Regulatory Guide 3.45

Nuclear Criticality Safety for Pipe Intersections Containing Aqueous Solutions of Enriched Uranyl Nitrate.

ML12184A017
Person / Time
Issue date:	11/30/1980
From:	Office of Nuclear Regulatory Research, NRC/OSD
To:
References
Task FP 925-5 RG-3.045
Download: ML12184A017 (2)

November.

.1 B8 U.S. NUCLEAR REGULATORY

COMMISSION

REGULATORY

GUIDE'" OFFICE OF STANDARDS

DEVELOPMENT

REGULATORY

GUIDE 3.45 (Task FP 925-5)NUCLEAR CRITICALITY

SAFETY FOR PIPE INTERSECTIONS

CONTAINING

AQUEOUS SOLUTIONS

OF ENRICHED URANYL NITRATE

A. INTRODUCTION

Section 70.22, "Contents of Applications," of 10 CFR Part 70,"Domestic Licensing of Special Nuclear Material," requires that applications for a specific license to own, acquire, deliver, receive, possess, use, or transfer special nuclear material con-tain proposed procedures to avoid accidental conditions of criticality.

This regulatory guide provides guidance for com-plying with this portion of the Commission's regulations by describing procedures acceptable to the NRC staff for the prevention of criticality accidents in the storage and process-ing of aqueous solutions of enriched uranyl nitrate in pipe intersections.

B. DISCUSSION

ANSI/ANS 8.9-1978, "Nuclear Criticality Safety Guide for Pipe Intersections Containing Aqueous Solutions of Enriched Uranyl Nitrate,"I

was prepared by Subcommittee

8, Fission-able Materials Outside Reactors, of the Standards Committee of the American Nuclear Society. ANSI/ANS 8.9-1978 was approved by the American National Standards Committee N 16, Nuclear Criticality Safety, in 1977 and subsequently by the American National Standards Institute (ANSI) on February 15, 1978.ANSI/ANS 8.9-1978 is applicable only to the storage and processing of homogeneous aqueous solutions of uranyl nitrate containing no more than 93.5 wt-% U-235 in intersecting pipe geometries consisting of single central columns with smaller intersecting arms. The standard presents tabulated maximum safe values, derived from an empirical model based on validated calculations and experimental data, for both the central column diameter and the total area of intersection of the arms with the column for conditions of partial and total reflection.

The standard also presents a general procedure to ascertain the safety of specific pipe intersections as well as guidance on model parameters and ICopies may be obtained from the American Nuclear Society, 555 North Kensington Avenue, La Grange Park, Illinois 60525.limitations.

In intersecting pipe geometries where the model does not apply, e.g., multiple columns or columns in the vicinity of other fissionable materials, the standard requires that experimental data or validated computational techniques be used to determine the safe configuration.

C. REGULATORY

POSITION The nuclear criticality safety practices and guidance for calculating safe pipe intersections for enriched uranyl nitrate solutions contained in ANSI/ANS 8.9-1978 provide procedures generally acceptable to the NRC staff for the prevention of criticality accidents in the storage and processing of aqueous solutions of enriched uranyl nitrate in pipe intersections.

Section 6 of ANSI/ANS 8.9-1978 lists additional documents referred to in the standard.

The specific applicability or acept-ability of two of these listed documents has been addressed in the latest version of the regulatory guides identified below: Standard'ANSI N16.1-1975 ANSI N16.9-1975 Regulatory Guide 3.4 3.41

D. IMPLEMENTATION

The purpose of this section is to provide information to applicants regarding the NRC staff's plan for using this regulatory guide.The methods described in this guide were applied in a unnber of specific cases during reviews and selected licensing actions.These methods reflect the latest general NRC approach to criticality safety in the storage and processing of aqueous solu-tions of enriched uranyl nitrate in pipe intersections.

There-fore, except in those cases in which the applicant proposes an acceptable alternative method for complying with specified portions of the Commission's regulations, the method described herein will be used in the evaluation of submittals for license applications submitted pursuant to 10 CFR Part 7

0. 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:

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Regulatory

1. Power Reactors 6. Products Guides are not substitutes for regulations, and compliance with 2. Research and Test Reactors 7. Transportation them Is not required.

Methods and solutions different from those set 3. Fuels and Materials Facilities

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This guide was revised as a result of substantive com- be obtained by writing the U.S. Nuclear Regulatory Commission, ments received from the public and additional staff review. Washington, D.C. 20555, Attention:

Publications Sales Manager.

VALUE/IMPACT

STATEMENT*

Regulatory Guide 3.45 (Task FP 925-5) endorses ANSI/ANS 8.9-1978, "Nuclear Criticality Safety Guide for Pipe Intersections Containing Aqueous Solutions of Enriched Uranyl Nitrate," which was approved by the American National Standards Institute on February 15, 1978. The A copy of the draft value/impact statement (published with Draft Guide FP 92$-5 in January 1980) is available for public inspection at 1717 H Street NW., Washington, D.C.nuclear criticality safety practices and guidance for calcula-ting safe pipe intersections contained in ANSI/ANS 8.9-1978 are acceptable to the NRC staff and to industry.

The guide provides a convenient reference for the licensee or license applicant in designing nuclear criticality safety programs to meet regulatory requirements and standards of good nuclear criticality safety practice.

The use of this guide should facilitate the licensing process with minimum impact on the NRC staff and industry.4 at Zt (U z 2 u~ 0 00 L)-00 44 -4 U 0 LU z LU..4 z rL)L a- z zL", Z L-40Z W 0 0-" >00 <~0 W l LL-C.,~z 00' C 0.- 0_tb- "0w 0 3.45-2