ML18032A737
| ML18032A737 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/10/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML18032A738 | List: |
| References | |
| TAC-00301, TAC-301, TAC-R00301, TAC-R00302, TAC-R00303, TAC-R301, TAC-R302, TAC-R303, NUDOCS 8803150303 | |
| Download: ML18032A737 (12) | |
Text
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0 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR: 8803150303 DOC. DATE: 88/03/10 NOTARIZED:
NO FACIL: 50-.260 Browns Ferry Nuclear Power Stations Unit 2i Tennessee AUTH. NAME AUTHOR AFFILIATION QRIDLEYe R.
Tennessee Valley Authority RECIP. NAME RECIPIENT AFFILIATION Document Contro I Branch (Doc ument Control Des k )
DOCKET 5 05000260
SUBJECT:
Forwards description of facility program for resolving issue of seismic qualification of drgwell steel Zc CY iteria BFN 50 C 7100'Detailed Design Criteria for Structural Acceptance of Drgwell Access Platforms."
DISTRIBUTION CODE:
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TITLE:
TVA Facilities Routine Correspondence NOTES: Q. Zech 3 cg.
1 cg.
ea to: Ebneteri Axelradi S.
Richardson'.
D. Liaw> K. Barr>
OI.
05000260 REC IP IENT ID CODE/NAME JAMERSONi C MORAN' COP IES LTTR ENCL 1
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TENNESSEE VALLEYAUTHORITY CHATTANOOGA. TENNESSEE 37401 5N 157B Lookout Place MAR 10 1988 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Authority Docket Nos.
50-260 BROWNS FERRY NUCLEAR PLANT (BFN) SEISMIC QUALIFICATION OF DRYWELL STEEL This letter describes the BFN program for the seismic qualification of drywell steel.
This letter supplements the information provided by section III.3.8 of revision 1 to the Browns Ferry Nuclear Performance Plan that was transmitted by S.
A. White's letter dated July 1, 1987.
Enclosure 1 to this letter describes the BFN program for resolving this issue.
Enclosure 2 provides the BFN drywell steel interim operability criteria.
TVA requests your review of this program and the issuance of a written statement documenting the programs acceptability.
Please refer any questions regarding this submittal to M. J.
May, Manager, BFN Site Licensing, (205) 729-3570.
Very truly yours, TENNESSEE VALLEY AUTHORITY Enclosures cc:
See page 2
R.
G idl y, D rec or Nuclear Licensing and Regulatory Affairs 8803i50303 880310 PDR ADDCK 05000260 P
PDR o>'n Equal Opportunity Empioyer
4I
U.S. Nuclear Regulatory Commission MAR 10 1988 cc (Enclosures):
Mr. K. P. Barr, Acting Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NH, Suite 2900 Atlanta, Georgia 30323 Mr. G.
G. Zech, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One Nhite Flint, North 11555 Rockville Pike Rockville, Maryland 20852 il Browns Ferry Resident Inspector Browns Ferry Nuclear Plant Route 12, P.O.
Box 637
- Athens, Alabama 35611
4 l"
V
Enclosure 1
TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT UNIT 2 DRYWELL STEEL PLATFORMS This report gives TVA's plan to demonstrate the adequacy of drywell steel platforms.
Issue A nonconforming condition report identified an unanalyzed attachment to one of the lower drywell platforms.
Investigation showed this to be part of a generic problem for all drywell platforms.
~Back round While dispositioning nonconforming condition report BFN-BWP-8309, the following was determined:
Drywell floor framing steel at elevations 563'nd 584'ad not been reevaluated for some loads which were added or revised since the original design, structural behavior of platforms under combined loadings was not completely evaluated and documented, and some configurations did not match drawings.
Additional findings were later identified in SCR BFN CEB
- 8634, 8640, and 8643 on platforms at elevations 604', 616',
and 628'.
Resolution To ensure the adequacy of drywell steel platforms, the following plan was implemented:
l.-
A detailed walkdown of all drywell platforms was performed to document the as-built configuration.
2.
Detailed analysis of each platform was performed using the GT-STRUDL program.
The model included primary as well as secondary steel that supports piping systems and cable trays.
All support loads considered were the maximum values for OBE and DBE load conditions.
Resulting stresses were compared to an interim Operability Criteria based on the AISC code.
The allowables are summarized in Table l.
3.
Modifications are necessary to meet the interim operability criteria on secondary steel beams and connections and are mainly due to safety relief valve piping loads.
Additionally, stiffener plates are being added to reduce the local stresses in beams at attachment points.
4.
Additional modifications will be made to correct installation problems observed during the walkdowns.
5.
All modifications necessary to meet operability criteria will be made before restart of unit 2.
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6.
The FSAR requires that the drywell steel platforms remain functional for loads due to the platform weight and all attachment loads.
Specific stress allowables are identified in FSAR Table 12.2.16.
These commitments are reflected in the design criteria for drywell steel platforms.
The drywell platform design will be brought up to the FSAR commitment postrestart incorporating final pipe support attachment loads consistent with the schedule for completion of the program to resolve IE Bulletin 79-14.
Modifications required to meet design criteria will be implemented before restart following the next refueling outage.
To ensure the structural adequacy of drywell platforms for future attachments, a long-term program has been established to monitor and evaluate new attachments.
Licensin Issue The Interim Operability Criteria used -to determine the. structural adequacy of drywell platforms allows 1.6 times the capacity 'S'ased on the AISC code, instead of the FSAR stress limits of 0.9Fy.
Justification The use of the Operability Criteria on an interim basis is considered justified because of the following:
1.
The interim operability criteria minimizes the modifications in highly congested radioactive areas now, while maintaining adequate industry accepted safety margins.
2.
The long-term program provides for updating the designs for the latest
'oads, resulting from the 79-14 program, and meeting the FSAR requirements.
3.
The operability cri teria is based on Standard Review Plan 3.8.3, which has been accepted for use on other nuclear power plants.
The drywell steel qualification program is comprehensive and assures the structural adequacy of the drywell steel platforms.
Steel Allowable
- Tension, Bending Stress TABLE 1
DRYWELL STEEL PLATFORMS CRITERIA COMPARISON INTERIM DESIGN CRITERIA
-. OPERABILITY up to 0.9Fy 1.6 X AISC REMARKS BASED ON SRP Steel Allowable Shear Stress up to 0.4Fy 1.6 X AISC BASED ON SRP Weld Allowable Shear Stress up to 0.4Fy of Base Metal 1.6 X AISC BASED ON SRP Concrete Anchor Factor of Safety Hedge
& Shell Type Hedge Type 4
Shell Type 5 for Tension 4 for Shear All Types 2
SIMILAR TO PIPE SUPPORT OPERABILITY CRITERIA
Enclosure 2
Browns Ferry Nuclear Plant Drywell Steel Interim Operability Criteria