1、Designation: E705 13E705 13aStandard Test Method forMeasuring Reaction Rates by Radioactivation of Neptunium-2371This standard is issued under the fixed designation E705; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 covers procedures for measuring reaction rates by assaying a fission product (F.P.) from the fission
3、reaction237Np(n,f)F.P.1.2 The reaction is useful for measuring neutrons with energies from approximately 0.7 to 6 MeV and for irradiation times upto 30 to 40 years.1.3 Equivalent fission neutron fluence rates as defined in Practice E261 can be determined.1.4 Detailed procedures for other fast-neutro
4、n detectors are referenced in Practice E261.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilit
5、yof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E170 Terminology Relating to Radiation Measurements and DosimetryE181 Test Methods for Detector Calibrat
6、ion and Analysis of RadionuclidesE261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation TechniquesE262 Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by RadioactivationTechniquesE320 Test Method for Cesium-137 in Nucl
7、ear Fuel Solutions by Radiochemical Analysis (Withdrawn 1993)3E393 Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission DosimetersE704 Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238E844 Guide for Sensor Set Design and Irradiation for Reactor Sur
8、veillance, E 706 (IIC)E944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E 706 (IIA)E1005 Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance, E 706 (IIIA)E1018 Guide for Application of ASTM Evaluated Cross Section
9、Data File, Matrix E706 (IIB)3. Terminology3.1 Definitions:3.1.1 Refer to Terminology E170.4. Summary of Test Method4.1 High-purity 237Np ( 1 MeV)fluence rate of 1 1011 cm2 s1, provided the 237Np is shielded from thermal neutrons (see Fig. 2 of Guide E844).5.4.2 Fission product production from photon
10、uclear reactions, that is, (,f) reactions, while negligible near-power and researchreactor cores, can be large for deep-water penetrations (1).55.5 Good agreement between neutron fluence measured by 237Np fission and the 54Fe(n,p)54Mn reaction has beendemonstrated (2). The reaction 237Np(n,f) F.P. i
11、s useful since it is responsive to a broader range of neutron energies than mostthreshold detectors.4 The sole source of supply of Vanadium-encapsulated monitors of high purity known to the committee at this time in the United States is Isotope Sales Div., Oak Ridge,TN 37830. In Europe, the sole sou
12、rce of supply is European Commission, JRC, Institute for Reference Materials and Measurements (IRMM) Reference Materials UnitRetieseweg 111, B-2440 Geel, Belgium. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments willreceive
13、careful consideration at a meeting of the responsible technical committee,1 which you may attend.5 The boldface numbers in parentheses refer to the list of references appended to this test method.TABLE 1 Recommended Nuclear Parameters for Certain FissionProductsFissionProductParentHalf-LifeA (6)Prim
14、aryRadiationA(7) (keV) Probability ofDecayA (7)MaximumUsefulIrradiationDuration95Zr 64.032 (6) d 724.192 (4) 0.4427 (22) 6 months756.725 (12) 0.543899Mo 65.94 (1) hr 739.500 (17) 0.1213 (22) 300 hours777.921 (20) 0.0426 (8)103Ru 39.26 (2) d 497.085 (10) 0.910 (12) 4 months137Cs 30.05 (8) yr 661.657
15、(3)B 0.8499 (20)B 3040 years140Ba140La 12.7527 (23) d 537.261 (3) 0.2439 (22) 11.5 months1596.21 (4) 0.9540 (8)C1.1515D144Ce 28.91 (5) d 133.515 (2) 0.1109 (19) 23 yearsAThe lightface numbers in parentheses are the magnitude of plus or minusuncertainties in the last digit(s) listed.BWith 137mBa (2.5
16、52 min) in equilibrium.CProbability of daughter 140La decay.DWith 140La (1.67855 d) in transient equilibrium.E705 13a25.6 The 237Np fission neutron spectrum-averaged cross section in several benchmark neutron fields are given in Table 3 ofPractice E261. Sources for the latest recommended cross secti
17、ons are given in Guide E1018. In the case of the 237Np(n,f)F.P.reaction, the recommended cross section source is the ENDF/B-VI cross section (MAT = 9346) revision 1 (3).Fig. 1 shows a plotof the recommended cross section versus neutron energy for the fast-neutron reaction 237Np(n,f)F.P.NOTE 1The dat
18、a are taken from the Evaluated Nuclear Data file, ENDF/B-VI, rather than the later ENDF/B-VII. This is in accordance with GuideE1018 Guide for Application of ASTM Evaluated Cross Section Data File, 6.1. since the later ENDF/B-VII data files do not include covarianceinformation. For more details see
19、Section H of (10)6. Apparatus6.1 Gamma-Ray Detection Equipment that can be used to accurately measure the decay rate of fission product activity are thefollowing two types (4):6.1.1 NaI(T1) Gamma-Ray Scintillation Spectrometer (see Test Methods E181 and E1005).6.1.2 Germanium Gamma-Ray Spectrometer
20、(see Test Methods E181 and E1005)Because of its high resolution, thegermanium detector is useful when contaminant activities are present.6.2 Balance, providing the accuracy and precision required by the experiment.6.3 Digital Computer, useful for data analysis, but is not necessary (optional).TABLE
21、2 Recommended Fission Yields for Certain FissionProductsAFissileIsotopeNeutronEnergyReactionProductTypeYieldJEFF 3.1B,AFission Yield (%)237Np(n,f) 0.5 MeV 95Zr RC 5.6147 2.7 %99Mo RC 7.6118 16.34 %103Ru RC 5.4305 12.7 %137Cs RC 6.2654 3.71 %137mBa RI 1.4802e-3 35.58 %140Ba RC 5.9160 3.82 %140La RI 6
22、.3568e-3 36.68 %144Ce RC 4.1230 4.7 %AThe JEFF-3.1/3.1.1 radioactive decay data and fission yields sub-libraries, JEFFReport 20, OECD 2009, Nuclear Energy Agency.BAll yield data given as a %; RC represents a cumulative yield; RI represents anindependent yield.FIG. 1 ENDF/B-VI Cross Section Versus En
23、ergy for the 237Np(n,f)F.P. ReactionE705 13a37. Materials7.1 Neptunium-237 Alloy or OxideHigh-purity 237Np in the form of alloy wire, foil, or oxide powder is available.7.1.1 The 237Np target material should be furnished with a certificate of analysis indicating any impurity concentrations.7.2 Encap
24、sulating MaterialsBrass, stainless steel, copper, aluminum, vanadium, and quartz have been used as primaryencapsulating materials. The container should be constructed in such a manner that it will not create significant perturbation of theneutron spectrum or fluence rate and that it may be opened ea
25、sily, especially if the capsule is to be opened remotely. Certainencapsulation materials, for example, quartz and vanadium, allow gamma-ray counting without opening the capsule since there areno interfering activities.8. Procedure8.1 Select the size and shape of the sample to be irradiated, taking i
26、nto consideration the size and shape of the irradiation space.The mass and exposure time are parameters that can be varied to obtain a desired count rate for a given neutron fluence rate.8.2 Weigh the sample to the accuracy and precision required of the experiment; encapsulate; and, if irradiated in
27、 a thermalneutron environment, surround with a suitable high-melting thermal neutron absorber.NOTE 2The melting point of elemental cadmium is 321C. For additional precautions, see Test Method E262.8.3 Irradiate the sample for the predetermined time period. Record the power level and any changes in p
28、ower during theirradiation, the time at the beginning and end of each power level, and the relative position of the monitors in the irradiation facility.8.4 Check the sample for activity from cross contamination by other monitors or material irradiated in the vicinity or from anyforeign substance ad
29、hering to the sample. Clean and reweigh, if necessary. If the sample is encapsulated oxide powder and if itis necessary to open the capsule, suitable containment will be required.8.4.1 If chemical separation is necessary, dissolution can be achieved in 6 N HCl-1 N HF with periodic additions of H2O2,
30、followed by fuming with H2SO4.NOTE 3Fuming with H2SO4 may expel volatile fission product ruthenium and, unless performed with care, losses of other fission products byspattering can occur.8.5 Analyze the sample for fission-product content in disintegrations per second (see Test Methods E181, E320, a
31、nd E1005).8.5.1 It is assumed that the available apparatus has been calibrated to measure F.P. activity, and that the experimenter is wellversed in the operation of the apparatus.8.5.2 Disintegration of 137Cs nuclei produces 0.661657-MeV gamma rays with a probability per decay of 0.82102. It isrecom
32、mended that a 137Cs activity standard is used.8.5.3 If the analyst is well versed in germanium counting and carefully calibrates the system, it is feasible to count137Cs-137mBa, 140Ba-140La, 95Zr, and 144Ce directly without chemical separation. An X-ray shield, at least 2 mm thickness, willbe requir
33、ed in the counting process.9. Calculation9.1 Calculate the saturation activity, As, as follows:As 5A/y12e 2ti!e 2tw!# (1)where: = disintegration constant for F.P., s1,A = number of disintegrations, measured during the counting period, s1,ti = irradiation duration, s,tw = elapsed time between the end
34、 of irradiation and counting, s, andy = fission yield.NOTE 4This equation applies where transient equilibrium has been established, is that of the parent species. This equation should not be appliedto the Ba/La line but can be applied to the other fission products. See Test Method E393 for reading t
35、he 140B/140La line.NOTE 5The equation for As is valid if the reactor operated at essentially constant power and if corrections for other reactions (for example, impurities,burnout, etc.) are negligible. Refer to Practice E261 for more generalized treatments.9.2 Calculate the reaction rate,6 Rs, as f
36、ollows:Rs 5As/No (2)where:No = number of target atoms.9.3 Refer to Practice E261 and Guide E944 for a discussion of the determination of fast neutron fluence rate.6 Within the context of this standard, the terms “fission rate” and “reaction rate” can be used synonymously.E705 13a410. Report10.1 Prac
37、tice E261 describes how data should be reported.11. Precision and BiasNOTE 6Measurement of uncertainty is described by a precision and bias statement in this standard. Another acceptable approach is to use Type Aand B uncertainty components (8, 9). This type A/B uncertainty specification is now used
38、 in International Organization for Standardization (ISO)Standards and this approach can be expected to play a more prominent role in future uncertainty analyses.11.1 General practice indicates that disintegration rates can be determined with a bias of 65 % (1S %) and with a precision of61 % (1S %).
39、(11)11.2 The 237Np cumulative fission product yields have an uncertainty between 2.3 % and 16.3 % (1S %) for the various fissionproducts of interest.12. Keywords12.1 fission dosimeter; fission product; fission reaction rates; Neptunium-237REFERENCES(1) Verbinski, V. V., et al, “Measurements and Calc
40、ulations of Photofission Effects in a Swimming Pool Type Reactor,” Transactions of the AmericanNuclear Society, Washington, DC, Vol 30, November 1978.(2) Barry, K. M., and Corbett, J. A., “Measurement of Neutron Fluence by Neptunium-237 and Uranium-238 Fission Dosimeters,” Nuclear Technology,Vol 11,
41、 May 1971.(3) ENDF/B-V Dosimetry Tape 531-G, Mat. No. 6399 (93-Np-237), October 1979.(4) Crouthamel, C. E. (Revised by Adams, F., and Dams, R.), Applied Gamma-Ray Spectrometry, Pergamon Press, 1970.(5) “ENDF-201, ENDF/B-VI Summary Documentation,” P. F. Rose, Ed. Brookhaven National Laboratory Report
42、 BNL-NCS-174, 4th Edition, October,1991.(6) Nuclear Wallet Cards, compiled by J. K. Tuli, National Nuclear Data Center, October 2011.(7) Nuclear Data retrieval program NUDAT, a computer file of evaluated nuclear structure and radioactive decay data, which is maintained by theNational Nuclear Data Ce
43、nter (NNDC), Brookhaven National Laboratory (BNL), on behalf of the International Network for Nuclear Structure DataEvaluation, which functions under the auspices of the Nuclear Data Section of the International Atomic Energy Agency (IAEA).(8) B.N. Taylor, C.E., Kuyatt, Guidelines for Evaluating and
44、 Expressing the Uncertainty of NIST Measurement Results, NIST Technical Note 1297.National Institute of Standards and Technology Gaithersburg, MD, 1994.(9) Guide in the Expression of Uncertainly in Measuremens, International Organization for Standardization, 1995 ISBN 9267101889.(10) “Special Issue
45、on Evaluated Nuclear Data file ENDF/B-VII.0.” Nuclear Data Sheets, J.K. Tuli Editor, Vol. 107, December 2006.(11) Adams, J.M., “Results for the NIST Round Robin Test of Fissionable Dosimeters in Reactor Leakage Spectrum,” Reactor Dosimetry: RadiationMetrology and Assessment, ASTM STP 1389, American
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