1、ANSI/ANS-1-2000conduct of critical experimentsANSI/ANS-1-2000REAFFIRMED October 11, 2007 ANSI/ANS-1-2000 (R2007) REAFFIRMED October 5, 2012 ANSI/ANS-1-2000 (R2012)This standard has been reviewed and reaffirmed with the recognition that it may reference other standards and documents that may have bee
2、n superseded or withdrawn. The requirements of this document will be met by using the version of the standards and documents referenced herein. It is the responsibility of the user to review each of the references and to determine whether the use of the original references or more recent versions is
3、 appropriate for the facility. Variations from the standards and documents referenced in this standard should be evaluated and documented. This standard does not necessarily reflect recent industry initiatives for risk informed decision-making or a graded approach to quality assurance. Users should
4、consider the use of these industry initiatives in the application of this standard. ANSI/ANS-1-2000American National Standardfor Conduct of Critical ExperimentsSecretariatAmerican Nuclear SocietyPrepared by theAmerican Nuclear SocietyStandards CommitteeWorking Group ANS-1Published by theAmerican Nuc
5、lear Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USAApproved March 23, 2000by theAmerican National Standards Institute, Inc.AmericanNationalStandardDesignation of this document as an American National Standard attests thatthe principles of openness and due process have been foll
6、owed 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 Nuclear Society; these procedures are accredited by the Amer-ican National Standards In
7、stitute, 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 to participate.An American National Standard is intended to aid industry, consumers,
8、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, or using prod-ucts, processes, or procedures not conforming to the standard.By publi
9、cation 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 at the time ofits approval and publication. Changes, if any, occurring through develo
10、pmentsin 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 of this standardare cautioned to determine the validity of copies in their possession
11、 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 for interpretation should be sent to the Standards Department atSociety Headquarters. Ac
12、tion 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 SocietyHeadquarters.Published byAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Ill
13、inois 60526 USACopyright 2000 by American Nuclear Society. All rights reserved.Any part of this standard may be quoted. Credit lines should read “Extracted fromAmerican National Standard ANSI0ANS-1-2000 with permission of the publisher, theAmerican Nuclear Society.” Reproduction prohibited under cop
14、yright convention unlesswritten permission is granted by the American Nuclear Society.Printed in the United States of AmericaForewordThis Foreword is not a part of American National Standard for Conduct of Critical Experiments,ANSI0ANS-1-2000.!Critical experiments are an essential part of nuclear re
15、search and development. They yieldinformation valuable for the design of nuclear reactors, for the specification of processesand operations with fissionable materials, and for furthering fundamental scientific knowledge.Because of this diversity of purpose and the exploratory nature of critical expe
16、riments, theirconduct differs from routine reactor operation. In many cases, for example, it is not possibleto predetermine the exact value of operational controls or of shutdown devices, for to obtainthe required information is the purpose of the experiment. Good practice dictates a minimumof pertu
17、rbations extraneous to the equipment necessary to the objective of the experiment.Accordingly, assemblies for this purpose are operated remotely behind shielding, and are oftenequipped with control and safety devices quite different from those in reactors designed toproduce power. The information de
18、manded from critical experiments requires great latitudein both the equipment and the operational practices, to allow the necessarily frequent andoften extensive changes in the assembly configuration.These characteristics result in a higher probability of an accidental nuclear excursion thancould be
19、 tolerated for reactors. This greater probability is made acceptable by the absence ofthe large fission-product inventory and large internal energy that characterize reactors whichhave produced power; effective radiation protection therefore can be provided in a properlydesigned facility by adherenc
20、e to simple operating rules.This standard contains nuclear safety criteria and practices that have evolved and have beentested during half a century of critical experimentation. It was initially prepared bySubcommittee ANS-1, Performance of Critical Experiments, of the American Nuclear SocietyStanda
21、rds Committee, and was approved by the Subcommittee on November 1, 1966. OnAugust 18, 1967, the document was certified by the Board of Directors of the Society asANS-STD.1-1967.A revision of ANS-STD. 1-1967 was prepared by Subcommittee ANS-1 on July 6, 1971, andwas certified by the Society as ANS-ST
22、D.1-1972 on September 19, 1972. The membership ofthe subcommittee which prepared that revision was:A. D. Callihan, Chairman, Union Carbide Corporation, Nuclear DivisionE. B. Johnson, Secretary, Union Carbide Corporation, Nuclear DivisionE. D. Clayton, Battelle Pacific Northwest LaboratoriesD. F. Han
23、len, Westinghouse Electric Corporation, Atomic Power DivisionR. G. Luce, General Electric Company, Knolls Atomic Power LaboratoryE. I. Nowstrup, U.S. Atomic Energy CommissionH. C. Paxton, Los Alamos Scientific LaboratoryG. A. Price, Brookhaven National LaboratoryW. C. Redman, Argonne National Labora
24、toryN. L. Snidow, Babcock and Wilcox CompanyThe stature of, and the breadth of interest in, this standard were increased on April 29, 1975,when it was approved as an American National Standard by the American National Stan-dards Institute, Inc. The designation then was ANSI N405-1975.The content of
25、N405-1975 was reaffirmed October 21, 1981, and the standard was revised in1986, with consensus being achieved on November 7. The membership of the ad hoc groupperforming those actions was:E. D. Clayton, Battelle Pacific Northwest LaboratoriesE. B. Johnson, Oak Ridge National LaboratoryD. W. Magnuson
26、, IndividualH. C. Paxton, IndividualA. D. Callihan, IndividualiThat version included textual modifications solely for the purpose of updating references andof recounting procedural matters necessary to the action. The technical content was in no wayaltered.The standard was again revised in 1998 with
27、 consensus achieved on August 27, 1999. Themembership of the working group responsible for the revision is:R. L. Seale, Chair, University of ArizonaR. D. Busch, University of New MexicoR. A. Knief, XE CorporationT. P. McLaughlin, Los Alamos National LaboratoryR. Paternoster, Los Alamos National Labo
28、ratoryS. S. Payne, U. S. Department of EnergyJ. S. Philbin, Sandia National LaboratoriesT. R. Schmidt, Sandia National LaboratoriesConsensus Committee N17, Research Reactors, Radiation Physics and Radiation Shielding,had the following membership at the time of its approval of this standard:Tawfik M.
29、 Raby, ChairShawn Coyne-Nalbach, SecretaryA. D. Callihan IndividualR.E.Carter E.G. & G.D. Cokinos Brookhaven National LaboratoriesB. Dodd Health Physics SocietyD. Duffey .American Institute of Chemical EngineersW. A. Holt .American Public Health AssociationW. C. Hopkins .Bechtel CorporationL. B. Mar
30、sh .U.S. Nuclear Regulatory CommissionJ. Miller .Institute of Electrical and Electronics EngineersJ. E. Olhoeft .IndividualT. M. Raby American Nuclear SocietyW. J. Richards U.S. Department of DefenseR. Seale .American Nuclear SocietyT. Schmidt .Sandia National LaboratoriesA. Smetana Savannah River L
31、aboratoryJ. F. Torrence National Institute of Standards TechnologyiiContentsSection Page1. Scope . 12. Definitions 12.1 Limitations . 12.2 Shall, Should, and May 12.3 Glossary of Terms . 13. Administrative Practices 14. Design Criteria 25. Operational Practices . 36. References 3 iii Conduct of Crit
32、ical Experiments1. ScopeThis standard provides for the safe conduct ofcritical experiments. Such experiments studyneutron behavior inafission device where theenergy produced is insufficient to require aux-iliary cooling, and the power history is such thatthe inventory of long-lived fission products
33、isinsignificant.2. Definitions2.1 Limitations. The definitions given beloware restrictive for the purposes of this standard.Other specialized terms are defined in the Glos-sary of Terms in Nuclear Science and Technol-ogy 1#1or have definitions accepted by usage.2.2 Shall, Should, and May. The word “
34、shall”is used to denote a requirement, the word “should”to denote a recommendation, and the word “may”to denote permission, neither a requirement nora recommendation. To conform with this stan-dard, all operations shall be performed in accor-dance with its requirements, but not necessarilywith its r
35、ecommendations.2.3 Glossary of Termsassembly area. A region in the vicinity of acritical assembly where personnel would haveinadequate protection from radiation associ-ated withacriticality accident.assembly shutdown. The state of the assem-bly when it is subcritical by at least one dollar.critical
36、assembly (assembly). A device orphysical system for performing critical experi-ments. Inacritical assembly, the energy pro-duced by fission is insufficient to requireauxiliary cooling, and the power history is suchthat the inventory of long-lived fission prod-ucts is insignificant.critical experimen
37、t (experiment). An exper-iment or series of experiments performed withafissionable material configuration which maybe at or near critical. The principal purpose ofthe experiment is the study of neutron behav-ior within the critical assembly.critical facility. All areas directly associatedwith operat
38、ion of one or more critical assemblies.criticality accident. The release of energyas a result of accidentally producing a self-sustaining or divergent fission chain reaction.management. The administrative body towhich the supervision of a critical facilityreports.neutron source. Any material, combin
39、ationof materials, or device that emits neutrons,including materials undergoing fission.remote operation. Planned reactivity addi-tions to a critical assembly with no personnelin the assembly area.safety device. A mechanism designed to re-duce the reactivity of a critical assembly.scram. A rapid red
40、uction of reactivity for shut-ting down the assembly.3. Administrative Practices3.1 Management shall assign responsibility andcommensurate authority for the safe operationof critical experiments unambiguously and sin-gularly through the line organization.3.2 Written general operational restrictions
41、foreach critical facility, based on a safety assess-ment and consideration of characteristics in-cluding shielding and confinement, shall beapproved by management and the cognizant reg-ulating authority. Criteria for the safety as-sessment may be derived from AmericanNational Standard for Format and
42、 Content ofSafety Analysis Reports for Research Reac-tors,ANSI0ANS-15.21-19962#. Criteria for op-erational restrictions may be derived fromAmerican National Standard for Developmentof Technical Specifications for Research Reac-tors, ANSI0ANS-15.1-1990 3#.3.3 Each new program of experiments shall bed
43、ocumented, independently reviewed, and ap-proved in a manner established by management.3.4 Operations personnel shall be trained toensure that they are capable of performing theirassigned work. Continuing training shall be pro-1Numbers in brackets refer to corresponding numbers in Sec-tion 6, Refere
44、nces.1vided to ensure maintenance of job proficiency.Criteria for personnel qualifications may be de-rived from American National Standard for Se-lection and Training of Personnel for ResearchReactors, ANSI0ANS-15.4-1988 4#.3.5 At least two persons who have qualifica-tions approved by management sha
45、ll be presentwhileacritical experiment isbeing performed.3.6 Before an experiment begins, the opera-tional and safety aspects shall be reviewed byall who are expected to take part in theoperation.3.7 Operations shall be planned so that no sin-gle operational action or procedural violationcould lead
46、to a criticality accident. Plannedsuperprompt criticality is outside the scope ofthis standard. Guidance for performance of ex-periments of that type is provided in AmericanNational Standard for Operation of Fast PulseReactors, ANSI0ANS-14.1-1989 5#.3.8 Manual operations with fissionable mate-rial,
47、such as transfer and storage, shall be per-formed in accordance with American NationalStandard for Nuclear Criticality Safety in Op-erations with Fissionable Materials Outside Re-actors, ANSI0ANS-8.1-1998 6#.3.9 Manual operations that result in reactiv-ity additions to a critical assembly should bel
48、imited to a predicted keffof 0.9 a neutronmultiplication of 10! for unknown configura-tions. Manual operations of known configura-tions with adequate control and analysis shoulduse a predicted keffnot to exceed 0.95 aneutron multiplication of 20!. When available,measured multiplication values shall
49、take pre-cedence over computed values.3.10 Additions of reactivity to a critical assem-bly beyond those permitted by 3.9 shall be madeby remote operation. Such additions shall becontinuously adjustable, except when the re-sulting reactivity is known with an accuracysuch that safety is not compromised.3.11 No person shall enter an assembly areaduring the performance of a critical experi-ment without the prior approval of the personresponsible for safety.3.12 During an addition of reactivity that re-quires remote operation, personnel shall be pro-tected by distance or shielding
