Regulatory Guide 3.47

Nuclear Criticality Control and Safety of Homogeneous Plutonium-Uranium Fuel Mixtures Outside Reactors

ML12220A064
Person / Time
Issue date:	07/31/1981
Revision:	0
From:	Office of Nuclear Regulatory Research
To:
References
FP 026-5 RG-3.047
Download: ML12220A064 (3)

U.S. NUCLEAR REGULATORY COMMISSION July 1981REGULATORY GUIDEOFFICE OF NUCLEAR REGULATORY RESEARCHREGULATORY GUIDE 3.47(Task FP 026-5)NUCLEAR CRITICALITY CONTROL AND SAFETY OF HOMOGENEOUSPLUTONIUM-URANIUM FUEL MIXTURES OUTSIDE REACTORSA. INTRODUCTIONSection 70.22, "Contents of applications," of 10CFRPart 70, "Domestic Licensing of Special Nuclear Material,"requires that applications for a specific license to own,acquire, deliver, receive, possess, use, or transfer specialnuclear material contain, among other things, proposedprocedures to avoid accidental conditions of criticality. Thisregulatory guide provides guidance for complying with thisportion of the Commission's regulations by describingprocedures acceptable to the NRC staff for the preventionof criticality accidents in operations involving homogeneousplutonium-uranium fuel mixtures outside reactors.B. DISCUSSIONmoderation, and tabulated subcritical concentration limitsfor plutonium in homogeneous mixtures of plutonium andnatural uranium of unlimited mass. Caution in the use ofthe subcritical limits in the standard is advised in establish-ing process specifications since the subcritical limits do notcontain margins for contingencies such as double batchingor inaccuracy of analytical techniques. The limits of thestandard are not applicable to heterogeneous systems. Also,the standard does not include the details of administrativecontrols, the design of processes or equipment, the descrip-tion of instrumentation for process control, or detailedcriteria to be met in transporting fissionable materials.C. REGULATORY POSITIONThe maximum subcritical limits for operations involvinghomogeneous mixtures of plutonium and uranium outsidereactors contained in ANSI/ANS 8.12-1978 are acceptableto the NRC staff when all conditions of ANSI/ANS 8.12-1978are satisfied.Section 6 of ANSI/ANS 8.12-1978 lists additional docu-ments referred to in the standard. The specific applicabilityor acceptability of two of these listed documents has beenaddressed in the latest version of the regulatory guidesidentified below:ANSI/ANS 8,12-1978, "Nuclear Criticality Control andISafety of Homogeneous Plutonium-Uranium Fuel MixturesFbutside Reactors,"1 was prepared by Subcommittee 8, Fission-able Materials Outside Reactors, of the Standards Committeeof the American Nuclear Society. ANSI/ANS 8.12-1978 wasapproved by the American National Standards CommitteeN16, Nuclear Criticality Safety, in 1977 and subsequentlyby the American National Standards Institute (ANSI) onJuly 17, 1978.ANSI/ANS 8.12-1978 provides guidance for the preventionof criticality accidents in operations with homogeneousplutonium-uranium fuel mixtures outside reactors. Thestandard applies to operations involving homogeneousplutonium-uranium fuel mixtures containing no more than30 wt-% plutonium combined with uranium containing nomore than 0.71 wt-% U-235. The standard presents tabulatedsubcritical limits and graphs for uniform aqueous mixturesof the oxides of plutonium and natural uranium, tabulatedsubcritical mass limits for single units of homogeneouslymixed oxides of plutonium and natural uranium at lowStandard1ANSI N16.1-1975ANSI N16.9-1975Regulatory Guide3.4 -Nuclear Criticality Safety inOperations with FissionableMaterials Outside Reactors3.41 -Validation of CalculationalMethods for Nuclear Criti-cality Safety1Copies may be obtained from the American Nuclear Society,555 North Kensington Avenue, LaGrange Park, Illinois 60525.USNRC REGULATORY GUIDESRegulatory Guides are issued to describe and make available to thepublic methods acceptable to the NRC staff of Implementingspecific parts of the Commission's regulations, to delineate tech-niques used by the staff in evaluating specific problems or postu-A ted accidents, or to provide guidance to applicants. Regulatoryuides are not substitutes for regulations, and compliance withem is not required. Methods and solutions different from those sett In the guides will be acceptable if they provide a basis for thefiundings requisite to the issuance or continuance of a permit orlicense by the Commission.This guide was issued after consideration of comments received fromthe public. Comments and suggestions for improvements in theseguides are encouraged at all times, and guides will be revised, asappropriate, to accommodate comments and to reflect new Informa-tion or experience.Comments should be sent to the Secretary of the Commission,U.S. Nuclear Regulatory Commission, Washington, D.C. 20555,Attention: Docketing and Service Branch.The guides are issued in the following ten broad divisions:1. Power Reactors 6. Products2. Research and Test Reactors 7. Transportation3. Fuels and Materials Facilities 8. Occupational Health4. Environmental and Siting 9. Antitrust and Financial Review5. Materials and Plant Protection 10. GeneralCopies of issued guides may be purchased at thecurrent GovernmentPrinting Office price. A subscription service for future guides in spe-cific divisions is available through the Government Printing Office.Information on the subscription service and current GPO prices maybe obtained by writing the U.S. Nuclear Regulatory Commission,Washington, D.C. 20555, Attention: Publications Sales Manage D. IMPLEMENTATIONThe purpose of this section is to provide information toapplicants regarding the NRC staff's plans for using thisregulatory guide.The methods described in this guide were applied in anumber of specific cases during reviews and selected licens-ing actions. These methods reflect the latest general NRCapproach to criticality safety in operations involvinghomogeneous plutonium-uranium fuel mixtures outsidereactors. Therefore, except in those cases in which theapplicant proposes an acceptable alternative method forcomplying with specified portions of the Commission'sregulations, the method described herein will be used afterthe issuance of this guide in the evaluation of submittalsfor license applications submitted pursuant to 10 CFRPart 70.VALUE/IMPACT STATEMENTThe NRC staff performed a value/impact assessment todetermine the proper procedural approach for providingguidance on the prevention of criticality accidents in opera-tions involving homogeneous plutonium-uranium fuelmixtures outside reactors. This assessment resulted in adecision to develop a regulatory guide that would endorseANSI/ANS 8.12-1978, "Nuclear Criticality Control andSafety of Homogeneous Plutonium-Uranium Fuel Mix-tures Outside Reactors." The results of this assessmentwere included in a draft regulatory guide on this subjectthat was issued for public comment in December 1980. Acopy of this draft guide and the associated value/impactstatement (identified by its task number, FP 026-5) isavailable for inspection and copying for a fee at the Com-mission's Public Document Room at 1717 H Street NW.,Washington, D.C.*, U.S. GOVERNMENT PRINTING OFFICE: 1981- 341-742:11863.47-2 UNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D. C. 20555OFFICIAL BUSINESSPENALTY FOR PRIVATE USE, $300POSTAGE AND FEES PAIOU.S. NUCLEAR REGULATORYCOMMISSION