1、Designation: E 393 96 (Reapproved 2002)Standard Test Method forMeasuring Reaction Rates by Analysis of Barium-140 FromFission Dosimeters1This standard is issued under the fixed designation E 393; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 determinin
3、g the amount ofthe fission product140Ba produced by the non-threshold reac-tions235U (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.1
4、40Ba emitsgamma rays of several energies; 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 determinedindirectly by counting its daughter product14
5、0La. This testmethod describes both procedure (a), the nondestructive deter-mination of140Ba by the direct counting of140La several daysafter irradiation, and procedure (b), the chemical separation of140Ba and the subsequent counting of140Ba or its daughter140La.1.3 With suitable techniques, fission
6、 neutron fluence ratescan be measured 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 i
7、n SI units are to be regarded asstandard.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
8、 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 697 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade PlutoniumDioxide Powders and Pellets2D 1193 Specification for Reagent Water3E 170 Terminology Relating to Radiation Measurementsand Do
9、simetry4E 181 Test Methods for Detector Calibration and Analysisof Radionuclides4E 261 Practice for Determining Neutron Fluence Rate, Flu-ence, and Spectra by Radioactivation Techniques4E 704 Test Method for Measuring Reaction Rates by Ra-dioactivation of Uranium-2384E 705 Test Method for Measuring
10、Reaction Rates By Ra-dioactivation of Neptunium-2374E 844 Guide for Sensor Set Design and Irradiation forReactor Surveillance, E706 (IIC)4E 944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, (IIA)4E 1005 Test Method for Application and Analysis of Radio-metric
11、 Monitors for Reactor Vessel Surveillance, E706(IIA)4E 1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E 706 (IIB)43. Terminology3.1 Definitions:3.1.1 Refer to Terminology E 170.4. Summary of Test Method4.1 For nondestructive analysis, the fission dosimeter isallowed to c
12、ool 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 crosssection is u
13、sed 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. The activity ofthe140Ba is determined by counting the 0.537 MeV gammaenergy peak. This information is then used a
14、s in 4.1 to give thereaction rate or the equivalent fission fluence rate.1This test method is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved Jan. 10, 199
15、6. Published March 1996. Originallypublished as E 393 84. Last previous edition E 393 90.2Annual Book of ASTM Standards, Vol 12.01.3Annual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 12.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、 PA 19428-2959, United States.5. Significance and Use5.1 Refer to Guide E 844 for the selection, irradiation, andquality control of neutron dosimeters.5.2 Refer to Practice E 261 for a general discussion of themeasurement of neutron fluence rate and fluence. The neutronspectrum must be known in orde
17、r 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 they can be obtained arediscussed in Guide E 1018.5.3 The reaction rate of a detector nuclide of known crosssectio
18、n, when combined with information about the neutronspectrum, permits the determination of the magnitude of thefluence rate impinging on the detector. Furthermore, if resultsfrom other detectors are available, the neutron spectrum can bedefined more accurately. The techniques for fluence rate andflue
19、nce determinations are explained in Practice E 261.5.4140Ba is a radioactive nuclide formed as a result ofuranium fission. Although it is formed in fission of any heavyatom, the relative yield will differ. Recommended fission yieldsfor140Ba production are given in Table 1. The direct (indepen-dent)
20、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 not significantly affect the accuracy of thenondestructive procedure and need not be considered.5.5 The half-life
21、 of140Ba is 12.752 days. Its daughter140Lahas a half-life of 1.6781 days.5The comparatively longhalf-life of140Ba allows the counting to be delayed severalweeks after irradiation in a high-neutron field. However, toachieve maximum sensitivity the daughter product140Lashould be counted five to six da
22、ys 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 count the140Ba directly.5.6 Because of its 12.752 day half-life and substantialfission yield,140Ba is useful for i
23、rradiation times up to aboutsix weeks in moderate intensity fields. One irradiation criterionis that the number of fissions produced should be approxi-mately 109or greater for good counting statistics. Also, if theirradiation time is substantially longer than six weeks theneutron fluence rate determ
24、ined will apply mainly to theneutron field existing during the latter part of the irradiation.The140Ba decay constant and yield are known more accuratelythan those of many fission products, so it is sometimes used asa standard or base reaction with which other measurements canbe normalized.6. Appara
25、tus6.1 For nondestructive analysis the chemical separationequipment, materials, and reagents are not required.6.2 A NaI(Tl) or Germanium Gamma-Ray Spectrometer, seeTest Methods E 181 and E 1005.6.3 Balance, providing the accuracy and precision requiredby the experiment.6.4 Centrifuge, clinical type,
26、 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. Reagents and Materials7.1 Purity of Fission DosimetersHigh purity uraniumpluto
27、nium, 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.7.1.2 Fission dosimeters shall be encapsulated in hermeti-cally sealed containers to avoid loss of
28、materials and forhealth-hazard requirements.67.1.3 In thermal reactors threshold reaction dosimeters (forexample,238U,237Np,232Th) shall be shielded from thermalneutrons with elemental, or compounds of, cadmium, gado-linium, or boron to prevent fission production from tracequantities (40 ppm) of235U
29、, and239Pu and to suppress5Nuclear Wallet Cards, compiled by J. K. Tuli, National Nuclear Data Center,July 1990.6Vanadium-encapsulated monitors of high purity are available from IsotopeSales Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830.TABLE 1 Recommended Cumulative Fission Yields fo
30、r140BaProductionFission DosimeterThermal or FastNeutron FieldFission Yield,%A,B235UTF5.84596 6 1%5.98741 6 1%238U F 5.845966 1%239Pu TF5.315386 1%5.37475 6 2%237Np F 5.47246 6 1.4 %232Th F 7.87647 6 2.8 %241Am TF5.95468 6 2.8 %4.99172 6 6%AThese ENDF/B-VI values are considered the best available dat
31、a. The uncer-tainties are expressed as a percentage of the fission yield.BEngland, T. R., and Rider, B. F., ENDF-349 Evaluation and Compilation ofFission Product Yields, Los Alamos National Laboratory, Los Alamos, NM, reportLA-UR-94-3106, ENDF-349, October 1994.TABLE 2 Independent Fission Yields for
32、140La ProductionFission DosimeterThermal or FastNeutron FieldFission Yield, %A,B235UTF5.25214 3 1036 64 %1.31401 3 1036 64 %238U F 1.38004 3 1056 64 %239Pu TF8.11109 3 1036 64 %1.17572 3 1026 64 %237Np F 4.421 3 1036 64 %232Th F 2.71003 3 1056 64 %241Am TF2.5758 3 1026 64 %2.07034 3 1026 32 %AThese
33、ENDF/B-VI values are considered the best available data. The uncer-tainties are expressed as a percentage of the fission yield.BEngland, T. R., and Rider, B. F., ENDF-349 Evaluation and Compilation ofFission Product Yields, Los Alamos National Laboratory, Los Alamos, NM, reportLA-UR-94-3106, ENDF-34
34、9, October 1994.E 3932buildup of interfering fissionable nuclides, for example,239Puin the238U dosimeter,238Np and238Pu in the237Np dosimeter,and233Uinthe232Th dosimeter (see Guide E 844).7.2 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is inten
35、ded thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.7Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use witho
36、ut lessening theaccuracy of the determination.7.3 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type II of Specification D 1193.7.4 Acetic Acid (36 %)Dilute 360 mL of glacial aceticacid to 1 L with water.7.5 Acetic Acid (6 %)Dilu
37、te 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 Ammonium 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
38、 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 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
39、a saturated so-lution 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.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
40、 polyethylene bottle.7.17 Hydrofluoric Acid (HF) (1 N).8. Preparation and Standardization of Barium Carrier8.1 Preparation and Standardization of Barium Carrier: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
41、 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 mL of aceticacid (36 %) and 10 mL of ammonium acetate solution. Bring toboiling; add 5 mL of Na2CrO4solution dropwise with stirring;boil for 1 min wi
42、th stirring. Cool the mixture to roomtemperature and filter the precipitated barium chromate(BaCrO4) through a fine preweighed sintered-glass crucible.8.2.2 Wash the precipitate three times with 5-mL portions ofdeionized water and three times with 5-mL portions of ethylalcohol. Dry at 110C, cool, an
43、d weigh. Calculate the bariumcontent as follows:Ba11, mg/mL 5 W/V! 3 0.5421 (1)where:W = milligrams of BaCrO4, andV = millilitres of carrier used.9. Procedure for Nondestructive Analysis9.1 Decide on the size and shape of sample to be irradiated(see Guide E 844).9.2 Weigh the sample to the accuracy
44、and precision of theexperiment.9.3 Place the sample in a cadmium, gadolinium, or boroncover if desired (see Guide E 844). Seal into a capsule whenrequired by safety considerations.9.4 Irradiate the sample for a predetermined period of time.Record the beginning and end of the irradiation period. Take
45、into account any reactor power variation during the exposureperiod.9.5 Prior to counting, remove any covering material fromthe dosimeter if it possesses interfering radionuclides. Ifencapsulated in quartz, copper, aluminum, or vanadium, theencapsulating material need not be removed before counting.9
46、.6 After five days after the irradiation, count the140Ladirectly on a gamma-ray spectrometer (1.596-MeV gamma), orby coincidence counting.8Waiting exactly five days beforecounting is not required, but the140La is at its maximum about134 h after the irradiation.10. Procedure for Radiochemical Analysi
47、s10.1 Decide on the size and shape of sample to be irradiated(see Guide E 844).10.2 Weigh the sample to the accuracy and precision of theexperiment.10.3 Place the sample in a cadmium, gadolinium, or boroncover if desired (see Guide E 844). Seal into a capsule whenrequired by safety considerations.10
48、.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 pe
49、riodbefore the chemical separation is started.10.5 Prior to counting, remove any covering material fromthe dosimeter. Dissolve the fission dosimeter in either 8 NHNO3to 0.05 N HF for uranium (see Test Method E 704), 12 NHNO30.05 N HF for plutonium (see Test Methods C 697), 6N HCl 1 N HF for neptunium (see Test Method E 705), orconcentrated HNO30.01 N HF for thorium. Heat if necessaryfor complete dissolution.10.6 Add 2 mL of standardized barium carrier. Transfer witha minimum amount of water into a 50-mL centrifuge tube.7“Reagent Chemicals, Ameri
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