1、ANSI/ANS-8.14-2004use of soluble neutronabsorbers in nuclearfacilities outside reactorsANSI/ANS-8.14-2004REAFFIRMED November 16, 2011 ANSI/ANS-8.14-2004 (R2011) This standard has been reviewed and reaffirmed with the recognition that it may reference other standards and documents that may have been
2、superseded or withdrawn.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 a
3、ppropriate 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 co
4、nsider the use of these industry initiatives in the application of this standard. ANSI/ANS-8.14-2004American National StandardUse of Soluble NeutronAbsorbers in NuclearFacilities Outside ReactorsSecretariatAmerican Nuclear SocietyPrepared by theAmerican Nuclear SocietyStandards CommitteeWorking Grou
5、p ANS-8.14Published by theAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USAApproved May 25, 2004by theAmerican National Standards Institute, Inc.AmericanNationalStandardDesignation of this document as an American National Standard attests thatthe principles of ope
6、nness 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 Nuclear Society; these procedures are accredited by
7、 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 to participate.An American National Standard is i
8、ntended 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, or using prod-ucts, processes, or procedures not
9、 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 at the time ofits approval and publication. Chang
10、es, 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 of this standardare cautioned to determine the va
11、lidity 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 for interpretation should be sent to the Standards D
12、epartment 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 SocietyHeadquarters.Published byAmerican Nuclear Society555 North
13、Kensington AvenueLa Grange Park, Illinois 60526 USACopyright 2004 by American Nuclear Society. All rights reserved.Any part of this standard may be quoted. Credit lines should read “Extracted fromAmerican National Standard ANSI0ANS-8.14-2004 with permission of the publisher,the American Nuclear Soci
14、ety.” Reproduction prohibited under copyright conventionunless written permission is granted by the American Nuclear Society.Printed in the United States of AmericaForewordThis foreword is not part of American National Standard “Use of Soluble NeutronAbsorbers in Nuclear Facilities Outside Reactors,
15、” ANSI0ANS-8.14-2004!This standard provides guidance for the use of soluble neutron absorbers forprocess and handling operations in which solutions of neutron absorbers areused for criticality control. This standard supplements the provisions for “Nu-clear Criticality Safety in Operations with Fissi
16、onable Materials Outside Reac-tors,” ANSI0ANS-8.1-1998, in providing more detailed guidance for the use ofsoluble neutron absorbers. Soluble neutron absorbers can be used as a primarymeans of criticality safety control or as defense in depth to provide an additionalsafety margin and as such make the
17、 safety of the system more robust. As withany parameter controlled for criticality safety, and particularly important withsoluble neutron absorbers, one must ensure that the controlled parameter ismaintained within the range that has been shown by experiment or evaluation tomaintain subcriticality.T
18、his standard prepared by Working Group ANS-8.14 was composed of the fol-lowing members:T. A. Reilly Chairman!, Westinghouse Safety Management Solutions, LLCR. D. Carter Past Chairman!, IndividualL. J. Berg, U.S. Nuclear Regulatory CommissionA. S. Garcia, U.S. Department of Energy, IdahoR. A. Knief,
19、XE CorporationR. C. McBroom, U.S. Department of Energy, Oak Ridge Operations OfficeL. M. Montierth, Idaho National Engineering and Environmental LaboratoryJ. A. Morman, Argonne National LaboratoryV. L. Risner, USECS. K. Skiles, NuclearSafety AssociatesR. E. Wilson, U.S. Department of Energy, Rocky F
20、lats Environmental Technology SiteThis standard was prepared under the guidance of Subcommittee 8, FissionableMaterials Outside Reactors, of the American Nuclear Society. Subcommittee 8 atthe time of initial ballot was composed of the following members:T. P. McLaughlin Chairman!, Los Alamos National
21、 LaboratoryJ. A. Schlesser Secretary!, Westinghouse Safety Management Solutions, LLCF. M. Alcorn, IndividualE. D. Clayton, IndividualA. S. Garcia, U.S. Department of Energy, IdahoN. Harris, BNFLC. M. Hopper, Oak Ridge National LaboratoryR. Kiyose, IndividualR. A. Libby, Pacific Northwest National La
22、boratoryD. A. Reed, Oak Ridge National LaboratoryT. A. Reilly, Westinghouse Safety Management Solutions, LLCH. Toffer, Fluor Federal ServicesG. E. Whitesides, IndividualConsensus Committee N16, Nuclear Criticality Safety, was composed of thefollowing members at the time of approval:C. M. Hopper Chai
23、rman!, Oak Ridge National LaboratoryR. A. Knief Vice-Chairman!, XE CorporationG. H. Bidinger, IndividualR. D. Busch, University of New MexicoM. S. Chatterton, U.S. Nuclear Regulatory CommissionH. L. Dodds, Jr., University of TennesseeR. S. Eby, American Institute of Chemical EngineersC. D. Manning,
24、Framatome ANPB. McLeod, Institute of Nuclear Materials ManagementS. P. Murray, Health Physics SocietyiH. C. Paxton, IndividualR. L. Reed, Westinghouse Safety Management Solutions, LLCB. M. Rothleder, U.S. Department of EnergyF. W. Sanders, IndividualD. R. Smith, IndividualR. G. Taylor, IndividualJ.
25、T. Thomas, IndividualR. M. Westfall, Oak Ridge National LaboratoryiiContentsSection Page1 Introduction . 12 Scope . 13 Definitions 13.1 Limitations 13.2 Shall, Should, May . 13.3 Glossary of Terms 14 Administrative Requirements and Guidance . 24.1 Neutron Absorber Selection . 24.2 System Design and
26、System Modifications 24.3 Criticality Safety Evaluations . 24.4 Quality Control Program 34.5 Facility Operation with Soluble Absorbers 35 References 3 iii Use of Soluble Neutron Absorbers inNuclear Facilities Outside Reactors1 IntroductionGuidance for criticality control in process andhandling opera
27、tions with fissile material is pre-sented in American National Standard “Nu-clear Criticality Safety in Operations withFissionable Materials Outside Reactors,” ANSI0ANS-8.1-1998 1#.1!However, for solutions thesingle parameter subcritical limits on unit mass,volume, concentration, and geometricdimen-
28、sions can be highly restrictive. Significantlylarger limits are possible if soluble neutron ab-sorbers2!are present in such solutions.ANSI0ANS-8.1-1998 provides general guidancefor the use of soluble neutron absorbers for crit-icality accident prevention. This standard3!pro-vides specificguidance fo
29、r the use of solubleneutron absorbers for criticality control. Expe-rience has shown that operations involving theuse of such absorbers can be performed both safelyand economically. When soluble neutron absorb-ers are present, but are not required for nuclearcriticality safety, their use is outside
30、the scope ofthis standard. Separate standards have been de-veloped to address specific applications of neu-tron absorbers. Examples areAmerican NationalStandard “Use of Borosilicate-Glass RaschigRings as a NeutronAbsorber in Solutions of Fis-sile Material,”ANSI0ANS-8.5-19962#andAmer-ican National St
31、andard “Use of Fixed NeutronAbsorbers in Nuclear Facilities Outside Reac-tors,” ANSI0ANS-8.21-1995 3#.2 ScopeThis standard provides guidance for the use ofsoluble neutron absorbers for criticality con-trol. This standard addresses neutron absorberselection, system design and modifications,safety eva
32、luations, and quality control programs.3 Definitions3.1 LimitationsThe definitions given below and in Sec. 3.3,“Glossary of Terms,” are of a restricted naturefor the purpose of this standard. Other special-ized terms are defined in Glossary of Terms inNuclear Science and Technology 4# and “Glos-sary
33、 of Nuclear Criticality Terms” 5#.3.2 Shall, should, and 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. To conform to this stan-dard, all operations sha
34、ll be performed in ac-cordance with its requirements but notnecessarily with its recommendations. Whenrecommendations are not implemented, justi-fication shall be documented.3.3 Glossary of termsneutron absorber: A neutron-capture mat-erial4!; also referred to as a neutron poison.nuclear criticality
35、 safety: Protection againstthe consequences of a criticality accident, pref-erably by prevention of the accident.soluble neutron absorber: Any neutron poi-son easily dispersed inliquid, solution, or1!Numbers in brackets refer to corresponding numbers in Section 5, “References.”2!Strictly speaking, a
36、bsorption is defined as “the neutron induced reaction including fission where the neutronceases to exist as a free particle.” Capture is “neutron absorption not leading to fission or other production.”However, by nuclear criticality safety convention, use of the terms absorption or absorber in the s
37、ense of thisstandard denotes the capture process.3!The current standard, ANSI0ANS-8.14-2004, is herein referred to as “this standard.”4!As applied in nuclear criticality safety, absorber implies nonfission absorption that is capture. See alsofootnote 2 above.!1suspension, used specifically to reduce
38、 the re-activity of a system and for which reactivitycredit is taken in the nuclear criticality safetyevaluation of the system.validation: A process to demonstrate that theanalytical methods used to compute the ef-fectiveness of the neutron absorber systemsfor criticality control meet predeterminedr
39、equirements.verification: The establishment of confir-mation of the truth or accuracy of a fact byinvestigation, comparison with a standard, orreference to the facts.4 Administrative requirementsand guidanceRequirements and guidance for the use of sol-uble neutron absorbers as a criticality safetyco
40、ntrol are grouped under five topics: solubleneutron absorber selection, system design andmodification, safety evaluations, quality con-trol program, and facility operations with sol-uble absorbers.4.1 Neutron absorber selection4.1.1 Selection of a soluble neutron absorbershall include assessment of
41、the operating en-vironment and of the chemical compatibilityof the neutron absorber with the process forwhich it is to be used. Consideration shallbe given to the solubility of the neutronabsorber and to materials and conditionse.g., temperature and pressure! that couldcause precipitation or plateou
42、t of the neutronabsorber.4.1.2 The soluble neutron absorber shall main-tain its minimum required neutron absorptioncapability during its intended operating life.4.1.3 Selection of a soluble neutron absorbershall include an assessment of the absorbereffectiveness under credible conditions of neu-tron
43、 moderation and reflection.4.1.4 Selection of a neutron absorber shall in-clude evaluation of radiation effects e.g., de-pletion by neutron absorption, radiolysis! overits operating life.4.1.5 Selection of a soluble neutron absorbershall include evaluation of the requirements ofoperations and of fis
44、sile material accountability.4.1.6 Selection of a soluble neutron absorbershould include evaluation of the requirementsof other safety disciplines.4.2 System design andsystem modificationsThe following system design requirements andrecommendations shall apply to both systemdesign and system modifica
45、tions.4.2.1 For the range evaluated as subcritical,the system design shall prevent inadvertentconcentration of fissile solution and removal ordilution of the neutron absorber.4.2.2 For the range evaluated as subcritical,the system design shall account for potentialdegradation of the neutron absorber
46、 and thechemicals used to dissolve or stabilize the neu-tron absorber.4.2.3 The design of the system equipment in-corporating soluble neutron absorbers shouldincorporate human factors engineering prac-tices for preparation, use, and control of theneutron absorber.4.2.4 The system design shall consid
47、er theneed for inspection, sampling, and verificationof the adequacy of the neutron absorbing capa-bility prior to use and during the operationallifetime of the neutron absorber.4.2.5 Ameans of verification shall be providedto determine that the system design, safety, andoperating requirements are m
48、et for all opera-tions that utilize soluble neutron absorbers.4.3 Criticality safety evaluations4.3.1 Evaluations shall include allowances foruncertainties in the neutron absorber concen-tration, distribution, and neutronic propertiesi.e., accuracy of neutron cross-section values!.4.3.2 Evaluations
49、shall include considerationof equipment design tolerances, chemical reac-tion tolerances, material substitutions, geom-etry changes, modeling assumptions, processvariables, neutron absorber isotopicdistribu-tion, and relevant uncertainties.American National Standard ANSI0ANS-8.14-200424.3.3 Evaluations shall consider the potentialfor neutron absorber degradation in the nor-mal operating environment due to physical orchemical actions and solution compositionchanges.4.3.4 Evaluations shall consider the effect onnuclear criticality safety of potential nonuni-form distribu
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