Regulatory Guide 3.1

Use of Borosilicate-Glass Raschig Rings as a Neutron Absorber in Solutions of Fissile Material

ML12220A057
Person / Time
Issue date:	09/30/1987
From:	Office of Nuclear Regulatory Research
To:
References
CE 602-4 RG-3.001, Rev. 2
Download: ML12220A057 (4)

Revision 2September 1987U.S. NUCLEAR REGULATORY COMMISSIONREGULATORY GUIDEOFFICE OF NUCLEAR REGULATORY RESEARCHREGULATORY GUIDE 3.1(Task CE 602-4)USE OF BOROSILICATE-GLASS RASCHIG RINGS AS A NEUTRONABSORBER IN SOLUTIONS OF FISSILE MATERIAL

A. INTRODUCTION

Section 70.22, "Contents of Applications," of 10 CFRPart 70, "Domestic Licensing of Special Nuclear Material,"requires that applications for a specific license to own,acquire, deliver, receive, possess, use, or transfer specialnuclear material contain proposed procedures to avoidaccidental conditions of criticality. Procedures for thispurpose include incorporating neutron-absorbing materialsuch as boron in process equipment. This regulatory guideprovides guidance for complying with this portion of theCommission's regulations by describing procedures accept-able to the NRC staff for the prevention of criticalityaccidents by use of borosilicate-glass raschig rings as aneutron absorber in solutions of fissile material.Any information collection activities mentioned in thisregulatory guide are contained as requirements in 10 CFRPart 70, which provides the regulatory basis for this guide.The information collection requirements in 10 CFR Part 70have been cleared under OMB Clearance No. 3150-0009.

B. DISCUSSION

ANSI/ANS-8.5-1986, "Use of Borosilicate-Glass RaschigRings as a Neutron Absorber in Solutions of Fissile Mate-rial,"' is a revision of ANSI/ANS-8.5-1979 and was pre-pared by Subcommittee 8, Fissionable Materials OutsideReactors, of the Standards Committee of the AmericanNuclear Society. ANSI/ANS-8.5-1986 was approved by theAmerican National Standards Committee N16, NuclearCriticality Safety, in 1985 and by the American NationalStandards Institute (ANSI) on January 3, 1986.1Copies may be obtained from the American Nuclear Society,555 North Kensington Avenue, La Grange Park, Illinois 60525.ANSI/ANS-8.5-1986 provides guidance on the use ofborosilicate-glass raschig rings as a neutron absorber insolutions of fissile material. The standard applies to theuse of borosilicate-glass raschig rings for primary and forsecondary criticality control in solutions containing 235U,239Pu, and 233U. The chemical and physical environment,properties of the rings and packed vessels, maintenanceinspection procedures, and criticality operating limits arespecified in the standard.Maximum permissible concentrations of homogeneoussolutions of plutonium or of uranium in vessels of unlimitedsize packed with borosilicate-glass raschig rings are specifiedin the standard. The concentration of these solutions isexpressed as the mass of plutonium or of uranium perunit volume. The density of hydrogen in any solutioncannot be less than 75 g/liter nor greater than 115 g/liter.Limitations on the relative abundance of the variousisotopes of plutonium are imposed in the specificationsapplicable to plutonium solutions.. The concentrationsspecified for uranium enriched in 23sU apply regardless ofthe 235U enrichment content but with a limitation on the233U content. For solutions of uranium containing up to5.0 wt-% 235U and up to 0.01 wt-% 233U (see Table 12 onpage 8 of the standard), the maximum permissible solutionconcentration is unrestricted. The concentrations specifiedfor solutions of 233U also apply to mixtures of 233U andother uranium isotopes.

C. REGULATORY POSITION

The guidance contained in ANSI/ANS-8.5-1986 forthe use of borosilicate-glass raschig rings as a neutronabsorber in solutions of fissile material provides a procedure2412Note that in Tble 1 (314) on page 8 of the standard, 41Pu >Pu should read Pu > u4 PU.USNRC REGULATORY GUIDESRegulatory Guides are Issued to describe and make available to thepublic methods acceptable to the NRC staff of Implementingspecific parts of the Commission's regulations, to delineate tech-niques used by the staff In evaluating specific problems or postu-lated accidents or to provide guidance to applicants. RegulatoryGuides are not substitutes for regulations, and compliance withthem Is not required. Methods and solutions different from those setout In the guides will be acceptable If they provide a basis for thefindings requisite to the Issuance or continuance of a permit orlicense by the Commission. -This guide was Issued after consideration of comments received fromthe public. Comments and suggestions for Improvements In theseguides are encouraged at all times, and guides will be revised, asappropriate, to accommodate comments and to reflect new Informa-tion or experience.Written comments may be submitted to the Rules and ProceduresBranch, DRR ADM, U.S. Nuclear Regulatory Commission,Washington, D6 20555.The guides are Issued In the following ten broad divisions:1. Power Reactors 6. Products2. Research and Test Reactors 7. Transportation3. Fuels and Materials Facilities 8. Occupational Health4. Environmental and Siting 9. Antitrust and Financial Review5. Materials and Plant Protection 10. GeneralCopies of Issued guides may be purchased from the GovernmentPrinting Office at the current GPO price. Information on currentGPO prices may be obtained by contacting the Superintendent ofDocuments, U.S. Government Printing Office, Post Office Box37082, Washington, DC 20013-7082, telephone (202)275-2060 or(202)275-2171.Issued guides may also be purchased from the National TechnicalInformation Service on a standing order basis. Details on thisservice may be obtained by writing NTIS, 5285 Rort Royal Road,Springfield, VA 22161.

generally acceptable to the NRC staff for the prevention ofaccidental conditions of criticality.Section 8.0 of ANSI/ANS-8.5-1986 lists additional docu-ments referred to in the standard. The specific applicabilityor acceptability of these listed documents will be coveredseparately in other regulatory guides, where appropriate.

D. IMPLEMENTATION

The purpose of this section is to provide information toapplicants regarding the NRC staff's plan for using thisregulatory guide.The methods described in this guide were applied in anumber of specific cases during reviews and selectedlicensing actions. These methods reflect the latest generalNRC approach to criticality safety in operations involvinguse of borosilicate-glass raschig rings as a neutron absorberin solutions of fissile material. Therefore, except in thosecases in which the applicant proposes an acceptable alter-native method for complying with specified portions ofthe Commission's regulations, the methods described inthis guide will be used in the evaluation of submittals inconnection with license applications submitted Uinder10 CFR Part 70.3.1-2 VALUE/IMPACT STATEMENTA draft value/impact statement was published with theoposed Revision 2 to Regulatory Guide 3.1 (Task CE602-4) when the draft guide was published for publiccomment in March 1987. No changes were necessary,so a separate value/impact statement for the finalguide has not been prepared. A copy of the draftvalue/impact statement is available for inspection andcopying for a fee at the Commission's Public DocumentRoom at 1717 H Street NW., Washington, DC, underTask CE 602-4.,.S. G.P.O. 1987-181-682:602123.1-3 UNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D.C. 20555FIRST CLASS MAILPOSTAGE It FEES PAIDUSNRCPERMIT No. G-67OFFICIAL BUSINESSPENALTY FOR PRIVATE USE, $300