ASTM E263-2018 Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron.pdf

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1、Designation: E263 13E263 18Standard Test Method forMeasuring Fast-Neutron Reaction Rates by Radioactivationof Iron1This standard is issued under the fixed designation E263; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o

2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method describes pro

3、cedures for measuring reaction rates by the activation reaction 54Fe(n,p)54Mn.1.2 This activation reaction is useful for measuring neutrons with energies above approximately 2.2 MeV and for irradiationtimes up to about 3 years (for longer irradiations, see three years, provided that the analysis met

4、hods described in Practice E261).are followed. If dosimeters are analyzed after irradiation periods longer than three years, the information inferred about the fluenceduring irradiation periods more than three years before the end of the irradiation should not be relied upon without supporting dataf

5、rom dosimeters withdrawn earlier.1.3 With suitable techniques, fission-neutron fluence rates above 108 cm2s1 can be determined. However, in the presence ofa high thermal-neutron fluence rate (for example, 2 1014 cm2s1) 54Mn depletion should be investigated.1.4 Detailed procedures describing the use

6、of 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 concerns, if any, associated with its use. It

7、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 accordance with internationally recognized princi

8、ples 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 Standards:2D1193 Specification for Reagent Wat

9、erE170 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 TechniquesE844 Guide for Sensor Set Design and Irradiation for Reacto

10、r SurveillanceE944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor SurveillanceE1005 Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel SurveillanceE1018 Guide for Application of ASTM Evaluated Cross Section Data File3. Terminology3.1 Definiti

11、ons:3.1.1 Refer to Terminology E170 for definitions of terms relating to radiation measurements and neutron dosimetry.1 This test method is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applications and is the direct responsibility of Subcommittee E10.05on Nuclear Radiation

12、Metrology.Current edition approved June 1, 2013Dec. 1, 2018. Published July 2013January 2019. Originally approved in 1965 as E263 65 T. Last previous edition approved in20092013 as E263 09.E263 13. DOI: 10.1520/E0263-13.10.1520/E0263-18.2 For referencedASTM standards, visit theASTM website, www.astm

13、.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.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what cha

14、nges 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 all cases only the current versionof the standard as published by ASTM is to be considered the offi

15、cial 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 iron is irradiated in a neutron field, thereby producing radioactive 54Mn from the 54Fe(n,p)54Mn activationreaction.4.2 The gamma r

16、ays emitted by the radioactive decay of54Mn are counted in accordance with Test Methods E181. The reaction rate, as defined by Practice E261, is calculated from thedecay rate and irradiation conditions.4.3 Radioassay of the 54Mn activity may be accomplished by directly counting the irradiated iron d

17、osimeter, or by firstchemically separating the 54Mn activity prior to counting.4.4 The neutron fluence rate above about 2.2 MeV can then be calculated from the spectral-weighted neutron activation crosssection as defined by Practice E261.5. Significance and Use5.1 Refer to Guide E844 for guidance on

18、 the selection, irradiation, and quality control of neutron dosimeters.5.2 Refer to Practice E261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors.5.3 Pure iron in the form of foil or wire is readily available and easily handled.5.4 Fig. 1 shows a p

19、lot of cross section as a function of neutron energy for the fast-neutron reaction 54Fe(n,p)54Mn (1).3 Thisfigure is for illustrative purposes only to indicate the range of response of the 54Fe(n,p)54Mn reaction. Refer to Guide E1018 fordescriptions of recommended tabulated dosimetry cross sections.

20、5.5 54Mn has a half-life of 312.13312.19 (3) days4 (2) and emits a gamma ray with an energy of 834.838 (5)834.855 (3) keV(2).5.6 Interfering activities generated by neutron activation arising from thermal or fast neutron interactions are 2.5789(1)-h2.57878 (46)-h 56Mn, 44.495 (9) day44.494 (12) days

21、 59Fe, and 1925.28 (1) day5.2711 (8) years 60Co (2,3). (Consult the latestversion of Ref (2) for more precise values currently accepted for the half-lives.) Interference from 56Mn can be eliminated bywaiting 48 h before counting. Although chemical separation of 54Mn from the irradiated iron is the m

22、ost effective method foreliminating 59Fe and 60Co, direct counting of iron for 54Mn is possible using high-resolution detector systems or unfolding or3 The boldface numbers in parentheses refer to the list of references located at the end of this test method.4 The un-bolded number in parenthesis aft

23、er the unit indicates the uncertainty in the least significant digits. For example, 1.89 (2) keV would indicate a value of 1.89 keV6 0.02 keV.FIG. 1 54Fe(n,p)54Mn Cross SectionE263 182stripping techniques, especially if the dosimeter was covered with cadmium or boron during irradiation. Altering the

24、 isotopiccomposition of the iron dosimeter is another useful technique for eliminating interference from extraneous activities when directsample counting is to be employed.5.7 The vapor pressures of manganese and iron are such that manganese diffusion losses from iron can become significant attemper

25、atures above about 700C. Therefore, precautions must be taken to avoid the diffusion loss of 54Mn from iron dosimetersat high temperature. Encapsulating the iron dosimeter in quartz or vanadium will contain the manganese at temperatures up toabout 900C.5.8 Sections 6, 7 and 8 that follow were specif

26、ically written to describe the method of chemical separation and subsequentcounting of the 54Mn activity. When one elects to count the iron dosimeters directly, those portions of Sections 6, 7 and 8 thatpertain to radiochemical separation should be disregarded.NOTE 1The following portions of this te

27、st method apply also to direct sample-counting methods: 6.1 6.3, 7.4, 7.9, 7.10, 8.1 8.5, 8.18, 8.19, and9 12.6. Apparatus (Note 1)6.1 HighResolution Gamma-Ray Spectrometer, because of its high resolution, the germanium detector is useful whencontaminant activities are present. See Test Methods E181

28、 and E1005.6.2 Precision Balance, able to achieve the required accuracy.6.3 Digital Computer, useful for data analysis (optional).6.4 Chemical Separation Cylinder, borosilicate glass, about 25-mL capacity, equipped with stopcock and funnel. This apparatusis illustrated in Fig. 2.6.5 Beakers, borosil

29、icate glass, 50 mL; volumetric flasks, 25 and 50 mL, and volumetric pipets, 1 mL.7. Reagents and Materials (Note 1)7.1 Purity of ReagentsReagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committe

30、e on Analytical Reagents of the American Chemical Society, whereFIG. 2 Ion-Exchange Separation ApparatusE263 183such specifications are available.5 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accura

31、cy of the activity determination.7.2 Purity of Water Unless otherwise indicated, references to water shall be understood to mean reagent-grade waterconforming to Specification D1193.7.3 Anion Exchange Resin, strongly basic type, 100 to 200 mesh size.7.4 Iron Foil or Wire, high purity.7.5 Hydrochlori

32、c Acid (sp gr 1.19, 1190 kg/m3)Concentrated hydrochloric acid (HCl).7.6 Hydrochloric Acid (1 + 3)Mix 1 volume of concentrated HCl (sp gr 1.19) with 3 volumes of water.7.7 Manganese Carrier Solution (10 mg MnCl2/cm3).7.8 Nitric Acid (sp gr 1.42, 1420 kg/m3)Concentrated nitric acid (HNO3).7.9 Encapsul

33、ating MaterialsBrass, stainless steel, copper, aluminum, quartz, or vanadium have been used as primaryencapsulating materials. The container should be constructed in such a manner that it will not create a significant flux perturbationand that it may be opened easily, especially if the capsule is to

34、 be opened remotely. (See Guide E844.)7.10 The purity of the iron is important in that no impurities should be present which produce long-lived radionuclides thatinterfere with the 54Mn radioassay. This condition includes species that will accompany 54Mn through the separation scheme andthat have ga

35、mma rays, of energy 0.6 MeVor higher.The presence of impurities may be determined either by emission spectroscopyor by activation analysis.8. Procedure (Note 1)8.1 Decide on the size and shape of the iron sample to be irradiated. Consider convenience in handling and available irradiationspace when m

36、aking this selection, but it is more important to ensure that sufficient 54Mn activity will be produced to permitaccurate radioassay. A preliminary calculation of the expected production of 54Mn, using the activation equation described inSection 9, will aid in selecting the mass of iron required.8.2

37、 Determine a suitable irradiation time.8.3 Weigh the iron sample. The chemical manipulations described below function best with an iron dosimeter weighing 10 to20 mg.NOTE 2It is necessary to avoid a high iron concentration in the solutions that are to be used for separation so that the efficiency of

38、 the ion-exchangeresin will not be seriously lowered. For the column described herein the amount of iron let onto the resin should not exceed 1 mg.8.4 Irradiate the samples for the predetermined time period. Record the power level and any changes in power during theirradiation, the time at the begin

39、ning and end of the irradiation, and the relative position of the monitors in the irradiation facility.8.5 A waiting period of 2 days is recommended between termination of the exposure and the start of counting. This allows2.58-h 56Mn, produced by fast-neutron reactions with56Fe and also by thermal-

40、neutron activation of impurity manganese, to decay below levels at which it may cause error in the 54Mnassay. Check the samples for activity from cross contamination by other monitors or material irradiated in the vicinity, and for anyforeign substance adhering to the sample. Clean, if necessary, an

41、d reweigh. If direct-counting techniques are used, disregard theremaining procedures to step 8.18.8.6 After irradiation, dissolve the sample in 10 mL of concentrated hydrochloric acid to which 2 drops of nitric acid have beenadded. The solution may be heated gently to hasten dissolution.8.7 After di

42、ssolution is complete, transfer the solution with washing to a 25-mL volumetric flask. Wash only with concentratedhydrochloric acid and use this also in diluting to the calibration mark on the volumetric flask.8.8 Prepare a slurry of anion exchange resin with distilled or deionized water and pour it

43、 into the ion exchange column apparatus(see Fig. 2) to a height of 100 mm. Place a glass-wool plug above the resin and keep the column under liquid at all times.8.9 Prepare the ion exchange column for use by passing concentrated hydrochloric acid through until it completely displacesthe water used t

44、o form the resin slurry.8.10 Transfer an aliquot of the sample solution by volumetric pipet to the empty funnel above the column. This aliquot shouldbe of sufficient volume so that accurate counting data can be obtained.8.11 Run the sample onto the column.5 “Reagent Chemicals, American Chemical Soci

45、ety Specifications,” Am. Chemical Soc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see “Analar Standards for Laboratory Chemicals,” BDH Ltd., Poole, Dorset, U.K., and the “United States Pharmacopeia.”E263 1848.12 Immediately pour a few mill

46、ilitres from a premeasured 50-mL volume of hydrochloric acid (1+3) into the funnel to washany remaining sample solution onto the column.8.13 Place a 50-mL volumetric flask, to which 1 mL of MnCl2 carrier solution has been added, under the tip of the column andopen the column stopcock.8.14 Add the re

47、maining hydrochloric acid (1+3) to the funnel and adjust the stopcock to obtain a flow rate of about 1 drop in5 to 10 s. This will allow elution of a 50-mL volume in about 2 h.8.15 Elute from the column until the solution reaches the calibration mark on the volumetric flask.NOTE 3To prepare the ion

48、exchange resin for further separations, run about 50 mL of distilled or deionized water through the column. This willremove iron and cobalt from the resin. Regenerate the column as before by passing concentrated hydrochloric acid through until the acid completelydisplaces the water.NOTE 4The 54Mn re

49、covery should be checked by passing a known54Mn spike solution and iron carrier through the column.8.16 Stopper the flask and invert several times to mix the contents thoroughly.8.17 Remove an accurately measured aliquot from the volumetric flask for radioassay. A 1-mL sample is convenient if thecounting is to be done with a well-type scintillation detector. If assay is to be made using a solid crystal, the aliquot can bedeposited into a cup planchet and dried under a heat lamp.8.18 Analyze the samples for 54Mn content in disintegrations per seco