ASTM E844-2018 6875 Standard Guide for Sensor Set Design and Irradiation for Reactor Surveillance.pdf

1、Designation: E844 18Standard Guide forSensor Set Design and Irradiation for Reactor Surveillance1This standard is issued under the fixed designation E844; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A

2、 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 guide covers the selection, design, irradiation,post-irradiation handling, and quality control of neutron do-simeters (sensors),

3、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 information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It

4、 is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on

5、standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E170 Terminology Relating to Radiation Me

6、asurements 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 Reactor Sur-veillanceE910 Test Method for Application and Analysis of HeliumAccum

7、ulation Fluence Monitors for Reactor Vessel Sur-veillanceE1005 Test Method for Application and Analysis of Radio-metric Monitors for Reactor Vessel SurveillanceE1018 Guide for Application of ASTM Evaluated CrossSection Data FileE1214 Guide for Use of Melt Wire Temperature Monitorsfor Reactor Vessel

8、SurveillanceE2005 Guide for Benchmark Testing of Reactor Dosimetryin Standard and Reference Neutron FieldsE2006 Guide for Benchmark Testing of Light Water ReactorCalculationsE2956 Guide for Monitoring the Neutron Exposure of LWRReactor Pressure Vessels3. Terminology3.1 Definitions:3.1.1 neutron dosi

9、meter, 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 fluence monitor (HAFM), damage monitor(DM), temperature monitor (TM

10、).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 neutron dosimetry, a fission or non-fission dosimeter,or combination of

11、 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 beachieved by the use of several dosimeters each coveringspecific neutron

12、 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. These reasonsinclude available analysis equipment, different cross

13、 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 chemical separa-tion requirements.1This guide is under the jurisdict

14、ion of ASTM Committee E10 on NuclearTechnology and Applicationsand is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved June 1, 2018. Published July 2018. Originally approvedin 1981. Last previous edition approved in 2014 as E844 09(2014)2. DOI:1

15、0.1520/E0844-18.2For 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 onthe ASTM website.Copyright ASTM International, 100 Barr Harbor

16、 Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendation

17、s issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Selection of Neutron Dosimeters and Thermal NeutronShields5.1 Neutron Dosimeters:5.1.1 The choice of dosimeter material depends largely onthe dosimetry technique employed, for example, radiometricmonitors, heliu

18、m 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 of alloys is valuable for certain applicationssu

19、ch 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, the reaction rates are usuallydeduced from the ab

20、solute 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 enough to allowfor time differences between the end

21、 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 measurements can be per-formed is restricted to

22、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 high power experiments, theproper sizing of dosimet

23、er 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 productnuclide buildup during irradiation. The appli

24、cable equation forsuch calculations is (in the absence of fluence-rate variations)as follows:A 5 No1 2 e2t1!e2t2! (1)where:A = expected disintegration rate (dps) for the prod-uct nuclide at the time of counting,No= number of target element atoms, = estimated fluence rate, = spectral averaged cross s

25、ection, = product of the nuclide fraction and (if appli-cable) 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 product nuclide.5.1.5 Eq 1 should not be used for the analysis

26、of dosimetrymeasurements unless it is known that the fluence rate wasapproximately constant over the duration of the irradiation, orthat the total duration of the irradiation was short compared tothe half life of the product nuclide.5.1.6 If the fluence rate during the irradiation period isvariable,

27、 a valid monitor of the fluence rate variation at thedosimeter location is essential. The validity of the fluence ratemonitoring method should be demonstrated by transport cal-culations or other evidence.5.1.7 When the requirements of 5.1.6 are met, then the totalirradiation period can be divided in

28、to a continuous series ofperiods during each of which is essentially constant. Equa-tions that replace Eq 1 for this case are given in Practice E261.5.1.8 For SSTRs and HAFMs, the same type of informationas for radiometric monitors (that is, total number of reactions)is provided. The difference bein

29、g that the end products (fissiontracks or helium) requires no time-dependent corrections andare therefore particularly valuable for long-term irradiations.5.1.9 Fission detectors shall be chosen that have accuratelyknown fission yields. Refer to Method E1005.5.1.10 In thermal reactors the correction

30、 for neutron selfshielding can be appreciable for dosimeters that have highlyabsorbing resonances (see 6.1.1).5.1.11 Dosimeters that produce activation or fission prod-ucts (that are utilized for reaction rate determinations) withhalf-lives that are short compared to the irradiation durationshould n

31、ot be used. Generally, radionuclides with half-livesless than three times the irradiation duration should be avoidedunless there is little or no change in neutron spectral shape orfluence rate with time.5.1.12 Dosimeters with half-lives as short as one third of theirradiation duration have been used

32、 in power reactor surveil-lance when the power history in nearby reactor channels wasavailable in accordance with 5.1.6 and 5.1.7.5.1.13 Tables 1-3 present various dosimeter elements.Listed are the element of interest, the nuclear reaction, and theavailable forms. For the intermediate energy region,

33、 the ener-gies of the principal resonances are listed in order of increasingenergy. 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 pr

34、oduced and E95aboveTABLE 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-AlIn115In(n,)116mIn In, In-AlFe58Fe(n,)59Fe FeFe54Fe(n,)55Fe FeL

35、i6Li(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, UO2,U3O8, alloysE844 182which 5 % of the activity is produce

36、d) for the235U 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,

37、generally 0.51 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 fi

38、lters include 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

39、 of 1 to 3 MeV includes the fissionmonitors238U,237Np, and232Th. These particular dosimetersmust be shielded from thermal neutrons to reduce fissionTABLE 2 Dosimeter ElementsIntermediate Neutron RegionEnergy of PrincipalResonance, eV(17)Dosimetry Reactions Element of Interest Available FormsA 6Li(n,

40、)3H Li LiF, Li-AlA 10B(n,)7Li B B, B4C, B-Al, B-NbA 58Ni(n,)59Ni(n,)56Fe Ni Ni1.457115In(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, alloys1325

41、9Co(n,)60Co Co Co, Co-Al, Co-Zr103858Fe(n,)59Fe Fe Fe337.355Mn(n,)56Mn Mn alloys57963Cu(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 inte

42、rmediate energy region and the principle resonance has negative energy (i.e. the cross 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 SectionUnce

43、rtainty(%)A,CAvailableFormsLowE05MedianE50HighE95237Np(n,f)FP Np 0.684 1.96 5.61 9.34 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 (deple

44、ted) 1.44 2.61 6.69 0.319 U, U-Al, UO3,U3O8, alloys232Th(n,f)FP Th 1.45 2.79 7.21 5.11 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(

45、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)46Sc 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 8.0

46、6 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 Ni, 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 covariancesourc

47、es are identified in Guide E1018 and in Refs (2,3).BOne half of the detector response 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

48、 1 level.DLow manganese content necessary.ELow cobalt content necessary.FLow iron content necessary.E844 183product production from trace quantities of235U,238Pu,and239Pu and to suppress buildup of interfering fissionablenuclides, for example,238Np and238Pu in the237Np dosimeter,239Pu in the238U dos

49、imeter, and233Uinthe232Th 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 above31012ncm2s1to prevent significant loss of58Co and58mCo by thermal neutron burnout (4).36. Design of Neutron Dosimeters, Thermal NeutronShields, and Capsules6.1 Neutron Dosimete