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
25、rd or base reaction with whichother measurements can be normalized.6. Apparatus6.1 For nondestructive analysis the chemical separationequipment, materials, and reagents are not required.6.2 A NaI(Tl) or Germanium Gamma-Ray Spectrometer, seeTest Methods E181 and E1005.6.3 Balance, providing the accur
26、acy and precision requiredby the experiment.6.4 Centrifuge, clinical type, accommodating 50-mL centri-fuge tubes.6.5 Steam Bath.6.6 Ice Bath.6.7 Drying Oven.6.8 Filter Cones.6.9 Fiberglass Filter Circles for filter cone.6.10 Centrifuge Tubes, 50-mL capacity.6.11 Fine Sintered-Glass Crucibles.7. Reag
27、ents and Materials7.1 Purity of Fission DosimetersHigh purity uraniumplutonium, neptunium, and thorium in the form of alloy wire,foil, or oxide powder are available.7.1.1 Target material shall be furnished with a certificate ofanalysis indicating any impurity concentrations.3Nuclear Wallet Cards, co
28、mpiled by J. K. Tuli, National Nuclear Data Center,April 2005.TABLE 1 Recommended Cumulative Fission Yields for140BaProductionFission DosimeterThermal or FastNeutron FieldFission Yield,%A,B235UTF6.21448 1 %5.977730 1 %238U F 5.81523 1 %239Pu TF5.35451 1.4 %5.32323 1.4 %237Np F 5.48848 2 %232Th F 7.8
29、7767 2.8 %241Am TF5.92114 2.8 %4.92101 4 %AThese ENDF/B-VI values are considered the best available data. The uncertain-ties are expressed as a percentage of the fission yield.BSpecial Issue on Evaluated Nuclear Data File ENDF/B-VII.0,” Nuclear DataSheets, J. K. Tuli Editor, Vol. 107, December 2006.
30、 Data available on theENDF/BVII web site at URL: http:/www.nndc.bnl.gov/exfor/endf00.htm.TABLE 2 Independent Fission Yields for140La ProductionFission DosimeterThermal or FastNeutron FieldFission Yield, %A,B235UTF5.21563 10364%2.03998 10464%238U F 2.48002 10564%239Pu TF1.01969 10264%9.86983 10364%23
31、7Np F 5.121 10364%232Th F 4.84989 10664%241Am TF1.5295 10264%2.0392 10232%AThese ENDF/B-VI values are considered the best available data. The uncertain-ties are expressed as a percentage of the fission yield.B“Special Issue on Evaluated Nuclear Data File ENDF/B-VII.0,” Nuclear DataSheets, J. K. Tuli
32、, Editor, Vol. 107, December 2006.E393 1327.1.2 Fission dosimeters shall be encapsulated in hermeti-cally sealed containers to avoid loss of materials and forhealth-hazard requirements.47.1.3 In thermal reactors threshold reaction dosimeters (forexample,238U,237Np,232Th) shall be shielded from therm
33、alneutrons with elemental, or compounds of, cadmium,gadolinium, or boron to prevent fission production from tracequantities (40 ppm) of235U, and239Pu and to suppressbuildup of interfering fissionable nuclides, for example,239Puin the238U dosimeter,238Np and238Pu in the237Np dosimeter,and233Uinthe232
34、Th dosimeter (see Guide E844).7.2 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications a
35、re available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.3 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as d
36、efinedby Type II of Specification D1193.7.4 Acetic Acid (36 %)Dilute 360 mL of glacial aceticacid to 1 L with water.7.5 Acetic Acid (6 %)Dilute 60 mL of glacial acetic acidto 1 L with water.7.6 Ammonium Acetate Solution (231 g/L)Dissolve 231 gof ammonium acetate in water and dilute to 1 L.7.7 Ammoni
37、um Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).7.8 Barium Carrier (10 mg Ba/mL)See Section 8.7.9 Ethyl Alcohol (95 %).7.10 Hydrochloric Acid (sp gr 1.42)Concentrated hydro-chloric acid (HCl).7.11 Iron Carrier (10 mg Fe+/mL)Dissolve 48.4 g ofFeCl36H2O in 100 mL of water and dilute
38、to 1 L with water.7.12 Nitric Acid, Fuming.7.13 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).7.14 Sodium Carbonate SolutionPrepare a saturated solu-tion of sodium carbonate (Na2CO3).7.15 Sodium Chromate Solution (243 g/L)Dissolve 243 gof sodium chromate (Na2CrO4) in water and dilute to 1 L
39、.7.16 Strontium Holdback Carrier (10 mg Sr/mL)Dissolve24.2 g of Sr(NO3)2in 1 L of water. Mix well, filter through aglass wool, and store in a polyethylene bottle.7.17 Hydrofluoric Acid (HF) (1 N).8. Preparation and Standardization of Barium Carrier8.1 Preparation and Standardization of Barium Carrie
40、r:8.1.1 Dissolve 19.0 g of barium nitrate (Ba(NO3)2)indeionized water and dilute to 1 L. Filter through glass wool andstore in a polyethylene bottle.8.2 Standardization of Barium Carrier:8.2.1 Pipet 5.0 mL of the carrier solution into a 250-mLbeaker and dilute to approximately 100 mL.Add 5 mLof acet
41、icacid (36 %) and 10 mLof ammonium acetate solution. Bring toboiling; add 5 mL of Na2CrO4solution dropwise with stirring;boil for 1 min with stirring. Cool the mixture to roomtemperature and filter the precipitated barium chromate(BaCrO4) through a fine preweighed sintered-glass crucible.8.2.2 Wash
42、the precipitate three times with 5-mLportions ofdeionized water and three times with 5-mL portions of ethylalcohol. Dry at 110C, cool, and weigh. Calculate the bariumcontent as follows:Ba11, mg/mL 5 W/V! 30.5421 (1)where:W = milligrams of BaCrO4, andV = millilitres of carrier used.9. Procedure for N
43、ondestructive Analysis9.1 Decide on the size and shape of sample to be irradiated(see Guide E844).9.2 Weigh the sample to the accuracy and precision of theexperiment.9.3 Place the sample in a cadmium, gadolinium, or boroncover if desired (see Guide E844). Seal into a capsule whenrequired by safety c
44、onsiderations.9.4 Irradiate the sample for a predetermined period of time.Record the beginning and end of the irradiation period. Takeinto account any reactor power variation during the exposureperiod.9.5 Prior to counting, remove any covering material fromthe dosimeter if it possesses interfering r
45、adionuclides. Ifencapsulated in quartz, copper, aluminum, or vanadium, theencapsulating material need not be removed before counting.9.6 After five days after the irradiation, count the140Ladirectly on a gamma-ray spectrometer (1.596-MeV gamma), orby coincidence counting.6Waiting exactly five days b
46、eforecounting is not required, but the140La is at its maximum about134 h after the irradiation.10. Procedure for Radiochemical Analysis10.1 Decide on the size and shape of sample to be irradiated(see Guide E844).10.2 Weigh the sample to the accuracy and precision of theexperiment.4Vanadium-encapsula
47、ted monitors of high purity are available from IsotopeSales Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830.5“Reagent Chemicals,American Chemical Society Specifications,”Am. Chemi-cal Soc., Washington DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Soci
48、ety, see “Reagent Chemicals and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”6Dierckx, R., Maracci, G., and Rustichelli, F., “Measurement of the La-140Fission Product Yield for Fissions in U-238 in a Thermal Reactor Type Spectrum,”Journal o
49、f Nuclear Energy, Vol 25, pp. 8589, 1971.E393 13310.3 Place the sample in a cadmium, gadolinium, or boroncover if desired (see Guide E844). Seal into a capsule whenrequired by safety considerations.10.4 Irradiate the sample for a predetermined period of time.Record the beginning and end of the irradiation period. Takeinto account any reactor power variation during the exposureperiod. Since the fission product to be extracted,140Ba, has a12.752-day half-life, there can be a several-day waiting periodb
