ASTM_C_1189_-_11.pdf

Designation:C118911Standard Guide toProcedures for Calibrating Automatic Pedestrian SNMMonitors1This standard is issued under the fixed designation C1189;the number immediately following the designation indicates the year oforiginal adoption or,in 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.1.Scope1.1 This guide covers calibrating the energy response of theradiation detectors and setting the discriminator and alarmthresholds used in automatic pedestrian special nuclear mate-rial(SNM)monitors.1.2 Automatic pedestrian SNM Monitors and their applica-tion are described in Guide C1112,which suggests that themonitors be calibrated and tested when installed and that,thereafter,the calibration should be checked and the monitortested with SNM at three-month intervals.1.3 Dependable operation of SNM monitors rests,in part,on an effective program to test,calibrate,and maintain them.The procedures and methods described in this guide may helpboth to achieve dependable operation and obtain timely warn-ing of misoperation.1.4 This guide can be used in conjunction with otherASTMstandards.Fig.1 illustrates the relationship between calibrationand other procedures described in standard guides,and it alsoshows how the guides relate to an SNM monitor user.Theguides below the user in the figure deal with routine proceduresfor operational monitors.Note that Guide C993 is an in-plantperformance evaluation that is used to verify acceptabledetection of SNM after a monitor is calibrated.The guidesshown above the user in Fig.1 give information on applyingSNM monitors(C1112)and on evaluating SNM monitors(C1169)to provide comparative information on monitor per-formance.2.Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsC993 Guide for In-Plant Performance Evaluation of Auto-matic Pedestrian SNM MonitorsC1112 Guide for Application of Radiation Monitors to theControl and Physical Security of Special Nuclear Material(Withdrawn 2014)3C1169 Guide for Laboratory Evaluation of Automatic Pe-destrian SNM Monitor PerformanceE876 Practice for Use of Statistics in the Evaluation ofSpectrometric Data(Withdrawn 2003)33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 calibrationa multistep procedure that uniformly ad-justs the energy response of a monitors detector array and setsthe operating parameters of its detection circuits for optimumperformance.In a few monitors,an additional analog adjust-ment of a signal detection circuit is required.3.1.2 SNMspecial nuclear material:plutonium of anyisotopic composition,233U,or enriched uranium as defined inTerminology C859.3.1.2.1 DiscussionThis term is used here to describe bothSNM and strategic SNM,which is plutonium,uranium-233,and uranium enriched to 20%or more in the235U isotope.3.1.3 SNM Monitora radiation detection system that mea-sures ambient radiation intensity,determines an alarm thresh-old from the result,and then when it monitors,sounds an alarmif its measured radiation intensity exceeds the threshold.3.1.3.1 DiscussionThe automatic pedestrian SNM moni-tor discussed here is a walk-through or wait-in portal ormonitoring booth.4.Summary of Guide4.1 This guide covers various instructions for calibratingSNM pedestrian monitors for optimum performance in normaloperation.The order of procedures is as follows.4.1.1 The energy response of inorganic or organic scintilla-tion detectors or of neutron proportional counters,is calibratedto produce appropriate signal pulse heights for SNM radiation(see Section 10).1This guide is under the jurisdiction of ASTM Committee C26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C26.12 on SafeguardApplications.Current edition approved June 1,2011.Published June 2011.Originallyapproved in 1991.Last previous edition approved in 2002 as C1189 02 which waswithdrawn January 2011 and reinstated June 2011.DOI:10.1520/C1189-11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.1.2 The monitors pulse height discriminators are cali-brated to form a region of interest containing SNM radiationfrom highly enriched uranium or low-burnup plutonium(seeSections 9 and 11),or for detecting neutrons in proportionalcounters(see Section 9).4.1.3 The monitors transient signal detection logic is ad-justed for appropriate response to walk-through or wait-inmonitoring(see Section 12).4.2 This guide covers adjusting various thresholds used inSNM monitors.4.2.1 This guide describes setting backg