ML19317D843
| ML19317D843 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/13/1977 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19317D839 | List: |
| References | |
| RO-269-77-20, NUDOCS 7912100572 | |
| Download: ML19317D843 (2) | |
Text
.
DUKE POWER COMPANY OCONEE UNIT 1, 2 AND 3 Report No.: R0-269/77-20 Renort Date: July 13, 1977 Occurrence Date: June 28, 1977 Facility: Oconee Units 1, 2 and 3, Seneca, South Carolina Identification of Occurrence:
125 VDC switching station battery charger failure; associated battery subsequently determined inoperable Conditions Prior to Occurrence: Unit 1 at 100 percent full power; Unit 2 in refuel-ing shutdown; Unit 3 at 80 percent full power Description of Occurrence:
On June 28, 1977, it was determined that one of the two 125 VDC switching station batteries had been effectively out of service for approximately eleven days. The battery cells were replaced and the battery returned to service within the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time period specified by Oconee Technical Specification 3.7.2(e). The events asso-ciated with the incident are as follows.
Beginning June 17, 1977 and continuing through June 20, 1977, several events recorder alarms were received indicating low voltage on the SY-1 battery bus. Appropriate corrective action was not taken in response to the alanns.
On June 20, 1977, during routine examination of the switchyard batteries a low voltage condition was noted. The SY-1 battery and charger were promptly removed from service and the SY-1 battery was connected to the standby battery charger for recharging. The SY-1 battery charger was repaired and then reconnected to the SY-1 battery to complete the charge. The SY-1 battery was returned to service when the terminal voltage across the battery was acceptable.
Recharging of SY-1 was accomplished without the use of the appropriate procedures and specific gravity readings to assure the full charge of the battery were not taken.
During a review conducted on June 28, 1977, of the initial battery charger failure, it was determined that the event was reportable and that the battery charging proced-ure had not been followed. Due to the low voltage after the battery charger failure, the battery was determined to be potentially inoperable.
Specific gravity and voltage readings were taken, and it was determined that the battery was inoperable. The decision was made on June 28, 1977, to replace the battery cells with identical cells from battery SY-4, a non-safety related switching station battery. The battery was then tested to assure load carrying capability and returned to service. This was accomplished within the time period specified in Technical Specification 3.7.2(e).
Apparent Cause of Incident:
The battery charger failed due to dirty contacts on control circuitry cards.
The con-tacts were cleaned and the charger functioned properly. When the battery charger was not operating, the battery cells were discharged to a low voltage. Recharge of these cells would have required approximately two weeks.
Therefore the battery cells were replaced.
n121oo 5 72
r "
1"uis occurrence is also attributable to personnel errors in failing to initiate prompt corrective action in response to the battery low voltage alarm. Addi-tionally, failure to follow proper procedures resulted in the return to service of an inoperable battery.
Analysis of Occurrence:
This occurrence resulted in the loss of one of the 125 VDC switching station batteries for approximately twelve days. The redundant battery was operable dur-ing this period and was capable of performing all required safety functions.
Therefore the health and safety of the public were not adversely affected by this incident.
Corrective Action:
l The control circuitry cards on the SY-1 battery charger were cleaned and the charger was returned to service. The battery cells in battery SY-1 were re-placed and the battery was properly tested and returned to service.
At the beginning of each shift, all computer point alarms, the backw alam lockout matrix, all illuminated statalarms and all events recorder summaries will be reviewed.
Responsibility for review of these alarms will be defined.
All procedures related to the operation and maintenance of batteries will be reviewed and rewritten as necessary to incorporate adequate limits for voltage and specific gravity readings and adequate instructions for resolving deficien-cies. Appropriate personnel will attend training sessions chich will define the function and importance of all safety related batteries.
Procedure poli-cies will also be reviewed with personnel to assure that procedures are used and are followed. Also, the preventive maintenance schedule for the switchyard bat-tery chargers will be reviewed for adequacy.
It is felt that this corrective action will assure that this incident will not reoccur.
1 i
l i
l
,