ML20126G632
| ML20126G632 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/29/1992 |
| From: | Zeringue O TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M80681, TAC-M80682, NUDOCS 9301040173 | |
| Download: ML20126G632 (4) | |
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- e' Terneu.ee vaEy AAxay, rssi cece a3 anu occowau asun xxxi O J.1ke",Zeringue vo rwane i num ieny twu+wo DEC 291992 U.S.
Nuclear Regulatory Commission ATTN:
Document Control Desk-Washington, D.C.
20555 Gentlemen:
In the Matter-Of
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Docket Nos. 50-259 Tennessee Valley Authority
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50-296 BROWNS FERRY NUCLEAR PIANT -(BFN) -
RESPONSE TO _ REQUEST FOR -
ADDITIONAL INFORMATION ON ELECTRICAL CABLES IN~ DIVISIONAL AND NONDIVISIONAL TRAYS iTdICH ARE PHYSICALLY--CONNECTED _(TAC:NOS.
M80681 AND M80682)
Reference:
. NRC letter dated April 8,-
1992 - Safety.
Evaluation of TVA Plans'to Resolve Electrical Cable Installation =and Separation' Issues for the Browns Ferry Nuclear Plant Units 1 and 3 In the referenced; letter, NRC requested additional information regarding; cable. separation discrepancies in; Units;
~
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1 and 3? associated with cables in~ divisional-and nondivisional cable trays which are-physically connected.
The. requested information is provided in Enclosure'1. contains a summary list ~of commitments.
04003G-I 8' h l l'
9301040173 921229~
PDR ADOCK 05000259_
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2 U.S.
Nuclear Regulatory Commission DEC 291992 Please refer.any questions to G.
D.
Pierce, Interim-Manager of Site Licensing, at (205) 729-7566.
Sincerely,
?: !,l f! 'l$Y 0.
J.
Zeringue Enclosure cc (Enclosure):
NRC Resident Inspector-
-Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Mr. Thierry-M. Ross, Project Manager U.S.
Nuclear Regulatory Commission One White Flint,-. North 11555 Rockville Pike Rockville, Maryland-'20852 Mr.
B. A. - Wilson, Project Chief U.S.
Nuclear Regulatory Commission-Region II 101 Marietta Street', NW, Suite 2900 Atlanta-Georgia 30323 m
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ENCLOSURE 1 ELECTRICAL CABLES IN DIVISIONAL AND NON DIVISIONAL TRAYS MilICH ARE PHYSICALLY CONNECTED The Electrical Cable Separations Analysis Report which was transmitted from TVA to NRC on October 23, 1989, contcins an evaluation of cables Within the Unit 3 cable trays that were routed in more than one division, violating the separations criteria.
At some locations, divisional and nondivisional cable D,
trays intersected.
Where these intersections were physically connected, it was possible for a nondivisional-cable to be routed in a divisional cable tray.
If the nondivisional cable had-previously been associated with cables of the opposite division, a separation violation resulted.
These routing errors were due to a computer cable routing program which assigned a nondivisional node point to the divisional /nondivisional cable tray intersection.
Nondivisional cables were then routed between nodo points without differentiation based upon previous divisional associations.
Computerized routing has not been-used since the discovery of the computer program problem. -Units 1 and 2 cables have always been routed manually and are, therefore, not subject to this error.
TVA has performed a 100 percent review of the. Unit 3 cable trays.
Two cables, PL1163 and 3PL575, were found to violate the separations criteria.
The power supplies to these cables were disconnected prior to Unit 2 Cycle 6 to procl"io a fault on-the cables from. propagating to more than one diviulon.
Cable _PL1163 will be double-isolated prior to restart of Unit-3.
Cable 3PL575 will be rerouted to correct the deficiency in accordance with TVA design requirements prior to Unit 3 restart.
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ENCLOSURE 2 COMMITMENTS 1.
Cable PL1163-will be double isolated prior to' restart-of Unit 3.
2.
Cable 3PL575 will be rerouted to correct the deficiency in accordanco with TVA design requirements prior to Uniti3 restart.
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