ML20236Y201
| ML20236Y201 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/08/1987 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8712110172 | |
| Download: ML20236Y201 (4) | |
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA, TENNESSEE 37401 SN 157B Lookout Place i
DEC 081987
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l U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 l'
Gentlemen:
In the Matter of Docket Nos. 50-327 1
Tennessee Valley Authority 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - REPLACEMENT ITEMS PROGRAM -(RIP) SEISMIC ADEQUACY VERIFICATION i
This letter is in response to the requirement to upgrade seismic adequacy justifications before SQN restart, as set forth in item 2 of the October 29, l
1987 letter received from James G. Keppler. TVA believes that some very l
important aspects of the original question have been overlooked and that a review of the RIP efforts with regard to seismic adequacy is in' order.
The' issue TVA has answered in the seismic adequacy portion of the RIP centers j
J around_ equipment originally procured to The Institute of Electrical and Electronics Engineers, Incorporated Standard 344/75.
Specifically, the integrity of-that equipment's original qualification was questioned when commercial grade items (CGIs) had been used as replacement parts as a result i
of normal maintenance activities.
It is essential at this point to understand l
that the equipment in question' was assembled by the original equipment l
manufacturer from CGIs and that the original CGIs were not qualified to any i
specific nuclear str.ndard.
The original CGIs were seismically qualified only as a part of a whole assembly using a prototype testing format.
It is important to note that 344/75 is very specific in component level qualifications; however, it does not specifically address actions to be taken for subcomponents introduced into the Equipment during normal maintenance e
activities.
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It was because no guidelines existed for subcomponent replacement that TVA l
adopted a program based on a reasonable engineering evaluation.
The program developed by TVA did nct attempt to qualify the replacements in question bu' did review those replacement items for seismic adequacy with respect to overall equipment qualification.
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8712110172 871208 PDR ADOCK 05000327 P
PDR An Equal Opportunity Employer
. U.S. Nuclear Regulatory Commission g Q g ]gg7 TVA employed both quantitative and qualitative methods to ensure the seismic qualification of the equipment had not been degraded.
The methods used by TVA included, among others, traditional seismic criteria, plant walkdowns, and experience data methodology developed by nuclear industry groups in conjunction with NRC for the resolution of more widespread seismic concerns regarding older nuclear plants.
TVA's maintenance replacement item activities were performed using the same part/model number or an equivalent item specified by the original manufacturer (e.g., like-for-like replacement). Mafy tradit'inal seismic criteria are r
inherent in like-for-like replacements (i.e., mass, mounting, center of l
gravity) and were an integral part of the evaluation.
The evaluation program l
verified that mounting configuration was unchanged and that no materials were issued that could have altered mounting configuration.
Further, TVA's maintenance program prohibits actual changes in plant configuration which eliminates concerns about unreviewed plant modifications.
The experience data, which includes seismic qualification test results as well as data derived from actual seismic events, is the latest method available to the industry and was used as an additional tool by qualified reviewers in the evaluation process. A combination of traditional seismic criteria, plant walkdowns when necessary, and experience data was used to provide the basis from which sound engineering evaluations could be made when no other established guidelines were available.
Engineering evaluations have been performed on over 100,000 maintenance request documents that potentially could have degraded the overall seismic adequacy of SQN unit 2.
Evaluations in accordance with item 2 of the NRC October 29, 1987 letter were upgraded as a result of the July inspection performed by the staff and to date have not vielded 2. single instance where the replacement item degraded the seismic qualification of its installed application.
The engineers performing the evaluations were familiar with all aspects of equipment qualification as it relates to seismic consideratic'ns and were specifically trained in the use of experience data as an evaluation tool.
In summary, TVA has made a conscious and reasonable effort to address the question of seismic qualification degradation as a result of maintenance replacement items.
This effort was based on sound engineering principles and was performed in a controlled, documented format by qualified individuals.
TVA has verified that the maintenance program at SQN did not-alter the seismic qualification of plant equipment.
Therefore, the seismic integrity of SQN unit 2 has not been degraded and no further action in this area is required before restart.
TVA will submit a program plan by January 27, 1988, that addresses item 1 of your October 29, 1987 letter and justifies reducing the scope of unit 2 postrestart and unit 1 commitments.
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.. U.S. Nuclear Regulatory Commission OQ Q$ ]ggf Your written response to this letter is requested to avoid unnecessary delays in SQN restart.
TVA believes the approach described in this letter and procedures that were made available for NRC review should be acceptable to NRC. Commitments made in this letter are outlined in the enclosure.
Please have someone from your staff telephone Joe Ziegler at 615/751-8077 if further information or clarification is necessary.
Very truly yours.
TENNESSEE. VALLEY AUTHORITY l,/.
R. Gridley, Dir tor Nuclear Licensi g and Regulatory A fairs Enclosure cc (Enclosure):
Mr. K. P. Barr, Acting Assistant Director for Inspection Programs TVA Projects. Division Office of Special Projects U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mt.'G. G. Zech, Assistant Director for Projects TVA Projects Division Office of Special Projects U.S. Nuclear Regulatory Commission 4350 East-West Highway EHH 32e Sethesda, Maryland 20814 Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379
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ENCLOSURE 1 TVA will submit a program plan that addresses item 1 of NRC's October 29, 1987 letter and justifies reducing the scope of unit 2 postrestart and unit I commitments by January 27, 1988.
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