ML19347C814
| ML19347C814 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 12/24/1973 |
| From: | Ross D JERSEY CENTRAL POWER & LIGHT CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8103040826 | |
| Download: ML19347C814 (3) | |
Text
Regu!sicry bochet File Jerse tral Power & Light Company g i *A Df!ID A
ADISON AVENUE AT PUNCH BOWL ROAD
- MORRISTOWN, N.J. 07960
- 201-539-6111
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Mr. A. Giambusso
.;bt Deputy Director for Reactor Projects
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Dear Mr. Giambusso:
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Subject:
. Oyster Creek Station Docket No. 50-219 125V DC Power Interruption The purpose of this letter is to report to you a momentary inter-ruption of 125V DC power supplying instrumentation associated with various safeguard systems. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D and G.
It is not considered a Technical Specification violation because the power interruption was on the order of milliseconds and the transfer switch performed as designed.
Notification of this event, as required by the Technical Specifications, paragraph 6.6.2.a, was made to the AEC, Region I, Directorate of Regulatory Operations, by telephone on Friday, December 14, 1973, and by telecopier that same day.
An electrical ground had developed on 125V DC distribution bus "A" resulting in electricians being called in at approximately 2300, December 13, 1973 to troubleshoot and repair this problem. Electrical grounds of this nature have been an infrequent problem in the past and, as of this time, no approved procedures have been developed.
It is common knowledge that any interruption of power to power panel "E" results in adverse effects regarding service to safeguard instrumentation.
Consequently, the electrician, who had performed this same maintenance activity of troubleshooting and repair on occasion in the past, proceeded to place a jumper in a position that would parallel the "A" and "B" distribution buses. This, then, provided non-interruptabic alternate feed to power panel "E" and by actuating the " break before make" throwover switch, it could be determined if the ground was in the "E" power panel by observing the indicating lights on the "B" bus. However, the electrician placed the jumper in the wrong position and effectivGly did not have the buses paralleled as desired. Upon pushing the local button for transferring the "E" power panel from the "A" to the "B" bus, there was a momentary interruption of power on the order of milliseconds, caused by the normal action of the " break before make" switch, with the following results:
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Mr. Giambusso December 24, 1973 1.
Operating CRD pump "A" tripped due to loss of power to low pump suction trip circuit. Operator immediately restarted Pump.
2.
"B" isolation condenser isolated due to loss of power to pipe-break monitoring system. Operator immediately reset isolation condenser isolation button and valving realigned properly for normal standby service.
3.
Clean-up system isolated due to loss of power to relaying associated with this function. Operator returned system to service as per normal procedure.
4.
DC power was lost to logic channel "C" (Core Spray System No. I) and logic channel "D" (Core Spray System No. II) for the brief interval. These channels immediately reset automatically requiring no operator action. Logic channels "A" and "B" were not effected and the redundant equipment in each system was available.
5.
DC power was lost to the logic channels of Containment Spray System No. I.
Again, with the rapid restoration of power, the logic was automatically restored. The redundant System No. II was not effected and would have operated if necessary. No operator action required.
6.
A trouble alarm was received on both diesel generators, but was immediately reset from the control room and was strictly 1
due to loss of DC power to the alarm relay and had no effect on automatic operation of the diesel generators.
7.
Lost DC power to main steam isolation valves, but had no effect on valve operation since AC power was still available and permitted valves to stay open.
8.
DC power was lost to miscellaneous annunciators and panels, i
but did not have any additional effect on the safe operation of the plant.
The cause of the interruption of the 125V DC power to panel "E" was the improper placement of the jumper used to parallel the "A" and "B" distribution
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buses.
Restoration of the equipment to ' normal status was accomplished through the automatic reset function of effected instrumentation. As noted above, the isolation condenser, CRD pump, clean-up syst2m and miscellaneous alarm functions were manually reset and restored to normal service immediately.
As the interval of time involved in this incident was on the order of milliseconds and all effected systems were reset immediately or within several seconds where operator action was required, the safety significance of this event i
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f Mr. Giambusso December 24, 1973 was minimal.
In the case of the isolation condenser, design redundancy was lost for the interval prior to the operator resetting the system.
- Ilowever, the redundant isolation condenser was available and would have performed if required.
To avoid a reoccurrence of this type in the future, the following action is being taken: Ground location procedures for the DC buses will be written and implemented, including a coded system that will tell the operator which switches may be operated depending on plant conditions and Technical Specification requirements. The administrative controls concerning jumpering and the lifting of leads are presently being reviewed and revised to prevent repetition of this event.
Enclosed are forty copies of this report.
Very truly yours, ht M Y
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Donald A. Ross Manager, Nuclear Generating Stations a
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Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I l
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