ML20003A517
| ML20003A517 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/23/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NCR-SQN-EEB-802, NUDOCS 8102040193 | |
| Download: ML20003A517 (2) | |
Text
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- nr 400 Chestnut Street Tower II January 23, 1981 Mr. James P. O' eilly, Director Office of Inspec on and Enforcement U.S. Nuclear Regul tory Commission Regdon II - Suite 3 0 101 Kirietta Street Atlanta, Georgia 3030
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - ERCW PUMP MOTOR RELAYS - NCR SQN EEB 8022 -
REVISED FINAL REPORT The subject deficiency was initially reported to NRC-OIE Inspector R. W. Wright on October 6,1980, in accordance with 10 CFR 50.55(e). A final report was submitted on November 5, 1980. Enclosed is our revised final report. This report has been revised to clarify the action taken to prevent a recurrence of similar problems.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety l
Enclosure
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cc Mr. Victor Stello, Director (Enclosuse)V Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 l
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ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 ESSEhTIAL RAW COOLING WATER PUMP MOTOR FILAYS NCR SQN EEB 8022 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency General Electric type IAC66 overcurrent relays with a tap range of 1.5 to 3.0 amperes were installed as part of the 6900 volt shutdown board. These relays formed the overcurrent protection system for the 600-hp essential raw cooling water (ERCW) pump motors located in the original ERCW pumping station. A new ERCW pumping station has been constructed with new ERCW pump motors rated at '00 hp.
These new 700-hp ERCW pump motors were installed usir.g the existing overcurrent protection system designed for the original 600-hp ERCW pump motors. The original overcurrent relays are not adequate to handle the increased amperage associated with the new 700-hp ERCW pump motors.
Safety Implications The increased amperage associated with the new 700-hp ERCW pump motors has resulted in the annunciation contacts being picked up and brazed together during normal operation. If an ERCW pump motor were to be shut down, it would not be possible to restart the motor because of failure of the relay-contact to reopen. This con <!ition could adversely affect the safe opera-tion of the plant because.of insufficient esse.-tial raw cooling water.
Corrective Action For the 700-hp ERCW pump motors that are now in operation, the overcurrent relays have been changed out with General Electric type IAC66 overcurrent relays with a tap range of 2.5 to 5.0 amperes. It has been verified that this range will allow the ERCW pump motors to start without damage to the relays and will coordinate with existing upstream protective devices.
The re=aining relays will be changed out with relays qualified to handle the increased amperage before final switchover to the new ERCW pumping station.
TVA has taken action to mitigate the 'possible recurrence of a similar problem by verbally instructing Division of Engineering Design (EN DES) employees to coordinate any design change with other groups, including groups within EN DES and the Divisions of Construction and Nuclear Power, to identify any systems or components which could be affected by the design change.
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