1、Designation: E523 11Standard Test Method forMeasuring Fast-Neutron Reaction Rates by Radioactivationof Copper1This standard is issued under the fixed designation E523; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t 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 covers procedures for measuring reac-tion rates by the activation reaction63Cu(n,a)60Co. The crosssectio
3、n for60Co produced in this reaction increases rapidlywith neutrons having energies greater than about 5 MeV.60Codecays with a half-life of 1925.27 days (60.29 days)(1)2andemits two gamma rays having energies of 1.1732278 and1.332492 MeV (1). The isotopic content of natural copper is69.17 %63Cu and 3
4、0.83 %65Cu (2). The neutron reaction,63Cu(n,g)64Cu, produces a radioactive product that emitsgamma rays which might interfere with the counting of the60Co gamma rays.1.2 With suitable techniques, fission-neutron fluence ratesabove 109cm2s1can be determined. The63Cu(n,a)60Coreaction can be used to de
5、termine fast-neutron fluences forirradiation times up to about 15 years (for longer irradiations,see Practice E261).1.3 Detailed procedures for other fast-neutron detectors arereferenced in Practice E261.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with
6、 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 Standards:3E170 Terminology Relating to Radiation Measurements andDosimetryE181
7、 Test Methods for Detector Calibration andAnalysis ofRadionuclidesE261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE844 Guide for Sensor Set Design and Irradiation forReactor Surveillance, E 706(IIC)E944 Guide for Application of Neutron Spectrum Ad
8、just-ment Methods in Reactor Surveillance, E 706 (IIA)E1005 Test Method for Application and Analysis of Radio-metric Monitors for Reactor Vessel Surveillance, E706(IIIA)E1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E706 (IIB)3. Terminology3.1 Definitions:3.1.1 Refer to
9、 Terminology E170.4. Summary of Test Method4.1 High-purity copper (1 g/g), thereported possible thermal component of the (n,a) reaction, andthe possibly significant cross sections for thermal neutrons for63Cu and60Co (that is 4.50 and 2.0 barns, respectively),(6)which will require burnout correction
10、s at high fluences.6. Apparatus6.1 NaI(Tl) or High Resolution Gamma-RaySpectrometerBecause of its high resolution, the germaniumdetector is useful when contaminant activities are present orwhen it is necessary to analyze before the 12.701 h64Cu hasdecayed.6.2 Precision Balance, able to achieve the r
11、equired accu-racy.7. Materials7.1 Copper MetalPure copper metal in the form of wire orfoil is available.7.1.1 The metal should be tested for impurities by a neutronactivation technique. If the measurement is to be made in athermal-neutron environment, there must be no cobalt impurity(1 g/g) because
12、the reaction59Co(n,g)60Co produces thesame product as produced in the subject reaction. To reducethis interference, the use of a thermal-neutron shield duringirradiation would be advisable if cobalt impurity is suspected.7.2 Encapsulating MaterialsBrass, stainless steel, copper,aluminum, quartz, or
13、vanadium have been used as primaryencapsulating materials. The container should be constructedin such a manner that it will not create significant fluxperturbation and that it may be opened easily, especially if thecapsule is to be opened remotely (see Guide E844).8. Procedure8.1 Decide on the size
14、and shape of the copper sample to beirradiated, taking into consideration the size and shape of theirradiation space. The mass and exposure time are parametersthat can be varied to obtain a desired disintegration rate for agiven neutron fluence rate level (see Guide E844).8.2 Weigh the sample.8.3 Ir
15、radiate the sample for the predetermined time period.Record the power level and any changes in power during theirradiation, the time at the beginning and end of the irradiation,and the relative position of the monitors in the irradiationfacility.8.4 A waiting period of about 6 days is recommendedbet
16、ween termination of the exposure and analyzing the samplefor60Co content. This allows the 12.701 h64Cu (1) to decay sothat there is no interference from the gamma rays emitted by64Cu, that is, the 0.511 and 1.34577 MeV gamma rays (1).However, analysis may be performed sooner if a suitablegamma-ray o
17、r peak analysis technique is used.8.5 Check the sample for activity from cross-contaminationby other irradiated materials. Clean, if necessary and reweigh.8.6 Analyze the sample for60Co content in disintegrationsper second using the gamma-ray spectrometer (see Test Meth-ods E181 and E1005).8.7 Disin
18、tegration of60Co nuclei produces 1.173228 MeVand 1.332492 MeV gamma rays with probabilities per decay of0.9985 and 0.999826 respectively.(1) When analyzing eitherpeak in the gamma-ray spectrum, a correction for coincidencesumming may be required if the sample is placed close to thedetector (10 cm or
19、 less) (see Test Methods E181).9. Calculations9.1 Calculate the saturation activity As, as follows:As5 A/1 2 exp 2 lti#! exp 2 ltw#!#(1)where:FIG. 163Cu(n,a)60Co Cross Section with EXFOR Experimental DataE523 112A =60Co disintegrations per second measured by count-ing,l = decay constant for60Co = 4.
20、16697 3 109s1,ti= irradiation duration s,tw= elapsed time between the end of irradiation andcounting, s.NOTE 2The equation for Asis valid if the reactor operated atessentially constant power and if corrections for other reactions (forexample, impurities, burnout, etc.) are negligible. Refer to Pract
21、ice E261for more generalized treatments.9.2 Calculate the reaction rate, Rs, as follows:Rs5 As/No(2)where:As= saturation activity, andNo= number of63Cu atoms.9.3 Refer to Practice E261 and Guide E944 for a discussionof fast-neutron fluence rate and fluence.10. Report10.1 Practice E261 describes how
22、data should be reported.11. Precision and BiasNOTE 3Measurement uncertainty is described by a precision and biasstatement in this standard. Another acceptable approach is to use Type Aand B uncertainty components (7,8). This Type A/B uncertainty specifi-cation is now used in International Organizati
23、on for Standardization (ISO)standards and this approach can be expected to play a more prominent rolein future uncertainty analyses.11.1 General practice indicates that disintegration rates canbe determined with a bias of 6 3 % (1S %) and with aprecision of 61 % (1S %).11.2 When this measured activi
24、ty is used in conjunctionwith a neutron spectrum to determine a neutron fluence, theenergy-dependent uncertainty of the spectrum and the crosssection are important considerations. The energy-dependentuncertainty, expressed as a percentage, for the63Cu(n,a)60Cocross section is shown in Fig. 2(3)11.3
25、Test results have been reported in well characterizedneutron benchmark fields.11.3.1 In the252Cf spontaneous fission reference neutronfield, the measured cross section is 0.6887 b 6 1.9 % (9) andthe calculated cross section using the RRDF-2002 cross sectionis 0.69248 b with a spectrum integrated cro
26、ss section uncer-tainty of 1.399 % (3) and a spectrum characterization uncer-tainty of 1.37 %. This results in a calculated-to-experimental(C/E) ratio of 1.0055 6 2.73 %.11.3.2 In the235U thermal neutron field, the measured crosssection is 0.4935 b 6 4.9 % (10) and the calculated crosssection using
27、the RRDF-2002 cross section is 0.53294 b witha spectrum integrated cross section uncertainty of 1.461 % (3)and a spectrum characterization uncertainty of 6.042 %. Thisresults in a calculated-to-experimental (C/E) ratio of 1.08 67.92 %.12. Keywords12.1 activation; activation reaction; copper; cross s
28、ection;dosimetry; fast-neutron monitor; neutron metrology; pressurevessel surveillance; reaction rateE523 113REFERENCES(1) Update of X-ray and Gamma Ray Decay Data Standards for DetectorCalibration and OtherApplications: Vol 1: Recommended Decay Data,High Energy Gamma Ray Standards and Angular Corre
29、lation Coeffi-cients, International Atomic Energy Agency, Vienna, report STI/PUB/1287, 2007.(2) Nuclear Wallet Cards, compiled by J. K. Tuli, National Nuclear DataCenter, April 2005.(3) Zolotarev, K. I., Ignatyuk, A. V., Mahokhin, V. N., Pashchenco, A. B.,“RRDF-98 Russian Reactor Dosimetry File, rep
30、ort IAEA-NDS-193,March 1999. The last full release was in 1998. Updated versionscorresponding to the RRDF-2002 library have been incorporated intothe IRDF-2002 dosimetry library.(4) International Reactor Dosimetry File 2002 (IRDF-2002, IAEA Tech-nical Report Series No. 452, International Atomic Ener
31、gy Agency,Vienna,Austria, 2006.Available at: http:/www-nds.iaea.org/irdf2002/index.html.(5) “EXFOR Formats Description for Users (EXFOR Basics),” reportIAEA-NDS-206, International Atomic Energy Agency, Vienna, Aus-tria, June 2008. On-line database available at URL: http:/www-nds.iaea.org/indg-nexp.h
32、tml. Data here as present on January 2011.(6) Mughabghab, S. F., Atlas of Neutron Resonances: Resonance Param-eters and Thermal Cross Sections Z=1-100, Elsevier, Amsterdam,2006.(7) Guide to the Expression of Uncertainty in Measurement, InternationalOrganization for Standardization, 1995, ISBN 92-67-
33、10188-9.(8) Taylor, B. N. and Kuyatt, C. E., Guidelines for Evaluating andExpressing the Uncertainty of NIST Measurement Results, NISTTechnical Note 1297, National Institute of Standards and Technology,Gaithersburg, MD, 1994.(9) Mannhart, W., Validation of Differential Cross Sections with IntegralDa
34、ta, Report INDC(NDS)-435, pp. 59-64, IAEA, Vienna, September2002.(10) Mannhart, W., Progress Report INDC(Ger)-045, pp. 40-43, 1999.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard
35、are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif no
36、t revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which
37、you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,Unit
38、ed States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. 2 Energy-dependent Uncertainty (%) for the63Cu(n,a)60Co Cross SectionE523 114
