ASTM E545-2005(2010) 8125 Standard Test Method for Determining Image Quality in Direct Thermal Neutron Radiographic Examination《测定直接热中子射线照相试验中成像质量的标准试验方法》.pdf

《ASTM E545-2005(2010) 8125 Standard Test Method for Determining Image Quality in Direct Thermal Neutron Radiographic Examination《测定直接热中子射线照相试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 E545-2005(2010) 8125 Standard Test Method for Determining Image Quality in Direct Thermal Neutron Radiographic Examination《测定直接热中子射线照相试验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: E545 05 (Reapproved 2010)Standard 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 the case

2、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 Department of Defense.1. Scope1.1 This test me

3、thod covers the use of an Image QualityIndicator (IQI) system to determine the relative2quality 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.

4、2 This standard does not purport to address the safetyconcerns, if any, associated with its use. 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

5、units are regarded to be standard.2. Referenced Documents2.1 ASTM Standards:3E543 Specification for Agencies Performing Nondestruc-tive TestingE748 Practices for Thermal Neutron Radiography of Mate-rialsE803 Test Method for Determining the L/D Ratio of Neu-tron Radiography BeamsE1316 Terminology for

6、 Nondestructive ExaminationsE2003 Practice for Fabrication of the Neutron RadiographicBeam Purity IndicatorsE2023 Practice for Fabrication of Neutron RadiographicSensitivity Indicators3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, see Terminology E1316, Section H.4. S

7、ummary of Test Method4.1 The judgment of the quality of a neutron radiograph isbased upon the evaluation of images 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

8、 to or following exposure ofthe test object under exactly the same conditions (refer toProcess Control Radiographs, 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

9、for quantitative determination of radiographic quality. It isa polytetrafluoroethylene block containing two boron 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

10、filmand processing quality. Densitometric measurements of theimage of the device permit quantitative determination 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 E200

11、3.Optionally, any BPI fabricated prior to publication of PracticeE2003 which conforms to Test Method E545 - 81 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

12、is a step-wedgedevice containing gaps and holes of known dimensions. Visualinspection of the image of this device provides subjectiveinformation regarding total radiographic sensitivity with re-spect to the step-block material. The SI shall be in accordance1This test method is under the jurisdiction

13、 of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.05 onRadiology (Neutron) Method.Current edition approved June 1, 2010. Published November 2010. Originallyapproved in 1975. Last previous edition approved in 2005 as E545 - 05. DOI:10.1520/E0545-05R1

14、0.2The 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, orcontact ASTM Customer Service a

15、t 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.with Practice E2023. Optionally, any SI fabricate

16、d prior topublication of Practice E2023 which conforms to Test MethodE545-81 through 91 may be used.4.2 Neutron radiography practices are discussed in PracticesE748.5. Significance and Use5.1 The BPI is designed to yield quantitative informationconcerning neutron beam and image system parameters tha

17、tcontribute to film exposure and thereby affect overall imagequality. In addition, the BPI can be used to verify theday-to-day consistency of the neutron radiographic quality.Gadolinium conversion screens and single-emulsion silver-halide films, exposed together in the neutron imaging beam,were used

18、 in the development and testing of the BPI. Use ofalternative detection systems may produce densitometric read-ings that are not valid 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 t

19、hat is the same as the object being neutronradiographed except with a known standard discontinuity,inclusion, omission, or flaw. The sensitivity indicators weredesigned to substitute for the reference standard and providequalitative information on hole and gap sensitivity.5.3 The number of areas or

20、objects to be radiographed andthe film acceptance standard used should be specified in thecontract, purchase order, specification, or drawings.6. Basis of Application6.1 Qualification of Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated in

21、accordance with Practice E543. The appli-cable revision of Practice E543 shall be specified in thecontractual agreement.6.2 Procedures and TechniquesThe procedures and tech-niques to be utilized shall be as described in this test methodunless otherwise specified. Specific techniques may be speci-fie

22、d in contractual documents.6.3 Extent of ExaminationThe extent of examination shallbe in accordance with Section 7 unless otherwise specified.6.4 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance withSection 11 unless otherwise specified. Ac

23、ceptance criteria (forexample, for reference radiographs) shall be specified in thecontractual agreement.7. Procedure7.1 The direction 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

24、as metallic gadolinium.7.3 Each radiograph shall include a beam purity indicatorand a sensitivity indicator (refer to Section 10 for 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

25、 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 aspossible 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 p

26、arallel against the filmcassette face during exposure or density readings will beinvalid.7.7 The cadmium wires in the BPI shall be oriented suchthat their longitudinal axis is perpendicular to the nearest filmedge.7.8 Measure the film densities using a diffuse transmissiondensitometer. The densitome

27、ter shall be accurate to 60.02density units.7.9 For the purpose of determining image quality, thebackground optical density shall be 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. Backgr

28、ound filmoptical density in the range from 2.0 to 3.0 across the filmshould not vary more than 65 % from the numerical mean offive 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 smallerth

29、an the film, the four outside measurements shall be taken 25to 30 mm from the edge of the beam located at 90 intervals.7.11 Radiographs 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

30、), gamma content (g), and pair productioncontent (P) by densitometric analysis of the BPI image. Makea determination of the constituents 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

31、 Determine the sensitivity level by visually analyzingthe image of the SI. Determine the values for G and H usingTables 2 and 3.7.14 Determine the neutron radiographic category fromTable 4.TABLE 1 Definitions of D ParametersDBFilm densities measured through the images of the boron nitride disks.DLFi

32、lm 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 the DLvalues.DDBDifference between the two DBvalues.E545 05 (2010)27.15 Visually comp

33、are the images of the cadmium wires inthe BPI. An obvious difference in image sharpness indicates anL/D ratio of 35 or less. Use Method E803 for quantifying theL/D ratio.7.16 If a lead shim is in the sensitivity indicator, visuallyinspect the image of the lead steps. If the holes are not visible,the

34、 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 designationis NC-H-G (see 9.1 and 7.13). Values for scattered neutroncontent, gamma content, and pair production c

35、ontent may bespecified at the option of the user. (When no designation ofNC-H-G is specified by the customer, radiographs shall beCategory 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 ei

36、ther of the cadmium wireappears significantly less sharp than the other image, the L/Dratio is lower than normally required. If the lead disksnoticeably appear either darker or lighter than the surroundingpolytetrafluoroethylene, there is either a high gamma content(lighter image) or a high pair pro

37、duction content (darkerimage).Any of these observations indicates the need for furtherimage analysis and subsequent determination of the usefulnessof the radiograph for that particular examination.9. Determination of Exposure Contributors9.1 Calculate the effective thermal neutron content, NC,asfoll

38、ows:NC 5DH2 higher DB1DDL!DH3 100 (1)where definitions of D parameters are given in Table 1.9.2 Calculate the effective scattered neutron 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 p

39、roduction content, P,asfollows:P 5 DDL/DH! 3 100 (4)10. Process Control Radiographs10.1 A process control radiograph (as defined in Terminol-ogy E1316, Section H)E1316 may be prepared for verificationof exposure and sensitivity requirements when the followingoccur:TABLE 2 Determination of HNOTE 1The

40、 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 Shim1C2C3C4C5B6B7B8B9A10 A11 A12 ATABLE 3 Determination of GNOTE

41、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 Gap1T2U3V4W5X6Y7ZTABLE 4 Neutron Radiographic CategoriesNOTE 1It should be recognized that these categories favor contrastfactors because the sensitiv

42、ity 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 g PI6566533II 60 6 6 6 4 4III 55 5 5 7 5 5IV 50 4 5 8 6 6V453 977E545 05 (2010)310.1.1 Th

43、e size or setup of objects is such that the object-scattered neutron level relative to background density, sensi-tivity, or facility-scattered neutrons exposure requirements iscause for nonconformance.10.1.2 The object configuration necessitates a film-to-beamorientation that does not permit satisfa

44、ctory 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 indicators to give adequate readings.10.1.4 The radiograph background density does not meetthe requirements of 7.10.10.2 The process cont

45、rol 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 suspectnonconforming exposure. Similar test objects may be in theimage.10.3 The film shall be normal to the beam axis.11. Certification11.1 Upon re

46、quest of the purchaser by contract or purchaseorder, the radiographing facility shall certify that the radio-graph was prepared and examined in accordance with this testmethod.12. Records12.1 Complete records of the technique details shall bemaintained by the examining facility for three years or as

47、specified in the basis of purchase.13. Keywords13.1 beam purity indicator; direct method; image qualityindicator; neutron radiography; sensitivity indicatorASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard

48、. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed

49、every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor