ASTM E545-2005 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查中成像质量的标准试验方法》.pdf

《ASTM E545-2005 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查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 E545-2005 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查中成像质量的标准试验方法》.pdf（4页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: E 545 05Standard Test Method forDetermining Image Quality in Direct Thermal NeutronRadiographic Examination1This standard is issued under the fixed designation E 545; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the

2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the use of an Image QualityIndicator (IQI) system to determine the relative2quality

3、ofradiographic images produced by direct, thermal neutronradiographic examination. The requirements expressed in thistest method are not intended to control the quality level ofmaterials and components.1.2 This standard does not purport to address the safetyconcerns, if any, associated with its use.

4、 It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.1.3 The values stated in SI units are regarded to be standard.2. Referenced Documents2.1 ASTM Standards:3E 543 Practice for

5、Agencies Performing NondestructiveTestingE 748 Practices for Thermal Neutron Radiography of Ma-terialsE 803 Method for Determining the L/D Ratio of NeutronRadiography BeamsE 1316 Terminology for Nondestructive TestingE 2003 Practice for Fabrication of Neutron RadiographicBeam Purity IndicatorsE 2023

6、 Practice for Fabrication of Neutron RadiographicSensitivity Indicators3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, see Terminology E 1316, Section H.4. Summary of Test Method4.1 The judgment of the quality of a neutron radiograph isbased upon the evaluation of imag

7、es obtained from indicatorsthat are exposed along with the test object. In cases of limitedfilm size or extended object size, the indicators may be exposedon another film immediately prior to or following exposure ofthe test object under exactly the same conditions (refer toProcess Control Radiograp

8、hs, Section 10). The IQI values mustbe determined from films with an optical density between 2.0to 3.0. Two types of IQIs are used.4.1.1 Beam Purity Indicator (BPI)The BPI is a deviceused for quantitative determination of radiographic quality. It isa polytetrafluoroethylene block containing two boro

9、n nitridedisks, two lead disks, and two cadmium wires.Akey feature ofthe BPI is the ability to make a visual analysis of its image forsubjective information, such as image unsharpness and filmand processing quality. Densitometric measurements of theimage of the device permit quantitative determinati

10、on of theeffective value for the thermal neutron content, gamma content,pair production content, and scattered neutron content. The BPIshall be constructed in accordance with Practice E 2003.Optionally, any BPI fabricated prior to publication of PracticeE 2003 which conforms to Test Method E 545 - 8

11、1 through 91may be used.4.1.2 Sensitivity Indicator (SI)The SI is one of severaldevices used for qualitative determination of the sensitivity ofdetail visible on a neutron radiograph. The SI is a step-wedgedevice containing gaps and holes of known dimensions. Visualinspection of the image of this de

12、vice provides subjectiveinformation regarding total radiographic sensitivity with re-spect to the step-block material. The SI shall be in accordancewith Practice E 2023. Optionally, any SI fabricated prior topublication of Practice E 2023 which conforms to Test MethodE 545-81 through 91 may be used.

13、4.2 Neutron radiography practices are discussed in PracticesE 748.5. Significance and Use5.1 The BPI is designed to yield quantitative informationconcerning neutron beam and image system parameters thatcontribute to film exposure and thereby affect overall imagequality. In addition, the BPI can be u

14、sed to verify the1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.05 onNeutron Radiography.Current edition approved June 1, 2005. Published June 2005. Originallyapproved in 1975. Last previous edition appr

15、oved in 2004 as E 545 - 99 (2004).2The numerical values obtained in the calculations described herein may varybetween different film processing systems, film types, and within one processingsystem if processing variables changes.3For referenced ASTM standards, visit the ASTM website, www.astm.org, o

16、rcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.day-to-day consis

17、tency of the neutron radiographic quality.Gadolinium conversion screens and single-emulsion silver-halide films, exposed together in the neutron imaging beam,were used in the development and testing of the BPI. Use ofalternative detection systems may produce densitometric read-ings that are not vali

18、d for the equations used in Section 9.5.2 The only truly valid sensitivity indicator is a referencestandard part. A reference standard part is a material orcomponent that is the same as the object being neutronradiographed except with a known standard discontinuity,inclusion, omission, or flaw. The

19、sensitivity indicators weredesigned to substitute for the reference standard and providequalitative information on hole and gap sensitivity.5.3 The number of areas or objects to be radiographed andthe film acceptance standard used should be specified in thecontract, purchase order, specification, or

20、 drawings.6. Basis of Application6.1 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated in accordance with Practice E 543. The appli-cable revision of Practice E 543 shall be specified in thecontractual agreement.6.2 Procedu

21、res and TechniquesThe procedures and tech-niques to be utilized shall be as described in this test methodunless otherwise specified. Specific techniques may be speci-fied in contractual documents.6.3 Extent of ExaminationThe extent of examination shallbe in accordance with Section 7 unless otherwise

22、 specified.6.4 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance withSection 11 unless otherwise specified. Acceptance criteria (forexample, for reference radiographs) shall be specified in thecontractual agreement.7. Procedure7.1 The direct

23、ion of the beam of radiation should be asperpendicular as possible to the plane of the film.7.2 Use Conversion screens that respond to neutrons ofthermal energies, such as metallic gadolinium.7.3 Each radiograph shall include a beam purity indicatorand a sensitivity indicator (refer to Section 10 fo

24、r exceptions).The indicators shall be located no less than 25 mm from anyedge of the exposed area of the film when feasible. Theindicators shall be located such that the image of the indicatorson the film do not overlap the image of the object.7.4 The SI should be oriented parallel to and as close a

25、spossible to the film.7.5 The SI should be oriented such that its thickest step isnot adjacent to the BPI or the objects being radiographed.7.6 The BPI surface must be parallel against the filmcassette face during exposure or density readings will beinvalid.7.7 The cadmium wires in the BPI shall be

26、oriented suchthat their longitudinal axis is perpendicular to the nearest filmedge.7.8 Measure the film densities using a diffuse transmissiondensitometer. The densitometer shall be accurate to 60.02density units.7.9 For the purpose of determining image quality, thebackground optical density shall b

27、e between 2.0 and 3.0measured at the hole in the center of the BPI.7.10 The only true measurement of the beam uniformity iswith a radiograph made without objects. Background filmoptical density in the range from 2.0 to 3.0 across the filmshould not vary more than 65 % from the numerical mean offive

28、measurements: one measurement at the center and onemeasurement approximately 25 to 30 mm toward the centerfrom each corner of the film. If the beam diameter is smallerthan the film, the four outside measurements shall be taken 25to 30 mm from the edge of the beam located at 90 intervals.7.11 Radiogr

29、aphs shall be free of any blemish that mayinterfere with subsequent examination of the image.7.12 Determine the thermal neutron content (NC), scatteredneutron content (S), gamma content (g), and pair productioncontent (P) by densitometric analysis of the BPI image. Makea determination of the constit

30、uents of film exposure bymeasuring the densities in the BPI image as shown in Table 1.Calculate the various exposure contributors by the equationsgiven in Section 9.7.13 Determine the sensitivity level by visually analyzingthe image of the SI. Determine the values for G and H usingTables 2 and 3.7.1

31、4 Determine the neutron radiographic category fromTable 4.7.15 Visually compare the images of the cadmium wires inthe BPI. An obvious difference in image sharpness indicates anL/D ratio of 35 or less. Use Method E 803 for quantifying theL/D ratio.7.16 If a lead shim is in the sensitivity indicator,

32、visuallyinspect the image of the lead steps. If the holes are not visible,the exposure contribution from gamma radiation is very high.8. Image Quality Levels8.1 The ASTM designation of quality level shall includethermal neutron content and sensitivity level. The designationTABLE 1 Definitions of D P

33、arametersDBFilm densities measured through the images of the boron nitride disks.DLFilm densities measured through the images of the lead disks.DHFilm density measured at the center of the hole in the BPI.DTFilm density measured through the image of the polytetrafluoroethylene.DDLDifference between

34、the DLvalues.DDBDifference between the two DBvalues.E545052is NC-H-G (see 9.1 and 7.13). Values for scattered neutroncontent, gamma content, and pair production content may bespecified at the option of the user. (When no designation ofNC-H-G is specified by the customer, radiographs shall beCategory

35、 I or II.)8.2 Visual analysis of the BPI requires inspection of twoareas the image of the cadmium wires and the image of theareas containing the lead disks. If either of the cadmium wireappears significantly less sharp than the other image, the L/Dratio is lower than normally required. If the lead d

36、isksnoticeably appear either darker or lighter than the surroundingpolytetrafluoroethylene, there is either a high gamma content(lighter image) or a high pair production content (darkerimage).Any of these observations indicates the need for furtherimage analysis and subsequent determination of the u

37、sefulnessof the radiograph for that particular examination.9. Determination of Exposure Contributors9.1 Calculate the effective thermal neutron content, NC,asfollows:NC 5DH2 higher DB1DDL!DH3 100 (1)where definitions of D parameters are given in Table 1.9.2 Calculate the effective scattered neutron

38、content, S,asfollows:S 5 DDB/DH! 3 100 (2)9.3 Calculate the effective gamma content, g, as follows:g5DT2 lower DL!/DH! 3 100 (3)9.4 Calculate the effective pair production content, P,asfollows:P 5 DDL/DH! 3 100 (4)10. Process Control Radiographs10.1 A process control radiograph (as defined in Termin

39、ol-ogy E 1316, Section H) may be prepared for verification ofexposure and sensitivity requirements when the followingoccur:10.1.1 The size or setup of objects is such that the object-scattered neutron level relative to background density, sensi-tivity, or facility-scattered neutrons exposure require

40、ments iscause for nonconformance.10.1.2 The object configuration necessitates a film-to-beamorientation that does not permit satisfactory density measure-ments for calculation of exposure by collimated thermalneutrons.10.1.3 The object setup or size does not permit the locationof image quality indic

41、ators to give adequate readings.10.1.4 The radiograph background density does not meetthe requirements of 7.10.TABLE 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 E 2

42、023.NOTE 3The dots on the SI represent holes in the optional lead shim.Value of H Shim1C2C3C4C5B6B7B8B9A10 A11 A12 ATABLE 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 E 2023.Value of G Gap1T2U

43、3V4W5X6Y7ZTABLE 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 use alower number category when sharpness is a

44、 more important factor thancontrast.Category NC H G S g PI6566533II 60 6 6 6 4 4III 55 5 5 7 5 5IV 50 4 5 8 6 6V453 977E54505310.2 The process control radiograph shall be prepared witha background film optical density of 2.0 to 3.0 and the sameimage quality indicators and exposure conditions as the

45、suspectnonconforming exposure. Similar test objects may be in theimage.10.3 The film shall be normal to the beam axis.11. Certification11.1 Upon request of the purchaser by contract or purchaseorder, the radiographing facility shall certify that the radio-graph was prepared and examined in accordanc

46、e with this testmethod.12. Records12.1 Complete records of the technique details shall bemaintained by the examining facility for three years or asspecified in the basis of purchase.13. Keywords13.1 beam purity indicator; direct method; image qualityindicator; neutron radiography; sensitivity indica

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