ASTM E393-2013 3750 Standard Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission Dosimeters《通过分析由裂变剂量计产生的钡-140来测定反应速率的标准试验方法》.pdf
《ASTM E393-2013 3750 Standard Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission Dosimeters《通过分析由裂变剂量计产生的钡-140来测定反应速率的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM E393-2013 3750 Standard Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission Dosimeters《通过分析由裂变剂量计产生的钡-140来测定反应速率的标准试验方法》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: E393 13Standard Test Method forMeasuring Reaction Rates by Analysis of Barium-140 FromFission Dosimeters1This standard is issued under the fixed designation E393; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 This test method describes two procedures for themeasurement of reaction rates by determining the amount ofthe fi
3、ssion product140Ba produced by the non-thresholdreactions235U(n,f),241Am(n,f), and239Pu(n,f), and by thethreshold reactions238U(n,f),237Np(n,f), and232Th(n,f).1.2 These reactions produce many fission products, amongwhich is140Ba, having a half-life of 12.752 days.140Ba emitsgamma rays of several ene
4、rgies; however, these are not easilydetected in the presence of other fission products. Competingactivity from other fission products requires that a chemicalseparation be employed or that the140Ba activity be deter-mined indirectly by counting its daughter product140La. Thistest method describes bo
5、th procedure (a), the nondestructivedetermination of140Ba by the direct counting of140La severaldays after irradiation, and procedure (b), the chemical separa-tion of140Ba and the subsequent counting of140Ba or itsdaughter140La.1.3 With suitable techniques, fission neutron fluence ratescan be measur
6、ed in the range from 107n (neutrons) cm2s1to approximately 1015ncm2s1.1.4 The measurement of time-integrated reaction rates withfission dosimeters by140Ba analysis is limited by the half-lifeof140Ba to irradiation times up to about six weeks.1.5 The values stated in SI units are to be regarded assta
7、ndard. No other units 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 of this standard to establish appro-priate safety and health practices and determine the app
8、lica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C697 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade PlutoniumDioxide Powders and PelletsD1193 Specification for Reagent WaterE170 Terminology Relating to Radiati
9、on Measurements andDosimetryE181 Test Methods for Detector Calibration and Analysis ofRadionuclidesE261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE704 Test Method for Measuring Reaction Rates by Radio-activation of Uranium-238E705 Test Method for
10、 Measuring Reaction Rates by Radio-activation of Neptunium-237E844 Guide for Sensor Set Design and Irradiation forReactor Surveillance, E 706 (IIC)E944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, E 706 (IIA)E1005 Test Method for Application and Analysis of
11、Radio-metric Monitors for Reactor Vessel Surveillance, E 706(IIIA)E1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E706 (IIB)3. Terminology3.1 Definitions:3.1.1 Refer to Terminology E170.4. Summary of Test Method4.1 For nondestructive analysis, the fission dosimeter isall
12、owed to cool for five days or more. The 1.596-MeV gammaenergy peak of140La, which is the daughter product of the140Ba, is then counted. This information, combined with thedecay constants for the La and the Ba, and the fission yield ofthe140Ba gives the reaction fission rate. When the proper cross1Th
13、is test method is under the jurisdiction ofASTM Committee E10 on NuclearTechnology and Applicationsand is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved June 1, 2013. Published July 2013. Originally approvedin 1984. Last previous edition appro
14、ved in 2008 as E393 08. DOI: 10.1520/E0393-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM
15、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1section is used with the reaction rate, the equivalent fissionfluence rate can be determined.4.2 For destructive analysis, the fission product140Ba isseparated from the irradiated fission dosimeter. Th
16、e activity ofthe140Ba is determined by counting the 0.537 MeV gammaenergy peak. This information is then used as in 4.1 to give thereaction rate.5. Significance and Use5.1 Refer to Guide E844 for the selection, irradiation, andquality control of neutron dosimeters.5.2 Refer to Practice E261 for a ge
17、neral discussion of themeasurement of neutron fluence rate and fluence. The neutronspectrum must be known in order to measure neutron fluencerates with a single detector. Also it is noted that cross sectionsare continuously being reevaluated. The latest recommendedcross sections and details on how t
18、hey can be obtained arediscussed in Guide E1018.5.3 The reaction rate of a detector nuclide of known crosssection, when combined with information about the neutronspectrum, permits the determination of the magnitude of thefluence rate impinging on the detector. Furthermore, if resultsfrom other dete
19、ctors are available, the neutron spectrum can bedefined more accurately. The techniques for fluence rate andfluence determinations are explained in Practice E261.5.4140Ba is a radioactive nuclide formed as a result ofuranium fission. Although it is formed in fission of any heavyatom, the relative yi
20、eld will differ. Recommended fission yieldsfor140Ba production are given in Table 1. The direct (indepen-dent) fission yield of the daughter product140La, which iscounted, is given in Table 2. These independent fission yieldsare relatively low compared to the140Ba cumulative fissionyield and will no
21、t significantly affect the accuracy of thenondestructive procedure and need not be considered.5.5 The half-life of140Ba is 12.752 days. Its daughter140Lahas a half-life of 1.6781 days.3The comparatively longhalf-life of140Ba allows the counting to be delayed severalweeks after irradiation in a high-
22、neutron field. However, toachieve maximum sensitivity the daughter product140Lashould be counted five to six days after the irradiation duringnondestructive analysis or five to six days after chemicalseparation if the latter technique is used.An alternative methodafter chemical separation is to coun
23、t the140Ba directly.5.6 Because of its 12.752 day half-life and substantialfission yield,140Ba is useful for irradiation times up to aboutsix weeks in moderate intensity fields. The number of fissionsproduced should be approximately 109or greater for goodcounting statistics. Also, if the irradiation
24、 time is substantiallylonger than six weeks, the neutron fluence rate determined willapply mainly to the neutron field existing during the latter partof the irradiation. The140Ba decay constant and yield areknown more accurately than those of many fission products, soit is sometimes used as a standa
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