ASTM E264-2008 952 Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Nickel《通过镍的放射性测量快中子反应速率的试验方法》.pdf

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1、Designation: E 264 08Standard Test Method forMeasuring Fast-Neutron Reaction Rates by Radioactivationof Nickel1This standard is issued under the fixed designation E 264; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l

2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers procedures for

3、 measuring reac-tion rates by the activation reaction58Ni(n,p)58Co.1.2 This activation reaction is useful for measuring neutronswith energies above approximately 2.1 MeV and for irradiationtimes up to about 200 days in the absence of high thermalneutron fluence rates (for longer irradiations, see Pr

4、acticeE 261).1.3 With suitable techniques fission-neutron fluence ratesdensities above 107cm2s1can be determined.1.4 Detailed procedures for other fast-neutron detectors arereferenced in Practice E 261.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are

5、 included in thisstandard.1.6 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 pr

6、ior to use.2. Referenced Documents2.1 ASTM Standards:2E 170 Terminology Relating to Radiation Measurementsand DosimetryE 181 Test Methods for Detector Calibration and Analysisof RadionuclidesE 261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE 844 G

7、uide for Sensor Set Design and Irradiation forReactor Surveillance, E 706(IIC)E 944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, E 706 (IIA)E 1005 Test Method forApplication andAnalysis of Radio-metric Monitors for Reactor Vessel Surveillance, E706(IIIA)E 10

8、18 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E 706 (IIB)3. Terminology3.1 Definitions:3.1.1 Refer to Terminology E 170.4. Summary of Test Method4.1 High-purity nickel is irradiated in a neutron field,thereby producing radioactive58Co from the58Ni(n,p)58Coactivation react

9、ion.4.2 The gamma rays emitted by the radioactive decay of58Co are counted in accordance with Test Methods E 181 andthe reaction rate, as defined by Practice E 261, is calculatedfrom the decay rate and irradiation conditions.4.3 The neutron fluence rate above about 2.1 MeV can thenbe calculated from

10、 the spectral-weighted neutron activationcross section as defined by Practice E 261.5. Significance and Use5.1 Refer to Guide E 844 for the selection, irradiation, andquality control of neutron dosimeters.1This test method is under the jurisdiction ofASTM Committee E10 on NuclearTechnology and Appli

11、cations and is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved July 1, 2008. Published September 2008. Originallyapproved in 1965. Last edition approved in 2002 as E 264 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, o

12、rcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.NOTEThe burnup corrections were computed using effective burn-upcross sections of 1650 b for58Co(n,g) and 1.4E5 b for58mCo(n,g).FIG.

13、 1 R Correction Values as a Function of Irradiation Time andNeutron Flux1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Refer to Practice E 261 for a general discussion of thedetermination of fast-neutron fluence rate with thresh

14、old de-tectors.5.3 Pure nickel in the form of foil or wire is readilyavailable, and easily handled.5.458Co has a half-life of 70.86 days3and emits a gammaray with an energy of 0.8107593-MeV.45.5 Competing activities65Ni(2.5172 h) and57Ni(35.60 h)are formed by the reactions64Ni(n,g)65Ni, and58Ni(n,2n

15、)57Ni,respectively.5.6 Asecond 9.04 h isomer,58mCo, is formed that decays to70.86-day58Co. Loss of58Co and58mCo by thermal-neutronburnout will occur in environments5,6having thermal fluencerates of 3 3 1012cm2s1and above. Burnout correctionfactors, R, are plotted as a function of time for several th

16、ermalfluxes in Fig. 1. Tabulated values for a continuous irradiationtime are provided in Hogg, et al.65.7 Fig. 2 shows a plot of cross section7versus energy forthe fast-neutron reaction58Ni(n,p)58Co. This figure is forillustrative purposes only to indicate the range of response ofthe58Ni(n,p) reacti

17、on. Refer to Guide E 1018 for descriptions ofrecommended tabulated dosimetry cross sections.NOTE 1The data is taken from the Evaluated Nuclear Data File,ENDF/B-VI, rather than the later ENDF/B-VII. This is in accordance withE 1018, section 6.1, since the later ENDF/B-VII data files do not includecov

18、ariance information. For more details see Section H of reference 8.86. Apparatus6.1 NaI (T1) or High Resolution Gamma-Ray Spectrometer.Because of its high resolution, the germanium detector isuseful when contaminant activities are present (see Test Meth-ods E 181 and E 1005).6.2 Precision Balance, a

19、ble to achieve the required accu-racy.6.3 Digital Computer, useful for data analysis (optional).7. Materials7.1 The nickel metal must be low in contained cobalt toprevent the production of60Co by thermal-neutron capture.Nickel produced by the carbonyl (Mond) process is sufficientlyfree of cobalt for

20、 even the most adverse conditions. Wheneverpossible, all nickel should be tested for interfering impuritiesby neutron activation.7.2 Encapsulating MaterialsBrass, stainless steel, copper,aluminum, quartz, or vanadium have been used as primaryencapsulating materials. The container should be construct

21、edin 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 E 844).8. Procedure8.1 Decide on the size and shape of nickel sample to beirradiated. This is influenced by the irradiation space and

22、 theexpected production of58Co. Calculate the expected produc-tion rate of58Co from the activation equation described inSection 9, and adjust the sample size and irradiation time sothat the58Co may be counted accurately.8.2 Determine the level of thermal-neutron fluence rate byincluding a thermal-fl

23、uence rate monitor. Place the sample in aboron or cadmium shield if required.8.3 Weigh the sample.8.4 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 irradiationperiod, and the rela

24、tive position of the monitors in theirradiation facility.8.5 A waiting period of at least 4 days is recommendedbetween termination of the exposure and start of counting. Thisallows the 9.04-h58mCo to decay entirely to the 70.86-day58Coground state. Activated impurities such as 2.52-h65Ni, 35.6-h57Ni

25、, and 23.72-h187W, sometimes observed in nickel pre-pared by high-temperature sintering in tungsten, will also beeliminated by allowing the sample to decay over an extendedperiod.8.6 Check the sample for activity from cross-contaminationby other irradiated materials. Clean, if necessary, and reweigh

26、.8.7 Analyze the sample for58Co content in disintegrationsper second using the gamma-ray spectrometer (see Test Meth-ods E 181 and E 1005).3J. K. Tulti, “Nuclear Wallet Cards,” National Nuclear Data Center, BrookhavenNational Laboratory, Upton, New York, April 2005.4Evaluated Nuclear Structure Data

27、File (ENSDF), a computer file of evaluatednuclear structure and radioactive decay data, which is maintained by the NationalNuclear Data Center (NNDC), Brookhaven National Laboratory (BNL), on behalfof the International Network for Nuclear Structure Data Evaluation, which functionsunder the auspices

28、of the Nuclear Data Section of the International Atomic EnergyAgency (IAEA). The URL is http;/www.nndc.bnl.gov/nndc/ensdf. The data quotedhere comes from the database as of January 1, 2002.5Hogg, C. H., Weber, L. D., and Yates, E. C., “Isomers and the Effects on FastFlux Measurements Using Nickel,”

29、Atomic Energy Commission R and D ReportIDO-16744, 1962.6Hogg, C. H., Weber, L. D.,Yates, E.C., “Thermal Neutron Cross Sections of theCo58Isomers and the Effect on Fast Flux Measurements Using Nickel,” IDO-16744AEC Research activation reaction; cross section; dosim-etry; fast-neutron monitor; neutron

30、 metrology; nickel; pressurevessel surveillance; reaction rateASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such

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33、ir 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,United States. Individual reprints (single or multiple copies) of this st

34、andard 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).9B. N. Taylor, C.E. Kuyatt, Guidelines for Evaluating and Expressing theUncertainty of NIST Measurement Results, NIST Technical Note 1297, NationalInstitute of Standards and Technology, Gaithersburg, MD, 1994.10Guide in the Expression of Uncertainty in Measurements , InternationalOrganization for Standardization, 1995, ISBN 9267101889.E264083