1、ANSI/ANS-8.24-2007validation of neutron transportmethods for nuclear criticalitysafety calculationsANSI/ANS-8.24-2007ANSI/ANS-8.24-2007American National StandardValidation of Neutron Transport Methodsfor Nuclear Criticality Safety CalculationsSecretariatAmerican Nuclear SocietyPrepared by theAmerica
2、n Nuclear SocietyStandards CommitteeWorking Group ANS-8.24Published by theAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USAApproved March 16, 2007by theAmerican National Standards Institute, Inc.AmericanNationalStandardDesignation of this document as an American N
3、ational Standard attests thatthe principles of openness and due process have been followed in the approvalprocedure and that a consensus of those directly and materially affected bythe standard has been achieved.This standard was developed under procedures of the Standards Committee ofthe American N
4、uclear Society; these procedures are accredited by the Amer-ican National Standards Institute, Inc., as meeting the criteria for AmericanNational Standards. The consensus committee that approved the standardwas balanced to ensure that competent, concerned, and varied interests havehad an opportunity
5、 to participate.An American National Standard is intended to aid industry, consumers, gov-ernmental agencies, and general interest groups. Its use is entirely voluntary.The existence of an American National Standard, in and of itself, does notpreclude anyone from manufacturing, marketing, purchasing
6、, or using prod-ucts, processes, or procedures not conforming to the standard.By publication of this standard, the American Nuclear Society does not insureanyone utilizing the standard against liability allegedly arising from or afterits use. The content of this standard reflects acceptable practice
7、 at the time ofits approval and publication. Changes, if any, occurring through developmentsin the state of the art, may be considered at the time that the standard issubjected to periodic review. It may be reaffirmed, revised, or withdrawn atany time in accordance with established procedures. Users
8、 of this standardare cautioned to determine the validity of copies in their possession and toestablish that they are of the latest issue.The American Nuclear Society accepts no responsibility for interpretations ofthis standard made by any individual or by any ad hoc group of individuals.Requests fo
9、r interpretation should be sent to the Standards Department atSociety Headquarters. Action will be taken to provide appropriate response inaccordance with established procedures that ensure consensus on theinterpretation.Comments on this standard are encouraged and should be sent to SocietyHeadquart
10、ers.Published byAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USACopyright 2007 by American Nuclear Society. All rights reserved.Any part of this standard may be quoted. Credit lines should read “Extracted fromAmerican National Standard ANSI0ANS-8.24-2007 with per
11、mission of the publisher,the American Nuclear Society.” Reproduction prohibited under copyright conventionunless written permission is granted by the American Nuclear Society.Printed in the United States of AmericaForewordThis Foreword is not a part of American National Standard “Validation of Neutr
12、onTransport Methods for Nuclear Criticality Safety Calculations,” ANSI0ANS-8.24-2007.!This standard goes beyondANSI0ANS-8.1-1998; R2007, “Nuclear Criticality Safetyin Operations with Fissionable Materials Outside Reactors,” to provide addi-tional detail about processes and techniques for the validat
13、ion of computer-basedneutron transport calculational methods used in nuclear criticality safety analy-ses. The ANS-8.24 working group has used its experience, results of conferenceson area of applicability and validation, and outside experts to expand on theconcepts identified in ANSI0ANS-8.1-1998;
14、R2007. More detail and method de-scriptions are provided here. Section 4.3 of ANSI0ANS-8.1-1998; R2007 estab-lishes the basic criteria for performing validation of calculational methods. Thissection contains material that was originally in a separate standard, ANSI0ANS-8.11-1975 Withdrawn 1983!, “Va
15、lidation of Calculational Methods for NuclearCriticality Safety,” but that was subsumed intoANSI0ANS-8.1-1983; R1988With-drawn in 1998!, “Nuclear Criticality Safety in Operations with Fissionable Ma-terials Outside Reactors.” As there is currently a greater reliance on computercalculations in critic
16、ality safety applications, it was felt that a separate standarddescribing the requirements for the validation of computer-based neutron trans-port methods was again needed.Criticality safety analysts have indicated the need for additional guidance be-yond that provided by ANSI0ANS-8.1-1998; R2007. F
17、or example, ANSI0ANS-8.1-1998; R2007 indicates validation shall be performed by comparison to “criticaland exponential experiments” and that the area of applicability for the valida-tion should be established from this comparison. However, criticality safetyanalysts would benefit from requirements a
18、nd recommendations on establish-ment of the area of applicability as well as criteria that should be considered inthe extension of the area of applicability, and the use of bias and bias uncertaintybased on comparison to experiments. The existing database of critical experi-ments was developed large
19、ly in a period when the fissile material operations andtechnical criteria were different from many of the current and planned opera-tions involving fissile material. However, as the number of experiments thatfocus on current and planned operations has decreased, the industry need tooptimize operatio
20、ns and reduce unnecessary conservatism has increased. Thus,the scrutiny and importance placed on validation has increased in recent years.This standard provides requirements and recommendations on proper validationprocesses and techniques for computer-based neutron transport calculationalmethods to
21、expand on the basic criteria established in ANSI0ANS-8.1-1998;R2007.This version of the standard was drafted by Working Group ANS-8.24 of Sub-committee 8 of the American Nuclear Society. The membership of the workinggroup at the time of issuance was as follows:R. D. Busch Chair!, University of New M
22、exicoJ. S. Bullington, Washington Safety Management Solutions, LLCC. D. Harmon, Los Alamos National LaboratoryJ. E. Hicks, U.S. Department of EnergyK. D. Kimball, NISYS CorporationD. C. Morey, U.S. Nuclear Regulatory CommissionC. V. Parks, Oak Ridge National LaboratoryA. W. Prichard, Pacific Northwe
23、st National LaboratoryB. M. Rothleder, U.S. Department of EnergyN. R. Smith, Serco Assurance, United KingdomR. W. Tayloe, IndividualC. S. Tripp, U.S. Nuclear Regulatory CommissioniF. E. Trumble, Washington Safety Management Solutions, LLCL. L. Wetzel, BWX Technologies, Inc.This standard was prepared
24、 under the guidance of ANS Subcommittee 8, Fis-sionable Materials Outside Reactors, which had the following membership at thetime of its approval:T. P. McLaughlin Chair!, IndividualJ. A. Schlesser Secretary!, Washington Safety Management Solutions, LLCF. M. Alcorn, IndividualH. D. Felsher, U.S. Nucl
25、ear Regulatory CommissionA. S. Garcia, U.S. Department of EnergyN. Harris, British Nuclear Fuel, PLCC. M. Hopper, Oak Ridge National LaboratoryB. O. Kidd, BWX TechnologiesR. A. Libby, Pacific Northwest National LaboratoryD. A. Reed, Oak Ridge National LaboratoryT. A. Reilly, IndividualH. Toffer, Flu
26、or Federal ServicesG. E. Whitesides, IndividualConsensus Committee N16, Nuclear Criticality Safety, had the following mem-bership at the time of its approval of this standard:C. M. Hopper Chair!, Oak Ridge National LaboratoryR. Knief Vice-Chair!, XE CorporationG. H. Bidinger, IndividualR. D. Busch,
27、University of New MexicoR. S. Eby, American Institute of Chemical EngineersM. A. Galloway, U.S. Nuclear Regulatory CommissionC. D. Manning, AREVA NPB. McLeod, Institute of Nuclear Materials ManagementS. P. Murray, Health Physics SocietyR. E. Pevey, University of TennesseeR. L. Reed, Washington Safet
28、y Management Solutions, LLCB. M. Rothleder, U.S. Department of EnergyW. R. Shackelford, Nuclear Fuel Services, Inc.R. G. Taylor, IndividualR. M. Westfall, Oak Ridge National LaboratoryL. L. Wetzel, BWX Technologies, Inc.R. E. Wilson, U.S. Department of EnergyiiContentsSection Page1 Introduction . 12
29、 Scope . 13 Definitions 14 Computer code system . 25 Selectionandmodelingofbenchmarks 26 Establishment of bias, bias uncertainty, and margins 37 Adequacy of the validation . 38 Documentation and independent technical review 49 References 4AppendicesAppendix A Examples of Physical and Derived Paramet
30、ers . 5Appendix B Sources of Information on Experiments 7Appendix C Annotated Bibliography for Use in Validation ofComputational Methods for Criticality Safety 9Appendix D Validation Example . 12TablesTableD.1 Processparametersanddata 13Table D.2 Parameters of benchmark experiments . 14Table D.3 Cal
31、culation results for the benchmark experiments . 15Table D.4 Comparison of benchmark applicability and processparameters 17FiguresFigure D.1 Benchmark results plotted against average lethargy energycausing fission . 18Figure D.2 Benchmark results plotted against uranium concentration 18Figure D.3 Be
32、nchmark results plotted against moderation ratioH0235U! . 18Figure D.4 Validation results showing the calculational margin andthe margin of subcriticality . 20 iii Validation of Neutron TransportMethods for Nuclear CriticalitySafety Calculations1 IntroductionThis standard amplifies the basic require
33、-ments and recommendations for validation asdescribed in ANSI0ANS-8.1-1998; R2007, “Nu-clear Criticality Safety in Operations with Fis-sionable Materials Outside Reactors” 1#,1!asapplied to computer-based neutron transportcalculational methods. Requirements and rec-ommendations for the validation of
34、 neutrontransport calculational methods applied to nu-clear criticality safety analyses are provided inthis standard. In particular, this standard pro-vides requirements and recommendations forselecting benchmarks; estimating the bias andbias uncertainty; selecting appropriate mar-gins, both within
35、and beyond the benchmarkapplicability; and documenting the validation.To conform with this standard, all operationsshall be performed in accordance with itsrequirements.2 ScopeThis standard provides requirements and rec-ommendations for validation, including es-tablishing applicability, of neutron t
36、ransportcalculational methods used in determining crit-ical or subcritical conditions for nuclear criti-cality safety analyses.3 Definitions3.1 LimitationsThe definitions given below are of a restrictednature for the purpose of this standard. Otherspecialized terms are defined in Glossary ofTermsinN
37、uclearScienceandTechnology2#andin Glossary of Nuclear Criticality Terms 3#.3.2 Shall, Should, MayThe word “shall” is used to denote a require-ment; the word “should” is used to denote arecommendation; and the word “may” is usedto denote permission, neither a requirementnor a recommendation.3.3 Gloss
38、ary of termsbenchmark:An experiment used for validation.benchmark applicability2!: The benchmarkparameters e.g., material compositions, geom-etry, neutron energy spectra! and their bound-ing values from which the bias and biasuncertainty of a calculational method areestablished.bias: The systematic
39、difference between calcu-lated results and experimental data. Positivebias is where the calculated results are greaterthan the experimental data.3!bias uncertainty: The uncertainty that ac-counts for the combined effects of uncertaintiesin the benchmarks, the calculational models ofthe benchmarks, a
40、nd the calculational method.calculational margin: An allowance for biasand bias uncertainty plus considerations of un-certainties related to interpolation, extrapola-tion, and trending.calculational method: The mathematical pro-cedures, equations, approximations, assump-tions, and associated numeric
41、al parameterse.g.,cross sections!that yield the calculated results.1!Numbers in brackets refer to corresponding numbers in Section 9, “References.”2!Benchmark applicability embodies the same concept as area of applicability as defined in ANSI0ANS-8.1-1998; R2007 1#.3!The sign of the bias is arbitrar
42、y. For the purpose of this standard, it has been defined to be positive whenthe calculated values exceed the experimental values, but it could be defined otherwise.1computercodesystem:Acalculationalmethod,computerhardware,andcomputersoftwarein-cluding the operating system!.margin of subcriticality:
43、An allowance be-yond the calculational margin to ensure sub-criticality.upper subcritical limit: A limit on the calcu-lated k-effective value established to ensure thatconditions calculated to be subcritical will ac-tually be subcritical.validation:Theprocessofquantifyinge.g.,es-tablishing the appro
44、priate bias and bias uncer-tainty!thesuitabilityofacomputercodesystemfor use in nuclear criticality safety analyses.validation applicability4!: A domain, whichcould be beyond the bounds of the benchmarkapplicability, within which the margins de-rived from validation of a calculational methodhave bee
45、n applied.verification: The process of confirming thatthe computer code system correctly performsintended numerical calculations.4 Computer code system4.1Verification of the computer code system shallbe completed prior to validation. Correct instal-lation and operation of the computer code sys-tem s
46、hould be documented.4.2The computer code system to be validated shallbe placed under an appropriate configurationcontrol program. Any change to the computercode system shall be evaluated to determine itseffect on the validation.5 Selection and modeling ofbenchmarks5.1Appropriate system or process pa
47、rameters thatcorrelate the experiments to the system or pro-cess under consideration shall be identified.See Appendix A for example physical and de-rived parameters.!5.2Normal and credible abnormal conditions forthe system or process shall be identified whendetermining the appropriate parameters and
48、their range of values.5.3Experiments shall be reviewed for complete-ness and accuracy of information prior to useas benchmarks. See Appendix B for severalsources of information on experiments.!5.4Selected benchmarks should encompass the ap-propriate parameter values spanning the rangeof normal and c
49、redible abnormal conditions an-ticipated for the system or process to which thevalidation will be applied.5.5Benchmarks selected should be consistent withthe modeling capabilities of the calculationalmethod.5.6To minimize systematic error, benchmarksshould be drawn from multiple, independentexperimental series and sources.5.7The calculational methods and analysis tech-niques e.g., albedos, variance reduction, cross-section processing! used to analyze the set ofbenchmarks shall be the same as those used toanalyze the system or process to which thevalidation is applie
