05000327/LER-1981-016-03, /03L-0:on 810206,diesel Generator 2B-B Breaker Tripped Twice While Attempting to Synchronize W/Tva Power Grid for Surveillance Test SI-7.Caused by Overcurrent During Paralleling Operation.Target Reset & Parallel Repeated
| ML20008E916 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/05/1981 |
| From: | Maddox S, Mcgriff J TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20008E914 | List: |
| References | |
| LER-81-016-03L, LER-81-16-3L, NUDOCS 8103100504 | |
| Download: ML20008E916 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 3271981016R03 - NRC Website | |
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Tennessee Valley Authority Sequoyah Nuclear Plant LER SUPPLEMENTAL INFORMATION SQRO-50-327/81016 Technical Specification Involved:
3.8.1.1 Reported Under Technical Specification:
6.9.1.13.6, 4.8.1.1.4 Date of Occurrence: 2/6/81 Time of Occurrence: 0915 CST Identification and Description of Occurrence:
During the conduct of Sarveillance Instruction SI-7 to verify operability of diesel generator (D/G) 2B-B, the D/G was started on a simulated loss of off-site power signal. The D/G started and accelerated properly; however, when the diesel was being synchronized with the TVA grid, the D/G breaker tripped twice. The breaker remained closed on the third attempt and the D/G was successfully loaded.
Conditions Prior to Occurrence:
Unit 1 in mode 4 at 210 F and cooling to mode 5.
Apparent Cause of Occurrence:
The D/G breaker apparently tripped on overcurrent during the paralleling operation which ties the D/G to the TVA grid for loading of the D/G for Surveillance Test SI-7.
Analysis of Occurrence:
During the performance of SI-7, the D/G started properly in response to a simulated loss of of fsite power signal. The D/G was being manually synchronized with the TVA grid when the D/G breaker was closed. The D/G breaker tripped immediately. The paralleling operation was attempted again and the breaker tripped again. On the third attempt the breaker remained closed and D/G 2B-B was successfully loaded.
Corrective Action
The immediate corrective action takenwas to verify that the D/G system align-ment was correct. The overcurrent relay, synchroscope and voltmeters were checked and verified to be correct. No further corrective actions are planned.
The overcurrent-relay and synchronizing circuits are cut out of the diesel generator control and logic for an emergency condition.
. Failure Data:
The following additional information is submitted in accordance with Technical Specification 4.8.1.1.4 and Regulatory Guide 1.108:
D/G Involved: 2B-B
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Failure Data: (Continued)
Failure No: N/A. The diesel generator breaker tripped on an overcurrent relay operation. This circuit and the synchronizing circuit are cut out during the emergency operation of the diesel generator. This was classified as an invalid test in accor-dance with Regulatory Guide 1.108, Position C.2.3.(2).
Cause of Failure: The D/G breaker tripped on an overcurrent relay operation.
The exact cause for the overcurrent condition is unknown.
The diesel generator system alignment was verified Corrective Measures:
The overcurrent relay, synchroscope,and volt-to be correct.
meters were verified to operate properly.
Length of Tine Inop:
34 minutes Surveillance Frequency: The present frequency is every seven (7) days.
This is in compliance with Regulatory Position C.2.d of Regulatory Guide 1.108 for three (3) failures in the last 100 valid tests.
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