ML20247D003
| ML20247D003 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/24/1989 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20247D009 | List: |
| References | |
| NUDOCS 8903300344 | |
| Download: ML20247D003 (6) | |
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TENNESSEE VALLEY AUTHORITY 4
CH ATTANOOGA, TENNESSEE 37401 5N 1578 Lookout Place MAR 241989 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 - INTEGRATED DESIGN INSPECTION (IDI) FOLLOW-UP ON REACTOR COOLANT PUMP (RCP) SUPPORT SEISMIC LOADS - NRC INSPECTION REPORT NOS. 50-327/88-13 AND 50-328/88-13
References:
1.
TVA letter to NRC dated March 2, 1988, "Sequoyah Nuclear Plant (SQN) - Integrated Design Inspection (IDI) - NRC Inspection Report Nos. 50-327/87-48 and 50-328/87-48" 2.
NRC letter to TVA dated May 26, 1988, " Inspection Report Nos.
50-327/88-13 and 50-328/88 Integrated Design Inspection Follow-Up" The commitment to perform an additional evaluation of the RCP supports resulted from questions that arose during NRC's IDI at SQN in February 1988.
Inspection report 88-13 (reference 2) documented NRC's investigation into this item and concluded that TVA's additional evaluation of the RCP support design could be performed postrestart.
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Enclosures 1 and 2 provide the results of the evaluation of the RCP supports.
Specifically, the enclosures provide an evaluation of the validity of the seismic loads contained in Westinghouse Electric Corporation's stress report SD-119.
TVA's original evaluation was transmitted by reference 1. provides an overall discussion of this issue.
This discussioi.
concludes that, after incorporation of the new seismic loads provided by Westinghouse, the RCP anchorage continues to meet the operability criteria for the low probability event of a combined loss of coolant accident and safe shutdown earthquake.
The operability criteria were reviewed and accepted by NRC during the IDI. TVA plans to resolve this issue by reducing the design basis loss of coolant accident loads by application of leak-before-break (LBB) technology to demonstrate compliance with both the SQN design basis criteria and the Final Safety Analysis Report commitments for the RCP anchorage.
SQN's application for LBB is currently being prepared and it will be submitted by a separate letter.
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l contains the Westinghouse report, " Structural Analysis and Evaluation of the Sequoyah Reactor' Coolant Pump Support Columns'" This-report summarizes.the design basis analysis and demonstrates the-
. structural. integrity of the SQN RCP supports.
Please direct questions concerning this issue to E. T. Knuettel at I
(615) 843-7215.
Very truly yours, TENNESS E VALLEY AUTHORITY' R.
idley, M ager Nuclear.Licen ing and Regulatory Affairs i
Enclosures cc (Enclosures):
Ms. S. C. Black, Assistant Director for Projects
'TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Ms. L. J. Watson, Acting Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 4
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ENCLOSURE 1 SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 REACTOR COOLANT PUMP (RCP) SEISMIC LOADS TITLE Relative magnitude of operating base earthquake (OBE) and safe shutdown earthquake (SSE) loads on the RCP anchorage.
DEFINITION AND BACKGROUND During NRC's integrated design inspection (IDI) at SQN in February 1988, an NRC reviewer inquired about the reasons for the calculated OBE loads on the RCP supports given in Westinghouse Electric Corporation's Report SD-119 being greater than the SSE loads..An explanation was transmitted by TVA to NRC as enclosure 2 to reference 1 of this enclosure. As stated oa page A4-17 of reference 2, NRC accepted that explanation for the restart af unit 2; but they requested that TVA provide edditional justification postrestart.
RESPONSE
Subsequent to the previous response of reference 1 Westinghouse conducted additional investigations, at TVA's request, that revealed that an invalid-assumption had been made in the original calculation of the RCP seismic loads. Upon notification by Westinghouse, TVA initiated condition adverse to quality report (CAQR) SQP880352 (reference 3), in conformance with TVA's quality assurance program, and proceeded with corrective action as described below.
As described in the Westinghouse report transmitted by reference 4 (enclosure 2), Westinghouse recalculated the seismic loads in combination with other design basis loads and investigated the possible implications of the invalid assumption on other equipment that Westinghouse had supplied to SQN and Watts Bar Nuclear Plant.
They concluded that the invalid assumption was confined to the SQN RCP column seismic loads and that the components in their scope of supply are structurally adequate.
TVA incorporated the new seismic loads from Westinghouse into the evaluation of the RCP anchorage system. The results of that evaluation demonstrate that the RCP anchorage continues to meet the operability criteria for the low probability event of a combined loss of coolant accident (LOCA) and SSE.
The operability criteria were reviewed and accepted by NRC during the IDI.
- Thus, even with the increase in seismic loads, the status of the anchorage system is unchanged.
The results of these evaluations are equally applicable to both units 1 and 2.
The plan for long-term resolution of this issue is to use the results of an ongoing leak-before-break effort to show that the design basis LOCA loads are lower than originally calculated. The results will then be applied to the evaluations of the RCP columns and anchorage systems, thus ensuring compliance with SQN design basis criteria and with the Final Safety Analysis Report commitments.
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References.
1.
TVA. letter to NRC dated March,2,1988,."Sequoyah Nuclear Plant.(SQN) -
Integrated Design Inspection (IDI);- NRC. Inspection Report Nos.
50-327/87-48 and 50-328/87-48 o
l 2. - NRC letter to TVA dated May 26, 1988, " Inspection Report Nos. 50-327/88-13
.L and 50-328/88 Integrated Design. Inspection Follow-Up" 3.
CAQA SQP380352 4.
Westinghouse letter to.TVA dated November. 21, 1988, " Tennessee Valley.
Authority Sequoyah Nuclear Power Plants Reevaluation of RCP Support Column H
Loads"-.(enclosure 2 to this' submittal) f i
t ENCLOSURE 2 Westinghouse Electric Corporation Letter to TVA dated November 21, 1988
" Tennessee Valley Authority Sequoyah Nuclear Power Plants Reeval'uation of RCP Support Column Loads" (B31 881130 001)
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ENCLOSURE 2 B31
'88 1130 001 Westinghouse EnergySystems
$3" Bectric Corporation g eng,n,,m3x33 NOV 301988 K. S. Seidle TVA-88-860 Civil Engineering Branch November 21, 1988 Tennessee Valley Authority 400 West Summit Hill Drive Ref: }! Ltr. TVA-88-668 Knoxville, TN 37902 June 10, 1988 TVA Contract No.
85P62-965930 RD# 428872 Tennessee Valley Authority Sequoyah Nuclear Power Plants Reevaluation of RCP Support Column loads
Dear Mr. Seidle:
We are submitting our report entitled,' " Structural. Analysis and Evaluation of the Sequoyah Reactor Coolant Pump Support Columns" Revision 0 dated September 1968. This final version of the report addresses the comments provided us by your staff.
This report was prepaFed for TVA for use in responding to the NRC's Integrated Design Investigation (IDI) finding associated with the RCP Support Column embedments and the validity of the seismic loads provided in our stress Report SD-119. Accordingly, the report summarizes the design basis analysis, and demonstrates the structural integrity of the Sequoyah RCP support columns, thus, serving as a basis for justification for continued operation of the Sequoyah units.
Very truly yours, WESTI GHOUSE ELECTRIC CORPORATION 3
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/7. A, ordi, Manager S} g SL26 C-K TVA Sequoyah Project Customer Projects Department cc: P. G. Trudel D. L. Lundy '
W. R. Mangiante D. M. Lafever R. E. Daniels K. R. Spates 0667e L
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