ML19305C340
| ML19305C340 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 03/20/1980 |
| From: | William Jones OMAHA PUBLIC POWER DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8003260577 | |
| Download: ML19305C340 (44) | |
Text
,
e, bh 7Et L-H~2L Omaha Public Power District 1623 HAMNEY
- OMAHA, NE5RASMA $5103 e T E L E PHO N E 63n.4000 AMCA CODF 40J March 20, 1980 Director of Nuclear Reactor Regulation ATTN: Mr. Robert W. Reid, Chief Operating Reactors Branch No. 4 U. S. Nuclear Regulatory Coninission Washington, D. C.
20555
Reference:
Docket No. 50-285 Gentlemen:
The Commission's letter of October 17, 1979, to the Omaha Public Power District requested information regarding loss of offsite power and the attendant effects on grid voltage and frequency at the fort Calhoun S ta ti on.
Provided herewith is the District's response to that request.
The attached report includes a description of all loss 'f offsite power events that have occurred at Fort Calhoun Station Unit 1.
Sincerely,
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f W. C. Jones Division Manager Production Operations WCJ/KJM/BJil/TLP:jnin
- Attach, cc: LeBoeuf, Lamb Leiby & MacRae 1333 New Hampshire Avenue, N. W.
Washington, D. C.
20036
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s0032 60677
v ATTACHMENT The network interconnections and the in-plant distribution systems for the Fort Calhoun Station Unit No. I are described in detail in section 8 of the FSAR. This response supplements that information.
Attached is a circuit diagram showing the 345 KV (Sub 3451) and 161 KV (Sub 1251) substations at the Fort Calhoun Station. Also shown are the circuits that interconnect these substations with the transmission grid. This diagram should be used in place of Figure 8.2-1 of the FSAR because some additional substations and circuits have been placed into service since the FSAR was published.
Circuit outage data was reviewed in order to determine the total number of loss of off-site power events that have occurred since the unit began operation in August,1973. Only forced outages were con-sidered, since the transients induced by such outages will bound those induced by scheduled outages. Outage data was accumulated for circuits 3422, 3423, 3424, 2431, and 1588. Since the 161 KV feed to Sub 1251 is radial from Sub 1226, outage data was also accumulated for circuits 1533 and 1566 because outages of these circuits could result in surges in circuit 1588.
A review of plant outage reports, control room logs, and strip charts was conducted in an attempt to correlate plant conditions with the circuit outage data. Sufficient data to adequately address the questions regarding voltage and frequency fluctuations does not exist.
For example, there are no voltage recorders on the 4160 volt plant buses.
In addition, there is no 161 KV bus voltage recorder, and the 345 KV bus voltage recorder was not operational until 1976. Also, the strip charts for voltage, frequency, and generator output are not re-quired to be retained for the life of the unit and some of them could not be located.
The 345 KV and 161 KV voltage levels are not interconnected at Substation 3451/1251. They can be interconnected at the 4160 volt level in the plant, but this is not the normal operating condition. Thus, at the Fort Calhoun Station, disturbances in one transmission system are not necessarily reflected in the other.
In most cases, it is impossible to draw conclusions from the data that is available.
A worksheet was prepared for each loss of off-site power eve Each worksheet contains information about the type of event, date and time of occurrence and circuit restoration, which circuits were in-volved, and the cause of the event.
To the extent possible, the effects on the plant buses were evaluated.
The completed worksheets are attached.
., Two of the questions regarding losses of all off-site power are answered below, rather than on the worksheets.
2.
If a turbine. trip occurred, how soon after did loss of off-site power occur?
A review of the total loss of off-site power events shows that they resulted from conditions external to the plant, rather than from turbine trips caused by internal conditions.
In addition, it should be noted that the turbine generator is equipped with an anticipatory trip on loss of off-site power.
3.
-If power was recovered promptly (10 minutes or less), was it due to automatic or manual actions?
All restorations from loss of off-site power at the Fort i
Calhoun Station are manual.
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' th Loss of Off-Site Power Event Type:
Partial (161 KV)
Date/ Time of Occurrence: September 25, 1973/11:57 p.m.
Date/ Time of Restoration: September 26, 1973/6:45 a.m.
Circuits Involved: 1588 Cause of Event: OCB #111 at Sub 1251 locked open due to storm in area.
The breaker was reclosed the following morning from the control room.
Effects on Plant Buses: Fast transfer of buses 1A3 and 1A4 to generator auxiliary transformers occurred successfully. Unit continued in operation.
No effects on generator voltage were apparent. This is the only avail-able chart.
Both diesel generators started and ran up to idle speed.
They were secured by Operations when it was apparent that they would not
, be needed.
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4 Loss of Off-Site Power Event
' Type: -Partial (345 KV)
Date/ Time of Occurrence: September'25, 1973/11:57 p.m.
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' Date/ Time of Restoration: September 26, 1973/11:59 p.m.
Circuits Involved: 3424 I
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Circuit outage caused by storm in area. Breaker Cause of Event:
reclosed by supervisory control.
Effects on Plant Buses: No effects on generator voltage were apparent.
This is the only chart available.
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Loss of Off-Site Power Event Type:
Partial (345 KV)
Date/ Time of Occurrence: December 20, 1973/11:58 a.m.
Date/ Time of Restoration: ' December 20, 1973/8:53 p.m.
Circuits Involved: 3424 Cause of Event: Circuit outage caused by phase to ground fault due to downed shield wire at structure #215.
Effects on Plant Busei: The generator voltage chart showed'a 500 volt decreasing spike. This is the only chart available.
The unit continued in operation. The event is noted in the control room 109
1 Loss of Off-Site Power Event Type: Loss of 161 KV integrity at Sub 1226 Date/ Time of Occurrence: May 10, 1974/7:31 p.m.
Date/ Time of Restoration: May 10, 1974/7:31 p.m.
Circuits Involved:
1566 Cause of Event: Momentary outage.
Cause unknown.
Effects on Plant Buses: Buses 1A1, lA2, 1A3, and 1A4 were all being fed from the house service transformers (161 KV) at the time of the event.
All buses successfully fast-transferred to the generator auxiliary transformers. Buses IA3 and 1A4 were manually transferred to the 161 KV source at 10:21 p.m. on May 10, 1974. No strip charts are available.
Normal unit operation continued.
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Loss of Off-Site Power Event Type: Loss of 161 KV integrity at Sub 1226 -
Date/ Time of Occurrence: May 10, 1974/7:55 p.m.
Date/ Time of Restoration: May 10, 1974/7:55 p.m.
Circuits Involved: -1566 Cause of Event: Momentary outage.
Cause unknown.
Effects on Plant Buses: "All buses were being fed from the generator auxiliary transformers at the time of this event.
(See previous event.)
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Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: May 18, 1974/2:53 p.m.
Date/ Time of Restoration: May 18, 1974/2:53 p.m.
Circuits Involved: 3424 Cause of Event: Momentary outage. Cause unknown.
Effects on Plant Buses: Generator voltage - 500 volt decreasing spike.
Generator watts - 20 MW spike.
(Only charts available.) The unit continued in operation. There is no control room log entry for this event.
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i Loss of Off-Site Power Event Type: -Partial (345 KV)
Date/ Time of Occurrence: August 8, 1974/5:05 p.m.
I Date/ Time of Restoration: August 8, 1974/5:05'p.m.
Circuits Involved: 3431 Cause of Event: Momentary outage.
Cause unknown.
Effects on Plant Buses: Generator watts - 10 MW spike. Generator voltage - 200 volt decreasing spike.
(Only charts available.) The unit 4
continued in operation. There is no control room log entry.
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Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: August 13, 1974/10:41 a.m.
Date/ Time of Restoration: August 13, 1974/11:39 a.m.
Circuits Involved: 3422 Cause of Event: Circuit outage caused by storm in area.
Effects on Plant Buses: Generator watts
-20 MW spike. Generator voltage - 500 volt decreasing spike.
(Only charts available.)
The unit tripped at 10:49 a.m. from 385 MW due to APD trips on RPS channels A and D.
The RPS trips were spurious and were caused by the
-vio ent e ectr cal storm in the area. The unit returned to service at l
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5:23 a.m. on August 14, 1974.
At the time of the trip, bus 1A2 failed to fast-transfer to the 161 KV source. A faulty relay was replaced.
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b-N Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: ~ January-29, 1975/11:11 a.m.
Date/ Time of Restoration: January 29, 1975/11:15 a.m.
Circuits Involved: 3431 Cause of Event: Outage caused by Iowa Public Service personnel working on metering at the Raun Substation.
Effects on Plant Buses: Generator MVAR - 15 MVAR spike.
(Only chart available.) The unit continued in operation. _ The event is noted in the control room log.
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Loss of Off-Site Power Event Type: Partial (345'KV)'
Date/ Time of Occurrence:
February 28, 1975/8:07 a.m.
Date/ Time of-Restoration:. February 28, 1975/8:07 a.m.
Circuits Involved: :3431 Cause of Event: PCB #4 was cleared for maintenance.
PCB #2 tripped and reclosed due to a flashover at the Raun Substation caused by contamin-ation.
' Effects on Plant Buses: The unit was shutdown for refueling at the time of the event. No plant data is available, and there are no control room log entries for this event.
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Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of 0ccurrence: March 1 1975/2:25 a.m.
Date/ Time of Restoration: March 1, 1975/2:32 a.m.
Circuits Involved: 3431 Cause of Event: With PCB #4 cleared for maintenance, PCB #2 tripped and locked out due to a flashover at-the Raun Substation caused by contamin-ation.
Effects on Plant Buses: The unit was out of service for refueling at the time of the event. No plant data is available, and there are no control room log entries for this event.
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k Loss of-Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: March 1, 1975/3:34 a.m.
Date/ Time of Restoration: March 1, 1975/3:34 a.m.
- Circuits Involved: 3431 Cause of Event: Momentary outage of PCB #2 with PCB #4 cleared for 4
maintenance.
Probable flashover at the Raun Substation due to con-tamination.
Effects on Plant Buses: See notes for event at 2:25 a.m.
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2-t Loss of Off-Site Power Event Type: Partial (345 Kt';
Date/ Time of Occurr9c ; 'Drch 1, 1975/4:56 a.m.
Date/ Time of Reste Om f(arch 1,.1975/4:56 a.m.
r Circuits Involveh ?hy, Cause of Event: /kAentary outage of PCB #2 with PCB #4 cleared for
- maintenance. Probable flashover at the Raun Substation due to con-tamina tion, d
Effects on Plant Buses: See notes for event at 2:25 a.m.
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4 Loss of Off-Site Power Event Type: Total
.Date/ Time of Occurrence: March 13, 1975/12:29 a.m.
Date/ Time of Restoration: March 13, 1975/11:34 a.m.
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Circuits Involved: 3423 1
Cause of Event: With circuit 1588 out of service for maintenance of the house service transformers, PCB's #4 and #5 (circuit 3423) tr'. ged i
due to faulty actuation of the fault pressure relay on the generator main transformer. The misoperation was caused by water in a junction box.
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4 Loss of Off-Site Power Event Type: Partial (345 KV)
Date/TimeLof Occurrence: March 17, 1975/2:32 p.m.
Date/ Time of Restoration: March 17,1975/2:37 p.m.
Circuits Involved:
3431 Cause of Event: PCB #4 tripped and locked out with PCB #2 cleared for maintenance. Caused by telephone company.
Effects on Plant Buses:.The unit was out of service for refueling at the time of the event. No plant data is available. The event is noted in the control room log.
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Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: April 7,1975/10:55 a.m.
Date/ Time of Restoration: April 7,1975/11:07 a.m.
Circuits Irvolved: 3431 Cause of Event: Trip caused by IPS technicians at the Raun Substation.
Breakers closed by supervisory control.
- Effects on Plant Buses: The unit was out of service for refueling at the time of this event.
No plant data is available. The event is noted in the control room log.
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Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: April 22, 1975/10:14 p.m.
Date/ Time of Restoration: April 22, 1975/10:14 p.m.
- Circuits' Involved: 3431-Cause of Event: PCB's #2 and #4 locked open. Cause unknown. Closed by supervisory control.
j Effects on Plant Buses: The unit was out of service for refueling at
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. the time of this event. No plant data is available.
The event is noted in-the control room log.
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Loss of Off-Site Power Event
- Type:
Partial (345 KV)
Date/ Time of.0ccurrence: June 3, 1975/11:42 a.m.
Date/ Time of Restoration: June 3, 1975/11:42 a.m.
Circuits Involved: 3431 Cause of Event: PCB's #2 and #4 locked open.. Caused by operation at the Raun Substation.
Closed by supervisory control.
Effects on Plant Buses: Generator voltage - very slight discontinuity.
Generator MVAR - gradual decrease of 10 MVAR between 11:40 a.m. and 1:15 p.m.
The unit continued in operation. There is no control room log en try.
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4 Loss of Off-Site Power Event 1
1 Type: -Partial (345 KV)
Date/ Time of Occurrence: June 3, 1975/1:53 p.m.
Date/ Time of Restoration: June 3, 1975/5:20 p.m.
Circuits Involved: 3431 Cause of Event: PCB's #2 and #4-locked open. Caused by operation at the Raun Substation. Closed by supervisory control after investigation.
Effects on Plant Buses: Generator voltage - no noticeable effect. The unit continued in operation. The event is noted in the control room log.
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Loss of Off-Site Power Event Type: Partial (345 KV)'
Date/ Time of Occurrence: November 9, 1975/10:18 a.m.
Date/ Time of Restoration: November 9, 1975/10:26 a.m.
Circuits Involved: 3424 Cause of Event: Cause unknown.
PCB #5 closed by supervisory control at 10:26 a.m.
PCB #6 closed by supervisory control at 3:40 p.m.
Effects on Plant Buses: Generator MW - no effect. Generator MVAR - no effect. The unit continued in operation. The event is noted in the control room log.
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Loss of Off-Site Power Event Type: - Partial (345 KV)
Date/ Time of Occurrence: December 9, 1975/12:01 p.m.
Date/ Time of Restoration: December 9, 1975/12:09 p.m.
Circuits Involved:
3431 Cause of Event: Cause of outage unknown.
Breakers closed successfully.
Effects on Plant Buses: Generator NW - 10 MW decreasing spikes when breakers tripped and reclosed. Generator MVAR - 5 MVAR decreasing step change when breakers tripped.
Stayed at that value when breakers were reclosed. The unit continued in operation. The event is noted in the control room log.
Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: December 27, 1975/11:56 a.m.
Date/ Time of Restoration: December 27, 1975/12:01 p.m.
Circuits Involved: 3431 Cause of Event: PCB's #2 and #4 locked out following the loss of a unit at IPS George Neal Station.
Effects on Plant Buses: Generator MW - +15 MW spike at time of trip.
Generator MVAR - several spikes, but none at the exact time of the trip.
Generator volts - no effect. The unit continued in operation. There is no control room log entry.
Loss of Off-Site Power Event Type:
Loss of 161 KV integrity at jub 1226 Date/ Time of Occurrence: January 7, 1976/11:59 a.m.
Date/ Time of Restoration:
anuary 7, 1976/12:06 p.m.
Circuits Involved:
1533 Cause of Event: Circuit 1533 tripped at Sub 1209 by an electrician working in the panel.
Effects on Fiant Buses: Generator MW - +10 MW spikes when the breakers tripped and reclosed. The unit continued in normal operation. There is no control room log entry.
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Loss of Off-Site Power Event Type: Total Date/ Time of Occurrence: February 21, 1976/2:34 a.m.
Date/ Time of Restoration: February 21, 1976/3:28 a.m.
Circuits Involved:
1588 and 3423 Cause of Event: Circuit 1588 tripped due to a phase-to-phase fault caused by a storm in the area.
Fast transfer of buses 1A3 and 1A4 failed, and the unit tripped on low RCS flow.
Effects on Plant Buses: All AC power, except instrument buses, was lost. Both diesel generators started automatically and were loaded by Operations. The 345 KV voltage chart shows a 45 KV negative spike at the time of the trip. This is the only data available.
A faulty Agastat relay in the fast transfer circuit was replaced.
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Loss of Off-Site Power Event Type: Partial (161 KV)
Date/ Time of Occurrence: March 29, 1976/10:43 p.m.
Date/ Time of Restcration: March 30, 1976/3:23 a.m.
Circuits Involved:
1588 Cause of Event: Failure of bushing on OCB #4 at Sub 1226 with OCB #6 already open due to a previous flashover. Fast transfer of buses 1A3 and 1A4 was completed, and no unit outage occurred.
Effects on Plant Buses: Diesel generator 1 started automatically. D2 did not, so it was started by Operations to prove its operability. The 161 KV system was returned to service with the fast transfer scheme disabled until further tests were completed.
The unit was out of service at the time of the event for incore detector replacement, and no plant data is available.
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Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: May 28, 1976/8:37 a.m.
Date/ Time of Restoration: May 28, 1976/8:48 a.m. (partial)
Circuits Involved: 3422, 3423, and 3424 Cause of Event: PCB's #5 and #6 were opened to isolate circuit 3424.
PCB #2 tripped due to the loss of bus potential to the line relays.
This"resulted in a transient due to partial load rejection.
The reactor tripped on high pressurizer pressure, tripping the turbine and PCB #4.
The generator disconnect was opened, and PCB #2 was closed at 8:48 a.m.
and PCB #4 was closed at 9:45 a.m.
Effects on Plant Buses: 345 KV voltage - +15 KV spike followed by unit trip. Generator MVAR - +50 MVAR spike followed by unit trip. Buses 1A1 and 1A2 fast transferred to the house service transformers (161 KV).
Both diesel generators started and came up to idle speed automatically.
They were secured at 10:01 a.m.
The unit returned to service at 9:52 p.m. on May 28, 1976.
As a result of this incident, the line relays for circuit 3422 were reset from 537 to 717 MVA and the potential circuit was modified.
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Loss of Off-Site Power Event Type: ' Partial (161 KV)
Date/ Time of Occurrence: February 10, 1977/5:29 a.m.
Date/ Time of Restoration: February 10, 1977/5:29 a.m.
Circuits Involved:
1588 Cause of Event: Momentary kick out of circuit 1588 caused by flashover of R phase lightning arrestor at Sub 1226 due to bird contamination.
Effects on Plant Buses: Generator MW - +10 MW spike. Generator MVAR -
+20 MVAR spike. Operation then continued at 10 MVAR lagging instead of 0.
Buses 1A3 and 1A4 fast transferred to the generator auxiliary transformers, and the unit continued in operation.
Diesel generator #1 started ar.d came up to idle speed.
D2 did not start automatically, so it was started by Operations to prove that it was operable. The system was returned to normal at 8:37 p.m.
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Loss of Off-Site Power Event Type:
Partial (345 KV)
Date/ Time of Occurrence: February 23, 1977/6:03 p.m.
Date/ Time of Restoration: February 24, 1977/8:38 a.m.
Circuits Involved:
3424 Cause of Event: Circuit outage caused by cross-arm failure at structure
- 87 (192rd Street and Highway 92).
Disconnects SW and 6E were opened and PCB's #5 and #6 closed at 9:08 p.m. on February 23, 1977. System returned to normal at 8:38 a.m. on February 24, 1977.
Effects on Plant Buses: Generator MW - +15, -10 MW spike at time of
- trip. Normal unit operation continued. The event is noted in the control room log.
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t Loss of Off-Site Power Event Type: Partial (345 KV)
Date/ Time of Occurrence: April 17,1977/8:33 p.m.
Date/ Time of Restoration: April 17,1977/8:33 p.m.
Circuits Involved: 3424 Cause of Event: Momentary outage caused by lightning.
Effects on Plant Buses: Generator MVAR
+20 MVAR spike. Normal unit operation continued. The event is noted in the control room log.
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Loss of Off-Site Power Event
. Type: Partial (345 KV)
Date/ Time of Occurrence: June 28, 1977/12:09 a.m.
1 Date/ Time of Restoration: June 28, 1977/12:14 a.m.
Circuits Involved: 3431 Cause of Event: Circuit outage caused by storm in area.
Effects on Plant Buses: Generator MW - +10 to 20 MW spikes when breakers tripped and reclosed. Generator MVAR - +15 MVAR spike when breakers tripped; +15 MVAR spike when breakers reclosed. Normal unit operation continued. The event is noted in the control room log.
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Loss of Off-Site Power Event Type: Total Date/ Time of Occ'urrence: August 2" 1977/10:53 a.m.
Date/ Time of Restoration: August 22, 1977/10:53 a.m. for circuit 1588
/12:43 p.m. for circuit 3423 on backfeed Circuits' Involved:
1588 and 3423 Cause of Event: Circuit 1588 tripped and reclosed due to faulty relays at Substation 1226. Fast transfer of buses 1A3 and 1A4 failed, and the unit tripped due to low RCS flow.
Effects on Plant Buses: Generator MW - unit trip from 465 MW. Gener-ator MVAR - inconclusive.
345 KV voltage - inconclusive. The diesel generators started automatically and were loaded by Operations. They were shutdown at 12:39 p.m.
The unit returned to service at 11:30 a.m.
on August 23, 1977.
A defective relay target reset device was replaced at Substation 1226.
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4 Loss of-Off-Site Power Event Type: Loss of 161 KV integrity at Sub 1226 Date/ Time of Occurrence: September 2, 1977/12:32 a.m.
r Date/ Time of Restoration: September 2, 1977/12:32 a.m.
Circuits Involved:
1533 Cause of Event: Momentary outage.
Cause unknown.
Effects on Plant Buses: 345 KV voltage - several spikes at approxi-mately 12:30 a.m.
The largest was -35 KV. Generator MW - several spikes ranging from +5 to +20 MW. Generator MVAR - several spikes.
The largest was +15 MVAR. Normal unit operation continued. There is no control room log entry.
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Loss of Off-Site Power Event Type: Loss of'161 KV integrity at Sub 1226 Date/ Time of Occurrence: September 8, 1977/8:36 p.m.
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- Date/ Time of Restoration: September 8, 1977/8:36 p.m.
Circuits Invol' ed:
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Cassa of Event: Momentary outage due to lightning in the area.
Effs.ts on Plant Buses: Generator MW - +5 MW spike. Generator MVAR -
inco clusive. No ink on chart. Normal unit operation continued. There is no control room log entry.
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Loss of Off-Site Power Event Type: Loss of 161 KV integrity at Sub 1226 Date/ Time of Occurrence: February 7, 1978/7:59 a.m..
Date/ Time of Restoration: Februa ry_ 7, 1978/7:59 a.m.
Circuits Involved: 1533 Cause of Event: Momentary outage caused by flashover of circuit 1534L At MOD at Sub 1209.
Effects on Plant Buses: Generator MW - no effect. Generator MVAR - no effect. Normal unit operation continued. There is no control room log entry.
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i Loss of Off-Site Power Event 4
Type: Partial (345 KV)
Date/ Time of Occurrence: February 10, 1978/11:23 p.m.
Date/ Time of Restoration: February 11, 1978/1:49 a.m.
Circuits Involved: PCB #6, Sub 3451 l
Cause of Event: Breaker tripped due to low gas pressure.
Effects on Plant Buses: No data is available. The event is not noted in the control room log.
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Loss of Off-Site Power Event Type: ' Partial (345 KV)
Date/ Time of Occurrence: May 19, 1978/4:08 p.m.
Date/ Time of Restoration: May 19, 1978/4:08 p.m.
Circuits Involved: 3424 Cause of Event: Momentary outage. Cause unknown.
Effects on Plant Buses:.The unit was out of service at the time of this event. 345 KV voltage - 62 KV spike.
There is no control room log entry.
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'a-Loss of Off-Site Power Event Type: ' Partial (345 KV)
' Date/ Time of Occurrence: June 22, 1978/2:16 p.m.
Date/ Time of Restoration: June 22, 1978/2:16 p.m.
I Circuits Involved: PCB #5, Sub 3451 Cause of Event: Momentary outage.
Cause unknown.
Effects on Plant Buses: 345 KV voltage - +8 KV spike. Normal unit operation continued. The event is noted in the control room log.
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Loss of Off-Site Power Event Type: Loss of 161 KV integrity at Sub 1226 Date/ Time of Occurrence: October 19, 1978/11:28 a.m.
Date/ Time of Restoration: October 19, 1978/11:28 a.m.
Circuits Involved: 1533 Cause of Event: Momentary outage due to lightning arrestor failure on circuit 1534 at Sub 1234.
J Effects on Plant Buses: Unit out of service for refueling. No plant data is available. There is no control room log entry.
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-4 Loss of Off-Site Power Event Type: Loss of 161 KV integrity at Sub 1226 Date/ Time of Occurrence: November 20, 1978/10:54 a.m.
Date/ Time of Restoratio n: November 20, 1978/10:54 a.m.
Circuits Involved:
1533 Cause of Event: Momentary outage. Cause unknown.
Effects on Plant Buses: Unit out of service for refueling. No plant data is available. There is no control room log entry.
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Loss of Off-Site Power Event Type:
Partial (345 KV)
Date/ Time of Occurrence: September 8, 1979/11:24 p.m.
Date/ Time of Restoration: September 9, 1979/9:39 p.m.
Circuits Involved: 3431 Cause of Event: Outage was caused by a line to ground fault due to a downed shield wire between structures #126 and #127.
The ring bus was restored at 1:32 a.m. on September 9,1979, after opening a disconnect.
The circuit was restored at 9:39 p.m. on September 9, 1979.
Effects on Plant Buses: 345 KV voltage - 23 KV spike. Generator MVAR - +30 MVAR spike. Unit operation continued at 110 MVAR lagging.
It had been 90 MVAR prior.to the event.
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