quantitative determination of radiographic quality. It is apolytetrafluoroethylene block containing two boron nitride disks, two lead disks, and two cadmium wires.Akey feature of the BPIis the ability to make a visual analysis of its image for subjective information

10、, such as image unsharpness and film and processingquality. Densitometric measurements of the image of the device permit quantitative determination of the effective value for thethermal neutron content, gamma content, pair production content, and scattered neutron content. The BPI shall be construct

11、ed inaccordance with Practice E2003. Optionally, any BPI fabricated prior to publication of Practice E2003 which conforms to TestMethod E545 - 81 through 91 may be used.1 This test method is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Su

12、bcommittee E07.05 on Radiology(Neutron) Method.Current edition approved June 1, 2010June 1, 2014. Published November 2010June 2014. Originally approved in 1975. Last previous edition approved in 20052010 asE545 - 05.E545 - 05(2010). DOI: 10.1520/E0545-05R10.10.1520/E0545-14.2 The numerical values ob

13、tained in the calculations described herein may vary between different film processing systems, film types, and within one processing systemif processing variables changes.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Ann

14、ual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.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

15、 technically possible to adequately depict all changes accurately, ASTM recommends that users 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.*A Summary of Changes section appears at the end of

16、 this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.1.2 Sensitivity Indicator (SI)The SI is one of several devices used for qualitative determination of the sensitivity of detailvisible on a neutron radiograph. The SI is a

17、 step-wedge device containing gaps and holes of known dimensions. Visual inspectionof the image of this device provides subjective information regarding total radiographic sensitivity with respect to the step-blockmaterial. The SI shall be in accordance with Practice E2023. Optionally, any SI fabric

18、ated prior to publication of Practice E2023which conforms to Test Method E545-81 through 91 may be used.4.2 Neutron radiography practices are discussed in Practices E748.5. Significance and Use5.1 The BPI is designed to yield quantitative information concerning neutron beam and image system paramete

19、rs that contributeto film exposure and thereby affect overall image quality. In addition, the BPI can be used to verify the day-to-day consistency ofthe neutron radiographic quality. Gadolinium conversion screens and single-emulsion silver-halide films, exposed together in theneutron imaging beam, w

20、ere used in the development and testing of the BPI. Use of alternative detection systems may producedensitometric readings that are not valid for the equations used in Section 9.5.2 The only truly valid sensitivity indicator is a reference standard part. A reference standard part is a material or co

21、mponentthat is the same as the object being neutron radiographed except with a known standard discontinuity, inclusion, omission, or flaw.The sensitivity indicators were designed to substitute for the reference standard and provide qualitative information on hole andgap sensitivity.5.3 The number of

22、 areas or objects to be radiographed and the film acceptance standard used should be specified in the contract,purchase order, specification, or drawings.6. Basis of Application6.1 Qualification of Nondestructive AgenciesIf specified in the contractual agreement, NDT agencies shall be qualified ande

23、valuated in accordance with Practice E543. The applicable revision of Practice E543 shall be specified in the contractualagreement.6.2 Procedures and TechniquesThe procedures and techniques to be utilized shall be as described in this test method unlessotherwise specified. Specific techniques may be

24、 specified in contractual documents.6.3 Extent of ExaminationThe extent of examination shall be in accordance with Section 7 unless otherwise specified.6.4 Reporting Criteria/Acceptance CriteriaReporting criteria for the examination results shall be in accordance with Section11 unless otherwise spec

25、ified. Acceptance criteria (for example, for reference radiographs) shall be specified in the contractualagreement.7. Procedure7.1 The direction of the beam of radiation should be as perpendicular as possible to the plane of the film.7.2 Use Conversion screens that respond to neutrons of thermal ene

26、rgies, such as metallic gadolinium.7.3 Each radiograph shall include a beam purity indicator and a sensitivity indicator (refer to Section 10 for exceptions). Theindicators shall be located no less than 25 mm from any edge of the exposed area of the film when feasible. The indicators shallbe located

27、 such that the image of the indicators on the film do not overlap the image of the object.7.4 The SI should be oriented parallel to and as close as possible to the film.7.5 The SI should be oriented such that its thickest step is not adjacent to the BPI or the objects being radiographed.7.6 The BPI

28、surface must be parallel against the film cassette face during exposure or density readings will be invalid.7.7 The cadmium wires in the BPI shall be oriented such that their longitudinal axis is perpendicular to the nearest film edge.7.8 Measure the film densities using a diffuse transmission densi

29、tometer. The densitometer shall be accurate to 60.02 densityunits.7.9 For the purpose of determining image quality, the background optical density shall be between 2.0 and 3.0 measured at thehole in the center of the BPI.7.10 The only true measurement of the beam uniformity is with a radiograph made

30、 without objects. Background film opticaldensity in the range from 2.0 to 3.0 across the film should not vary more than 65 % from the numerical mean of fivemeasurements: one measurement at the center and one measurement approximately 25 to 30 mm toward the center from eachcorner of the film. If the

31、beam diameter is smaller than the film, the four outside measurements shall be taken 25 to 30 mm fromthe edge of the beam located at 90 intervals.7.11 Radiographs shall be free of any blemish that may interfere with subsequent examination of the image.E545 1427.12 Determine the thermal neutron conte

32、nt (NC), scattered neutron content (S), gamma content (), and pair production content(P) by densitometric analysis of the BPI image. Make a determination of the constituents of film exposure by measuring thedensities in the BPI image as shown in Table 1. Calculate the various exposure contributors b

33、y the equations given in Section 9.7.13 Determine the sensitivity level by visually analyzing the image of the SI. Determine the values for G and H using Tables2 and 3.7.14 Determine the neutron radiographic category from Table 4.7.15 Visually compare the images of the cadmium wires in the BPI.An ob

34、vious difference in image sharpness indicates an L/Dratio of 35 or less. Use Method E803 for quantifying the L/D ratio.7.16 If a lead shim is in the sensitivity indicator, visually inspect the image of the lead steps. If the holes are not visible, theexposure contribution from gamma radiation is ver

35、y high.8. Image Quality Levels8.1 The ASTM designation of quality level shall include thermal neutron content and sensitivity level. The designation isNC-H-G (see 9.1 and 7.13). Values for scattered neutron content, gamma content, and pair production content may be specifiedat the option of the user

36、. (When no designation of NC-H-G is specified by the customer, radiographs shall be Category I or II.)8.2 Visual analysis of the BPI requires inspection of two areas the image of the cadmium wires and the image of the areascontaining the lead disks. If either of the cadmium wire appears significantl

37、y less sharp than the other image, the L/D ratio is lowerthan normally required. If the lead disks noticeably appear either darker or lighter than the surrounding polytetrafluoroethylene,there is either a high gamma content (lighter image) or a high pair production content (darker image). Any of the

38、se observationsindicates the need for further image analysis and subsequent determination of the usefulness of the radiograph for that particularexamination.9. Determination of Exposure Contributors9.1 Calculate the effective thermal neutron content, NC, as follows:NC5DH 2higher DB1DL!DH3100 (1)wher

39、e definitions of D parameters are given in Table 1.TABLE 1 Definitions of D ParametersDB Film densities measured through the images of the boron nitride disks.DL Film densities measured through the images of the lead disks.DH Film density measured at the center of the hole in the BPI.DT Film density

40、 measured through the image of the polytetrafluoroethylene.DL Difference between the DL values.DB Difference between the two DB values.TABLE 1 Definitions of D ParametersDB Film densities measured through the images of the boron nitride disks.DL Film densities measured through the images of the lead

41、 disks.DH Film density measured at the center of the hole in the BPI.DT Film density measured through the image of the polytetrafluoroethylene.DL Difference between the DL values.DB Difference between the two DB values.E545 1439.2 Calculate the effective scattered neutron content, S, as follows:TABL

42、E 2 Determination of HNOTE 1The value of H reported is the largest consecutive numberedhole that is visible in the image.NOTE 2For hole sizes and shim thicknesses, refer to Practice E2023.NOTE 3The dots on the SI represent holes in the optional lead shim.Value of H Shim1 C2 C3 C4 C5 B6 B7 B8 B9 A10

43、A11 A12 ATABLE 2 Determination of HNOTE 1The value of H reported is the largest consecutive numberedhole that is visible in the image.NOTE 2For hole sizes and shim thicknesses, refer to Practice E2023.NOTE 3The dots on the SI represent holes in the optional lead shim.Value of H Shim1 C2 C3 C4 C5 B6

44、B7 B8 B9 A10 A11 A12 AE545 144S 5DB/DH!3100 (2)9.3 Calculate the effective gamma content, , as follows:5DT 2lower DL!/DH)3100 (3)9.4 Calculate the effective pair production content, P, as follows:P 5DL/DH!3100 (4)10. Process Control Radiographs10.1 A process control radiograph (as defined in Termino

45、logy E1316, Section H)E1316 may be prepared for verification ofexposure and sensitivity requirements when the following occur:TABLE 3 Determination of GNOTE 1The value of G reported is the smallest gap that can be seenat all absorber thicknesses.NOTE 2For gap sizes, refer to Practice E2023.E2003Valu

46、e of G Gap1 T2 U3 V4 W5 X6 Y7 ZTABLE 3 Determination of GNOTE 1The value of G reported is the smallest gap that can be seenat all absorber thicknesses.NOTE 2For gap sizes, refer to Practice E2023.E2003Value of G Gap1 T2 U3 V4 W5 X6 Y7 ZTABLE 4 Neutron Radiographic CategoriesNOTE 1It should be recogn

47、ized that these categories favor contrastfactors because the sensitivity indicators do not permit accurate determi-nation of sharpness alone. It may, therefore, be advantageous to use alower number category when sharpness is a more important factor thancontrast.Category NC H G S PI 65 6 6 5 3 3II 60

48、 6 6 6 4 4III 55 5 5 7 5 5IV 50 4 5 8 6 6V 45 3 5 9 7 7TABLE 4 Neutron Radiographic CategoriesNOTE 1It should be recognized that these categories favor contrastfactors because the sensitivity indicators do not permit accurate determi-nation of sharpness alone. It may, therefore, be advantageous to u

49、se alower number category when sharpness is a more important factor thancontrast.Category NC H G S PI 65 6 6 5 3 3II 60 6 6 6 4 4III 55 5 5 7 5 5IV 50 4 5 8 6 6V 45 3 5 9 7 7E545 14510.1.1 The size or setup of objects is such that the object-scattered neutron level relative to background density, sensitivity, orfacility-scattered neutrons exposure requirements is cause for nonconformance.10.1.2 The object configuration necessitates a film-to-beam orientation that does not permit satisfactory density measurementsfor calculation of exposu