ASTM_E_2971_-_14.pdf

Designation:E297114Standard Test Method forDetermination of Effective Boron-10 Areal Density inAluminum Neutron Absorbers using Neutron AttenuationMeasurements1This standard is issued under the fixed designation E2971;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 test method is intended for quantitative determina-tion of effective boron-10(10B)areal density(mass per area of10B,usually measured in grams-10B/cm2)in aluminum neu-tron absorbers.The attenuation of a thermal neutron beamtransmitted through an aluminum neutron absorber is com-pared to attenuation values for calibration standards allowingdetermination of the effective10B areal density.This test istypically performed in a laboratory setting.This method isvalid only under the following conditions:1.1.1 The absorber contains10B in an aluminum or alumi-num alloy matrix.1.1.2 The primary neutron absorber is10B.1.1.3 The test specimen has uniform thickness.1.1.4 The test specimen has a testing surface area at leasttwice that of the thermal neutron beams surface cross-sectional area.1.1.5 The calibration standards of uniform compositionspan the range of areal densities being measured.1.1.6 The areal density is between 0.001 and 0.080 grams of10B per cm2.1.1.7 The thermalized neutron beam is derived from afission reactor,sub-critical assembly,accelerator or neutrongenerator.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards2C1671 Practice for Qualification and Acceptance of BoronBased Metallic Neutron Absorbers for Nuclear CriticalityControl for Dry Cask Storage Systems and TransportationPackagingE1316 Terminology for Nondestructive Examinations3.Terminology3.1 For definitions of terms used in this test method,refer toTerminology E1316.4.Summary of Test Method4.1 In this test method,aluminum neutron absorbers areplaced in a thermal neutron beam and the number of neutronstransmitted through the material in a known period of time iscounted.The neutron count can be converted to10B arealdensity by performing the same test on a series of appropriatecalibration standards and comparing the results.4.2 This test method uses a beam of neutrons with theneutron energy spectrum thermalized by an appropriate mod-erator.Other methods such as neutron diffraction may be usedto generate a thermal neutron beam.4.3 A beam of thermal neutrons shall be derived from afission reactor,sub-critical assembly,accelerator or neutrongenerator.5.Significance and Use5.1 The typical use of this test method is determination of10B areal density in aluminum neutron absorber materials usedto control criticality in systems such as:spent nuclear fuel drystorage canisters,transfer/transport nuclear fuel containers,spent nuclear fuel pools,and fresh nuclear fuel transportcontainers.1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.05 onRadiology(Neutron)Method.Current edition approved June 1,2014.Published July 2014.Originally approvedin 2014.DOI:10.1520/E2971-14.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2 Areal density measurements are also used in the inves-tigation of the uniformity in10B spatial distribution.5.3 The expected users of this standard include designers,suppliers,neutron absorber users,testing labs,and consultantsin the field of nuclear criticality analysis.5.4 Another known method used to determine areal densityof10B in aluminum neutron absorbers is an analytical chemicalmethod as mentioned in Practice C1671.However,the analyti-cal chemical method does not measure the“effective”10B arealdensity as measured by neutron attenuation.6.Interferences6.1 Counts not associated with attenuation by the sampleshall be accounted for by measuring and incorporating back-ground readings.Background reading will vary depending onthe set up of the electronics of the system and the presence/absence of high energy photons.6.2 Measured count rates approaching the background countrate may limit the abilities of a system to accurately measurehighly attenuating sampl