ASTM_E_2059_-_15.pdf

Designation:E205915Standard Practice forApplication and Analysis of Nuclear Research Emulsions forFast Neutron Dosimetry1This standard is issued under the fixed designation E2059;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 Nuclear Research Emulsions(NRE)have a long andillustrious history of applications in the physical sciences,earthsciences and biological sciences(1,2)2.In the physicalsciences,NRE experiments have led to many fundamentaldiscoveries in such diverse disciplines as nuclear physics,cosmic ray physics and high energy physics.In the appliedphysical sciences,NRE have been used in neutron physicsexperiments in both fission and fusion reactor environments(3-6).Numerous NRE neutron experiments can be found inother applied disciplines,such as nuclear engineering,environ-mental monitoring and health physics.Given the breadth ofNRE applications,there exist many textbooks and handbooksthat provide considerable detail on the techniques used in theNRE method.As a consequence,this practice will be restrictedto the application of the NRE method for neutron measure-ments in reactor physics and nuclear engineering with particu-lar emphasis on neutron dosimetry in benchmark fields(seeMatrix E706).1.2 NRE are passive detectors and provide time integratedreaction rates.As a consequence,NRE provide fluence mea-surements without the need for time-dependent corrections,such as arise with radiometric(RM)dosimeters(see TestMethod E1005).NRE provide permanent records,so thatoptical microscopy observations can be carried out any timeafter exposure.If necessary,NRE measurements can be re-peated at any time to examine questionable data or to obtainrefined results.1.3 Since NRE measurements are conducted with opticalmicroscopes,high spatial resolution is afforded for fine struc-ture experiments.The attribute of high spatial resolution canalso be used to determine information on the angular anisot-ropy of the in-situ neutron field(4,5,7).It is not possible foractive detectors to provide such data because of in-situperturbations and finite-size effects(see Section 11).1.4 The existence of hydrogen as a major constituent ofNRE affords neutron detection through neutron scattering onhydrogen,that is,the well known(n,p)reaction.NRE mea-surements in low power reactor environments have beenpredominantly based on this(n,p)reaction.NRE have alsobeen used to measure the6Li(n,t)4He and the10B(n,)7Lireactions by including6Li and10B in glass specks near themid-plane of the NRE(8,9).Use of these two reactions doesnot provide the general advantages of the(n,p)reaction forneutron dosimetry in low power reactor environments(seeSection 4).As a consequence,this standard will be restricted tothe use of the(n,p)reaction for neutron dosimetry in low powerreactor environments.1.5 LimitationsThe NRE method possesses three majorlimitations for applicability in low power reactor environ-ments.1.5.1 Gamma-Ray SensitivityGamma-rays create a sig-nificant limitation for NRE measurements.Above a gamma-rayexposure of approximately 0.025 Gy,NRE can become foggedby gamma-ray induced electron events.At this level ofgamma-ray exposure,neutron induced proton-recoil tracks canno longer be accurately measured.As a consequence,NREexperiments are limited to low power environments such asfound in critical assemblies and benchmark fields.Moreover,applications are only possible in environments where thebuildup of radioactivity,for example,fission products,islimited.1.5.2 Low Energy LimitIn the measurement of tracklength for proton recoil events,track length decreases asproton-recoil energy decreases.Proton-recoil track length be-low approximately 3m in NRE can not be adequately mea-sured with optical microscopy techniques.As proton-recoiltrack length decreases below approximately 3 m,it becomesvery difficult to measure track length accurately.This 3 mtrack length limit corresponds to a low energy limit ofapplicability in the range of approximately 0.3 to 0.4 MeV forneutron induced proton-recoil measurements in NRE.1This practice is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applications,and is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved Oct.1,2015.Published November 2010.Originallyapproved in 2000.Last previous edition approved in 2010 as E2059-06(2010).DOI:10.1520/E2059-15.2The boldface numbers in parentheses refer to the list of references at the end ofthe text.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 1.5.3 High-Energy LimitsAs a consequence of finite-sizelimitations,fast-neutron spectrometry measurements are lim-ited to 15 MeV.The limit for in-situ spectr