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)

Revision 1 U.S. NUCLEAR REGULATORY COMMISSION April 1979 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 3.43 NUCLEAR CRITICALITY SAFETY IN THE STORAGE

OF FISSILE MATERIALS

A. INTRODUCTION

of each storage cell and of the storage array.

These tabulated values do not include the Section 70.22, "Contents of Applications," of effects of moderation by hydrogenous materials

10 CFR Part. 70, "Domestic Licensing of Special contiguous to the fissile materials. Evaluation Nuclear Material," requires that applications of these effects by use of a validated computa- for a specific license to own, acquire, deliver, tional technique is recommended in the stand- receive, possess, use, or transfer special ard. The standard also presents guidance on nuclear material contain proposed procedures reduction factors to be applied to the tabulated to avoid accidental' conditions of criticality. mass limits to account for the effects of posi- This regulatory guide provides guidance for tion and double batching of fissile material in a complying with this portion of the Commission's storage cell, the reflecting properties of con- regulations by describing procedures accept- crete or other masonry construction materials able to the NRC staff for the prevention of used in the storage facility, and the proximity criticality accidents in the storage of fissile of individual storage arrays.

materials outside nuclear reactors.

B. DISCUSSION

The nuclear criticality safety practices, ANSI N16.5-1975, "Guide for Nuclear Criti- limits, and conditions for the storage of fissile cality Safety in the Storage of Fissile Mate- material and the guidance for other storage rial, "' was prepared by Subcommittee 8, Fis- configurations contained in ANSI N16.5-1975 sionable Materials Outside Reactors, of the provide procedures generally acceptable to the Standards Committee of the American Nuclear NRC staff for the prevention of criticality Society. ANSI N16.5-1975 was approved by the accidents in the storage of fissile materials out- American National Standards Committee N16, side nuclear reactors subject to the following:

Nuclear Criticality Safety, in 1974 and sub- sequently by the American National Standards 1. Use of ANSI N16.5-1975 is not a sub- Institute (ANSI) on April 12, 1975. stitute for detailed nuclear criticality safety analyses for specific storage arrangements for ANSI N16.5-1975 is applicable to the storage fissile materials.

of fissile materials as metals and oxides. Its applicability is limited to 100 wt-% U-233, ura- 2. The mass limits tabulated in the standard nium containing more than 30 wt-% U-235, and that are marked by a superscript "a" to show plutonium containing more than 80 wt-% Pu-239 that they exceed 90 percent of the critical mass (all percentages based on metal content only). of a water-reflected sphere should not be used The standard presents tabulated mass limits of unless it can be demonstrated that their use these fissile materials in storage cells of could not result in criticality under conditions idealized water-reflected storage arrays. involving errors or accidents such as double Caution in the use of the tabulated values in batching or water immersion.

the standard is advised to ensure subcriticality 3. The tabulated masses in the standard are

• Lines indicate substantive changes from previous issue. not acceptable without all of the appropriate

'Copies may be obtained from the American Nuclear Society, adjustments called for by the standar

d. License

"555 North Kensington Avenue, La Grange Park, Illinois 60525. applicants wanting to use the standard should, USNRC REGULATORY GUIDES Corment ehouid be .ntto the Secretary of the Cornmison, U.S. Nulear Regratory Commission, Waslhirton, D.C. 20, Attention: Docke an&W

Regulatory Guides ae ismued to decicdbe and mie avaisla to the public sevce Brench.

mnethods acceptable to the NAC staff of 'pcfic

1:lse pats of the Commissio's regulations, to delinetoe n .M d by the staff In owue- The gurdes we issued in the followng tn broad divimione:

aling rod* pA olsm o pIsswte l ad I, IpovMid to guplden to applicants Regulatory Guides we not .stitts for regulaions and ccm- 1. Powe Reector 6. Products pianc@ with them a not requied. Mehods and solutions dIffe t from thorn 2. Ieseh end Tet Reactora 7. Tranaportation sat out in Oneguidee will be acceptable Nfthe provide a basis for the linmbg 3. Fusl and Matonals Facilities 8. Occupetional Health requioi to th osisance or continuance of a pani or e by tO 4. Enuonomeled idtSin 9. Antitrust and Financial Review *

Cou on. 5. Materials and Plm Protection 10. General RequMs fto snle coapi of esued guides lwhtch rtsy be reproduced) or for conwtiento andl mjsetalaton tor iWromwernenl In fthse guides wreanorwaged at pleosment on an autorneft distribution iet tor single. coie of future gide tirmes nd gAdes wl be rMd, l11 I napproprite, to accommodte conmmm in FdM divisiorm ouid be mod. in wting to the U.S. Nuclear Roeglory end tloreflect no hnnetomon or We*n- This qgui roed as a resu Cosenuis*on, Wseeingamn, D.C. 20M, Atterntion: Directm. D on of of m*,eestiavs commem receive from fth pubc end additional easff revLe. Techncl Winf tion ad Document Contol.

among other things, demonstrate that the re- The methods described in this guide were quirements of paragraphs 5.3 through 5.6 of applied in a number of specific cases during the standard have been met. reviews and selected licensing actions. These methods reflect the latest general NRC

4. Section 7 of ANSI N16.5-1975 lists addi- approach to criticality safety in the storage of tional documents referred to in the standard. certain types of fissile material outside of The specific applicability or acceptability of nuclear reactors. Therefore, except in those these listed documents will be covered cases in which the applicant proposes an separately in other regulatory guides, where acceptable alternative method for complying appropriate. with specified portions of the Commission's regulations, the method described herein is

D. IMPLEMENTATION

being and will continue to be used in the evaluation of submittals for license applications The purpose of this section is to provide submitted pursuant to 10 CFR Part 70 until information to applicants regarding the NRC this guide is revised as a result of suggestions staff's plans for using this regulatory guide. from the public or additional staff review.

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