1、Designation: C 1269 97 (Reapproved 2003)Standard Practice forAdjusting the Operational Sensitivity Setting of In-PlantWalk-Through Metal Detectors1This standard is issued under the fixed designation C 1269; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, 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.INTRODUCTIONNuclear regulatory authorities require personnel entering designated security are
3、as 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 requ
4、irements.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 likel
5、y to-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
6、for 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 o
7、bject specifications orspecify specific test objects. These should be specified by theregulatory authority.1.3 This practice uses information developed by PracticeC 1270, or an equivalent procedure, which identifies thecritical test object (from a specified set of test objects), itscritical orientat
8、ion, and the critical test path through thedetection zone. In the case of Practice C 1270, the informationis found on the detection sensitivity map(s) for each in-plantwalk-through metal detector.1.4 This practice is one of several developed to assistoperators of nuclear facilities with meeting the
9、metal 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 met
10、al detectors.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:C 1238 Guide for Installation of Walk-Through Metal De-tectors2C 1270 Practice for Detection Sensitivity Mapping of In-Plan
11、t Walk-Through Metal Detectors2C 1309 Practice for Performance Evaluation of In-PlantWalk-Through Metal DetectorsF 1468 Practice for the Evaluation of Metallic WeaponsDetectors for Controlled Access Search and Screening33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 clean-tes
12、ter, na person 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 metall
13、ic objects may 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,metallic surgical implants, undergarment support metal, metal1This practice is under the
14、jurisdiction of ASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.12 on SafeguardApplications.Current edition approved Dec. 10, 1997. Published June 1998. Originallyapproved in 2000. Last previous edition approved in 1997 as C 1269 97.2Annual Book of ASTM S
15、tandards, Vol 12.01.3Annual Book of ASTM Standards, Vol 15.07.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.zippers, etc. In the absence of other criteria, a clean testerpassing through a metal detector shall not cause a disturbanc
16、esignal greater than 10 % of that produced when carrying thecritical test object through the detector. Test objects requiringmore 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) a
17、nd a height between 1.44 to 1.93m (57 to 75 in.). Should a given detector be sensitive to bodysize because of design or desired 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 sens
18、itivity hand-held metal detector toensure that no metal is present.3.1.2 critical orientationthe orthogonal orientation of atest 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
19、sensitivitysetting to be detected compared to the sensitivity settingsrequired to detect the object in all other orthogonal orienta-tions. See Fig. 1 for handgun orientations3.1.2.1 DiscussionCritical orientations are determined bytesting using a mapping procedure such as described inPractice C 1270
20、.3.1.2.2 DiscussionThe term critical orientation can beapplied in two ways. Critical orientation can refer to the worstcase orthogonal 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 t
21、est path.3.1.3 critical sensitivity setting, nthe lowest sensitivitysetting of a detector at which the critical test object in 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
22、test element.3.1.5 critical test object, nsee test object.3.1.6 critical test path, nthe straight-line shortest-coursepath through the portal aperture, as defined by an element onthe detection sensitivity map, that produces the smallestdetection signal or weakest detection for the critical test obje
23、ctin its critical orientation. (see Figs. 2 and 3)3.1.7 detection sensitivity map, n(see Fig. 2) a depictionof the grid used to 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 thedetec
24、tability of the test object.3.1.7.1 DiscussionThese values are relative and describethe detection sensitivity pattern within the 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 Orthog
25、onal Orientations for a HandgunNOTE 1Numbers are sensitivity setting values for a hypotheticaldetector. The numbers represent 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 M
26、apFIG. 3 3-D View of Detection Zones and Test GridC 1269 97 (2003)2single orthogonal orientation. The value is usually the mini-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
27、is a sampleform for a potential detection sensitivity map configuration.3.1.8 detection zonethe volume within the portal aperture.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 detectionsens
28、itivity map; (2) the rectilinear volume through the detec-tion zone defined by coincident elements of identical gridworks placed 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 patht
29、hrough the detection zone of a detector undergoing mapping,detection sensitivity, or detection sensitivity verification test-ing. (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 p
30、ractice,orthogonal orientation refers to alignment of the longitudinalaxis of a test object along the xyz axes of the Cartesiancoordinate 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 detecto
31、r. (SeeFig. 1 for handgun orientations)3.1.16 test element, n(see Figs. 2 and 3) for the purpose oftesting, it is necessary to define discrete and repeatablestraight-line shortest-course test paths through the detectionzone. This can be done by using two identical networks (grids)made of nonconducti
32、ve/nonmagnetic material attached acrossthe entry and exit planes of the portal aperture so the networkscoincide. A test object on 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 reason
33、ably straight-line shortest-course path through thedetection zone. If the networks are constructed so that they canbe put in-place 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 thebou
34、ndaries of two corresponding network openings and itrepresents a straight-line shortest-course path through thedetection zone.3.1.16.1 DiscussionOn a detection sensitivity map thecorresponding networks appear as a rectangular grid with eachelement of the grid representing a test path through thedete
35、ction zone. The element defining the critical test path is thecritical test element.3.1.17 test grid, na network of nonconductive/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
36、 material should notbe hygroscopic.3.1.17.1 DiscussionSee Fig. 2 for an example ofa4by9element test grid.3.1.18 test object, nmetallic 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 obj
37、ects that, in its critical orientation,produces the weakest detection signal anywhere in the detec-tion zone. The group referred 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 t
38、est objects may have orientations atdifferent locations in the detection zone that result in nearcritical sensitivity settings. Hence, 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 representi
39、ngspecial nuclear material shielding that might be used in a theftscenario.3.1.18.4 DiscussionIt is usually a metallic container ormetallic material configured as a credible gamma-radiationshield for a specific type and quantity of special nuclearmaterial. The object is specified by a regulatory aut
40、hority or isbased on the facility threat analysis, or both.3.1.18.5 weapon test object, na handgun(s) or simulatedhandgun designated 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 b
41、locks of metal shaped likea handgun will likely not cause a metal detector to react thesame as it would to the intricate shapes and 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 scree
42、ning device, usually an arch-type portal,using an electromagnetic field within its portal structure(aperture) for detecting metallic 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
43、 m/s (112to 212steps/s).3.1.20.1 DiscussionThe average casual walk rate is about134 steps/s.3.1.20.2 shielding test object, nsee 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
44、critical test element in thenormal operating fashion. The metal detector sensitivity isadjusted upward, starting from a setting 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 sen
45、sitivity setting.5. Significance and Use5.1 Performing this procedure from this practice shouldresult in a properly adjusted walk-through metal detectoroperating at or near the optimum sensitivity setting for theenvironment in which it is installed.C 1269 97 (2003)35.2 This practice determines the l
46、owest sensitivity settingrequired to detect a specified test object and establishes asensitivity setting suitable for most operational 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
47、and confidence level, asrequired by regulatory authorities.6. Precautions6.1 This practice assumes no changes in the metal detectionpattern 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
48、or sensitivity, such asdamage to the detector or changes in the operating environ-ment, make sure that the detection zone is mapped 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 ar
49、chitecture, 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 number of variables certain to arisewith field installations and operating methods (for example,continuous walk versus pausing in the portal) caution shouldalways be observed wh
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