Regulatory Guide 3.41

Validation of Calculational Methods for Nuclear Criticality Safety

ML12184A016
Person / Time
Issue date:	05/31/1977
From:	Office of Nuclear Regulatory Research, NRC/OSD
To:
References
RG-3.041, Rev. 1
Download: ML12184A016 (4)

Revision 1 U.S. NUCLEAR REGULATORY COMMISSION

May 1977 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 3.41 VALIDATION OF CALCULATIONAL METHODS

FOR NUCLEAR CRITICALITY SAFETY

A. INTRODUCTION

Applicants for licenses under 10 CFR Parts 50 or

70 proposing to handle, process, or store quantities of fissile material outside reactors sufficient to form a critical mass are required to demonstrate that their controls will prevent accidental criticality under nor- mal or accident conditions. Each application must in- clude information on personnel, equipment, and procedures. Although the equipment and procedures used to prevent criticality may be, and often are, based on designs and methods of demonstrated validity already in the literature, the applicant may choose to use his own methods of calculation, which, of course, must be demonstrated to be valid by com- parison with experimental data. This guide provides a procedure acceptable to the NRC staff for validating methods of calculation. Although these measures are broadly applicable, it is anticipated that they will be applied primarily to electronic computer codes.

B. DISCUSSION

Subcommittee 8 on Fissionable Material Outside Reactors of the Standards Committee of the American Nuclear Society has developed a standard that delineates requirements for establishing the validity and area of applicability of a calculational method used in assessing nuclear criticality safety.

This standard was approved by American National Standards Committee N16, Nuclear Criticality Safety, and was approved as an American National Standard by the American National Standards In- stitute (ANSI) on September 18, 1975, under the designation ANS-8-II/N 16.9-1975, "Validation of Calculational Methods for Nuclear Criticality Safety."

As indicated by the scope of the standard, it is con- cerned only with validation of calculational methods and does not address important related questions

• Lines indicate substantive changes from previous issues.

such as the margin of safety to be used with the method or the qualifications of the personnel respon- sible for the data input.

C. REGULATORY POSITION

The guidelines for validation of calculational methods for nuclear criticality safety contained in ANSI N16.9-1975, "Validation of Calculational Methods for Nuclear Criticality Safety,"' provide a generally acceptable procedure for establishing the validity and area of applicability of calculational methods used in assessing nuclear criticality safety.

However, it will not be sufficient merely to refer to this guide in describing the validation of a method.

The details of the validation indicated in Section 4.6 of the standard should be provided to demonstrate the adequacy of the safety margins relative to the bias and criticality parameters and to demonstrate that the calculations embrace the range of variables to

,which the method will be applied.

D. IMPLEMENTATION

The purpose of this section is to provide informa- tion to applicants regarding the NRC staff s plans for using this regulatory guide.

This guide reflects current NRC staff practice.

Therefore, except in those cases in which the appli- cant proposes an acceptable alternative method for complying with specified portions of the Commis- sion's regulations, the method described herein is be- ing and will continue to be used in the evaluation of submittals for special nuclear material license, operating license, or construction permit applications until this guide is revised as a result of suggestions from the public or additional staff review.

'Copies may be obtained from the American Nuclear Society, 244 East Ogden Avenue, Hinsdale, Illinois 60521.

USNRC REGULATORY GUIDES

Comments should be sent to the Secretary of the Commission, US. Nuclear Regu- latory Commission, Washington. D.C.

20555, Attention: Docketing and Service Regulatory Guides are issued to describe and mat-e available to the public methods Branch.

acceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff rn evaluating specific problems The guides are issued in the following ten broad divisions:

or postulated accidents, or to provide guidance to applicants.

Regulatory Guides are not substitutes for regulations, and compliance with them is not required.

1. Power Reactors

6. Products Methods and solutions different from those set out in the guides will be accept-

2. Research and Test Reactors

7. Transportation able if they prourde a basis for the findings requisite to the issuance or continuance

3. Fuelsand Materials Facilities

8. Occupational Health of a permit or license by the Commission.

4. Environmental and Siting

9. Antitrust Review

5. Materials and Plant Protection

10. General Comments and suggestions for improvements in these guides are encouraged at all Requests for single copies of issued guides (which may be reproduced) or for place- times, and guides will be revised, as appropriate, to accommodate comments and ment on an automatic distribution list for single copies of future guides in specific to reflect new information or experience.

This guide was revised as a result of divisions should be made in writing to the U.S. Nuclear Regulatory Commission, substantive comments received from the public and additional staff review.

Washington, D.C.

20555, Attention:

Director, Division of Document Control.

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