1、Designation: E844 09 (Reapproved 2014)1Standard Guide forSensor Set Design and Irradiation for Reactor Surveillance,E 706 (IIC)1This standard is issued under the fixed designation E844; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year 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.1NOTEFigures 1 and 2 were updated and editorial changes were made in September 2014.1. Scope1.1 This guide covers t
3、he selection, design, irradiation,post-irradiation handling, and quality control of neutron do-simeters (sensors), thermal neutron shields, and capsules forreactor surveillance neutron dosimetry.1.2 The values stated in SI units are to be regarded asstandard. Values in parentheses are for informatio
4、n only.1.3 This standard does not purport to address all of thesafety problems, 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 limitations prior to use.2. Refer
5、enced Documents2.1 ASTM Standards:2E170 Terminology Relating to Radiation Measurements andDosimetryE261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE854 Test Method for Application and Analysis of SolidState Track Recorder (SSTR) Monitors for React
6、orSurveillance, E706(IIIB)E910 Test Method for Application and Analysis of HeliumAccumulation Fluence Monitors for Reactor VesselSurveillance, E706 (IIIC)E1005 Test Method for Application and Analysis of Radio-metric Monitors for Reactor Vessel Surveillance, E 706(IIIA)E1018 Guide for Application of
7、 ASTM Evaluated CrossSection Data File, Matrix E706 (IIB)E1214 Guide for Use of Melt Wire Temperature Monitorsfor Reactor Vessel Surveillance, E 706 (IIIE)E2005 Guide for Benchmark Testing of Reactor Dosimetryin Standard and Reference Neutron FieldsE2006 Guide for Benchmark Testing of Light Water Re
8、actorCalculations3. Terminology3.1 Definitions:3.1.1 neutron dosimeter, sensor, monitora substance irra-diated in a neutron environment for the determination ofneutron fluence rate, fluence, or spectrum, for example: radio-metric monitor (RM), solid state track recorder (SSTR), heliumaccumulation fl
9、uence monitor (HAFM), damage monitor(DM), temperature monitor (TM).3.1.2 thermal neutron shielda substance (that is,cadmium, boron, gadolinium) that filters or absorbs thermalneutrons.3.2 For definitions or other terms used in this guide, refer toTerminology E170.4. Significance and Use4.1 In neutro
10、n dosimetry, a fission or non-fission dosimeter,or combination of dosimeters, can be used for determining afluence rate, fluence, or neutron spectrum in nuclear reactors.Each dosimeter is sensitive to a specific energy range, and, ifdesired, increased accuracy in a fluence-rate spectrum can beachiev
11、ed by the use of several dosimeters each coveringspecific neutron energy ranges.4.2 A wide variety of detector materials is used for variouspurposes. Many of these substances overlap in the energy ofthe neutrons which they will detect, but many differentmaterials are used for a variety of reasons. T
12、hese reasonsinclude available analysis equipment, different cross sectionsfor different fluence-rate levels and spectra, preferred chemicalor physical properties, and, in the case of radiometricdosimeters, varying requirements for different half-lifeisotopes, possible interfering activities, and che
13、mical separa-tion requirements.1This guide is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applicationsand is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved June 1, 2014. Published July 2014. Originally approvedin 1981
14、. Last previous edition approved in 2009 as E844 09. DOI: 10.1520/E0844-09R14E01.2For 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
15、 onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Selection of Neutron Dosimeters and Thermal NeutronShields5.1 Neutron Dosimeters:5.1.1 The choice of dosimeter material depends largely onthe dosimetry technique e
16、mployed, for example, radiometricmonitors, helium accumulation monitors, track recorders, anddamage monitors.At the present time, there is a wide variety ofdetector materials used to perform neutron dosimetry measure-ments. These are generally in the form of foils, wires, powders,and salts. The use
17、of alloys is valuable for certain applicationssuch as (1) dilution of high cross-section elements, (2) prepa-ration of elements that are not readily available as foils or wiresin the pure state, and (3) preparation to permit analysis of morethan one dosimeter material.5.1.2 For neutron dosimeters, t
18、he reaction rates are usuallydeduced from the absolute gamma-ray radioanalysis (thereexist exceptions, such as SSTRs, HAFMs, damage monitors).Therefore, the radiometric dosimeters selected must havegamma-ray yields known with good accuracy (98 %). Thehalf-life of the product nuclide must be long eno
19、ugh to allowfor time differences between the end of the irradiation and thesubsequent counting. Refer to Method E1005 for nuclear decayand half-life parameters.5.1.3 The neutron dosimeters should be sized to permitaccurate analysis. The range of high efficiency countingequipment over which accurate
20、measurements can be per-formed is restricted to several decades of activity levels (5 to 7decades for radiometric and SSTR dosimeters, 8 decades forHAFMs). Since fluence-rate levels at dosimeter locations canrange over 2 or 3 decades in a given experiment and over 10decades between low power and hig
21、h power experiments, theproper sizing of dosimeter materials is essential to assureaccurate and economical analysis.5.1.4 The estimate of radiometric dosimeter activity levelsat the time of counting include adjustments for the decay of theproduct nuclide after irradiation as well as the rate of prod
22、uctnuclide buildup during irradiation. The applicable equation forsuch calculations is (in the absence of fluence-rate perturba-tions) as follows:A 5 No1 2 e2t1!e2t2! (1)where:A = expected disintegration rate (dps) for the productnuclide at the time of counting,No= number of target element atoms, =
23、estimated fluence-rate density level, = spectral averaged cross section, = product of the nuclide fraction and (if applicable)of the fission yield,1e-t1= buildup of the nuclide during the irradiationperiod, t1,e-t2= decay after irradiation to the time of counting, t2,and = decay constant for the pro
24、duct nuclide.5.1.5 For SSTRs and HAFMs, the same type of informationas for radiometric monitors (that is, total number of reactions)is provided. The difference being that the end products (fissiontracks or helium) requires no time-dependent corrections andare therefore particularly valuable for long
25、-term irradiations.5.1.6 Fission detectors shall be chosen that have accuratelyknown fission yields. Refer to Method E1005.5.1.7 In thermal reactors the correction for neutron selfshielding can be appreciable for dosimeters that have highlyabsorbing resonances (see 6.1.1).5.1.8 Dosimeters that produ
26、ce activation or fission products(that are utilized for reaction rate determinations) with half-lives that are short compared to the irradiation duration shouldnot be used. Generally, radionuclides with half-lives less thanthree times the irradiation duration should be avoided unlessthere is little
27、or no change in neutron spectral shape or fluencerate with time.5.1.9 Tables 1-3 present various dosimeter elements. Listedare the element of interest, the nuclear reaction, and theavailable forms. For the intermediate energy region, the ener-gies of the principal resonances are listed in order of i
28、ncreasingenergy. In the case of the fast neutron energy region, the 95 %response ranges (an energy range that includes most of theresponse for each dosimeter is specified by giving the energiesE05below which 5 % of the activity is produced and E95abovewhich 5 % of the activity is produced) for the23
29、5U neutronthermal fission spectrum are included.5.2 Thermal Neutron Shields:5.2.1 Shield materials are frequently used to eliminateinterference from thermal neutron reactions when resonanceand fast neutron reactions are being studied. Cadmium iscommonly used as a thermal neutron shield, generally 0.
30、51 to1.27 mm (0.020 to 0.050 in.) thick. However, because elemen-tal cadmium (m.p. = 320C) will melt if placed within thevessel of an operating water reactor, effective thermal neutronfilters must be chosen that will withstand high temperatures oflight-water reactors. High-temperature filters includ
31、e cadmiumoxide (or other cadmium compounds or mixtures), boron(enriched in the10B isotope), and gadolinium. The thickness ofthe shield material must be selected to account for burnoutfrom high fluences.5.2.2 In reactors, feasible dosimeters to date whose responserange to neutron energies of 1 to 3 M
32、eV includes the fissionmonitors238U,237Np, and232Th. These particular dosimetersTABLE 1 Dosimeter ElementsThermal Neutron RegionElement ofInterestNuclear Reaction Available FormsB10B(n,)7Li B, B4C, B-Al, B-NbCo59Co(n,)60Co Co, Co-Al, Co-ZrCu63Cu(n,)64Cu Cu, Cu-Al, Cu(NO3)2Au197Au(n,)198Au Au, Au-AlI
33、n115In(n,)116mIn In, In-AlFe58Fe(n,)59Fe FeFe54Fe(n,)55Fe FeLi6Li(n,)3H LiF, Li-AlMn55Mn(n,)56Mn alloysNi58Ni(n,)59Ni(n,)56Fe NiPu239Pu(n,f)FP PuO2, alloysSc45Sc(n,)46Sc Sc, Sc2O3Ag109Ag(n,)110mAg Ag, Ag-Al, AgNO3Na23Na(n,)24Na NaCl, NaF, NaITa181Ta(n,)182Ta Ta, Ta2O5U (enriched)235U(n,f)FP U, U-Al,
34、 UO2,U3O8, alloysE844 09 (2014)12must be shielded from thermal neutrons to reduce fissionproduct production from trace quantities of235U,238Pu,and239Pu and to suppress buildup of interfering fissionablenuclides, for example,238Np and238Pu in the237Np dosimeter,239Pu in the238U dosimeter, and233Uinth
35、e232Th dosimeter.Thermal neutron shields are also necessary for epithermalspectrum measurements in the 5 107to 0.3-MeV energyrange. Also, nickel dosimeters used for the fast activationreaction58Ni(n,p)58Co must be shielded from thermal neutronsin nuclear environments having thermal fluence rates abo
36、ve31012ncm2s1to prevent significant loss of58Co and58mCo by thermal neutron burnout (4).36. Design of Neutron Dosimeters, Thermal NeutronShields, and Capsules6.1 Neutron DosimetersProcedures for handling dosim-eter materials during preparation must be developed to ensure3The boldface number in paren
37、theses refers to the list of references at the end ofthe guide.TABLE 2 Dosimeter ElementsIntermediate Neutron RegionEnergy of PrincipalResonance, eV(17)Dosimetry Reactions Element of Interest Available FormsA 6Li(n,)3H Li LiF, Li-AlA 10B(n,)7Li B B, B4C, B-Al, B-NbA 58Ni(n,)59Ni(n,)56Fe Ni Ni1.45711
38、5In(n,)116mIn In In, In-Al4.28181Ta(n,)182Ta Ta Ta, Ta2O54.906197Au(n,)198Au Au Au, Au-Al5.19109Ag(n,)110mAg Ag Ag, Ag-Al, AgNO321.806232Th(n,)233Th Th Th, ThO2, Th(NO3)4B 235U(n,f)FP U U, U-Al, UO2,U3O8, alloys13259Co(n,)60Co Co Co, Co-Al, Co-Zr103858Fe(n,)59Fe Fe Fe337.355Mn(n,)56Mn Mn alloys57963
39、Cu(n,)64Cu Cu Cu, Cu-Al, Cu(NO3)20.2956243239Pu(n,f)FP Pu PuO2, alloys281023Na(n,)24Na Na NaCl, NaF, NaI329545Sc(n,)46Sc Sc Sc, Sc2O3778854Fe(n,)55Fe Fe FeAThis reaction has no resonance that contributes in the intermediate energy region and the principle resonance has negative energy (i.e. the cros
40、s section is 1/v).BMany resonances contribute in the 1 100 eV region for this reaction.TABLE 3 Dosimeter ElementsFast Neutron RegionDosimetryReactionsElement ofInterestEnergy Response Range (MeV)A,BCross SectionUncertainty(%)A,CAvailableFormsLowE05MedianE50HighE95237Np(n,f)FP Np 0.684 1.96 5.61 9.34
41、 Np2O3, alloys103Rh(n,n)103mRh Rh 0.731 2.25 5.73 3.10 Rh93Nb(n,n)93mNb Nb 0.951 2.57 5.79 3.01 Nb, Nb2O5115In(n,n)115mIn In 1.12 2.55 5.86 2.16 In, In-Al14N(n,)11B N 1.75 3.39 5.86 TiN, ZrN, NbN238U(n,f)FP U (depleted) 1.44 2.61 6.69 0.319 U, U-Al, UO3,U3O8, alloys232Th(n,f)FP Th 1.45 2.79 7.21 5.1
42、1 Th, ThO29Be(n,)6Li Be 1.59 2.83 5.26 Be47Ti(n,p)47Sc Ti 1.70 3.63 7.67 3.77 Ti58Ni(n,p)58Co Ni 1.98 3.94 7.51 2.44 Ni, Ni-Al54Fe(n,p)54Mn Fe 2.27 4.09 7.54 2.12 Fe32S(n,p)32P S 2.28 3.94 7.33 3.63 CaSO4,Li2SO432S(n,)29Si S 1.65 3.12 6.06 Cu2S, PbS58Ni(n,)55Fe Ni 2.74 5.16 8.72 Ni, Ni-Al46Ti(n,p)46
43、Sc Ti 3.70 5.72 9.43 2.48 Ti56Fe(n,p)56Mn FeD5.45 7.27 11.3 2.26 Fe56Fe(n,)53Cr Fe 5.19 7.53 11.3 Fe63Cu(n,)60Co CuE4.53 6.99 11.0 2.36 Cu, Cu-Al27Al(n,)24Na Al 6.45 8.40 11.9 1.19 Al, Al2O348Ti(n,p)48Sc Ti 5.92 8.06 12.3 2.56 Ti47Ti(n,)44Ca Ti 2.80 5.10 9.12 Ti60Ni(n,p)60Co NiE4.72 6.82 10.8 10.3 N
44、i, Ni-Al55Mn(n,2n)54Mn MnF11.0 12.6 15.8 13.54 alloysAEnergy response range was derived using the ENDF/B-VI235U fission spectrum, Ref (1), MT = 9228, MF = 5, MT = 18. The cross section and associated covariancesources are identified in Guide E1018 and in Refs (2,3).BOne half of the detector response
45、 occurs below an energy given by E50; 95 % of the detector response occurs below E95and 5 % below E05.CUncertainty metric only reflects that component due to the knowledge of the cross section and is reported at the 1 level.DLow manganese content necessary.ELow cobalt content necessary.FLow iron con
46、tent necessary.E844 09 (2014)13personnel safety and accurate nuclear environment character-ization. During dosimeter fabrication, care must be taken inorder to achieve desired neutron fluence-rate results, especiallyin the case of thermal and resonance-region dosimeters. Anumber of factors must be c
47、onsidered in the design of adosimetry set for each particular application. Some of theprincipal ones are discussed individually as follows:6.1.1 Self-Shielding of NeutronsThe neutron self-shielding phenomenon occurs when high cross-section atomsin the outer layers of a dosimeter reduce the neutron f
48、luencerate to the point where it significantly affects the activation ofthe inner atoms of the material. This is especially true ofmaterials with high thermal cross sections and essentially allresonance detectors. This can be minimized by using lowweight percentage alloys of high-cross-section mater
49、ial, forexample, Co-Al,Ag-Al, B-Al, Li-Al. It is not as significant forthe fast region where the cross sections are relatively low;therefore, thermal and resonance detectors shall be as thin aspossible. Mathematical corrections can also be made to bringthe material to “zero thickness” but, in general, the smaller thecorrection, the more accurate will be the results. Both theoreti-cal treatments of the complex corrections and experimentaldeterminations are published (5-17).6.1.2 Self-Absor
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