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
From:	Office of Nuclear Regulatory Research
To:
References
FP 026-5 RG-3.047
Download: ML12220A064 (3)

U.S. NUCLEAR REGULATORY COMMISSION July 1981 REGULATORY GUIDE

OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE 3.47 (Task FP 026-5)

NUCLEAR CRITICALITY CONTROL AND SAFETY OF HOMOGENEOUS

PLUTONIUM-URANIUM FUEL MIXTURES OUTSIDE REACTORS

A. INTRODUCTION

moderation, and tabulated subcritical concentration limits for plutonium in homogeneous mixtures of plutonium and Section 70.22, "Contents of applications," of 10CFR natural uranium of unlimited mass. Caution in the use of Part 70, "Domestic Licensing of Special Nuclear Material," the subcritical limits in the standard is advised in establish- requires that applications for a specific license to own, ing process specifications since the subcritical limits do not acquire, deliver, receive, possess, use, or transfer special contain margins for contingencies such as double batching nuclear material contain, among other things, proposed or inaccuracy of analytical techniques. The limits of the procedures to avoid accidental conditions of criticality. This standard are not applicable to heterogeneous systems. Also, regulatory guide provides guidance for complying with this the standard does not include the details of administrative portion of the Commission's regulations by describing controls, the design of processes or equipment, the descrip- procedures acceptable to the NRC staff for the prevention tion of instrumentation for process control, or detailed of criticality accidents in operations involving homogeneous criteria to be met in transporting fissionable materials.

plutonium-uranium fuel mixtures outside reactors.

C. REGULATORY POSITION

ANSI/ANS 8,12-1978, "Nuclear Criticality Control and The maximum subcritical limits for operations involving ISafety of Homogeneous Plutonium-Uranium Fuel Mixtures homogeneous mixtures of plutonium and uranium outside Fbutside Reactors," 1 was prepared by Subcommittee 8, Fission- reactors contained in ANSI/ANS 8.12-1978 are acceptable able Materials Outside Reactors, of the Standards Committee to the NRC staff when all conditions of ANSI/ANS 8.12-1978 of the American Nuclear Society. ANSI/ANS 8.12-1978 was are satisfied.

approved by the American National Standards Committee N16, Nuclear Criticality Safety, in 1977 and subsequently by the American National Standards Institute (ANSI) on Section 6 of ANSI/ANS 8.12-1978 lists additional docu- July 17, 1978. ments referred to in the standard. The specific applicability or acceptability of two of these listed documents has been ANSI/ANS 8.12-1978 provides guidance for the prevention addressed in the latest version of the regulatory guides of criticality accidents in operations with homogeneous identified below:

plutonium-uranium fuel mixtures outside reactors. The standard applies to operations involving homogeneous plutonium-uranium fuel mixtures containing no more than Standard 1 Regulatory Guide

30 wt-% plutonium combined with uranium containing no more than 0.71 wt-% U-235. The standard presents tabulated subcritical limits and graphs for uniform aqueous mixtures ANSI N16.1-1975 3.4 - Nuclear Criticality Safety in of the oxides of plutonium and natural uranium, tabulated Operations with Fissionable subcritical mass limits for single units of homogeneously Materials Outside Reactors mixed oxides of plutonium and natural uranium at low ANSI N16.9-1975 3.41 - Validation of Calculational

1 Copies may be obtained from the American Nuclear Society, Methods for Nuclear Criti-

555 North Kensington Avenue, LaGrange Park, Illinois 60525. cality Safety USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Regulatory Guides are issued to describe and make available to the Attention: Docketing and Service Branch.

public methods acceptable to the NRC staff of Implementing specific parts of the Commission's regulations, to delineate tech- The guides are issued in the following ten broad divisions:

niques used by the staff in evaluating specific problems or postu- A ted accidents, or to provide guidance to applicants. Regulatory 1. Power Reactors 6. Products uides are not substitutes for regulations, and compliance with 2.

em is not required. Methods and solutions different from those set Research and Test Reactors 7. Transportation t In the guides will be acceptable if they provide a basis for the 3. Fuels and Materials Facilities 8. Occupational Health fiundings requisite to the issuance or continuance of a permit or 4. Environmental and Siting 9. Antitrust and Financial Review license by the Commission. 5. Materials and Plant Protection 10. General This guide was issued after consideration of comments received from Copies of issued guides may be purchased at thecurrent Government Printing Office price. A subscription service for future guides in spe- the public. Comments and suggestions for improvements in these guides are encouraged at all times, and guides will be revised, as cific divisions is available through the Government Printing Office.

appropriate, to accommodate comments and to reflect new Informa- Information on the subscription service and current GPO prices may be obtained by writing the U.S. Nuclear Regulatory Commission, tion or experience. Washington, D.C. 20555, Attention: Publications Sales Manager.

D. IMPLEMENTATION

approach to criticality safety in operations involving homogeneous plutonium-uranium fuel mixtures outside The purpose of this section is to provide information to reactors. Therefore, except in those cases in which the applicants regarding the NRC staff's plans for using this applicant proposes an acceptable alternative method for regulatory guide. complying with specified portions of the Commission's regulations, the method described herein will be used after The methods described in this guide were applied in a the issuance of this guide in the evaluation of submittals number of specific cases during reviews and selected licens- for license applications submitted pursuant to 10 CFR

ing actions. These methods reflect the latest general NRC Part 70.

VALUE/IMPACT STATEMENT

The NRC staff performed a value/impact assessment to tures Outside Reactors." The results of this assessment determine the proper procedural approach for providing were included in a draft regulatory guide on this subject guidance on the prevention of criticality accidents in opera- that was issued for public comment in December 1980. A

tions involving homogeneous plutonium-uranium fuel copy of this draft guide and the associated value/impact mixtures outside reactors. This assessment resulted in a statement (identified by its task number, FP 026-5) is decision to develop a regulatory guide that would endorse available for inspection and copying for a fee at the Com- ANSI/ANS 8.12-1978, "Nuclear Criticality Control and mission's Public Document Room at 1717 H Street NW.,

Safety of Homogeneous Plutonium-Uranium Fuel Mix- Washington, D.C.

• , U.S. GOVERNMENT PRINTING OFFICE: 1981- 341-742:1186

3.47-2

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D. C. 20555 POSTAGE AND FEES PAIO

U.S. NUCLEAR REGULATORY

OFFICIAL BUSINESS

COMMISSION

PENALTY FOR PRIVATE USE, $300