1、Designation: E 2003 98 (Reapproved 2004)Standard Practice forFabrication of the Neutron Radiographic Beam PurityIndicators1This standard is issued under the fixed designation E 2003; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the 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 practice covers the material and fabrication of aBeam Purity Indicator (BPI), which can be used to d
3、eterminethe relative quality of radiographic images produced by direct,thermal neutron radiographic examination.1.2 The values stated in SI units are regarded to be standard.1.3 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof
4、the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 543 Practice for Agencies Performing NondestructiveTestingE 545 Method for Determining Image Quality in Dir
5、ectThermal Neutron Radiographic ExaminationE 748 Practices for Thermal Neutron Radiography of Ma-terialsE 1316 Terminology for Nondestructive Examinations3. Terminology3.1 Definitions For definitions of terms used in thispractice, see Terminology E 1316, Section H.4. Summary of Practice4.1 The BPI i
6、s used for quantitative determination ofthermal neutron radiographic quality. It consists of a polytet-rafluoroethylene block containing two boron nitride disks, twolead disks and two cadmium wires. A key feature of the deviceis the ability to make visual analysis of its image for subjectivequality
7、information. Densitometric measurements of the imageof the device permit quantitative determination of radiographiccontrast, low-energy photon contribution, pair production con-tribution, image unsharpness, and information regarding filmand processing quality.4.2 Neutron radiography practices are di
8、scussed in PracticeE 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. For proper measurements of film exposure due to theneutron beam cons
9、tituents, the BPI must be fabricated inaccordance with this practice.5.2 This practice shall be followed for the fabrication of allBeam Purity Indicators to be used with Method E 545 todetermine image quality in direct thermal neutron radiography.6. Basis of Application6.1 Qualification of Nondestru
10、ctive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E 543. The applicablerevision of Practice E 543 shall be specified in the contractualagreement.6.2 Procedures and TechniquesThe procedures and tech-niques to be utilized shal
11、l be as described in this practice unlessotherwise specified. Specific techniques may be specified in thecontractual agreement.6.3 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance withSections 9 and 10 unless otherwise specified. Acceptance
12、criteria, for example, for reference radiographs, shall bespecified in the contractual agreement.6.4 Reexamination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed inthis practice and, if required, shall be specified in the contrac-tual agreement.7. Beam Purity Ind
13、icator (BPI)7.1 The BPI shall be constructed of polytetrafluoroethylene,cadmium, lead, and boron nitride.1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.05 onRadiology (Neutron) Method.Current edition appr
14、oved May 1, 2004. Published June 2004. Originallyapproved in 1998. Last previous edition approved in 1998 as E 2003 - 98e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, re
15、fer 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.7.2 The construction and dimensions shall be as shown inFig. 1.7.3 The BPI may be encased in a frame for easy mountingbut s
16、hall not be enclosed in a dust cover nor shall any materialcover either side of the BPI face.7.4 Cadmium and lead shall be at least 99.9 % pure elemen-tal material.7.5 Boron nitride shall be hot-pressed, minimum 40 %elemental boron.7.6 The polytetrafluoroethylene block tolerances shall be 610 %.7.7
17、The tolerances for the holes and the grooves shall besuch that the disks and the wires do not fall out during use.8. Fabrication8.1 Individual Components:8.1.1 Form the polytetrafluoroethylene base by milling an8-mm thick sheet of the material into a 25-mm square.8.1.2 Drill a 16 6 1-mm hole in the
18、center of the unit.8.1.3 Mill two 4-mm diameter by 2-mm deep holes centered4-mm from adjacent corners on one face of the unit.8.1.4 Cut two lengths of 0.7 6 1-mm diameter cadmiumwire, each 12-mm long.8.1.5 Mill a groove in the base between the holes milled in8.1.3. The groove should be 0.04 mm deepe
19、r and 0.04 mmnarrower than the diameter of the wire cut in 8.1.4, so the wirewill be flush and tight. The groove may extend to the outsideedge of the unit (see Fig. 1).8.1.6 Repeat the process on the opposite face, makingcertain that the holes are not stacked upon each other.8.1.7 Prepare a 4-mm dia
20、meter rod of boron nitride (a lathemay be used).8.1.8 Cut off two 2-mm thick disks from the rod machinedin 8.1.7.8.1.9 Prepare a 4-mm diameter rod of lead (a lathe may beused).8.1.10 Cut off two 2-mm thick disks from the rod machinedin 8.1.9.8.2 Assembly:8.2.1 Place the polytetrafluoroethylene block
21、 with the twoholes and groove on the left side.8.2.2 Insert a lead disk (as prepared in 8.1.9 and 8.1.10) inthe upper hole.8.2.3 Insert a boron nitride disk (as prepared in 8.1.7 and8.1.8) in the lower hole.8.2.4 Insert a cadmium wire piece (as prepared in 8.1.4) intothe groove between the two disks
22、, making certain the wire isflush, tight, and centered.8.2.5 Turn the block over and orient it so that the groove andholes are on the left side. Repeat the steps specified in 8.2.1through 8.2.4.8.2.6 The final assembly shall conform to Fig. 1.9. Certification9.1 Upon request of the purchaser by cont
23、ract or purchaseorder, any fabricator of the BPI described in this practice shallprovide materials certification. To verify correct assembly andfunctionality, a comparison thermal neutron radiograph of theassembled BPI with that of a reference BPI (preferably on asingle neutron radiograph) shall be
24、provided.PolytetrafluoroethyleneCadmium 99.9 % pureLead 99.9 % pureBN-Boron nitrideHot-pressed, 40 % min elemental boronNOTE 1Pb and BN disks are 4-mm in diameter and 2-mm thick (minimum thickness).FIG. 1 Beam Purity IndicatorE 2003 98 (2004)29.2 The comparison thermal neutron radiograph of theassem
25、bled BPI along with a reference BPI shall show thefollowing:9.2.1 The disks and wires are properly placed and intact.9.2.2 Using Method E 545 (latest revision), calculate thevalues for thermal neutron, scattered neutron, gamma, and pairproduction content.9.2.3 The values should be comparable to thos
26、e of thereference BPI.9.2.4 Assign a unique identification number to the accept-able unit and mark the BPI. The identification number shall besuch that it shall not interfere with any density readings used tocalculate any exposure contributors (see Method E 545, latestrevision).9.3 The comparison th
27、ermal neutron radiograph of theassembled BPI with the reference BPI shall meet quality levelCategory I specified in Method E 545, latest revision.9.4 Any BPI fabricated in accordance with Method E 545from 1981 through 1991 is assumed to be a reference BPI(unless there is known to be a disqualifying
28、deficiency).10. Records10.1 Complete records of the fabrication details shall bemaintained by the manufacturing facility for three years or asspecified in the basis of purchase.11. Keywords11.1 beam purity indicator; direct method; image qualityindicator; neutron radiography; sensitivity indicatorAS
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32、 on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E 2003 98 (2004)3
