ML20247L190
| ML20247L190 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/26/1989 |
| From: | May R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8908010176 | |
| Download: ML20247L190 (3) | |
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' TENNESSEE VALLEY AUTHORITY OH ATTANOOGA. TENNESSEE 37401 5N 1578 Lookout Place JUL 261989 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C.
20555 Gontlemen:
In the Matter of
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Docket No. 50-327 Tennessee Valley Authority I
'SEQUOYAH NUCLEAR PLANT (SQN) UNIT 1 - EVALUATION OF 10 CFR 50.49 VERTICAL CONDUIT RUNS
Reference:
TVA letter to NRC dated December 8, 1986, "Sequoyah Nuclear Plant (SQN) - Cable Pulling Questions:
Supplemental Responses" In the referenced letter, TVA committed to inspect all 10 CFR 50.49 vertical conduit runs and evaluate, schedule, and implement any corrective actions by the Unit 1 Cycle 4 refueling outage.
TVA has now determined, however, that it is appropriate to limit the scope of the commitment to the 10 CFR 50.49 vertical conduit runs in the Unit 1 annulus.
Based on the evaluation of the Unit 2 vertical conduit runs, it has been concluded that the potential for cable failure because of excessive static sidewall pressure in unsupported cables is limited to the annules only. After a review for Unit 2 of approximately 2,800 cables, a walkdown of 480 conduits, and calculations on 403 cables (including 129 cables in the annulus), there was only 1 conduit in the auxiliary building that was in nonconformance with the Naticnal Electrical Code's (NEC) cable support requirements and exceeded the maximum allowable sidewall pressure limits.
Despite the nonconformance, the 6 cables in that conduit were not damaged. Conversely, there were 7~ conduits containing a total of 48 cables in the Unit 2 annulus that exceeded both the NEC spacing limits and the sidewall pressure limits.
In these conduits also, no cable damage was detected.
TVA expects similar results for Unit 1 and plans to limit the evaluations to the Unit 1 annulus area.
Additionally, TVA will inspect, evaluate, and correct, if necessary, the Unit 1 conduit and cables corresponding to those identified as deficiert in Unit 2.
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- fA: summary: statement of'the' revised. commitment is contained in the enclosure,
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y Please' direct questions concerning this. issue to B. S..Schofield at
-(615)'843-6172.
'Ve.ry truly yours, TENNESSEE VALLEY AUTHORITY
$7 Mana r, Nucletr Licensing and Regulatory Affairs
. Enclosure :
cc (Enclosure):
- Ms. S. C.. Black, Assi.stant Director.
for.l Projects '.
TVA Projects Division 1
U.S. Nuclear Regulatory Commission One White Flint, North
- 11555:Rockville' Pike' Rockville,. Maryland 20852:
Mr. B. A. Wilson, Assistant Director.
foreInspection Programs-t.TVA Projects Division
- U.S. Nuclear' Regulatory. Commission Region II-101..Marietta Street, NW,. Suite 2900 Atlanta, Georgia 30323 4
.NRC Resident ~ Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road i
Soddy Daisy,' Tennessee 37379 o
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ENCLOSURE.
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i Revised Commitment:
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7-For' Unit -1,- TVN w11111nspect all l10 CFR 50.49' vertical ' conduit runs' in the
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. annulus and will evaluate,. schedule, and. implement-any. required corrective
. action by.the lend of the Unit 1 Cycle 4 refueling outage.. Additionally, by Lthe end of the Unit 1 Cycle.4 refueling outage, TVA will inspect, evaluate,
. ar:d correct, if. necessary,- the Unit 1_ conduit and cables' corresponding to
'those! identified as' deficient in Unit 2.
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