ML20147E117
| ML20147E117 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/13/1987 |
| From: | White S TENNESSEE VALLEY AUTHORITY |
| To: | James Keppler NRC OFFICE OF SPECIAL PROJECTS |
| Shared Package | |
| ML082310196 | List: |
| References | |
| FOIA-87-726 NUDOCS 8801210021 | |
| Download: ML20147E117 (5) | |
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TENNESSEE VALLEY AUTHORITY CH ATTANOOG A. TENNESSEE 37401 6N 38A Lookout Place March 13, 1987 Mr. James G. Keppler Director of Special Projects U. S. Nuclear Regulatory Conssission Airwrights dullding Suite 50318 Washington, D.C.
20555
Dear Mr. seppler:
In the Matter of
)
Docket No:
50-327 Tennessee Valley Authority
)
50-328 Sequoyah (SQN) Design Calculations Review I have received and reviewed the March 5,1987 letter from James M. Taylor (NRC-IE) on the referenced calculations review being conducted by TVA.
At the time I received this letter, TVA had already initiated the necessary actions to resolve the observations made by NRC during the calculations review inspection.
These issues were discussed by TVA with the NRC inspection team during the intpection snd at the February 13, 1987 NRC exit meeting in Knoxville, Tennessee.
Our formal response to the NRC findings from this inspection is scheduled for March 27, 1987.
I feel it is important, however, to respond now to the March S. 1987 letter. The response is enclosed with this letter. These response actions were reviewed by C. H. For, Jr., and W. E. Pennell of my staff with your staff (Ebneter (part timel, Miller, Imbro. Parthill, Richardson, Zwolinski, Llaw, et al) in Bethesdr., Maryland on March 10, 1987.
The NRC findings are being actressed with target dates of April 1, 1987, for completion of the technical verifiest'on of calculations and June 1, 1987, for issue of the calculations program integration leg.
- ach finding is being addressed to determine (a) the nature of tha specific finding's impact and (b) the extent of its generic applicability.
Ine April 1, 1987 schedule is ambitious and may require some minor revisions later this month.
In susmeary, the actions required to respond to the inspection findings have been identified and are being implemeM ed.
Resolution of the calculations technical adequacy issue does not represent an impact to my current July 1987 schedule for SQN unit 2 resta.rt.
Verl truly yours.
TENNESSEE VALLEY AUTHORITY h1 a
PDR S. A. White Manager of Nuclear Power Cnclosvre
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An Equal Cecertunity Employ er
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ENCLOSURE TVA RL'SPONSE TO ISSUES IN KARCH 5, 1987 J. M. TAYLOR LETTER SEQUOYAH CALCULATIONS REVIEW I.
GENERIC ISSUES 1.
Notification to Site Manaaer of Analysis Results With Plant.
Operatina Procedures and Surveillance Requirements InDact The specific instance cited involved a calculation which indicated that Class 1E batteries should be modified. The plant manager's staff was not notified of this needed change at the time the calculation was completed.
Nofification was provided in December of 1986.
The electrical angineering branch is conducting a review of all calculations required for Unit 2 restart to determine if any other cases involving technical specification impact exist. The review will be completed by April 1, 1987.
The TVA design process requires that engineering changes be accomplished by an engineering change notice (ECN). As part of the ECM preparation, impacts on matters such as the plant technical specificatior. most be assessed. Also, the ebange must be subjected to an Unreviewed Safety Question Determination (USQD) in accordance with 10C7R50.59 if the ECN involves an operating plant. The other DNE engineering disciplines are reviewing their activities to confirm that the procedures covering ECN reviews have been complied with. This activity will be subject to oversight by Engineering As surance (EA).
2.
What Defielencies Exist in the Pre-Operatina License (0L) i Calculations?
Each of the branches was directed to perform a generic review of their calculations records to evaluate this concern. The following is a summary of the approach taken and the results obtained to date:
NEB - Some post-OL calculations have been found to lag behind the plant modificatiors.
No significant pre-OL problems have been found.
l EEB - There were deficiencies in the electrical calculations j
completed prior to OL.
All electrical calculations required to support restart are being regenerated.
MEB - The calculations review covered both the pre and post-OL.
calculations.
Some deficiencies were found.n the pre-OL.
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calculations.
These deficiencies are being corrected.
I CEB-Both pre-and post-OL calculations are being reviewed on a sampling oasis.
Most of the problems identified are in the use of alternate analysis and post-OL calculations.
The branch calculations review is scheduled for completion by April 1, 1987. -_
4 3.
Civil Engineering Calculations Review Records The volene of civil engineering calculations is much larger than that in the other branchs9.
In recognition of this large volume of calculations, the reviews performed by a number of independent specialist organizations were used to establish the level of compliance with procedures requirements.
Among the organizations commissioned were Bechtel. Impe11. Gilbert / Commonwealth, and Black &
%eatch. The NRC reviewers expressed a concera in that they were not able to determine the scope and depth of these prior reviews.
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Each of the prior reviews is documented.
TVA is in the process of preparing a comprehensive "Civil Engineering Analysis Verification Report" which extracts and assembles key results from the indisidual reviews.
This report is scheduled for completion by April 1, 1987.
In addition. TVA will be prepared to demonstrate (for future NRC inspections) the basis for the structure of the civil engineering calculations verification plan.
4.
Calculations Program Integration The NRC reviewers expressed concern that they did not have visibility of a comprehensive analysis program integration system.
Areas of particular concerns are (a) calculations supporting engineering changes and (b) interaction between calculations and modifications thereto.
Work is progressing on the production of a comprehensive analysis status tracking and control log.
Features of the log are (a) integretion of the calculations from all four branches.
(b) identification of analyses requirad to support design changes, and (c) identification of interf ace links between calculations.
This ' sos is scheduled to be in place by June 1, 1987.
5.
DB&VP and Calculation Integration In response to the concern that no strong integestion existed between the nuclear and mechanical branches calculations programs and the DBVP both disciplines have expanded their programs to specifically review a number of calculations supporting engineering changes in the DBVP.
II.
SPECIFIC ISSUES The following discussion responds to the like numbered items in the March 5, 1987 letter.
Additional detail will be provided in the response to NRC's inspection report when it is received by TVA.
1.
Main Steam Valve Room Floor Design pressure and concrete strength assumptions contained in the original calculations have been checked with the following results:
Parametee_
Old Value New Value Design Pressure 9 PSIG 7 PSIG i
Concrete-Strength 5000 lb/in2 6100 lb/in2 j
The new values will increase the floor margin of safety relative to that reported in the original calculations.
2.
Ausillarv Buildina Steel _ Platform Calculations A sample total of five platforms is involved in the response to this finding. We hsve completed review and update as necessary of calculations for three of the five platforms. The review has factored in the as-built geometry and materials conditions.
In all instances, the structural margins have'been found to be. positive.
The balance of the pre-restart calculations will be reviewed and revised by May 22, 1987.
3.
C_ontainment pressure Transmitter Accuraev The pressure transducer identified was installed as a result of the TMI "Lessons Learned" program. We agree that it did not have high measurement accuracy at vacuum conditions.
A search for a more accurate transducer is in progress.
The procedures which permitted the selection and installation of this transducer are being evaluated.
It should be noted the containment building vacuum relief valves operate at -0.1 PSIG.
Existing containment building pressure monitoring transducers will monitor the pressures down to this level with the required level of accuracy.
No adverse safety implications exist; therefore, this is a post-restart ites.
4.
Cemponent Coolina Water System Dosian Pressure The original system design pressure was set at 150 PSIG based upon a calculated maximum system operating pressure of 148 PSIG.
Calculation of the revised system operating pressure, including consideration of the surge tant relief valve setpoint, is underway.
It is anticipated that the margins of safety in the system components are adequate to accommodate the design pressure increase.
This analysis update will be completed by April 1, 1987.
Additional actione by TVA, including possible rotesting to justify increased system design pressure, will be identified at that time.
5.
8CCS Pump NPSH Calculation The calculation reviewed was for a large LOCA.
This condition defines the limiting condition for pump flow rate. The calculations will be retitled to reflect the "large LOCA" applicability.
Flow rates associated with the "small LOCA" are reduced, and a reduced NPSH is acceptable for this coadition.
i calculation is being prepared to confirm and document the acceptability of this condition.
Beth of the above actions will be complete by April 1, 1987.
7.
l 6.
A_nalysis Documentation for Buried ERCW Pipina Seisale stress analysis calculations for buried piping are being regenerated. The pipes and penetrations are being evaluated to the requirements of the appropriate code.
Special attention is being given to penetrations and to natural scil / backfill soil interfaces.
To date, all calculated stresses have been less than those allowed.
This calculation regeneration task is on schedule for completion by April 1, 1987.
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