1、Designation: E944 08E944 13Standard Guide forApplication of Neutron Spectrum Adjustment Methods inReactor Surveillance, E 706 (IIA)1This standard is issued under the fixed designation E944; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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.1. Scope1.1 This guide covers the analysis and interpretation of the physics dosimetry for Light Water Reactor
3、(LWR) surveillanceprograms. The main purpose is the application of adjustment methods to determine best estimates of neutron damage exposureparameters and their uncertainties.1.2 This guide is also applicable to irradiation damage studies in research reactors.1.3 This standard does not purport to ad
4、dress all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E170 Terminolo
5、gy Relating to Radiation Measurements and DosimetryE262 Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by RadioactivationTechniquesE263 Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of IronE264 Test Method for Measuring Fast-Ne
6、utron Reaction Rates by Radioactivation of NickelE265 Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32E266 Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of AluminumE343 Test Method for Measuring Reaction Rates by Analysis o
7、f Molybdenum-99 Radioactivity From Fission Dosimeters(Withdrawn 2002)3E393 Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission DosimetersE481 Test Method for Measuring Neutron Fluence Rates by Radioactivation of Cobalt and SilverE482 Guide for Application of Neutron Trans
8、port Methods for Reactor Vessel Surveillance, E706 (IID)E523 Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of CopperE526 Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of TitaniumE693 Practice for Characterizing Neutron Exposures in Iron and LowAl
9、loy Steels in Terms of Displacements PerAtom (DPA),E 706(ID)E704 Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238E705 Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237E706 Master Matrix for Light-Water Reactor Pressure Vessel Surveillance Standard
10、s, E 706(0) (Withdrawn 2011)3E844 Guide for Sensor Set Design and Irradiation for Reactor Surveillance, E 706 (IIC)E853 Practice for Analysis and Interpretation of Light-Water Reactor Surveillance Results, E706(IA)E854 Test Method for Application and Analysis of Solid State Track Recorder (SSTR) Mon
11、itors for Reactor Surveillance,E706(IIIB)1 This guide is under the jurisdiction ofASTM Committee E10 on Nuclear Technology andApplicationsand is the direct responsibility of Subcommittee E10.05 on NuclearRadiation Metrology. A brief overview of Guide E944 appears in Master Matrix E706 in 5.3.1(IIA).
12、Current edition approved Nov. 1, 2008Jan. 1, 2013. Published January 2009January 2013. Originally approved in 1983. Last previous edition approved in 20022008 asE944 02.E944 08. DOI: 10.1520/E0944-08.10.1520/E0944-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM
13、 Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website. DOI: 10.1520/E0944-08.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standa
14、rd 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 all cases
15、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 States1E910 Test Method for Application and Analysis of Helium Accumulation Fluence Monito
16、rs for Reactor Vessel Surveillance,E706 (IIIC)E1005 Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance, E 706 (IIIA)E1018 Guide for Application of ASTM Evaluated Cross Section Data File, Matrix E706 (IIB)E2005 Guide for Benchmark Testing of Reactor Dosim
17、etry in Standard and Reference Neutron FieldsE2006 Guide for Benchmark Testing of Light Water Reactor Calculations2.2 Nuclear Regulatory Commission Documents:4NUREG/CR-1861 PCA Experiments and Blind TestNUREG/CR-2222 Theory and Practice of General Adjustment and Model Fitting ProceduresNUREG/CR-3318
18、 LWR Pressure Vessel Surveillance Dosimetry Improvement Program: PCA Experiments, Blind Test, andPhysics-Dosimetry Support for the PSF ExperimentNUREG/CR-3319 LWR Power Reactor Surveillance Physics-Dosimetry Data Base CompendiumNUREG/CR-5049 Pressure Vessel Fluence Analysis and Neutron Dosimetry2.3
19、Electric Power Research Institute:5EPRI NP-2188 Development and Demonstration of an Advanced Methodology for LWR Dosimetry Applications2.4 Government Document:4NBSIR 853151 Compendium of Benchmark Neutron Fields for Reactor Dosimetry3. Significance and Use3.1 Adjustment methods provide a means for c
20、ombining the results of neutron transport calculations with neutron dosimetrymeasurements (see Test Method E1005 and NUREG/CR-5049) in order to obtain optimal estimates for neutron damage exposureparameters with assigned uncertainties. The inclusion of measurements reduces the uncertainties for thes
21、e parameter values andprovides a test for the consistency between measurements and calculations and between different measurements (see 3.3.3). Thisdoes not, however, imply that the standards for measurements and calculations of the input data can be lowered; the results of anyadjustment procedure c
22、an be only as reliable as are the input data.3.2 Input Data and Definitions:3.2.1 The symbols introduced in this section will be used throughout the guide.3.2.2 Dosimetry measurements are given as a set of reaction rates (or equivalent) denoted by the following symbols:ai,i 51,2, (1)These data are,
23、at present, obtained primarily from radiometric dosimeters, but other types of sensors may be included (see 4.1).3.2.3 The neutron spectrum (see Terminology E170) at the dosimeter location, fluence or fluence rate (E) as a function ofneutron energy E, is obtained by appropriate neutronics calculatio
24、ns (neutron transport using the methods of discrete ordinates orMonte Carlo, see Guide E482). The results of the calculation are customarily given in the form of kmultigroup group fluences orfluence rates.j 5*EjEj11E!dE,j 51,2,k (2)where:Ej and Ej+1 are the lower and upper bounds for the j-th energy
25、 group, respectively.respectively, and k is the total number of groups.3.2.4 The reaction cross sections of the dosimetry sensors are obtained from an evaluated cross section file. The cross sectionfor the i-th reaction as a function of energy E will be denoted by the following:iE!,i 51,2, (3)Used i
26、n connection with the group fluences, Eq 2, are the calculated group-averaged cross sections ij. These values are definedthrough the following equation:ij5*EjEj11E!iE!dE/j (4)i 51,2,n;j51,2,k3.2.5 Uncertainty information in the form of variances and covariances must be provided for all input data. A
27、ppropriatecorrections must be made if the uncertainties are due to bias producing effects (for example, effects of photo reactions).3.3 Summary of the Procedures:4 Available from Superintendents of Documents, U. S. Government Printing Office, Washington, DC 20402.5 Available from the Electric Power
28、Research Institute, P. O. Box 10412, Palo Alto, CA 94303.E944 1323.3.1 An adjustment algorithm modifies the set of input data as defined in 3.2 in the following manner (adjusted quantities areindicated by a tilde, for example, i):ai 5ai1ai (5)E!5E!1E! (6)E!5E!1E! (6)or for group fluence ratesj 5j1j
29、(7)iE!5iE!1iE!, (8)or for group-averaged cross sectionsij5ij1ij (9)The adjusted quantities must satisfy the following conditions:ai 5*0E!iE!dE,i 51,2,n (10)ai 5*0E!iE!dE,i 51,2,n (10)or in the form of group fluence ratesa i 5(j51kijj,i 51,2,n (11)Since the number of equations in Eq 11 is much smalle
30、r than the number of adjustments, there exists no unique solution to theproblem unless it is further restricted. The mathematical algorithm in current adjustment codes are intended to make theadjustments as small as possible relative to the uncertainties of the corresponding input data. The more rec
31、ent codes Codes likeSTAYSL, FERRET, LEPRICON, and LSL-M2 (see Table 1) are based explicitly on the statistical principles such as “MaximumLikelihood Principle” or “Bayes Theorem,” which are generalizations of the well-known least squares principle. Using variancesand correlations of the input fluenc
32、e, dosimetry, and cross section data (see 4.1.1, 4.2.2, and 4.3.3), even the older codes, notablySAND-II and CRYSTALBALL, can be interpreted as application of the least squares principle although the statistical assumptionsare not spelled out explicitly (see Table 1).Adetailed discussion of the math
33、ematical derivations can be found in NUREG/CR-2222and EPRI NP-2188.3.3.1.1 An important problem in reactor surveillance is the determination of neutron fluence inside the pressure vessel wall atlocations which are not accessible to dosimetry. Estimates for exposure parameter values at these location
34、s can be obtained fromadjustment codes which adjust fluences simultaneously at more than one location when the cross correlations between fluences atdifferent locations are given. LEPRICON has provisions for the estimation of cross correlations for fluences and simultaneousadjustment. LSL-M2 also al
35、lows simultaneous adjustment, but cross correlations must be given.3.3.2 The adjusted data i, etc., are, for any specific algorithm, unique functions of the input variables. Thus, uncertainties(variances and covariances) for the adjusted parameters can, in principle, be calculated by propagation the
36、 uncertainties for theinput data. Linearization may be used before calculating the uncertainties of the output data if the adjusted data are nonlinearfunctions of the input data.3.3.2.1 The algorithms of the adjustment codes tend to decrease the variances of the adjusted data compared to thecorrespo
37、nding input values. The linear least squares adjustment codes yield estimates for the output data with minimum variances,that is, the “best” unbiased estimates. This is the primary reason for using these adjustment procedures.3.3.3 Properly designed adjustment methods provide means to detect inconsi
38、stencies in the input data which manifestthemselves through adjustments that are larger than the corresponding uncertainties or through large values of chi-square, or both.(See NUREG/CR-3318 and NUREG/CR-3319.)Any detection of inconsistencies should be documented, and output data obtainedfrom incons
39、istent input should not be used. All input data should be carefully reviewed whenever inconsistencies are found, andefforts should be made to resolve the inconsistencies as stated below.3.3.3.1 Input data should be carefully investigated for evidence of gross errors or biases if large adjustments ar
40、e required. Notethat the erroneous data may not be the ones that required the largest adjustment; thus, it is necessary to review all input data. Dataof dubious validity may be eliminated if proper corrections cannot be determined. Any elimination of data must be documentedand reasons stated which a
41、re independent of the adjustment procedure. Inconsistent data may also be omitted if they contributelittle to the output under investigation.3.3.3.2 Inconsistencies may also be caused by input variances which are too small. The assignment of uncertainties to the inputdata should, therefore, be revie
42、wed to determine whether the assumed precision and bias for the experimental and calculationaldata may be unrealistic. If so, variances may be increased, but reasons for doing so should be documented. Note that in statisticallybased adjustment methods, listed in Table 1 the output uncertainties are
43、determined only by the input uncertainties and are notE944 133affected by inconsistencies in the input data (see NUREG/CR-2222). Note also that too large adjustments may yield unreliable databecause the limits of the linearization are exceeded even if these adjustments are consistent with the input
44、uncertainties.3.3.4 Using the adjusted fluence spectrum, estimates of damage exposure parameter values can be calculated. These parametersare weighted integrals over the neutron fluencep 5*o E!wE!dE (12)p 5*o E!wE!dE (12)or for group fluencesp 5(j51kjwj (13)p 5(j51kjwj (13)with given weight (respons
45、e) functions w(E) or w j, respectively. The response function for dpa of iron is listed in Practice E693.Fluence greater than 1.0 MeV or fluence greater than 0.1 MeV is represented as w(E) = 1 for E above the limit and w(E) = 0 forE below.TABLE 1 Available Unfolding CodesProgram Solution Method Code
46、 AvailableFrom Refer-ences CommentsSAND-II semi-iterative RSICC Prog. No. CCC-112, CCC-619, PSR-3451A contains trial spectra library. No output uncertainties in theoriginal code, but modified Monte Carlo code provides outputuncertainties (2, 3, 4)SPECTRA statistical, linear estimation RSICC Prog. No
47、. CCC-1085, 6 minimizes deviation in magnitude, no output uncertainties.IUNFLD/UNFOLDstatistical, linear estimation 7 constrained weighted linear least squares code using B-splinebasic functions. No output uncertainties.WINDOWS statistical, linear estimation, linearprogrammingRSICC Prog. No. PSR-136
48、, 1618 minimizes shape deviation, determines upper and lower boundsfor integral parameter and contribution of foils to bounds andestimates. No statistical output uncertainty.RADAK,SENSAKstatistical, linear estimation RSICC Prog. No. PSR-1229, 10,11,12 RADAK is a general adjustment code not restricte
49、d to spectrumadjustment.STAYSL statistical linear estimation RSICC Prog. No. PSR-11313 permits use of full or partial correlation uncertainty data foractivation and cross section data.NEUPAC(J1) statistical, linear estimation RSICC Prog. No. PSR-17714, 15 permits use of full covariance data and includes routine ofsensitivity analysis.FERRET statistical, least squares with log normala priori distributionsRSICC Prog. No. PSR-1452, 3 flexible input options allow the inclusion of both differe
