ANS 8 10-2015 Criteria for Nuclear Criticality Safety Controls in Operations with Shielding and Confinement.pdf

1、An American National StandardPublished by the American Nuclear Society 555 N. Kensington AveLa Grange Park, IL 60526ANSI/ANS-8.10-2015 Criteria for Nuclear Criticality Safety Controlsin Operations with Shielding and ConfinementANSI/ANS-8.10-2015ANSI/ANS8.102015American National Standard Criteria for

2、 Nuclear Criticality Safety Controls in Operations with Shielding and ConfinementSecretariatAmerican Nuclear SocietyPrepared by theAmerican Nuclear Society Standards Committee Working Group ANS-8.10Published by theAmerican Nuclear Society 555 North Kensington Avenue La Grange Park, Illinois 60526 US

3、AApproved February 12, 2015 by theAmerican National Standards Institute, Inc.American National Standard ANSI/ANS-8.10-2015Designation of this document as an American National Standard attests that the principles of openness and due process have been followed in the approval procedure and that a cons

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13、-2015The American Nuclear Society (ANS) Standards Committee will provide responses to inquiries about requirements, recommendations, and/or permissive statements (i.e., “shall,” “should,” and/or “may,” respectively) in American National Standards that are developed and approved by ANS. Responses to

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18、ANSI/ANS-8.10-2015iAmerican National Standard ANSI/ANS-8.10-2015(This Foreword is not a part of American National Standard, “Criteria for Nuclear Criticality Safety Controls in Operations with Shielding and Confinement,” ANSI/ANS-8.10-2015.)This standard amplifies the conditions necessary for the co

19、ntrol of criticality in fissionable materials set forth in American National Standard “Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors,” ANSI/ANS-8.12014. Criteria for the prevention of criticality accidents are presented herein for facilities that provide adequa

20、te protection for personnel and the public against radiation and releases of radioactive materials resulting from accidental criticality. The radiation dose limits contained in the 1983 version of this standard were reexamined. The recommended radiation doses in Section 4.2.1 of this standard were a

21、djusted to be consistent with Section 5.9 of ICRP 103 (2007). This standard recognizes the usefulness and protective features of shielding against radiation and confinement of radioactive materials and allows a relaxation of criticality safety criteria when shielding and confinement meet criteria sp

22、ecified in this standard. If personnel are located remotely from the fissionable materials, distance may serve in lieu of some or all of the shielding. In the context of this standard, the shielding and confinement properties may exist because of the radioactive material processed in normal operatio

23、ns, or they may be designed into the facility expressly to protect against the effects of criticality accidents.This standard was initiated as the result of a survey conducted in September 1968 to establish the need for and the feasibility of such a standard. A working group was appointed by Subcomm

24、ittee 8 of the Standards Committee of the American Nuclear Society in November 1968, and the first draft was submitted in June 1969. In response to comments and discussions, the working group subsequently prepared twelve succeeding drafts over a fiveyear period. Some of the later revisions were the

25、consequence of recommendations from American National Standard Committee N16 during 1972. The standard was then adopted by the American National Standards Committee N16 in 1974 under the title “Criteria for Nuclear Criticality Safety Controls in Operations Where Shielding Protects Personnel.”The pre

26、scribed fiveyear review of N16.81975/ANS8.10 leading to ANSI/ANS8.101983 was performed by a working group of Subcommittee 8 of the ANS Standards Committee, the originating body. The working group was composed of B. F. Gore and E. D. Clayton of the Battelle Pacific Northwest Laboratories. They recomm

27、ended a single substantive change in the standard along with minor wording changes in the standard and in its title to reflect the broadened content. ANSI/ANS8.101983 defined a criterion for determining the adequacy of a facilitys confinement of radioactive materials under accident conditions based

28、upon a maximum radiation dose that could be received by a member of the public located outside the restricted area surrounding the facility. Definition of this criterion removed perceived ambiguity in the wording of the previous version.This standard might reference documents and other standards tha

29、t have been superseded or withdrawn at the time the standard is applied. A statement has been included in the references section that provides guidance on the use of references.This standard does not incorporate the concepts of generating riskinformed insights, performancebased requirements, or a gr

30、aded approach to quality assurance. The user is advised that one or more of these techniques could enhance the application of this standard.This revision of American National Standard ANSI/ANS8.102015 was prepared by Working Group ANS8.10 of Subcommittee 8 of the Standards Committee of the Forewordi

31、iAmerican National Standard ANSI/ANS-8.10-2015American Nuclear Society. Working Group ANS8.10 had the following membership at the time of the Revision:A. W. Prichard (Chair), Pacific Northwest National LaboratoryD. G. Bowen, Oak Ridge National LaboratoryL. M. Farrell, AREVA Inc.J. Hicks, U.S. Depart

32、ment of EnergyD. S. Kimball, Lawrence Livermore National LaboratoryL. E. Paulson, GE Hitachi, Nuclear EnergyThis revised standard was prepared under the guidance of ANS Subcommittee 8, Fissionable Materials Outside Reactors, which had the following membership at the time of its approval of this revi

33、sion:L. E. Paulson (Chair), GE Hitachi, Nuclear Energy M. Crouse (Secretary), Link Solutions, Inc.J. S. Baker, Savannah River Nuclear SolutionsE. Elliott, Los Alamos National Laboratory D. Erickson, Savannah River Nuclear SolutionsA. S. Garcia, U.S. Department of EnergyB. O. Kidd, Babcock and (b) sh

34、ielding and confinement provided are adequate to meet the radiation dose limits set forth in this section.The criteria that are presented in Sec. 4 consider only the adequacy of the shielding and confinement for criticality accidents. Additional shielding and confinement may be required by the proce

35、ss conditions.4.2 Adequacy of shielding and confinementShielding and confinement are considered adequate when the following conditions would be satisfied during and subsequent to a criticality accident. However, better shielding and confinement are desirable if practical.4.2.1 Radiation doseFor desi

36、gn evaluation purposes, the radiation source strengths and releases may be estimated using detailed analysis of credible criticality accidents. Appendix A and its references show examples of how this may be accomplished. The shielding and confinement should be such that the total effective dose rece

37、ived by an individual located at any point outside the shielded and confined area will not exceed 10 rem (0.10 Sv) during and subsequent to a criticality accident. In addition, the shielding and confinement should be such that the total effective dose received by an individual outside the restricted

38、 area will not exceed 0.5 rem (5 mSv).3)4.2.2 Shielding and confinement criterionThe shielding and confinement system of a facility shall be designed to limit the dose resulting from exposure to direct radiation and to radionuclides generated by the criticality accident and released from the facilit

39、y to that specified by Sec. 4.2.1.2)ICRP 103 3.3)For purposes of design evaluation for credible criticality accidents, doses stated are five times the ICRP 103 3 planned special exposure limit for both individual and members of the public.32American National Standard ANSI/ANS-8.10-20154.2.3 Structur

40、al integrityThe shielding and confinement system shall be designed to withstand physical damage from credible events and maintain function.4.2.4 Distance in lieu of shieldingIf personnel are located remotely from the fissionable materials, distance may serve in lieu of some or all of the shielding,

41、provided personnel entry into the intervening distance is controlled, and the other conditions set forth in Section 4.2 are met.5 Criticality safety practicesWhere shielding and confinement were in place, the consequences of previous process criticality accidents have been primarily disruption of pr

42、ocesses and related costs 4. Accordingly, if these consequences are acceptable, an increased likelihood of a criticality accident is acceptable when the consequence to personnel is low due to the facility design. This may be reflected in reduced conservatism in the process analysis. However, plant d

43、esign and operations are premised on good engineering practices, which dictate that criticality accidents shall not occur under normal and credible abnormal conditions where personnel are at risk.5.1 Single contingency operationThe number of unlikely changes in process conditions as detailed in Sect

44、ion 4.2.2 of ANSI/ANS8.12014 1, Double Contingency Principle, may be reduced to unity when the criteria of this standard are met. Design of operations in which a single unlikely change in process conditions might result in a criticality accident should be kept to a minimum.4)If criticality accident

45、prevention relies primarily on administrative requirements (e.g., failing to add a neutron absorber or exceeding a mass limit might lead to a criticality accident), then procedures should be written such that no single, inadvertent departure from procedures can cause a criticality accident. 5.2 Meth

46、ods for unshielded facilitiesThis standard in no way precludes the application of ANSI/ANS8.12014 1 to facilities with shielding and confinement.5)6 ReferencesThe user is advised to review each of the following references to determine whether it, a more recent version, or a replacement document is t

47、he most pertinent for each application. When alternate documents are used, the user is advised to document this decision and its basis.1 ANSI/ANS-8.1-2014, “Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors,” American Nuclear Society, La Grange Park, Illinois.2 H.

48、C. Paxton, Glossary of Nuclear Criticality Safety Terms, LA-11627-MS (October 1989). 3 2007 Recommendations of the International Commission on Radiological Protection (Users Edition), ICRP Publication 103 (Users Edition), Ann. ICRP 37 (2-4).4 McLaughlin, et al., “A Review of Criticality Accidents,”

49、LA-13638, Los Alamos National Laboratory (2000).4)Appendix B provides examples of fissionable material operations in which a single change in process conditions is controlled.5)A facility may implement this standard intermittently, as required by operations.54American National Standard ANSI/ANS-8.10-2015Appendix A(This Appendix is not part of American National Standard, “Criteria for Nuclear Criticality Safety Controls in Operations with Shielding and Confinement,” ANSI/ANS-8.10-2015, but is included for information purposes only.)Fis