Regulatory Guide 3.43

Nuclear Criticality Safety in the Storage of Fissile Materials

ML13038A433
Person / Time
Issue date:	04/30/1979
From:	NRC/OSD, Office of Nuclear Regulatory Research
To:
References
RG-3.043, Rev. 1
Download: ML13038A433 (2)

U.S. NUCLEAR REGULATORY COMMISSIONRevision 1April 1979REGULATORY GUIDEOFFICE OF STANDARDS DEVELOPMENTREGULATORY GUIDE 3.43NUCLEAR CRITICALITY SAFETY IN THE STORAGEOF FISSILE MATERIALSA. INTRODUCTIONSection 70.22, "Contents of Applications," of10 CFR Part. 70, "Domestic Licensing of SpecialNuclear Material," requires that applicationsfor a specific license to own, acquire, deliver,receive, possess, use, or transfer specialnuclear material contain proposed proceduresto avoid accidental' conditions of criticality.This regulatory guide provides guidance forcomplying with this portion of the Commission'sregulations by describing procedures accept-able to the NRC staff for the prevention ofcriticality accidents in the storage of fissilematerials outside nuclear reactors.B. DISCUSSIONANSI N16.5-1975, "Guide for Nuclear Criti-cality Safety in the Storage of Fissile Mate-rial, "' was prepared by Subcommittee 8, Fis-sionable Materials Outside Reactors, of theStandards Committee of the American NuclearSociety. ANSI N16.5-1975 was approved by theAmerican National Standards Committee N16,Nuclear Criticality Safety, in 1974 and sub-sequently by the American National StandardsInstitute (ANSI) on April 12, 1975.ANSI N16.5-1975 is applicable to the storageof fissile materials as metals and oxides. Itsapplicability is limited to 100 wt-% U-233, ura-nium containing more than 30 wt-% U-235, andplutonium containing more than 80 wt-% Pu-239(all percentages based on metal content only).The standard presents tabulated mass limits ofthese fissile materials in storage cells ofidealized water-reflected storage arrays.Caution in the use of the tabulated values inthe standard is advised to ensure subcriticality*Lines indicate substantive changes from previous issue.'Copies may be obtained from the American Nuclear Society,"555 North Kensington Avenue, La Grange Park, Illinois 60525.of each storage cell and of the storage array.These tabulated values do not include theeffects of moderation by hydrogenous materialscontiguous to the fissile materials. Evaluationof these effects by use of a validated computa-tional technique is recommended in the stand-ard. The standard also presents guidance onreduction factors to be applied to the tabulatedmass limits to account for the effects of posi-tion and double batching of fissile material in astorage cell, the reflecting properties of con-crete or other masonry construction materialsused in the storage facility, and the proximityof individual storage arrays.C. REGULATORY POSITIONThe nuclear criticality safety practices,limits, and conditions for the storage of fissilematerial and the guidance for other storageconfigurations contained in ANSI N16.5-1975provide procedures generally acceptable to theNRC staff for the prevention of criticalityaccidents in the storage of fissile materials out-side nuclear reactors subject to the following:1. Use of ANSI N16.5-1975 is not a sub-stitute for detailed nuclear criticality safetyanalyses for specific storage arrangements forfissile materials.2. The mass limits tabulated in the standardthat are marked by a superscript "a" to showthat they exceed 90 percent of the critical massof a water-reflected sphere should not be usedunless it can be demonstrated that their usecould not result in criticality under conditionsinvolving errors or accidents such as doublebatching or water immersion.3. The tabulated masses in the standard arenot acceptable without all of the appropriateadjustments called for by the standard. Licenseapplicants wanting to use the standard should,USNRC REGULATORY GUIDESRegulatory Guides ae ismued to decicdbe and mie avaisla to the publicmnethods acceptable to the NAC staff of 1:lse 'pcfic pats of theCommissio's regulations, to deli netoe n .M d by the staff In owue-aling pA olsm pIssw l o te ad , I to IpovMid guplden toapplicants Regulatory Guides we not .stitts for regulaions and ccm-pianc@ with them a not requied. Mehods and solutions dIffe t from thornsat out in One guidee will be acceptable Nf the provide a basis for the linmbgrequioi to th osisance or continuance of a pani or e by tOCou on.conwtiento andl mjsetalaton tor iWromwernenl In fthse guides wre anorwaged atl11 tirmes nd gAdes wl be rMd, I napproprite, to accommodte conmmmend tlo reflect no hnnetomon or We*n- This qgui roed as a resuof m*,eestiavs commem receive from fth pubc end additional easff revLe.Corment ehouid be .nt to the Secretary of the Cornmison, U.S. NulearRegratory Commission, Waslhirton, D.C. 20, Attention: Docke an&Wsevce Brench.The gurdes we issued in the followng tn broad divimione:1. Powe Reector 6. Products2. Ieseh end Tet Reactora 7. Tranaportation3. Fusl and Matonals Facilities 8. Occupetional Health4. Enuonomeled idtSin 9. Antitrust and Financial Review *5. Materials and Plm Protection 10. GeneralRequMs fto snle coapi of esued guides lwhtch rtsy be reproduced) or forpleosment on an autorneft distribution iet tor single. coie of future gidein FdM divisiorm ouid be mod. in wting to the U.S. Nuclear RoegloryWseeingamn, D.C. 20M, Atterntion: Directm. D on ofTechncl Winf tion ad Document Conto among other things, demonstrate that the re-quirements of paragraphs 5.3 through 5.6 ofthe standard have been met.4. Section 7 of ANSI N16.5-1975 lists addi-tional documents referred to in the standard.The specific applicability or acceptability ofthese listed documents will be coveredseparately in other regulatory guides, whereappropriate.D. IMPLEMENTATIONThe purpose of this section is to provideinformation to applicants regarding the NRCstaff's plans for using this regulatory guide.The methods described in this guide wereapplied in a number of specific cases duringreviews and selected licensing actions. Thesemethods reflect the latest general NRCapproach to criticality safety in the storage ofcertain types of fissile material outside ofnuclear reactors. Therefore, except in thosecases in which the applicant proposes anacceptable alternative method for complyingwith specified portions of the Commission'sregulations, the method described herein isbeing and will continue to be used in theevaluation of submittals for license applicationssubmitted pursuant to 10 CFR Part 70 untilthis guide is revised as a result of suggestionsfrom the public or additional staff review.(I'.~zu0.0 ~az00 0'045Uz00z0.