ImageVerifierCode 换一换
格式:PDF , 页数:18 ,大小:344.92KB ,
资源ID:530166      下载积分:5000 积分
快捷下载
登录下载
邮箱/手机:
温馨提示:
如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
如填写123,账号就是123,密码也是123。
特别说明:
请自助下载,系统不会自动发送文件的哦; 如果您已付费,想二次下载,请登录后访问:我的下载记录
支付方式: 支付宝扫码支付 微信扫码支付   
注意:如需开发票,请勿充值!
验证码:   换一换

加入VIP,免费下载
 

温馨提示:由于个人手机设置不同,如果发现不能下载,请复制以下地址【http://www.mydoc123.com/d-530166.html】到电脑端继续下载(重复下载不扣费)。

已注册用户请登录:
账号:
密码:
验证码:   换一换
  忘记密码?
三方登录: 微信登录  

下载须知

1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。
2: 试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。
3: 文件的所有权益归上传用户所有。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 本站仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

版权提示 | 免责声明

本文(ASTM E2059-2006 Standard Practice for Application and Analysis of Nuclear Research Emulsions for Fast Neutron Dosimetry《快中子剂量测定用核研究乳剂的应用和分析标准规程》.pdf)为本站会员(brainfellow396)主动上传,麦多课文库仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文库(发送邮件至master@mydoc123.com或直接QQ联系客服),我们立即给予删除!

ASTM E2059-2006 Standard Practice for Application and Analysis of Nuclear Research Emulsions for Fast Neutron Dosimetry《快中子剂量测定用核研究乳剂的应用和分析标准规程》.pdf

1、Designation: E 2059 06Standard Practice forApplication and Analysis of Nuclear Research Emulsions forFast Neutron Dosimetry1This standard is issued under the fixed designation E 2059; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,

2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 Nuclear Research Emulsions (NRE) have a long andillustrious history of applications in the physical scie

3、nces, earthsciences and biological sciences (1,2)2. In the physical sci-ences, NRE experiments have led to many fundamental dis-coveries in such diverse disciplines as nuclear physics, cosmicray physics and high energy physics. In the applied physicalsciences, NRE have been used in neutron physics e

4、xperimentsin both fission and fusion reactor environments (3-6). Numer-ous NRE neutron experiments can be found in other applieddisciplines, such as nuclear engineering, environmental moni-toring and health physics. Given the breadth of NRE applica-tions, there exist many textbooks and handbooks tha

5、t provideconsiderable detail on the techniques used in the NRE method.As a consequence, this practice will be restricted to theapplication of the NRE method for neutron measurements inreactor physics and nuclear engineering with particular empha-sis on neutron dosimetry in benchmark fields (see Matr

6、ixE 706).1.2 NRE are passive detectors and provide time integratedreaction rates. As a consequence, NRE provide fluence mea-surements without the need for time-dependent corrections,such as arise with radiometric (RM) dosimeters (see TestMethod E 1005). NRE provide permanent records, so thatoptical

7、microscopy observations can be carried out anytimeafter exposure. If necessary, NRE measurements can be re-peated at any time to examine questionable data or to obtainrefined results.1.3 Since NRE measurements are conducted with opticalmicroscopes, high spatial resolution is afforded for fine struc-

8、ture experiments. The attribute of high spatial resolution canalso be used to determine information on the angular anisot-ropy of the in-situ neutron field (4,5,7). It is not possible foractive detectors to provide such data because of in-situperturbations and finite-size effects (see Section 11).1.

9、4 The existence of hydrogen as a major constituent ofNRE affords neutron detection through neutron scattering onhydrogen, that is, the well known (n,p) reaction. NRE mea-surements in low power reactor environments have beenpredominantly based on this (n,p) reaction. NRE have alsobeen used to measure

10、 the6Li (n,t)4He and the10B(n,a)7Lireactions by including6Li and10B in glass specks near themid-plane of the NRE (8,9). Use of these two reactions doesnot provide the general advantages of the (n,p) reaction forneutron dosimetry in low power reactor environments (seeSection 4).As a consequence, this

11、 standard will be restricted tothe use of the (n,p) reaction for neutron dosimetry in low powerreactor environments.1.5 LimitationsThe NRE method possesses three majorlimitations for applicability in low power reactor environ-ments.1.5.1 Gamma-Ray SensitivityGamma-rays create a sig-nificant limitati

12、on for NRE measurements.Above a gamma-rayexposure of approximately 3R, NRE can become fogged bygamma-ray induced electron events. At this level of gamma-ray exposure, neutron induced proton-recoil tracks can nolonger be accurately measured. As a consequence, NREexperiments are limited to low power e

13、nvironments such asfound in critical assemblies and benchmark fields. Moreover,applications are only possible in environments where thebuildup of radioactivity, for example, fission products, islimited.1.5.2 Low Energy LimitIn the measurement of tracklength for proton recoil events, track length dec

14、reases asproton-recoil energy decreases. Proton-recoil track length be-low approximately 3 in NRE can not be adequately measuredwith optical microscopy techniques. As proton-recoil tracklength decreases below approximately 3, it becomes verydifficult to measure track length accurately. This 3 track1

15、This practice is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applications , and is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved Jan. 1, 2006. Published February 2006. Originallyapproved in 2000. Last previous editio

16、n approved in 2005 as E 2059 - 05.2The boldface numbers in parentheses refer to the list of references at the end ofthe text.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.length limit corresponds to a low energy limit of applicabil

17、ityin the range of approximately 0.3 to 0.4 MeV for neutroninduced proton-recoil measurements in NRE.1.5.3 High-Energy LimitsAs a consequence of finite-sizelimitations, fast-neutron spectrometry measurements are lim-ited to #15 MeV. The limit for in-situ spectrometry in reactorenvironments is #8MeV.

18、1.5.4 Track Density LimitThe ability to measure protonrecoil track length with optical microscopy techniques dependson track density. Above a certain track density, a maze orlabyrinth of tracks is created, which precludes the use ofoptical microscopy techniques. For manual scanning, thislimitation a

19、rises above approximately 104tracks/cm2, whereasinteractive computer based scanning systems can extend thislimit up to approximately 105tracks/cm2. These limits corre-spond to neutron fluences of 106107cm2, respectively.1.6 Neutron Spectrometry (Differential Measurements)For differential neutron spe

20、ctrometry measurements in lowpower reactor environments, NRE experiments can be con-ducted in two different modes. In the more general mode, NREare irradiated in-situ in the low power reactor environment.This mode of NRE experiments is called the 4p mode, sincethe in-situ irradiation creates tracks

21、in all directions (see 3.1.1).In special circumstances, where the direction of the neutronflux is known, NRE are oriented parallel to the direction of theneutron flux. In this orientation, one edge of the NRE faces theincident neutron flux, so that this measurement mode is calledthe end-on mode. Sca

22、nning of proton-recoil tracks is differentfor these two different modes. Subsequent data analysis is alsodifferent for these two modes (see 3.1.1 and 3.1.2).1.7 Neutron Dosimetry (Integral Measurements)NREalso afford integral neutron dosimetry through use of the (n,p)reaction in low power reactor en

23、vironments. Two differenttypes of (n,p) integral mode dosimetry reactions are possible,namely the I-integral and the J-integral (10,11). Proton-recoiltrack scanning for these integral reactions is conducted in adifferent mode than scanning for differential neutron spectrom-etry (see 3.2). Integral m

24、ode data analysis is also different thanthe analysis required for differential neutron spectrometry (see3.2). This practice will emphasize NRE (n,p) integral neutrondosimetry, because of the utility and advantages of integralmode measurements in low power benchmark fields.2. Referenced Documents2.1

25、ASTM Standards:3E 706 Master Matrix for Light-Water Reactor PressureVessel Surveillance Standards, E 706(0)E 854 Test Method for Application and Analysis of SolidState Track Recorder (SSTR) Monitors for Reactor Sur-veillance, E706(IIIB)E 910 Test Method for Application and Analysis of HeliumAccumula

26、tion Fluence Monitors for Reactor Vessel Sur-veillance, E706 (IIIC)E 944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, E 706 (IIA)E 1005 Test Method forApplication andAnalysis of Radio-metric Monitors for Reactor Vessel Surveillance, E706(IIIA)3. Alternate Mo

27、des of NRE Neutron Measurements3.1 Neutron Spectrum MeasurementsThe neutron energyrange of interest in reactors environments covers approxi-mately nine orders of magnitude, extending from thermalenergies up to approximately 20 MeV. No single high-resolution method of neutron spectrometry exists that

28、 cancompletely cover this energy range of interest (12). Work withproton-recoil proportional counters has not been extendedbeyond a few MeV, due to the escape of more energetic protonsfrom the finite sensitive volume of the counter. In fact,correction of in-situ proportional counters for such finite

29、-sizeeffects can be non-negligible above 0.5 MeV (13). Finite-sizeeffects are much more manageable in NRE because of thereduced range of recoil protons. As a consequence, NRE fastneutron spectrometry has been applied at energies up to 15MeV (3). For in-situ spectrometry in reactor environments,NRE m

30、easurements up to 8.0 MeVare possible with very smallfinite-size corrections (14-16).3.1.1 4p ModeIt has been shown (3-6) that a neutronfluence-spectrum can be deduced from the integral relationshipME! 5 npV*E snpE! FE!EdE (1)where:F(E) = neutron fluence in n/(cm2MeV),snp(E) = neutron-proton scatter

31、ing cross section (cm2)atneutron energy, E,E = neutron or proton energy (MeV),np= atomic hydrogen density in the NRE (atoms/cm3),V = volume of NRE scanned (cm3), andM (E) = proton spectrum (protons/MeV) observed in theNRE volume V at energy E.The neutron fluence can be derived from Eq 1 and takes th

32、eform:FE! 5 EsnpE!npVdMdE(2)Eq 2 reveals that the neutron fluence spectrum at energy Edepends upon the slope of the proton spectrum at energy E.Asa consequence, approximately 104tracks must be measured togive statistical accuracies of the order of 10 % in the neutronfluence spectrum (with a correspo

33、nding energy resolution ofthe order of 10 %). It must be emphasized that spectralmeasurements determined with NRE in the 4p mode areabsolute.3.1.2 End-On ModeDifferential neutron spectrometrywith NRE is considerably simplified when the direction ofneutron incidence is known, such as for irradiations

34、 in colli-mated or unidirectional neutron beams. In such exposures, thekinematics of (n,p) scattering can be used to determine neutronenergy. Observation of proton-recoil direction and proton-recoil track length provide the angle of proton scatteringrelative to the incident neutron direction, u, and

35、 the proton3For 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.E2059062energy, Ep, respectively. In terms of thes

36、e observations, theneutron energy, En, is simply:En5Epcos2u(3)In collimated or unidirectional neutron irradiations, theemulsion is exposed end-on as depicted in Fig. 1. The end-onmode can be used to advantage in media where neutronscattering is negligible for two types of benchmark fieldexperiments,

37、 namely:3.1.2.1 Benchmark field validation of the NRE method orcharacterization of point neutron sources, for example, thestandard252Cf neutron field at the National Institute of Stan-dards and Technology (NIST) (17).3.1.2.2 Measurement of leakage neutron spectra at suffi-ciently large distances fro

38、m the neutron source, for example,neutron spectrum measurements at the Little Boy Replica(LBR) benchmark field (18).3.2 Integral ModeIt is possible to use emulsion data toobtain both differential and integral spectral information.Emulsion work is customarily carried out in the differentialmode (3-6)

39、. In contrast, NRE work in the integral mode is amore recent concept and, therefore, a fuller explanation of thisapproach is included below. In this integral mode, NREprovide absolute integral reaction rates, which can be used inspectral adjustment codes. Before these recent efforts, suchcodes have

40、not utilized integral reaction rates based on NRE.The significance of NRE integral reaction rates stems from theunderlying response, which is based on the elastic scatteringcross section of hydrogen. This snp(E) cross section isuniversally accepted as a standard cross section and is knownto an accur

41、acy of approximately 1 %.3.2.1 The I Integral RelationThe first integral relationshipfollows directly from Eq 1. The integral in Eq 1 can be definedas:IET! 5*ET s E!EFE! dE (4)Here I (ET) possesses units of proton-recoil tracks/MeV perhydrogen atom. Clearly I (ET) is a function of the lower protonen

42、ergy cut-off used for analyzing the emulsion data. Using Eq4 in Eq 1, one finds the integral relation:IET! 5MET!npV(5)I (ET) is evaluated by using a least squares fit of the scanningdata in the neighborhood of E=ET. Alternatively, since:MET! 5 MRT!dRE!dE(6)where: R (E) is the proton-recoil range at

43、energy E in theNRE and dR/dE is known from the proton range-energyrelation for the NRE. One need only determine M (R)intheneighborhood ofR=RT. Here M(R) is the number ofproton-recoil tracks/micron observed in the NRE. Conse-quently, scanning efforts can be concentrated in the neighbor-hood of R=RTin

44、 order to determine I (ET). In this manner, theaccuracy attained in I (ET) is comparable to the accuracy of thedifferential determination of F(E), as based on Eq 2, but witha significantly reduced scanning effort.3.2.2 The J Integral RelationThe second integral relationcan be obtained by integration

45、 of the observed proton spectrumM (ET). From Eq 1:*EminMET!dET5 npV*EmindET *ET sE!EFE!dE (7)where: Eminis the lower proton energy cut-off used inanalyzing the NRE data. Introducing into Eq 7 the definitions:Emin! 5*EminMET!dET(8)and:JEmin! 5*EmindET *ET sE!EFE! (9)has:FIG. 1 Geometrical Configurati

46、on for End-On Irradiation of NREE2059063JEmin! 5Emin!npV(10)Hence, the second integral relation, namely Eq 10, can beexpressed in a form analogous to the first integral relation,namely Eq 5. Here (Emin) is the integral number of proton-recoil tracks per hydrogen atom observed above an energy Eminin

47、the NRE. Consequently the integral J (Emin) possesses unitsof proton-recoil tracks per hydrogen atom. The integral J(Emin) can be reduced to the form:JEmin! 5*EminS1EminEDsE!FE!dE (11)In addition by using Eq 6, the observable (Emin) can beexpressed in the form:Emin! 5*RminMR!dR (12)Hence, to determi

48、ne the second integral relationship, oneneed only count proton-recoil tracks above R=Rmin. Tracksconsiderably longer than Rminneed not be measured, butsimply counted. However, for tracks in the neighborhood of R=Rmin, track length must be measured so that an accuratelower bound Rmincan be effectivel

49、y determined.4. Significance and Use4.1 Integral Mode DosimetryAs shown in 3.2, two differ-ent integral relationships can be established using proton-recoilemulsion data. These two integral reactions can be obtainedwith roughly an order of magnitude reduction in scanningeffort. Consequently this integral mode is an important comple-mentary alternative to the customary differential mode of NREspectrometry. The integral mode can be applied over extendedspatial regions, for example, perhaps up to as many as tenin-situ locati

copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
备案/许可证编号:苏ICP备17064731号-1