ASTM E705-2018 Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237.pdf

1、Designation: E705 13aE705 18Standard 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.90 years, provided that the analysis methods described in Practice E261 are followed. If dosimeters are analyzedafter irradiation period

4、s longer than 90 years, the information inferred about the fluence during irradiation periods more than 90years before the end of the irradiation should not be relied upon without supporting data from dosimeters withdrawn earlier.1.3 Equivalent fission neutron fluence rates as defined in Practice E2

5、61 can be determined.1.4 Detailed procedures for other fast-neutron 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

6、concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.7 This international standard was developed in acc

7、ordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM

8、Standards:2E170 Terminology Relating to Radiation Measurements and DosimetryE181 Test Methods for Detector Calibration and Analysis of RadionuclidesE261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation TechniquesE262 Test Method for Determining Thermal Neutron R

9、eaction Rates and Thermal Neutron Fluence Rates by RadioactivationTechniquesE320 Test Method for Cesium-137 in Nuclear 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 Measuri

10、ng Reaction Rates by Radioactivation of Uranium-238E844 Guide for Sensor Set Design and Irradiation for Reactor SurveillanceE944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor SurveillanceE1005 Test Method for Application and Analysis of Radiometric Monitors for Reactor Vess

11、el SurveillanceE1018 Guide for Application of ASTM Evaluated Cross Section Data File3. Terminology3.1 Definitions:3.1.1 Refer to Terminology E170.1 This test method is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applicationsand is the direct responsibility of Subcommittee

12、E10.05 onNuclear Radiation Metrology.Current edition approved Aug. 1, 2013Dec. 1, 2018. Published August 2013December 2018. Originally approved in 1979. Last previous edition approved 2013 asE705 13.E705 13a. DOI: 10.1520/E0705-13A.10.1520/E0705-18.2 For referencedASTM standards, visit theASTM websi

13、te, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an AS

14、TM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In a

15、ll cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 High-purity 237Np ( 1 MeV)fluence rate of 1 1

16、011 cm2 s1, provided the 237Np is shielded from thermal neutrons (see Fig. 2 of Guide E844).5.4.2 Fission product production from photonuclear reactions, that is, (,f) reactions, while negligible near-power and researchreactor cores, can be large for deep-water penetrations (13).5.5 This dosimetry r

17、eaction is important in the area of reactor retrospective dosimetry (4, 5). Good agreement between neutronfluence measured by 237Np fission and the 54Fe(n,p)54Mn reaction has been demonstrated (26, 7). The reaction 237Np(n,f) F.P.is useful since it is responsive to a broader range of neutron energie

18、s than most threshold detectors.5.5.1 Fig. 1 shows the energy-dependent cross section for this dosimetry reaction. The figure shows that, while it is not strictlya threshold detector, because of its sensitivity in the greater than 0.1 MeV neutron energy range it can function as a detector withgood s

19、ensitivity in the fast neutron region. In the fast fission 252Cf spontaneous fission benchmark field, 1 % of the 237Np fissiondosimeter response comes from neutrons with an energy less than 0.1 MeV. In the cavity of a fast burst 235U reactor, 5 % of the237Np ifssion dosimeter response comes from neu

20、trons with an energy less than 0.1 MeV. In the cavity of a well-moderatedpool-type research reactor 50 % of the fission response from the 237Np(n,f) reaction comes from energies less than 0.1 MeV. Theimportance of this low neutron energy sensitivity should be determined based on the aplication.5.6 T

21、he 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 sections 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

22、VI Russian Reactor Dosimetry File, RRDF (8).cross section(MAT = 9346) revision 1 This recommended cross section is identical, for energies up to 20 MeV, to what is found in the latestInternational Atomic Energy (IAEA) International Reactor Dosimetry and Fusion File, IRDFF-1.05 (39).) . Fig. 1 shows

23、 a plot ofthe recommended cross section versus neutron energy for the fast-neutron reaction 237Np(n,f)F.P.NOTE 1The data are taken from the Evaluated Nuclear Data file, ENDF/B-VI, rather than the later ENDF/B-VII. This is in accordance with Guide4 The sole source of supply of Vanadium-encapsulated m

24、onitors of high purity known to the committee at this time in the United States is Isotope Sales Div., Oak theNational Isotope Development Center, Isotope Business Office, Oak Ridge National Laboratory, Oak Ridge, TN 37830. In Europe, the sole source of supply is EuropeanCommission, JRC, Institute f

25、or Reference Materials and Measurements (IRMM) Reference Materials Unit Retieseweg 111, B-2440 Geel, Belgium. If you are aware ofalternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible

26、technical committee,1 which you may attend.5 The boldface numbers in parentheses refer to the list of references appended to this test method.E705 182E1018 Guide for Application of ASTM Evaluated Cross Section Data File, 6.1. since the later ENDF/B-VII data files do not include covarianceinformation

27、 For more details see Section H of (4)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 (510):6.1.1 NaI(T1) Gamma-Ray Scintillation Spectrometer (see Test Methods E181 and E1005).6.1.2 Germanium

28、 Gamma-Ray Spectrometer (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 nec

29、essary (optional).7. 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 Encapsulating MaterialsBrass, st

30、ainless 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 easily, especially if the cap

31、sule 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.TABLE 1 Recommended Nuclear Parameters for Certain FissionProductsFissionProductParentHalf-LifeA (6)PrimaryRa

32、diationA(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 (3)B

33、0.8499 (20)B 3040 years140Ba140La 12.7527 (23) d 537.261 (3) 0.2439 (22) 11.5months1596.21 (4) 0.9540 (8)C1.1515D144Ce 28.91 (5) d 133.515 (2) 0.1109 (19) 23 yearsTABLE 1 Recommended Nuclear Parameters for Certain FissionProductsFissionProductParentHalf-LifeA,E(1)PrimaryRadiationA,E(1) (keV) Probabi

34、lity ofDecayA,E(1)MaximumUsefulIrradiationDuration95Zr 64.032 (6) days 724.193 (3) 0.4427 (22) 6 months756.729 (12) 0.5438 (22)99Mo 2.747 (6) days 739.500 (17) 0.122 (15) 300 h777.921 (20) 0.0428 (8)103Ru 39.247 (13) days 497.085 (10) 0.910 (12) 4 months137Cs 30.05 (8) years 661.657 (3)B 0.8499 (20)

35、B 90 years140Ba140La 12.753 (4) days 537.303 (6) 0.2439 (22) 11.5months1596.203 (13) 0.9540 (5)C1.1516 (5)D144Ce 284.89 (6) days 133.5152 (20) 0.1083 (12) 23 yearsAThe The lightface numbers in parentheses are the magnitude of plus or minusuncertainties in the last digit(s) listed.BWith With 137mBa (

36、2.552 min) in equilibrium.CProbability Probability of daughter 140La decay.DWith With 140La (1.67855(1.67850 d) in transient equilibrium.E Primary reference for half-life, gamma energy, and gamma emission probabilityis Ref (1) when data is available. Note this reference is to the BIPM data that wasr

37、ecommended at the time of the recommended fission yields were set, that is, asof 2009, and not to the latest Vol 8 data that was published in 2016.E705 1838. Procedure8.1 Select the size and shape of the sample to be irradiated, taking into consideration the size and shape of the irradiation space.T

38、he 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 a thermalneutron environment, surround with a suitable high-me

39、lting thermal neutron absorber.NOTE 1The 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 power during theirradiation, the time at the beginning and end o

40、f 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 adhering to the sample. Clean and reweigh, if necessary. If the s

41、ample 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,followed by fuming with H2SO4.NOTE 2Fuming with H2SO4 may expel

42、 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, and E1005).8.5.1 It is assumed that the available apparatus has

43、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 0.82102.0.8499. Itis recommended that a 137Cs activity standard is used.8.5.3 If t

44、he 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,thickness of lead or an equivalent areal density of a high atomic weig

45、ht (Z40) material, will be required in the counting process.TABLE 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

46、 3.71 %137mBa RI 1.4802e-3 35.58 %140Ba RC 5.9160 3.82 %140La RI 6.3568e-3 36.68 %144Ce RC 4.1230 4.7 %TABLE 2 Recommended Fission Yields for Certain FissionProductsAFissileIsotopeNeutronEnergyCReactionProductTypeYieldJEFF 3.1.1B,AFission Yield (%)237Np(n,f) 0.4 MeV 95Zr RC 5.6147 2.7 %99Mo RC 7.621

47、8 16.304 %103Ru RC 5.43050 12.7 %137Cs RC 6.26540 3.71 %137mBa RI 1.48020e-3 35.58 %140Ba RC 5.73800 2.3 %140La RI 6.35680e-3 36.68 %144Ce RC 4.12300 4.7 %AThe The JEFF-3.1/3.1.1 radioactive decay data and fission yields sub-libraries,JEFF Report 20, OECD 2009, Nuclear Energy Agency.Agency (2).BAll

48、All yield data given as a %; RC represents a cumulative yield; RI representsan independent yield.C The neutron energy represents a generic “fast neutron” spectrum and has beencharacterized in the JEFF 3.1.1 fission yield library as having an average neutronenergy of 0.4 MeV.E705 1849. Calculation9.1

49、 Calculate the saturation activity, As, as follows:As 5A/y12e 2ti!e 2tw!# (1)As 5 Aexptw#1 2 exp 2ti#!(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 of irradiation and counting, s, andy = fission yield.NOTE 3This 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