1、Designation: E523 16Standard 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,)60Co. The crosssection
3、 for60Co produced in this reaction increases rapidlywith neutrons having energies greater than about 4.5 MeV.60Co decays with a half-life of 1925.27 days (60.29 days)(1)2and emits two gamma rays having energies of 1.1732278 and1.332492 MeV(1). The isotopic content of natural copper is69.17 %63Cu and
4、 30.83 %65Cu(2). The neutron reaction,63Cu(n,)64Cu, produces a radioactive product that emitsgamma rays (1.34577 MeV (E1005) which might interferewith the counting of the60Co gamma rays.1.2 With suitable techniques, fission-neutron fluence ratesabove 109cm2s1can be determined. The63Cu(n,)60Coreactio
5、n can be used to determine fast-neutron fluences forirradiation times up to about 15 years, provided that theanalysis methods described in Practice E261 are followed. Ifdosimeters are analyzed after irradiation periods longer than 15years, the information inferred about the fluence during irra-diati
6、on periods more than 15 years before the end of theirradiation should not be relied upon without supporting datafrom dosimeters withdrawn earlier.1.3 Detailed procedures for other fast-neutron detectors arereferenced in Practice E261.1.4 This standard does not purport to address all of thesafety con
7、cerns, 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 Standards:3E170 Terminology Relating to Radiation
8、 Measurements andDosimetryE181 Test Methods for Detector Calibration and Analysis 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 Ap
9、plication of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, E 706 (IIA)E1005 Test Method for Application and Analysis of Radio-metric Monitors for Reactor Vessel SurveillanceE1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E706 (IIB)3. Terminology3.1 Defini
10、tions:3.1.1 Refer to Terminology E170.4. Summary of Test Method4.1 High-purity copper (1 g/g), thereported possible thermal component of the (n,) reaction, andthe possibly significant cross sections for thermal neutrons for63Cu and60Co (that is 4.50 and 2.0 barns, respectively),(6)which will require
11、 burnout corrections at high fluences.6. Apparatus6.1 NaI(Tl) or High Resolution Gamma-Ray SpectrometerBecause of its high resolution, the germanium detector isuseful when contaminant activities are present or when it isnecessary to analyze before the 12.701-h half-life64Cu hasdecayed away.6.2 Preci
12、sion Balance, able to achieve the required 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
13、 no cobalt impurity(1 g/g) because the reaction59Co(n,)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 s
14、teel, copper,aluminum, quartz, or 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
15、. Procedure8.1 Decide on the size 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
16、 E844).8.2 Weigh the sample.8.3 Irradiate 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
17、 of about 6 days is recommendedbetween 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
18、 sooner if a suitablegamma-ray or 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 Me
19、th-ods E181 and E1005).8.7 Disintegration 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 place
20、d close to thedetector (10 cm or less) (see Test Methods E181).9. Calculations9.1 Calculate the saturation activity As, as follows:As5A1 2 e2ti!e2tw(1)where:A =60Co disintegrations per second measured by counting,FIG. 163Cu(n,)60Co Cross Section with EXFOR ExperimentalDataE523 162 = decay constant f
21、or60Co = 4.16697 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
22、 to Practice E261for more generalized treatments.9.2 Calculate the reaction rate, Rs, as follows:Rs5 As/No(2)where:As= saturation activity, andN0= 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 descr
23、ibes how 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 specifica-tion is now used in International Or
24、ganization 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% (1 %) and with aprecision of 61%(1 %).11.2 When this measured act
25、ivity 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,)60Cocross section is shown in Fig. 2(3)11.
26、3 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 c
27、ross 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 usin
28、g 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
29、 section;dosimetry; fast-neutron monitor; neutron metrology; pressurevessel surveillance; reaction rate;63Cu(n,)60CoREFERENCES(1) Update of X-ray and Gamma Ray Decay Data Standards for DetectorCalibration and Other Applications: Vol 1: Recommended DecayData, High Energy Gamma Ray Standards and Angul
30、ar CorrelationCoefficients, International Atomic Energy Agency, Vienna, reportSTI/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,
31、 report 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
32、Energy 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,Austria, June 2008. On-line database available at URL: http:/www-nds.iaea.org/indg-ne
33、xp.html. 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 9
34、2-67-10188-9.(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 Integ
35、ralData, Report INDC(NDS)-435, pp. 59-64, IAEA, Vienna, September2002.(10) Mannhart, W., Progress Report INDC(Ger)-045, pp. 40-43, 1999.FIG. 2 Energy-dependent Uncertainty (%) for the63Cu(n,)60CoCross SectionE523 163ASTM International takes no position respecting the validity of any patent rights as
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