1、Designation: C1269 97 (Reapproved 2012)Standard Practice forAdjusting the Operational Sensitivity Setting of In-PlantWalk-Through Metal Detectors1This standard is issued under the fixed designation C1269; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the 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.INTRODUCTIONNuclear regulatory authorities require personnel entering designated security areas
3、to be screenedfor concealed weapons. Additionally, in security areas containing specified quantities of specialnuclear materials, personnel exiting the facility are required to be screened for metallic nuclearshielding material. Walk-through metal detectors are widely used to implement these require
4、ments.Nuclear regulatory authorities usually specify an assortment of metal detector test objects that mustall be detected by walk-through metal detectors. This practice provides a procedure for adjusting theoperational sensitivity setting to the lowest setting necessary to detect the least likely t
5、o-be-detectedtest object in its least likely to-be-detected orientation while passing through the detection zone in theweakest known detection path. All other test objects will then be detected at this sensitivity settinganywhere in the detection zone.1. Scope1.1 This practice covers a procedure for
6、 adjusting theoperational sensitivity of in-plant walk-through metal detec-tors. Performance of this procedure should result with in-plantwalk-through metal detectors being adjusted to an initialoperational sensitivity setting suitable for performance testing.1.2 This practice does not set test obje
7、ct specifications orspecify specific test objects. These should be specified by theregulatory authority.1.3 This practice uses information developed by PracticeC1270, or an equivalent procedure, which identifies the criticaltest object (from a specified set of test objects), its criticalorientation,
8、 and the critical test path through the detectionzone. In the case of Practice C1270, the information is foundon the detection sensitivity map(s) for each in-plant walk-through metal detector.1.4 This practice is one of several developed to assistoperators of nuclear facilities with meeting the meta
9、l detectionperformance requirements of the regulatory authorities (seeAppendix).1.5 This standard practice is neither intended to set perfor-mance levels nor limit or constrain technologies.1.6 This practice does not address safety or operationalissues associated with the use of walk-through metal d
10、etectors.1.7 The values stated in SI units are to be regarded asstandards. The values given in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2C1238 Guide for Installation of Walk-Through Metal De-tectorsC1270 Practice for Detection Sensitivity Mapping of In-Plant Walk
11、-Through Metal DetectorsC1309 Practice for Performance Evaluation of In-PlantWalk-Through Metal DetectorsF1468 Practice for Evaluation of Metallic Weapons Detec-tors for Controlled Access Search and Screening3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 clean-tester, na pers
12、on who does not carry anyextraneous metallic objects that would significantly alter thesignal produced when the person carries a test object.3.1.1.1 DiscussionSmaller test objects require more com-plete elimination of metallic objects. By example but notlimitation, such extraneous metallic objects m
13、ay include:metallic belt buckles, metal buttons, cardiac pacemakers, coins,metal frame eyeglasses, hearing aids, jewelry, keys, mechani-cal pens and pencils, shoes with metal shanks or arch supports,1This practice is under the jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct
14、 responsibility of Subcommittee C26.12 on SafeguardApplications.Current edition approved Jan. 1, 2012. Published January 2012. Originallyapproved in 1994. Last previous edition approved in 1997 as C1269 97(2003).DOI: 10.1520/C1269-97R12.2For referenced ASTM standards, visit the ASTM website, www.ast
15、m.org, orcontact 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.metallic
16、surgical implants, undergarment support metal, metalzippers, etc. In the absence of other criteria, a clean testerpassing through a metal detector shall not cause a disturbancesignal greater than 10 % of that produced when carrying thecritical test object through the detector. Test objects requiring
17、more complete elimination of extraneous metal to obtain lessthan 10 % signal disturbance.3.1.1.2 DiscussionThe tester shall have a weight between50 to 104 kg (110 to 230 lb) and a height between 1.44 to 1.93m (57 to 75 in.). Should a given detector be sensitive to bodysize because of design or desir
18、ed sensitivity, the physical sizeof testers should be smaller and within a narrower range.3.1.1.3 DiscussionIt is recommended that the clean testerbe surveyed with a high sensitivity hand-held metal detector toensure that no metal is present.3.1.2 critical orientationthe orthogonal orientation of at
19、est object that produces the smallest detection signal orweakest detection anywhere in the detection zone; the orthogo-nal orientation of a test object that requires a higher sensitivitysetting to be detected compared to the sensitivity settingsrequired to detect the object in all other orthogonal o
20、rienta-tions. See Fig. 1 for handgun orientations3.1.2.1 DiscussionCritical orientations are determined bytesting using a mapping procedure such as described inPractice C1270.3.1.2.2 DiscussionThe term critical orientation can beapplied in two ways. Critical orientation can refer to the worstcase or
21、thogonal orientation in a single test path or the worstcase orthogonal orientation for all the test paths (the entiredetection zone). The two are coincident in the critical test path.3.1.3 critical sensitivity setting, nthe lowest sensitivitysetting of a detector at which the critical test object in
22、 itscritical orientation is consistently detected (10 out of 10 testpasses) when passed through the detection zone on the criticaltest path.3.1.4 critical test element, nsee test element.3.1.5 critical test object, nsee test object.3.1.6 critical test path, nthe straight-line shortest-coursepath thr
23、ough the portal aperture, as defined by an element onthe detection sensitivity map, that produces the smallestdetection signal or weakest detection for the critical test objectin its critical orientation. (see Figs. 2 and 3)3.1.7 detection sensitivity map, n(see Fig. 2) a depictionof the grid used t
24、o define test paths through the detection zonewith each element of the grid containing a value, usually thesensitivity setting of the detector, that is indicative of thedetectability of the test object.3.1.7.1 DiscussionThese values are relative and describethe detection sensitivity pattern within t
25、he detection zone forthe specific test object. The values are derived by identicallytesting each defined test path using a specific test object in aFIG. 1 Six Standard Orthogonal Orientations for a HandgunNOTE 1Numbers are sensitivity setting values for a hypotheticaldetector. The numbers represent
26、the lowest sensitivity setting at which theobject was detected ten out of ten consecutive test passes through theindicated test path.FIG. 2 Example of Detection Sensitivity MapFIG. 3 3-D View of Detection Zones and Test GridC1269 97 (2012)2single orthogonal orientation. The value is usually the mini
27、-mum sensitivity setting of the detector that will cause aconsistent alarm (10 out of 10 test passes) when the test objectis passed through the detection field. Appendix X2 is a sampleform for a potential detection sensitivity map configuration.3.1.8 detection zonethe volume within the portal apertu
28、re.3.1.9 detector, nsee walk-through metal detector.3.1.10 element, nsee test element.3.1.11 grid, nsee test grid.3.1.12 grid element, n(1) a single block on a detectionsensitivity map; (2) the rectilinear volume through the detec-tion zone defined by coincident elements of identical gridworks place
29、d on either side of the portal aperture. (see Figs. 2and 3)3.1.12.1 test path, nas defined by an element on adetection sensitivity map, a straight-line shortest-course paththrough the detection zone of a detector undergoing mapping,detection sensitivity, or detection sensitivity verification test-in
30、g. (see Fig. 3)3.1.13 in-plant, adjinstalled in the location, position, andoperating environment where the device will be used.3.1.14 orthogonal orientationas used in this practice,orthogonal orientation refers to alignment of the longitudinalaxis of a test object along the xyz axes of the Cartesian
31、coordinate system; x is horizontal and across the portal, y isvertical, and z is in the direction of travel through the portal.3.1.15 portal, nsee walk-through metal detector. (SeeFig. 1 for handgun orientations)3.1.16 test element, n(see Figs. 2 and 3) for the purpose oftesting, it is necessary to
32、define discrete and repeatablestraight-line shortest-course test paths through the detectionzone. This can be done by using two identical networks (grids)made of nonconductive/nonmagnetic material attached acrossthe entry and exit planes of the portal aperture so the networkscoincide.Atest object on
33、 the end of a probe can then be passedfrom one side of the portal aperture to the other side throughcorresponding openings, which results in the test object takinga reasonably straight-line shortest-course path through thedetection zone. If the networks are constructed so that they canbe put in-plac
34、e identically each time they are used, then the testpaths through the detection zone are repeatable over time.Thus, a test element is the volume of space defined by theboundaries of two corresponding network openings and itrepresents a straight-line shortest-course path through thedetection zone.3.1
35、.16.1 DiscussionOn a detection sensitivity map thecorresponding networks appear as a rectangular grid with eachelement of the grid representing a test path through thedetection zone. The element defining the critical test path is thecritical test element.3.1.17 test grid, na network of nonconductive
36、/nonmagnetic material, such as string or tape, can be stretchedacross the entry and exit planes of the portal aperture to definetest paths through the portal aperture; the material should notbe hygroscopic.3.1.17.1 DiscussionSee Fig. 2 for an example ofa4by9element test grid.3.1.18 test object, nmet
37、allic item meeting dimension andmaterial criteria used to evaluate detection performance.3.1.18.1 critical test objectthe one test object out of anygiven group of test objects that, in its critical orientation,produces the weakest detection signal anywhere in the detec-tion zone. The group referred
38、to consists of one or more objectsthat are to be detected at the same detector setting.3.1.18.2 DiscussionDepending on the particular detector,some orientation sensitive test objects may have orientations atdifferent locations in the detection zone that result in nearcritical sensitivity settings. H
39、ence, care must be taken indetermining the critical test object, its critical orientation, andthe critical test path.3.1.18.3 shielding test objecta test object representingspecial nuclear material shielding that might be used in a theftscenario.3.1.18.4 DiscussionIt is usually a metallic container
40、ormetallic material configured as a credible gamma-radiationshield for a specific type and quantity of special nuclearmaterial. The object is specified by a regulatory authority or isbased on the facility threat analysis, or both.3.1.18.5 weapon test object, na handgun(s) or simulatedhandgun designa
41、ted by or satisfying the regulatory authorityrequirement for a weapon test object.3.1.18.6 DiscussionCare must be taken when selecting ordesigning a mock handgun. Simple blocks of metal shaped likea handgun will likely not cause a metal detector to react thesame as it would to the intricate shapes a
42、nd variable compo-nents of a real handgun. Most government agencies use actualguns for testing.3.1.19 walk-through metal detector (detector, portal), nafree-standing screening device, usually an arch-type portal,using an electromagnetic field within its portal structure(aperture) for detecting metal
43、lic objects, specifically weaponsor metallic shielding material, or both, on persons walkingthrough the portal.3.1.20 walk speed (normal), nwalk speed is between 0.5to 1.3 m/s (112 to 212 steps/s).3.1.20.1 DiscussionThe average casual walk rate is about134 steps/s.3.1.20.2 shielding test object, nse
44、e test object.3.1.20.3 weapon test object, nsee test object.4. Summary of Practice4.1 A clean-tester carries the critical test object in thecritical orientation through the critical test element in thenormal operating fashion. The metal detector sensitivity isadjusted upward, starting from a setting
45、 where no alarms occur,until the lowest sensitivity setting is found where 10 consecu-tive passes result with 10 consecutive alarms. This value is theinitial operational sensitivity setting.5. Significance and Use5.1 Performing this procedure from this practice shouldresult in a properly adjusted wa
46、lk-through metal detectoroperating at or near the optimum sensitivity setting for theenvironment in which it is installed.C1269 97 (2012)35.2 This practice determines the lowest sensitivity settingrequired to detect a specified test object and establishes asensitivity setting suitable for most opera
47、tional needs.5.3 This practice may be used to establish an initial sensi-tivity setting for follow-on procedures that determine crediblevalues for probability of detection and confidence level, asrequired by regulatory authorities.6. Precautions6.1 This practice assumes no changes in the metal detec
48、tionpattern or sensitivity from the time of initial detection sensi-tivity mapping. If an event or circumstance has occurred thatmay effect a change in the detection field or sensitivity, such asdamage to the detector or changes in the operating environ-ment, make sure that the detection zone is map
49、ped again. Thedetector must be mapped following maintenance on the detec-tor controller or archway internal parts, after movement of thedetector for any reason, and when architecture, electrical andmechanical equipment, or furnishings are added, removed orsubstantially changed within approximately 10 m of thedetector. It is suggested that detectors be mapped yearly as partof a maintenance program to ensure no unrecognized changeshave taken place in the detector or its environment that affectdetection performance.6.2 Because of the large nu
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