ML050610322

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John T. Larkin Memo Request to Waive Acrs/Acnw Review of Proposed Revision to Regulatory Guide 3.71, Nuclear Criticality Safety Standards for Fuels and Materials Facilities
ML050610322
Person / Time
Issue date: 03/25/2005
From: Strosnider J
Office of Nuclear Material Safety and Safeguards
To: Larkins J
NRC/ACNW, Advisory Committee on Reactor Safeguards
References
DG-3023, RG.3.071
Download: ML050610322 (24)
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March 25, 2005MEMORANDUM TO:John T. Larkins, Executive DirectorAdvisory Committee on Reactor Safeguards and Advisory Committee on Nuclear WasteFROM:Jack R. Strosnider, Director/RA/Office of Nuclear Material Safety and Safeguards

SUBJECT:

REQUEST TO WAIVE ADVISORY COMMITTEE ON REACTORSAFEGUARDS AND ADVISORY COMMITTEE ON NUCLEAR WASTE REVIEW OF PROPOSED REVISION TO REGULATORY GUIDE 3.71, "NUCLEAR CRITICALITY SAFETY STANDARDS FOR FUELS AND MATERIALS FACILITIES"The staff of the U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Material Safetyand Safeguards (NMSS), has prepared a draft revision of Regulatory Guide (RG) 3.71, which is temporarily identified as Draft Regulatory Guide DG-3023. For your information, Attachment 1 to this memorandum is a copy of Draft Regulatory Guide DG-3023, Attachment 2 briefly describes the changes, and Attachment 3 shows the differences between the current andrevised versions of the guide in redlining and strikethrough.Prior to 1998, the NRC issued a variety of regulatory guides to endorse most of the Series 8nuclear criticality safety standards promulgated by the American National Standards Institute and the American Nuclear Society (ANSI/ANS). The original publication of RG 3.71 (in 1998) consolidated and superseded the other regulatory guides (which the NRC subsequentlywithdrew) without altering any existing licensing commitments or introducing new requirements.

Specifically, the NRC withdrew RG 3.1-1987, RG 3.4-1986, RG 3.43-1979, RG 3.45-1989, RG 3.47-1981, RG 3.57-1986, RG 3.58-1986, RG 3.68-1994, RG 3.70-1997, and RG 8.12-1988.With this memorandum, the NMSS staff is asking the Advisory Committee on ReactorSafeguards (ACRS) and Advisory Committee on Nuclear Waste (ACNW) to waive their reviews of the revised guide. In support of this request, we note that the guidance contained in thedocument does not involve a backfit. As indicated in Attachment 2, the revisions involve (1) endorsing one new standard developed since the NRC originally published RG 3.71 in 1998,(2) endorsing six newer versions of standards currently in RG 3.71, (3) clarifying one current endorsement to reflect revisions to the related standard since 1998, (4) clarifying endorsement of one standard that ANSI/ANS withdrew after 1998, and (5) incorporating editorial changes to reflect the NRC's current regulatory guide format. If you have any questions regarding the revision of RG 3.71, please contact Harry Felsher at(301) 415-5521 or HDF@nrc.gov

.Attachments: 1. Draft Regulatory Guide DG-3023 2. Description of Changes to Regulatory Guide 3.71

3. Redline Strikeout Comparison of NRC Regulatory Guide 3.71 If you have any questions regarding the revision of RG 3.71, please contact Harry Felsher at(301) 415-5521 or HDF@nrc.gov

.Attachments: 1. Draft Regulatory Guide DG-3023 2. Description of Changes to Regulatory Guide 3.71

3. Redline Strikeout Comparison of NRC Regulatory Guide 3.71DISTRIBUTION
FCSS r/fNMSS r/fML050610322
  • See Previous ConcurrenceINDICATE IN BOX: "E"=COPY W/ATT/ENCL; "C"=COPY W/O ATT/ENCL; "N"=NO COPYOFFICETSGETSGETechEditorCFCSSNMSSNAMEHFelsher *MGalloway *PGarrity *RPiersonJStrosniderDATE03/02/0503/08/0503/03/05 03/24/05 3/25/05Attachment 1

This regulatory guide is being issued in draft form to involve the public in the early stages of the development of a regulatory position in thisarea. It has not received staff review or approval and does not represent an official NRC staff position.Public comments are being solicited on this draft guide (including any implementation schedule) and its associated regulatory analysis orvalue/impact statement. Comments should be accompanied by appropriate supporting data. Written comments may be submitted to t heRules and Directives Branch, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. Comments maybe submitted electronically through the NRC's interactive rulemaking Web page at http://www.nrc.gov/what-we-do/regulatory/rulemaking.html

.Copies of comments received may be examined at the NRC Public Document Room, 11555 Rockville Pike, Rockville, MD. Comments will bemost helpful if received by April 11, 2005

.Requests for single copies of draft or active regulatory guides (which may be reproduced) or for placement on an automatic distribution list forsingle copies of future draft guides in specific divisions should be made to the U.S. Nuclear Regulatory Commission, Washington, DC 20555,Attention: Reproduction and Distribution Services Section, or by fax to (301) 415-2289; or by email to Distribution@nrc.gov. Electronic copiesof this draft regulatory guide are available through the NRC's interactive rulemaking Web page (see above); the NRC's public Web site underDraft Regulatory Guides in the Regulatory Guides document collection of the NRC's Electronic Reading Room athttp://www.nrc.gov/reading-rm/doc-collections/; and the NRC's Agencywide Documents Access and Management System (ADAMS) athttp://www.nrc.gov/reading-rm/adams.html, under Accession No. ML050390450. Note, however, that the NRC has temporarily limited publicaccess to ADAMS so that the agency can complete security reviews of publicly available documents and remove potentially sensiti veinformation. Please check the NRC's Web site for updates concerning the resumption of public access to ADAMS. U.S. NUCLEAR REGULATORY COMMISSION March 2005OFFICE OF NUCLEAR REGULATORY RESEARCH Division 3 DRAFT REGULATORY GUIDEContact: H.D. Felsher, (301) 415-5521DRAFT REGULATORY GUIDE DG-3023(Proposed Revision 1 of Regulatory Guide 3.71, dated August 1998)NUCLEAR CRITICALITY SAFETY STANDARDSFOR FUELS AND MATERIAL FACILITIESA. INTRODUCTIONThis revised regulatory guide provides licensees and applicants with updated guidanceconcerning criticality safety standards that the U.S. Nuclear Regulatory Commission (NRC) hasendorsed for use with nuclear fuels and material facilities. As such, this guide describes methods thatthe NRC staff considers acceptable for complying with the NRC's regulations in Title 10, Parts 70 and 76, of the Code of Federal Regulations (10 CFR Parts 70 and 76).In 10 CFR Part 70, "Domestic Licensing of Special Nuclear Material," Section 70.20, "GeneralLicense To Own Special Nuclear Material," defines a specific license to acquire, deliver, receive, possess, use, transfer, import, or export special nuclear material. According to 10 CFR 70.22, "Contents of Applications," each application for such a license must contain proposedprocedures to avoid nuclear criticality accidents. In 10 CFR Part 76, "Certification of Gaseous Diffusion Plants," Section 76.87, "Technical Safety Requirements," states that the technical safety requirementsshould reference procedures and equipment that are applicable to criticality prevention. The NRC staff has developed this regulatory guide to provide guidance on complying withthese portions of the NRC's regulations by describing procedures for preventing nuclear criticalityaccidents in operations that involve handling, processing, storing, and/or transporting specialnuclear material at fuel and material facilities. This regulatory guide endorses specific nuclearcriticality safety standards developed by the American Nuclear Society's Standards Subcommittee 8 (ANS-8), "Operations with Fissionable Materials Outside Reactors." This guide is not intended to be used by nuclear reactor licensees.Regulatory guides are issued to describe to the public methods that the NRC staffconsiders acceptable for use in implementing specific parts of the agency's regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents,and to provide guidance to applicants. Regulatory guides are not substitutes for regulations, and compliance with regulatory guides is not required. Regulatory guides are issued in draft form to solicit public comment and involve the public in developing the agency's regulatory positions.

Draft regulatory guides have not received complete staff review; therefore, they do not represent official NRC staff positions.This draft regulatory guide contains information collections that are covered by therequirements of 10 CFR Part 70, which the Office of Management and Budget (OMB) approvedunder OMB control number 3150-0009. The NRC may neither conduct nor sponsor, and aperson is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number. However, this draft regulatory guide contains additional information collections that are covered by the requirementsof 10 CFR 76.8, which apply to a wholly-owned instrumentality of the United States and affect fewer than ten respondents. As a result, OMB clearance is not required pursuant to the Paperwork Reduction Act (44 U.S.C. 3501, et seq.). B. DISCUSSIONThe NRC initially issued Regulatory Guide 3.71 in 1998 to provide guidance concerningprocedures that the staff considered acceptable for complying with the agency's regulatoryrequirements in 10 CFR 70.20, 70.22 and 76.87. Toward that end, the original guide endorsedspecific safety standards that ANS-8 developed to provide guidance, criteria, and best practices for use in preventing and mitigating criticality accidents during operations that involve handling,processing, storing, and/or transporting special nuclear material at fuel and material facilities. The original guide also took exceptions to certain portions of individual ANSI/ANS-8 standards.

In addition, the original guide consolidated and replaced a number of earlier NRC regulatoryguides, thereby providing all of the relevant guidance in a single document.The ANS-8 standards endorsed in Regulatory Guide 3.71 were approved by the AmericanNuclear Society's Consensus Committee N16 on Nuclear Criticality Safety, as well as the American National Standards Institute (ANSI). Nonetheless, each ANSI/ANS-8 standard is reviewed every 5 years by a working group of expert practitioners in the area so that it can be revised, reaffirmed, or withdrawn, as appropriate to reflect the current state of the art. (This time can be extended to as long as 10 years or more under special circumstances.) New standards are also added when the need arises. Since the timing and issuance of individual standards is independent of the other standards, the list of current standards and their respective dates ofissuance is constantly changing.As a result, since the NRC published Regulatory Guide 3.71 in 1998, several ANSI/ANS-8nuclear criticality safety standards have been added, reaffirmed, revised, or withdrawn.

Consequently, the NRC staff has decided to update this guide to clarify which standards theagency endorses and to clearly state exceptions to individual standards. This proposed revision does not change any of the guidance provided in Regulatory Guide 3.71; rather, it providesguidance concerning changes that have occurred since the NRC published the original guide in1998. For completeness, this guide restates the endorsements and exceptions stated inRegulatory Guide 3.71, as applicable, while identifying endorsements of or exceptions to new ormodified standards. Since the ANSI/ANS-8 standards are constantly being issued, revised, reaffirmed, or withdrawn, the NRC staff plans to revise this guide on a regular basis. C. REGULATORY POSITIONThe ANSI/ANS-8 nuclear criticality safety standards provide procedures andmethodologies that the NRC staff considers generally acceptable for use in preventing andmitigating nuclear criticality accidents. However, use of the ANSI/ANS-8 nuclear criticality safety standards is not a substitute for detailed nuclear criticality safety analyses for specific operations.

In addition, inclusion of a reference to another standard in an endorsed standard does not imply

NRC endorsement of the referenced standard.The NRC staff will follow the requirements denoted in the ANSI/ANS-8 standards. Theword "shall" in an ANSI/ANS-8 standard denotes a requirement; the word "should" denotes a recommendation; and the word "may" denotes permission (neither a requirement nor a recommendation). When a licensee or applicant commits to an ANSI/ANS-8 standard cited in this regulatory guide, the licensee or applicant must perform all operations in accordance with the requirements stated in that standard, but not necessarily with its recommendations. Licensees orapplicants may follow the recommendations given in the ANSI/ANS-8 standards, unless an exception is stated in this regulatory guide, otherwise specified in 10 CFR Parts 70 or 76, or addressed by other acceptable methods.1.ANSI/ANS-8 Nuclear Criticality Standards Endorsed by the NRCThe NRC endorses the following ANSI/ANS-8 nuclear criticality safety standards:*ANSI/ANS-8.5-1996 (Reaffirmed in 2002), "Use of Borosilicate-Glass Raschig Rings as aNeutron Absorber in Solutions of Fissile Material"*ANSI/ANS-8.6-1983 (Reaffirmed in 2001), "Safety in Conducting SubcriticalNeutron-Multiplication Measurements In Situ"*ANSI/ANS-8.7-1998, "Nuclear Criticality Safety in the Storage of Fissile Materials"*ANSI/ANS-8.12-1987 (Reaffirmed in 2002), "Nuclear Criticality Control and Safety ofPlutonium-Uranium Fuel Mixtures Outside Reactors"*ANSI/ANS-8.14-2004, "Use of Soluble Neutron Absorbers in Nuclear Facilities OutsideReactors"*ANSI/ANS-8.15-1981 (Reaffirmed in 1995), "Nuclear Criticality Control of Special ActinideElements"*ANSI/ANS-8.19-1996, "Administrative Practices for Nuclear Criticality Safety"*ANSI/ANS-8.20-1991 (Reaffirmed in 1999), "Nuclear Criticality Safety Training"*ANSI/ANS-8.21-1995 (Reaffirmed in 2001), "Use of Fixed Neutron Absorbers in NuclearFacilities Outside Reactors"*ANSI/ANS-8.22-1997, "Nuclear Criticality Safety Based on Limiting and ControllingModerators"*ANSI/ANS-8.23-1997, "Nuclear Criticality Accident Emergency Planning and Response" 2.ANSI/ANS-8 Nuclear Criticality Standards Endorsed by the NRC withExceptionsThe NRC endorses the following ANSI/ANS-8 nuclear criticality safety standards, buttakes exception to certain sections, as follows:*ANSI/ANS-8.1-1998, "Nuclear Criticality Safety in Operations with Fissionable MaterialsOutside Reactors"The guidance on validating calculational methods for nuclear criticality safety, as specifiedin ANSI/ANS-8.1-1998, provides a procedure that is acceptable to the NRC staff forestablishing the validity and applicability of calculational methods used in assessingnuclear criticality safety. However, it is not sufficient to merely refer to this standard in describing the validation of a method. Rather, a licensee or applicant should provide thedetails of validation (as stated in Section 4.3.6 of the standard) to (1) demonstrate theadequacy of the margins of subcriticality relative to the bias and criticality parameters, (2) demonstrate that the calculations embrace the range of variables to which the method willbe applied, and (3) demonstrate the trends in the bias upon which the licensee or applicant will base the extension of the area of applicability. In addition, the details ofvalidation should state computer codes used, operations, recipes for choosing code options (where applicable), cross-section sets, and any numerical parameters necessary to describe the input.*ANSI/ANS-8.3-1997 (Reaffirmed in 2003), "Criticality Accident Alarm System"The guidance on criticality accident alarm systems, as specified in ANSI/ANS-8.3-1997(reaffirmed in 2003), is generally acceptable to the NRC staff. An exception is that 10 CFR 70.24, "Criticality Accident Requirements," requires criticality alarm systems ineach area in which special nuclear material is handled, used, or stored, whereas Section 4.2.1 of the standard merely requires an evaluation for such areas. Another exception isthat 10 CFR 70.24 and 10 CFR 76.89, "Criticality Accident Requirements," require thateach area must be covered by two detectors, whereas Section 4.5.1 of the standard permits coverage by a single reliable detector. Finally, 10 CFR 70.24 and 10 CFR 76.89 require a monitoring system capable of detecting a nuclear criticality thatproduces an absorbed dose in soft tissue of 20 rads of combined neutron and gamma radiation at an unshielded distance of 2 meters from the reacting material within 1 minute.*ANSI/ANS-8.10-1983 (Reaffirmed in 1999), "Criteria for Nuclear Criticality Safety Controlsin Operations With Shielding and Confinement"The guidance on using shielding and confinement as a nuclear criticality safety control, asspecified in ANSI/ANS-8.10-1983 (reaffirmed in 1999), is generally accepted by the NRC staff. An exception to Section 4.2.1 of the standard is the assumption that the radiationsource strengths and releases from a nuclear criticality accident arise from an excursion occurring in an unfavorable geometry containing a solution of 400 g/L of uranium enriched in U-235. The excursion produces an initial burst of 1x10 18 fissions in 0.5second, followed successively at 10-minute intervals by 47 bursts of 1.9x10 17 fissions, fora total of 1x10 19 fissions in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The excursion is assumed to be terminated byevaporation of 100 liters of the solution. Licensees and applicants may use a less-conservative nuclear criticality accident condition if detailed analyses of credible nuclear criticality accidents are performed and shown to be applicable to the conditions being evaluated. *ANSI/ANS-8.17-1984 (Reaffirmed in 1997), "Criticality Safety Criteria for the Handling,Storage, and Transportation of LWR Fuel Outside Reactors"The general safety criteria and criteria to establish subcriticality, as specified inANSI/ANS-8.17-1984 (reaffirmed in 1997), provide guidance that is acceptable to the NRC staff for preventing nuclear criticality accidents in handling, storing, and transportingfuel assemblies at fuel and material facilities. The only exception is that licensees andapplicants may take credit for fuel burnup only when the amount of burnup is confirmed by physical measurements that are appropriate for each type of fuel assembly in the environment in which it is to be stored.3.ANSI/ANS-8 Nuclear Criticality Standards Withdrawn by the NRCThe NRC has withdrawn its endorsement of ANSI/ANS-8.9-1987 (Reaffirmed in 1995),"Nuclear Criticality Safety Criteria for Steel-Pipe Intersections Containing Aqueous Solutions of Fissile Materials." This standard, which was listed in Regulatory Guide 3.71-1998, has subsequently been withdrawn by ANS (i.e., it is a historical standard). Although the NRC haswithdrawn its endorsement of the standard, there is nothing technically wrong with this standardand it would be acceptable for licensees and applicants to use it. D. IMPLEMENTATIONThe purpose of this section is to provide information to applicants and licensees regardingthe NRC staff's plans for using this draft regulatory guide. No backfitting is intended or approvedin connection with the issuance of this guide.The NRC has issued this draft guide to encourage public participation in its development. Except when an applicant or licensee proposes or has previously established an acceptable alternative method for complying with specified portions of the NRC's regulations, the methods tobe described in the active guide will reflect public comments and will be used in evaluatingsubmittals in connection with license applications submitted under 10 CFR Part 70, "Domestic Licensing of Special Nuclear Material," and 10 CFR Part 76, "Certification of Gaseous Diffusion Plants."REGULATORY ANALYSISThe NRC published a draft regulatory analysis when the agency issued the original draftof this guide (as DG-3013) for public comment in January 1998. Since that time, several ANSI/ANS 8 nuclear criticality safety standards have been added, reaffirmed, revised, or withdrawn. Consequently, the NRC staff has decided to update this guide to clarify whichstandards the agency endorses and to clearly state exceptions to individual standards. However, this proposed revision does not change any of the guidance provided in Regulatory Guide 3.71; rather, it provides guidance concerning changes that have occurred since the NRC published theoriginal guide 1998. Consequently, the NRC staff has not prepared a separate regulatoryanalysis for this revised regulatory guide. The original regulatory analysis for DG-3013 is available for inspection or copying (for a fee) in the NRC's Public Document Room (PDR), whichis located at 11555 Rockville Pike, Rockville, Maryland. The PDR's mailing address is USNRCPDR, Washington, DC 20555-0001. The PDR can also be reached by telephone at (301) 415-4737 or (800) 397-4205, by fax at (301) 415-3548; and by email to PDR@nrc.gov

.BACKFIT ANALYSISThis proposed revision of Regulatory Guide 3.71 does not require a backfit analysis, asdescribed in 10 CFR 70.76(b) and 10 CFR 76.76(b), because it does not impose a new or amended provision in the Commission's rules or a regulatory staff position interpreting the Commission's rules that is either new or different from a previous applicable staff position. In addition, this regulatory guide does not require modification or addition to structures, systems,components, or design of a facility or the procedures or organization required to design,construct, or operate a facility. Rather, a licensee or applicant is free to select a preferredmethod for achieving compliance with a license or the rules or orders of the Commission, as described in 10 CFR Parts 70 and 76.

Brief Description of the Changes to Regulatory Guide 3.71The staff of the U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Material Safetyand Safeguards (NMSS), has prepared a draft revision of Regulatory Guide (RG) 3.71, which is temporarily identified as Draft Regulatory Guide DG-3023. This revision involves the following specific changes:*endorsing one new Series 8 nuclear criticality safety standard that the American NationalStandards Institute and the American Nuclear Society (ANSI/ANS) developed since the NRC originally published RG 3.71 in 1998*endorsing six newer versions of standards currently in RG 3.71

  • clarifying one current endorsement to reflect revisions to the related standard since 1998*clarifying endorsement of one standard that ANSI/ANS withdrew after 1998*incorporating editorial changes to reflect the NRC's current regulatory guide formatThe remainder of this attachment briefly describes the nature and intent of these five changes.

(1)Endorsing one new standard developed since the NRC published RG 3.71 in 1998:*ANSI/ANS-8.14-2004, "Use of Soluble Neutron Absorbers in Nuclear FacilitiesOutside Reactors," is not addressed in the current version of RG 3.71. This standard was developed to address the need to provide information about soluble neutron absorbers that is more detailed than the information provided in the general nuclear criticality safety standard ANSI/ANS-8.1. The working group that developed ANSI/ANS-8.14 included representatives from the NRC, NRClicensees, the U.S. Department of Energy (DOE), DOE contractors, the nuclear industry, and unaffiliated members of the nuclear criticality safety community. Thus, ANSI/ANS-8.14 reflects input from all potential users of the standard.(2)Endorsing six newer versions of standards currently in NRC RG 3.71:*ANSI/ANS-8.5-1996 (Reaffirmed in 2002), "Use of Borosilicate-Glass RaschigRings as a Neutron Absorber in Solutions of Fissile Material," was reaffirmed after the NRC published the current version of RG 3.71. The working group did notmake any technical changes to the standard.*ANSI/ANS-8.6-1983 (Reaffirmed in 2001), "Safety in Conducting SubcriticalNeutron-Multiplication Measurements In Situ," was reaffirmed after the NRC published the current version of RG 3.71. The working group did not make any technical changes to the standard.*ANSI/ANS-8.7-1998, "Nuclear Criticality Safety in the Storage of Fissile Materials,"was revised after the NRC published the current version of RG 3.71. The revisedstandard includes several textual enhancements and tabulated changes resulting from the working group's confirmatory evaluations, which revealed that uncertainties associated with the calculated values were larger than previously evaluated. Therefore, the working group removed Table 5.12 and portions of Tables 5.2, 5.5,and 5.6. Thus, the working group made appropriate technicalchanges to the standard. *ANSI/ANS-8.12-1987 (Reaffirmed in 2002), "Nuclear Criticality Control and Safetyof Plutonium-Uranium Fuel Mixtures Outside Reactors," was reaffirmed after the

NRC published the current version of RG 3.71. The working group did not makeany technical changes to the standard.*ANSI/ANS-8.20-1991 (Reaffirmed in 1999), "Nuclear Criticality SafetyTraining,"was reaffirmed after the NRC published the current version of RG 3.71. The working group did not make any technical changes to the standard.*ANSI/ANS-8.21-1995 (Reaffirmed in 2001), "Use of Fixed Neutron Absorbers inNuclear Facilities Outside Reactors," was reaffirmed after the NRC published thecurrent version of RG 3.71. The working group did not make any technical changes to the standard.(3)Clarifying one current endorsement to reflect revisions to the related standard since 1998:*ANSI/ANS-8.1-1998, "Nuclear Criticality Safety in Operations with FissionableMaterials Outside Reactors," was revised after the NRC published the currentversion of RG 3.71. The working group made changes in the validation section, but did not alter the intent of the previous version. Instead, those changesprovided clarification and amplification. Thus, the working group made appropriate changes to the standard. Nonetheless, given the extent of the changes in the validation section and the date of the standard, the NRC staff hadto modify its earlier exception to the standard. However, there is no change in the intent of the NRC's previous endorsement with exception.(4)Clarifying endorsement of one standard that ANSI/ANS withdrew after 1998:*ANSI/ANS-8.9-1987 (Reaffirmed in 1995), "Nuclear Criticality Safety Criteria forSteel-Pipe Intersections Containing Aqueous Solutions of Fissile Materials," is addressed in the current version of RG 3.71. However, ANSI/ANS has since withdrawn this standard (i.e., it is a historical standard). Although the NRC staffhas withdrawn its endorsement of the standard, there is nothing technically wrongwith this standard, and it remains acceptable for use by licensees and applicants.(5)Incorporating editorial changes to reflect the NRC's current regulatory guide format:*Draft Regulatory Guide DG-3023 was prepared in consultation with a staffmember from the NRC's Office of Nuclear Regulatory Research (RES). That RESstaff member is responsible for formatting regulatory guides according to agency standards, is an experienced NRC technical editor, and has concurred on thepackage.

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(Draft was issued as DG-3013, Published 1/98)August 1998A. IntroductionDRAFT REGULATORY GUIDE DG-3023(Proposed Revision 1 of Regulatory Guide 3.71, dated August 1998)NUCLEAR CRITICALITY SAFETY STANDARDSFOR FUELS AND MATERIAL FACILITIESA. INTRODUCTIONThis revised regulatory guide provides licensees and applicants with updated guidanceconcerning criticality safety standards that the U.S. Nuclear Regulatory Commission (NRC) hasendorsed for use with nuclear fuels and material facilities. As such, this guide describesmethods that the NRC staff considers acceptable for complying with the NRC's regulations inTitle 10, Parts 70 and 76, of the Code of Federal Regulations (10 CFR Parts 70 and 76).In 10 CFR Part 70, "Domestic"Domestic Licensing of Special Nuclear Material,"" Section 70.20, "General"General License To Own Special Nuclear Material,"" defines a specific license toacquire, deliver, receive, possess, use, transfer, import, or export special nuclear material.

According to 10 CFR 70.22, "Contents"Contents of Applications,"" each application for such alicense must contain proposed procedures to avoid nuclear criticality accidents. In 10 CFR Part

76, "Certification"Certification of Gaseous Diffusion Plants,"" Section 76.87, "Technical"TechnicalSafety Requirements,"" states that the technical safety requirements should referenceprocedures and equipment that are applicable to criticality prevention.ThisThe NRC staff has developed this regulatory guide has been developed to provideguidance on complying with these portions of the NRC

s regulations by describing proceduresfor preventing nuclear criticality accidents in operations involvingthat involve handling,processing, storing, and and/or transporting special nuclear material at fuel s and materialfacilities. This regulatory guide endorses specific ANSI/ANS-8 nuclear criticality safety standardsfor these purposes. This guide also consolidates and replaces the guidance from a number ofregulatory guides, thereby withdrawing those regulatory guides.developed by the AmericanNuclear Society's Standards Subcommittee 8 (ANS-8), "Operations with Fissionable MaterialsOutside Reactors." This guide is not intended to be used by nuclear reactor licensees.TheRegulatory guides are issued to describe to the public methods that the NRC staffconsiders acceptable for use in implementing specific parts of the agency's regulations, toexplain techniques that the staff uses in evaluating specific problems or postulated accidents,and to provide guidance to applicants. Regulatory guides are not substitutes for regulations, andcompliance with regulatory guides is not required. Regulatory guides are issued in draft form tosolicit public comment and involve the public in developing the agency's regulatory positions. Draft regulatory guides have not received complete staff review; therefore, they do not representofficial NRC staff positions.This draft regulatory guide contains information collections contained in this regulatoryguide that are covered by the requirements of 10 CFR Part 70, which were approved by theOffice of Management and Budget, approval (OMB) approved under OMB control number 3150-0009, and 10 CFR Part 76. The NRC may notneither conduct or sponsornor sponsor , and aperson is not required to respond to, a collection of information unless itan information collectionrequest or requirement unless the requesting document displays a currently valid OMB controlnumber.

B. DiscussionThe American Nuclear Society's Standards Subcommittee 8, "Operations with FissionableMaterials Outside Reactors" (ANS-8), has developed national standards for the prevention andmitigation of However, this draft regulatory guide contains additional information collections thatare covered by the requirements of 10 CFR 76.8, which apply to a wholly-owned instrumentalityof the United States and affect fewer than ten respondents. As a result, OMB clearance is notrequired pursuant to the Paperwork Reduction Act (44 U.S.C. 3501, et seq.).B. DISCUSSIONThe NRC initially issued Regulatory Guide 3.71 in 1998 to provide guidance concerningprocedures that the staff considered acceptable for complying with the agency's regulatoryrequirements in 10 CFR 70.20, 70.22 and 76.87. Toward that end, the original guide endorsedspecific safety standards that ANS-8 developed to provide guidance, criteria, and best practicesfor use in preventing and mitigating criticality accidents duringduring operations that involvehandling, processing, storing, and and/or transporting special nuclear material s at fuel s andmaterial facilities. These national standards have beenThe original guide also took exceptions tocertain portions of individual ANSI/ANS-8 standards. In addition, the original guide consolidatedand replaced a number of earlier NRC regulatory guides, thereby providing all of the relevantguidance in a single document.The ANS-8 standards endorsed in Regulatory Guide 3.71 were approved by the American Nuclear SocietySociety's Consensus Committee N16 on Nuclear Criticality Safety and by, as well as the American National Standards Institute (ANSI). Nonetheless, each ANSI/ANS-8standard is reviewed every 5 years by a working group of expert practitioners in the area so thatit can be revised, reaffirmed, or withdrawn, as appropriate to reflect the current state of the art. (This time can be extended to as long as 10 years or more under special circumstances.) Newstandards are also added when the need arises. Since the timing and issuance of individualstandards is independent of the other standards, the list of current standards and their respectivedates of issuance is constantly changing.As a result, since the NRC published Regulatory Guide 3.71 in 1998, several ANSI/ANS-8nuclear criticality safety standards have been added, reaffirmed, revised, or withdrawn. Consequently, the NRC staff has decided to update this guide to clarify which standards theagency endorses and to clearly state exceptions to individual standards. This proposed revisiondoes not change any of the guidance provided in Regulatory Guide 3.71; rather, it providesguidance concerning changes that have occurred since the NRC published the original guide in1998. For completeness, this guide restates the endorsements and exceptions stated inRegulatory Guide 3.71, as applicable, while identifying endorsements of or exceptions to new ormodified standards. Since the ANSI/ANS-8 standards are constantly being issued, revised,reaffirmed, or withdrawn, the NRC staff plans to revise this guide on a regular basis.C. REGULATORY POSITIONThe ANSI/ANS-8 nuclear criticality safety standards provide guidance and criteria ongood practices forprocedures and methodologies that the NRC staff considers generallyacceptable for use in preventing and mitigating nuclear criticality accidents. However, use of theANSI/ANS-8 nuclear criticality safety standards is not a substitute for detailed nuclear criticalitysafety at fuels and material facilities.

The ANSI/ANS-8 national standards list additional documents as references. The specificapplicability or acceptability of these listed documents will be covered separately in otheranalysesfor specific operations. In addition, inclusion of a reference to another standard in an endorsedstandard does not imply NRC endorsement of the referenced standard.The NRC staff will follow the requirements denoted in the ANSI/ANS-8 standards. Theword "shall" in an ANSI/ANS-8 standard denotes a requirement; the word "should" denotes arecommendation; and the word "may" denotes permission (neither a requirement Nor arecommendation). When a licensee or applicant commits to an ANSI/ANS-8 standard cited inthis regulatory guides, where appropriate.C. Regulatory PositionTheguide, the licensee or applicant must perform all operations in accordance with therequirements stated in that standard, but not necessarily with its recommendations. Licensees orapplicants may follow the recommendations given in the ANSI/ANS-8 standards, unless anexception is stated in this regulatory guide, otherwise specified in 10 CFR Parts 70 or 76, oraddressed by other acceptable methods.

1.ANSI/ANS-8 Nuclear Criticality Standards Endorsed by the NRCThe NRC endorses the following ANSI/ANS-8 nuclear criticality safety standarddocuments describe procedures and recommendations that should be followed to prevent andmitigate nuclear criticality accidents.ANSI/ANS-8.1-1983 (Reaffirmed in 1988), "Nuclear Criticality Safety in Operations withFissionable Materials Outside Reactors"ANSI/ANS-8.3-1997, "Criticality Accident Alarm System"standards:

  • ANSI/ANS-8.5-1996 (Reaffirmed in 2002), "Use"Use of Borosilicate-Glass Raschig Rings as a Neutron Absorber in Solutions of Fissile Material

""*ANSI/ANS-8.6-1983 (Reaffirmed in 1995 2001), "Safety"Safety in Conducting SubcriticalNeutron--Multiplication Measurements In Situ

""*ANSI/ANS-8.7-1975 (Reaffirmed in 1987)7-1998 , "Guide for Nuclear"Nuclear CriticalitySafety in the Storage of Fissile Materials" ANSI/ANS-8.9-1987(Reaffirmed in 1995), "Nuclear Criticality Safety Criteria for Steel-PipeIntersections Containing Aqueous Solutions of Fissile Materials"<ANSI/ANS-8.10-1983 (Reaffirmed in 1988), "Criteria for Nuclear Criticality Safety Controls inOperations With Shielding and Confinement"Materials"

  • ANSI/ANS-8.12-1987 (Reaffirmed in 1993 2002), "Nuclear"Nuclear Criticality Control andSafety of Plutonium-Uranium Fuel Mixtures Outside Reactors"Reactors"*ANSI/ANS-8.14-2004, "Use of Soluble Neutron Absorbers in Nuclear Facilities OutsideReactors"*ANSI/ANS-8.15-1981 (Reaffirmed in 1995), "Nuclear"Nuclear Criticality Control of SpecialActinide Elements"ANSI/ANS-8.17-1984 (Reaffirmed in 1997), "Criticality Safety Criteria for the Handling, Storage,and Transportation of LWR Fuel Outside Reactors"ANSI/ANS-8. 19-1996, "AdministrativeElements"*ANSI/ANS-8.19-1996, "Administrative Practices for Nuclear Criticality Safety

""*ANSI/ANS-8.20-1991 (Reaffirmed in 1999), "Nuclear"Nuclear Criticality Safety Training

""*ANSI/ANS-8.21-1995 (Reaffirmed in 2001), "Use"Use of Fixed Neutron Absorbers in Nuclear Facilities Outside Reactors

""*ANSI/ANS-8.22-1997, "Nuclear"Nuclear Criticality Safety Based on Limiting andControlling Moderators

""*ANSI/ANS-8.23-1997, "Nuclear"Nuclear Criticality Accident Emergency Planning andResponse" The methods described in theResponse"2.ANSI/ANS-8 Nuclear Criticality Standards Endorsed by the NRC with ExceptionsThe NRC endorses the following ANSI/ANS-8 nuclear criticality safety standards havebeen applied in a number of specific cases during reviews and selected licensing actions. Thesemethods reflect the latest general NRC approach to nuclear criticality safety in operationsinvolving handling, processing, storing, and transporting special nuclear material at fuels andmaterial facilities.Most of the ANSI/ANS-8 nuclear criticality safety standards have been endorsed by NRCin other regulatory guides. This regulatory guide consolidates and replaces the followingregulatory guides without altering any existing licensing commitments nor introducing any newrequirements. These regulatory guides are therefore being withdrawn.Regulatory Guide 3.1, "Use of Borosilicate-Glass Raschig Rings as a Neutron Absorber inSolutions of Fissile Material" (Revision 2, September 1987)Regulatory Guide 3.4, "Nuclear, but takes exception to certain sections, as follows:

  • ANSI/ANS-8.1-1998, "Nuclear Criticality Safety in Operations with Fissionable Materials atFuels and Materials Facilities" (Revision 2, March 1986)Regulatory Guide 3.43, "Nuclear Criticality Safety in the Storage of Fissile Materials" (Revision 1,April 1979)Regulatory Guide 3.45, "Nuclear Criticality Safety for Steel-Pipe Intersections ContainingAqueous Solutions of Fissile Materials" (Revision 1, April 1989)Regulatory Guide 3.47, "Nuclear Criticality Control and Safety of Homogeneous Plutonium-Uranium Fuel Mixtures Outside Reactors" (July 1981)Regulatory Guide 3.57, "Administrative Practices for Nuclear Criticality Safety at Fuels andMaterials Facilities" (October 1986)Regulatory Guide 3.58, "Criticality Safety for Handling, Storing, and Transporting LWR Fuel atFuels and Materials Facilities" (October 1986)Regulatory Guide 3.68, "Nuclear Criticality Safety Training" (April 1994)Regulatory Guide 3.70, "Use of Fixed Neutron Absorbers at Fuels and Materials Facilities"(August 1997)Regulatory Guide 8.12, "Criticality Accident Alarm Systems" (Revision 2, October 1988)

The ANSI/ANS-8 nuclear criticality safety standards listed above provide procedures andmethodology generally acceptable to the NRC staff for the prevention and mitigation of nuclearcriticality accidents. However, use of the ANSI/ANS-8 nuclear criticality safety standards is not asubstitute for detailed nuclear criticality safety analyses for specific operations. Exceptions tosome of the ANSI/ANS-8 nuclear criticality safety standards are as follows.The guidelines forReactors"The guidance on validating calculational methods for nuclear criticality safety contained

,as specified in ANSI/ANS-8.1-1983 (Reaffirmed in 1988), "Nuclear Criticality Safety inOperations with Fissionable Materials Outside Reactors," provide a procedure acceptableto the NRC1-1998, provides a procedure that is acceptable to the NRC staff forestablishing the validity and applicability of calculational methods used in assessingnuclear criticality safety. However, it will is not be sufficient to merely to refer to thisguidestandard in describing the validation of a method.

TRather, a licensee or applicantshould provide the details of validation (as stated in Section 4.3.6 of the standard shouldbe provided to demonstrate) to (1) demonstrate the adequacy of the margins ofsubcriticality relative to the bias and criticality parameters, to(2) demonstrate that thecalculations embrace the range of variables to which the method will be applied, and todemonstrateand (3) demonstrate the trends in the bias upon which the licensee orapplicant will base the extension of the area of applicability will be based.. In addition, the details of validation should state computer codes used, operations,recipes for choosing code options (where applicable), cross-section sets, and any numericalparameters necessary to describe the input.

  • ANSI/ANS-8.3-1997 (Reaffirmed in 2003), "Criticality Accident Alarm System"The guidance on criticality accident alarm systems contained, as specified in ANSI/ANS-8.3- 1997, "Criticality Accident Alarm System3-1997 (reaffirmed in 2003)

," is generallyacceptable to the NRC staff. An exception is that criticality alarm systems are required by10 CFR 70.24,"Criticality "Criticality Accident Requirements,"" requires criticality alarmsystems in each area in which special nuclear material is handled, used, or stored, whileSectionwhereas Section 4.2.1 of the standard merely requires an evaluation for suchareas. Another exception is that each area is required by 10 CFR 70.24 and 10 CFR 76.89, "Criticality"Criticality Accident Requirements," to" require that each area must becovered by two detectors, whereas Section 4.5.1 of the standard permits coverage by asingle reliable detector. Finally, 10 CFR 70.24 and 10 CFR 76.89 require a monitoringsystem capable of detecting a nuclear criticality that produces an absorbed dose in softtissue of 20 rads of combined neutron and gamma radiation at an unshielded distance of2 meters from the reacting material within 1 minute is required by 10 CFR 70.24 and 10CFR 76.89.

.

  • ANSI/ANS-8.10-1983 (Reaffirmed in 1999), "Criteria for Nuclear Criticality Safety Controlsin Operations With Shielding and Confinement" The guidance on using shielding and confinement as a nuclear criticality safety controlcontained, as specified in ANSI/ANS-8.10-1983 (Reaffirmed in 1988), "Criteria for NuclearCriticality Safety Controls in Operations with Shielding and Confinement,"reaffirmed in1999), is generally accepted by the NRC staff. An exception to Section 4.2.1 of thestandard is the assumption that the radiation source strengths and releases from anuclear criticality accident are assumed to be ise from an excursion occurring in anunfavorable geometry containing a solution of 400 g/l L of uranium enriched in U

--235. The excursion produces an initial burst of 1E+18 1x10 18 fissions in 0.5 second, followedsuccessively at 10

-minute intervals by 47 bursts of 1.9E+ 179x10 17 fissions, for a total of1E+191x10 19 fissions in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The excursion is assumed to be terminated byevaporation of 100 liters of the solution.

ALicensees and applicants may use a less-conservative nuclear criticality accident condition may be used if detailed analyses ofcredible nuclear criticality accidents are performed and shown to be applicable to the conditions being evaluated.

  • ANSI/ANS-8.17-1984 (Reaffirmed in 1997), "Criticality Safety Criteria for theHandling, Storage, and Transportation of LWR Fuel Outside Reactors"The general safety criteria and criteria to establish subcriticality contained in ANSI/ANS-8.17-1997, "Criticality Safety Criteria for the Handling, Storage, and Transportation of LWRFuel Outside Reactors,", as specified in ANSI/ANS-8.17-1984 (reaffirmed in 1997),provide guidance that is acceptable to the NRC staff for preventing nuclear criticalityaccidents in handling, storing, and transporting fuel assemblies at fuel s and materialfacilities. The only exception is that licensees and applicants may take credit for fuelburnup may be taken only when the amount of burnup is confirmed by physicalmeasurements that are appropriate for each type of fuel assembly in the environment in which it is to be stored.The NRC staff will follow the requirements as denoted in the ANSI/ANS-8 nationalstandards. The word "shall" in a standard denotes a requirement, the word "should" denotes arecommendation, and the word "may" denotes permission, neither a requirement nor arecommendation. When an applicant or licensee commits to the ANSI/ANS-8 national standardscited in this regulatory guide, all operations must be performed in accordance with therequirements stated in the national standards but not necessarily with its recommendations.Recommendations given in the ANSI/ ANS-8 national standards may be followed unless anexception is stated in this regulatory guide or otherwise specified in 10 CFR Part 70 or Part 76, oraddressed by other acceptable methods.D. Implementation 3.ANSI/ANS-8 Nuclear Criticality Standards Withdrawn by the NRCThe NRC has withdrawn its endorsement of ANSI/ANS-8.9-1987 (Reaffirmed in 1995),"Nuclear Criticality Safety Criteria for Steel-Pipe Intersections Containing Aqueous Solutions ofFissile Materials." This standard, which was listed in Regulatory Guide 3.71-1998, hassubsequently been withdrawn by ANS (i.e., it is a historical standard). Although the NRC haswithdrawn its endorsement of the standard, there is nothing technically wrong with this standardand it would be acceptable for licensees and applicants to use it.

D. IMPLEMENTATIONThe purpose of this section is to provide information to applicants and licensees regardingthe NRC staff

s plans for using this draft regulatory guide.Except in those cases in which No backfitting is intended or approved in connection withthe issuance of this guide.The NRC has issued this draft guide to encourage public participation in its development. Except when an applicant or licensee proposes or has previously established an acceptablealternative method for complying with the specified portions of the NRC

s regulations, the methods to be described in thisthe active guide will reflect public comments and will be used inthe evaluation of in evaluating submittals in connection with license applications submitted under 10 CFR Part 70, "Domestic"Domestic Licensing of Special Nuclear Material,"" and 10 CFR Part 76, "Certification"Certification of Gaseous Diffusion Plants.

""E. Regulatory AnalysisREGULATORY ANALYSIS AThe NRC published a draft regulatory analysis was published withwhen the agencyissued the original draft of this guide when it was published(as DG-3013) for public comment(Task DG-3013, January 1998). No changes were necessary, soin January 1998. Since thattime, several ANSI/ANS-8 nuclear criticality safety standards have been added, reaffirmed,revised, or withdrawn. Consequently, the NRC staff has decided to update this guide to clarifywhich standards the agency endorses and to clearly state exceptions to individual standards. However, this proposed revision does not change any of the guidance provided in RegulatoryGuide 3.71; rather, it provides guidance concerning changes that have occurred since the NRCpublished the original guide 1998. Consequently, the NRC staff has not prepared a separateregulatory analysis has not been prepared for Rthis revised regulatory G guide 3.71. A copy of t T he draftoriginal regulatory analysis for DG-3013 is available for inspection or copying (for a fee)in the NRCs Public Document Room at 2120 L Street NW.(PDR), which is located at 11555Rockville Pike, Rockville, Maryland. The PDR's mailing address is USNRC PDR, Washington, DC, under Task DG-3013. 20555-0001. The PDR can also be reached by telephone at (301) 415-4737 or (800) 397-4205,by fax at (301) 415-3548; and by email to PDR@nrc.gov

.BACKFIT ANALYSISThis proposed revision of Regulatory Guide 3.71 does not require a backfit analysis, asdescribed in 10 CFR 70.76(b) and 10 CFR 76.76(b), because it does not impose a new oramended provision in the Commission's rules or a regulatory staff position interpreting theCommission's rules that is either new or different from a previous applicable staff position. Inaddition, this regulatory guide does not require modification or addition to structures, systems,components, or design of a facility or the procedures or organization required to design,construct, or operate a facility. Rather, a licensee or applicant is free to select a preferredmethod for achieving compliance with a license or the rules or orders of the Commission, asdescribed in 10 CFR Parts 70 and 76.

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