ASTM E704-2008 952 Standard Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238《用铀238的放射活化测定反应速率的测试方法》.pdf

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1、Designation: E 704 08Standard Test Method forMeasuring Reaction Rates by Radioactivation of Uranium-2381This standard is issued under the fixed designation E 704; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev

2、ision. 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 assaying a fission product (F.P.) from the fissionreaction

3、238U(n,f)F.P.1.2 The reaction is useful for measuring neutrons withenergies from approximately 1.5 to 7 MeV and for irradiationtimes up to 30 to 40 years.1.3 Equivalent fission neutron fluence rates as defined inPractice E 261 can be determined.1.4 Detailed procedures for other fast-neutron detector

4、s arereferenced in Practice E 261.1.5 The values stated in SI units are to be regarded asstandard. No other unites of measurement are 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

5、 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:2E 170 Terminology Relating to Radiation Measurementsand DosimetryE 181 Test Methods for Detector Calibration and

6、Analysisof RadionuclidesE 261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE 262 Test Method for Determining Thermal Neutron Re-action and Fluence Rates by Radioactivation TechniquesE 320 Test Method for Cesium-137 in Nuclear Fuel Solu-tions by Radi

7、ochemical Analysis3E 393 Test Method for Measuring Reaction Rates byAnaly-sis of Barium-140 From Fission DosimetersE 705 Test Method for Measuring Reaction Rates by Ra-dioactivation of Neptunium-237E 844 Guide for Sensor Set Design and Irradiation forReactor Surveillance, E 706(IIC)E 944 Guide for A

8、pplication 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 1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E 706 (IIB)3. Termino

9、logy3.1 Definitions:3.1.1 Refer to Terminology E 170.4. Summary of Test Method4.1 High-purity238U ( 1 MeV)fluence rate of 1 3 1011cm2s1provided the238U is shieldedfrom thermal neutrons (see Fig. 2 of Guide E 844).5.4.2 Fission product production from photonuclear reac-tions, that is, (g,f) reactions

10、, while negligible near-power andresearch-reactor cores, can be large for deep-water penetrations(1).45.5 Good agreement between neutron fluence measuredby238U fission and the54Fe(n,p)54Mn reaction has been dem-onstrated (2). The reaction238U(n,f) F.P. is useful since it isresponsive to a broader ra

11、nge of neutron energies than mostthreshold detectors.5.6 The238U fission neutron spectrum-averaged cross sec-tion in several benchmark neutron fields is given in Table 3 ofPractice E 261. Sources for the latest recommended crosssections are given in Guide E 1018. In the case ofthe238U(n,f)F.P. react

12、ion, the recommended cross sectionsource is the ENDF/B-VI release 8 cross section(MAT = 9237) (3). Fig. 1 shows a plot of the recommendedcross section versus neutron energy for the fast-neutronreaction238U(n,f)F.P.NOTE 1The data is taken from the Evaluated Nuclear Data File,ENDF/B-VI, rather than th

13、e later ENDF/B-VII. This is in accordance withGuide E 1018, Section 6.1, since the later ENDF/B-VII data files do notinclude covariance information. Some covariance information existsfor238U in the standard sublibrary, but this is only for energies greaterthan 1 MeV. For more details, see Section H

14、of Ref 4.6. Apparatus6.1 Gamma-Ray Detection Equipment that can be used toaccurately measure the decay rate of fission product activity arethe following two types (5):6.1.1 NaI(T1) Gamma-Ray Scintillation Spectrometer (seeTest Methods E 181 and E 1005).6.1.2 Germanium Gamma-Ray Spectrometer (see Tes

15、tMethods E 181 and E 1005)Because of its high resolution,the germanium detector is useful when contaminant activitiesare present.6.2 Balance, providing the accuracy and precision requiredby the experiment.6.3 Digital Computer, useful for data analysis (optional).7. Materials7.1 Uranium-238 Alloy or

16、OxideHigh-purity238Uintheform of alloy wire, foil, or oxide powder is available.7.1.1 The238U target material should be furnished with acertificate of analysis indicating any impurity concentrations.7.2 Encapsulating MaterialsBrass, stainless steel, copper,aluminum, quartz, or vanadium have been use

17、d as primaryencapsulating materials. The container should be constructedin such a manner that it will not create significant perturbation4The boldface numbers in parentheses refer to the list of references appended tothis test method.TABLE 1 Recommended Nuclear Parameters for Certain FissionProducts

18、FissionProductParentHalf-LifeA(6)PrimaryRadiationA(7) (keV)g ProbabilityofDecayA(7)MaximumUsefulIrradiationDuration95Zr 64.032 (6) d 724.192 (4) 0.4427 (22) 6 months756.725 (12) 0.543899Mo 2.7489 (6) d 739.500 (17) 0.1213 (22) 300 hours777.921 (20) 0.0426 (8)103Ru 39.26 (2) d 497.084 (6) 0.910 (12)

19、4 months137Cs 30.03 (5) yr 661.657 (3)B0.8510B3040 years140Ba 140La 12.752 (3) d 537.261 (4) 0.2439 (23) 11.5 months1596.21 (4) 0.954 (14)C1.1515D144Ce 289.91 (5) d 133.515 (2) 0.1109 (10) 23 yearsAThe lightface numbers in parentheses are the magnitude of plus or minusuncertainties in the last digit

20、(s) listed.BWith137mBa (2.552 min) in equilibrium.CProbability of daughter140La decay.DWith140La (1.6781 d) in transient equilibrium.TABLE 2 Recommended Fission Yields for Certain FissionProductsAFissileIsotopeNeutronEnergyReactionProductTypeYieldENDF/B-VIIA,BFission Yield %238U(n,f) 0.5 MeV95Zr RC

21、6.01736 6 4%99Mo RC 6.16825 6 1.4 %103Ru RC 6.27532 6 1.4 %137Cs RC 6.05254 6 1%137mBa RI 6.56004e-6 6 64 %140Ba RC 5.81523 6 0.7 %140La RI 2.48002e-5 6 64 %144Ce RC 4.54797 6 1.4 %A“Special Issue on Evaluated Nuclear Data File ENDF/B-VII.0,” Nuclear DataSheets, J. K. Tuli, editor, Vol 107, December

22、 2006. Data available on theENDF/B-VII, Online, http:/www.nndc.bnl.gov/exfor/endf00.htm, July 1, 2008.BAll yield data given as a %; RC represents a cumulative yield; RI represents anindependent yield.E704082of the neutron spectrum and fluence rate and that it may beopened easily, especially if the c

23、apsule is to be openedremotely. Certain encapsulation materials, for example, quartzand vanadium, allow gamma-ray counting without opening thecapsule since there are no interfering activities.8. Procedure8.1 Select the size and shape of the sample to be irradiated,taking into consideration the size

24、and shape of the irradiationspace. The mass and exposure time are parameters that can bevaried to obtain a desired count rate for a given neutron fluencerate.8.2 Weigh the sample to the accuracy and precision requiredof the experiment; encapsulate; and, if irradiated in a thermalneutron environment,

25、 surround with a suitable high-meltingthermal neutron absorber.NOTE 2The melting point of elemental cadmium is 321C. Foradditional precautions, see Test Method E 262.8.3 Irradiate the sample for the predetermined time period.Record the power level and any changes in power during theirradiation, the

26、time at the beginning and end of each powerlevel, and the relative position of the monitors in the irradiationfacility.8.4 Check the sample for activity from cross contaminationby other monitors or material irradiated in the vicinity or fromany foreign substance adhering to the sample. Clean andrewe

27、igh, if necessary. If the sample is encapsulated oxidepowder and if it is necessary to open the capsule, a suitablecontainment will be required.8.4.1 If chemical separation is necessary, dissolution can beachieved in 8 N HNO3-0.05 N HF.NOTE 3If an ion-exchange separation is to be subsequently per-fo

28、rmed, follow the dissolution by fuming with sulfuric acid (H2SO4)toexpel fluorides. Fuming with H2SO4, however, may expel volatile fissionproduct ruthenium, and, unless performed with care, losses of other fissionproducts by spattering can occur.8.5 Analyze the sample for fission-product content in

29、dis-integrations per second (see Test Methods E 181, E 320, andE 1005).8.5.1 It is assumed that the available apparatus has beencalibrated to measure F.P. activity and that the experimenter iswell versed in the operation of the apparatus.8.5.2 Disintegration of137Cs nuclei produces 0.662-MeVgamma ra

30、ys with a probability per decay of 0.852. It isrecommended that a137Cs activity standard is used.8.5.3 If the analyst is well versed in germanium countingand carefully calibrates the system, it is feasible to count137Cs-137mBa,140Ba-140La,95Zr, and144Ce directly without chemicalseparation.9. Calcula

31、tion9.1 Calculate the saturation activity, As, as follows:As5 A/y1 2 exp2lti!exp2ltw!# (1)where:l = disintegration constant for F.P., s1,A = number of disintegrations measured during the count-ing period, s1,ti= irradiation duration, s,tw= elapsed time between the end of irradiation andcounting, s,

32、andy = fission yield.NOTE 4This equation applies where transient equilibrium has beenestablished, l is that of the parent species. This equation should not beFIG. 1 ENDF/B-VI Cross Section Versus Energy for the238U(n,f)F.P. ReactionE704083applied to the Ba/La line but can be applied to the other fis

33、sion products.See Test Method E 393 for reading the140Ba/140La line.NOTE 5The equation for Asis valid if the reactor operated at essen-tially constant power and if corrections for other reactions (for example,impurities, burnout, etc.) are negligible. Refer to Practice E 261 for moregeneralized trea

34、tments.9.2 Calculate the reaction rate,5Rs, as follows:Rs5 As/No(2)where:No= number of target atoms.9.3 Refer to Practice E 261 and Guide E 944 for a discus-sion of the determination of fast-neutron fluence rate andfluence.10. Report10.1 Practice E 261 describes how data should be reported.11. Preci

35、sion and BiasNOTE 6Measurement uncertainty is described by a precision and biasstatement in this standard. Another acceptable approach is to use Type Aand B uncertainty components (8, 9). This Type A/B uncertainty specifi-cation is now used in International Organization for Standardization (ISO)Stan

36、dards and this approach can be expected to play a more prominentrole in future uncertainty analyses.11.1 General practice indicates that disintegration rates canbe determined with a bias of 6 5 % (1S %) and with aprecision of 61 % (1S %) (10).11.2 The238U cumulative fission product yields have anunc

37、ertainty between 1.4 % and 6 % (1S %) for the variousfission products as indicated in Table 1.12. Keywords12.1 fission dosimeter; fission product; fission reactionrates; Uranium-238REFERENCES(1) Verbinski, V. V., et al, “Measurements and Calculations of PhotofissionEffects in a Swimming Pool Type Re

38、actor,” Transactions of theAmerican Nuclear Society, Vol 30, Washington, DC, November 1978.(2) Barry, K. M., and Corbett, J.A., “Measurement of Neutron Fluence byNeptunium-237 and Uranium-238 Fission Dosimeters,” Nuclear Tech-nology, Vol 11, May 1971.(3) “ENDF-201, ENDF/B-VI Summary Documentation,”

39、P. F. Rose, ed.,Brookhaven National Laboratory Report BNL-NCS-174, 4th Edition,October 1991.(4) “Special Issue on Evaluated Nuclear Data File ENDF/B-VII.0,”Nuclear Data Sheets, J. K. Tuli, ed., , Vol 107, December 2006.(5) Crouthamel, C. E. (Revised by Adams, F., and Dams, R.), AppliedGamma-Ray Spec

40、trometry, Pergamon Press, 1970.(6) Nuclear Wallet Cards, compiled by J. K. Tuli, National Nuclear DataCenter, April 2005.(7) Nuclear Data retrieval program NUDAT, a computer file of evaluatednuclear structure and radioactive decay data, which is maintained bythe National Nuclear Data Center (NNDC),

41、Brookhaven NationalLaboratory (BNL), on behalf of the International Network for NuclearStructure Data Evaluation, which functions under the auspices of theNuclear Data Section of the International Atomic Energy Agency(IAEA).(8) Taylor, B. N., Kuyatt, C. E., “Guidelines for Evaluating and Express-ing

42、 the Uncertainty of NIST Measurement Results,” NIST TechnicalNote 1297, National Institute of Standards and Technology, Gaithers-burg, MD, 1994.(9) Guide in the Expression of Uncertainty in Measurements, InternationalOrganization for Standardization, 1995, ISBN 9267101889.(10) Adams, J. M., “Results

43、 from the NIST Round Robin Test ofFissionable Dosimeters in a Reactor Leakage Spectrum,” ReactorDosimetry: Radiation Metrology and Assessment, ASTM STP 1389,American Society for Testing and Materials, West Conshohocken,PA, 2001ASTM International takes no position respecting the validity of any paten

44、t 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 patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision a

45、t any time by the responsible technical committee and must be reviewed every five years andif not 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 commen

46、ts will receive careful consideration at a meeting of theresponsible technical committee, which 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

47、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 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).5Within the context of this test method, the terms “fission rate” and “reactionrate” can be used synonymously.E704084