ML20154M592
| ML20154M592 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/27/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| TAC-00022, TAC-00023, TAC-00024, TAC-22, TAC-23, TAC-24, NUDOCS 8806020015 | |
| Download: ML20154M592 (8) | |
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TENNESSEE VALLEY AUTHORITY SN 157B Lookout Place MAY 271988 U.S. Nuclear Regulatory Conunission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-259 Tennessee Valley Authority
)
50-260 50-29C BROWNS FERRY NUCLFAR PLANT (BFN) - SEISMIC QUALIFICATION OF CONDUIT - (NRC TAC 00022, 00023, AND 00024)
This letter describes the BFN program for the seismic qualification of conduit. This material ;cas requested by R. J. Clark's letter dated July 31, 1986 to S. A. White. This letter supplements the information provided by my letter dated April 8, 1987 and section III.3.4 of revision 1 to the BFN Performance Plan which was transmitted by S. A. White's letter dated July 1, 1987 and incorporates resolutions to the NRC staff's concerns as discussed in our May 18, 1988 meetin6 to this letter describes the BFN program for resolving this issue. Enclosure 2 is a copy of the interim operability criteria. TVA requests your review of this program and the issuance of a written statement documenting the progrants acceptability.
Please refer any questions regarding this submittal to M. J. May, Manager, BFN Site Licensing, (205) 729-3570.
Very truly yours, l
TENNESSEE VALLEY AUTHORITY I
R. Gridley, Di ect r Nuclear Licensing and i
Regulatory Affairs Enclosures cc: See page 2 Q
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8806020015 880527 PDR ADOCK 05000259 P
DCD An Equal Opportun!ty Employcr l
U.S. Nuclear Regulatory Commission ll if g g
cc (Enclosures):
Mr. K. P. Barr, Acting Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission y.
Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. G. G. Zech, Adsistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission OnLiWhite Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Browns Ferry Resident Inspector
< Browns Ferry Nuclear Plant Route'12. P.O. Box 637 Athens, Alabama 35611 f
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e ENCLOSURE 1 Seismic Design Issues - Conduit Qualification Program The following is provided in responso to the July 31, 1986 letter from R. J. Clark to S. A. White and Request 'for Additional Information Item No. 2 of enclosure 2 to that letter:
2.
Conduit Qualification Program - please provide information similar to Item 1 above (background information, long-term correctivo actions, and implementation schedulo) for the conduit qualification program.
Part I - Background Historical background on the issue of soismic design of conduits is provided in Section I.C, "Executive Summary and Historical Background,"
of the DNE Program Document, "Inspection and Scismic Qualification of Existing Electrical Conduit and Conduit Supports," which was provided as an enclosure to the April 8, 1987 submittal from R. Gridley, Part II - Corrective Action Program The following documents, provided as enclosures to the April 8, 1987 submittal from R. Gridley, presented the details of the BFN conduit seismic qualification program:
DNE Program Document, "Inspection and Scismic Qualification of Existing Electrical Conduit Supports," issued October 16, 1986 -
Program overview.
Project Instruction BFEP-PI 85-02, Revision 3, "Scismic Qualification of Existing Electrical Conduit and Conduit Supports," issued October 15, 1986 - Details DNE's method for inspection and seismic qualification of existing electrical conduits and conduit supports in Class I structures at BFN.
The following documents, provided as enclosures to the April 8, 1987 submittal from R. Gridley, presented additional supporting information for the conduit qualification program:
Design Criteria BFN-50-723, "Seismically Qualifying conduit Supports,"
issued March 28, 1986, as modified by Exception Number EX-BFN-50-723-1, dated May 29, 1986 - Gives seismic qualification requirements.
Exception Number EX-BFN-50-723-1 was never implemented.
Its proposed use is being
' withdrawn by this submittal.
TVA test report WR28-4-900-176, "An Experimental Investigation of Vibration Dacping in Aluminum Electrical Conduit," dated March 1986 -
Describes TVA tests used in determining natural frequencies and damping values for aluminum olcetrical conduit.
. TVA test report WR28-4-900-140, "A Preliminary Study of Vibration Damping in Electrical Conduit," revised March 1986 - Describes tests used to determine damping values for stool electrical conduit.
Wyle Laboratories Soismic Qualificatlon Test Report No. 17743-1, "Test Report on_Scismic Qualification / Verification of Various Aluminum Electrical Conduit Configurations," dated May 9, 1986 - Demonstrated "that the specimens tested possessed sufficient structural integrity to withstand the proscribed qualification level scismic environment."
The majority of the design and modification work associated with the conduit qualification program has been completed.
Modifications required for unit 2 interim qualification are scheduled for completion by restart.
Part III - Conclusion and Roquest for Review Certain aspects of the conduit qualification program involve the utilization of new techniques for interim operability to demonstrato original design basis was satisfactory.
In this regard, NRC is requested to take the following actions:
Review and approvo for interim qualification, bounding calculations a.
demonstrating the adequacy of the type of features accepted by a seismic experienco data baco review.
b.
Review and approve for interim qualification, use of the Interim Operability Critoria (Lead Civil Engincor Instruction BFEP-TI-C1).
c.
Concur that long-term qualification bo implemented in accordance with the guidelines developed by the Soismic Qualification Utility Croup (SQUG) to resolvo Unresolved Safety Issues (USI) A-46 and to a schedule consistent with the resolution of USI A-46 for Browns Ferry Nuclear Plant.
En e /asure e2 QA Record B22 :88 0523 010 TENNESSEE VALLEY AUTHORITY Tennessee Valb Division of Nuclear Engineering Authority LEAD CIVIL ENGINEER INSTRUCTION BFEP-TI-Cl TITLE:
OPERABILITY CRITERIA FOR CONDUIT AND CONDUIT SUPPORTS - BRO'n'NS FERRY s
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r REVISION RO R1 R2 R3 R4 R5 ISSUE DATE g/23/gg gf PREPARED CHECKED C
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OPERABILITY CRITERIA FOR CONDUIT AND CONDUIT SUPPORTS - BROWNS-FERRY g,.
Revision DESCRIPTION OF REVISION o l',o
- No; Original Issue 4
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TVA 10534 (EN DES 4 78)
OPERABILITY CRITERIA FOR CONDUIT
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AND CONDUIT SUPPORTS - BROWNS FERRY BFEP-TI-C1 1.0 PURPOSE The purpose of this instructi,on is to provide engineering guidelines for implementing Browns Ferry operability criteria as applicable to conduit and conduit supports.
2.0 SCOPE These guidelines shall apply to conduit and supports in TVA Class I structures, for which conduit or conduit support modifications are required; i.e.,
any physical modification of conduit or conduit support required as a result of the inability to qualify according to Design Criteria BFN-50-C-7104 Section 5 (Reference 6.1).
Modifications will be prioritized into two groups; those that require implementation for operability and those that require implementation for design criteria.
Operability modifications are those conduit and conduit support modifications that do not comply with the criteria in this document. Design criteria modifications are those conduit and conduit support mcdifications that comply with the requirements of this document but are necessary for design criteria compliance.
3.0 CONDUlT STRESS EVALUATION CRITERIA For conduit systems that do not meet the design criteria BFN-50-C-7104 a conduit system operability review may be performed as follows.
Conduit stresses and conduit support reactions shall be generated using a seven percent damped' spectra.
The conduit shall be evaluated for dead weight plus Design Basis Earthquake (DBE), to ensure that the stress in the conduit is limited to a maximum of 2.0 Fy, reduced by a stress intensification factor of 0.75 times 2.3 for threaded connections as app]1 cable.
Cast iron components may be evaluated as equivalent conduit stresses established by test.
In cases where conduit exceeds the stress allowables, qualification may be demonstrated by furtherianalysis, test, or safety significance evaluation.
This approach shall be used only on a case-specific basis.
4.0 CONDUIT SUPPORT EVALUATION CRITERIA 4.1 Load Combinations For the purpose of this evaluation, the only load combination considered is dead load plus the DBE.
4.2 Allowable _ Limits The following limits shall be used in the evaluations.
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,..,,0pERABIh1TY CRITERIA FOR CONDULT AND CONDUlT SUPPORTS - UROWNS FERRY
' BFMP-TI-C 1 4. 2 '.1 - Supports Condull supports shall be evaluated based on stress allowables or test data as follows.
Acceptabic flexural /and tenslic stresses shall be the Icssor of 0.7F and 1.2F and 90 percent of the critical u
y buckling stress as defined in AISC specification (Reference 6.2) for compressive loads.
Acceptabic shear stresses shall be the icsser of 0.42F and 0.72F u
y.
Acceptable loads based on test data shall consider mean less one standard deviallon capacity.
4.2.3 Bolting The allowabic cLeess for botting shall be the minimum speelfled yicid stress of the colt material. When the yield stress of the bolt material is not specified,'the allowabic stress shall be 10 percent of the minimum specified ultimale strength.
4.2.4 ConcretehxpansionAnchors The minimum factors of safety for concreto expansion anchors (wedge & shell types) shall be 2.0 (Reference 6.3).
4.2.5 Load Sharing Between Supports
.For supports that do not meet the interim allowabic stress criteria presented herein, a case-by-case evaluation may be performed that considers redisleibullon of load to adjacent supports.
The ofroct of load tedistribullon on conduit stress shall be considered in accordance with secllon 3.0.
The adjacent conduit supports shall meet the allowabics contained in this criteria document.
5.0 DOCUMENTATION Engineering evaluallons performed to determine the acceptability of modifications shall be documented in calculations performed in accordance with the applicabid QA reqpirements.
6.0 REFERENCES
6.1 Design Critoria for Uccign of Supports BFN-50-C-7104.
6.2 Specificallon for the Design, Fabrication, and Krection of Structural Steel Buildings, AISC 1TH and 8TH Edillons.
6.3 Concral Anchorage to Concrete, Civil Design Standard DS-CL.7.1.
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