ML19340E295
| ML19340E295 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 01/09/1981 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101130086 | |
| Download: ML19340E295 (5) | |
Text
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A CORStiliisis 9 power J
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go General offices: 212 West Michigen Avenue, Jackson, Mickleen 49201 * (517) 788 4550 January 9, 1981 Director, Nuclear Reactor Regulation Att Mr Dennis M Crutchfield, Chief Operating Reactors Branch No 5 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - ADEQUACY OF THE OFF-SITE POWER SYSTEMS NRC letter dated September 25, 1979 requested additional information concern-ing the plant off-site grid as indicated by its enclosure. The requested information is provided as Attachment I to this letter which includes events in addition to those referenced in your letter.
Problems encountered in generating, relocating and assembling this information in the required form have caused an extension in the requested submittal date for this information. This situation was discussed with the NRC staff. We i
l regret any disturbance this may have caused in the conduct of your review.
David P Hoffman (Signed)
David P Hoffman Nuclear Licensing Administrator 1
CC Director, Region III, USh7C 57C Resident Insoector - Big Rock Point l
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ATTACHMENT I LOSS OF OFF-SITE POWER EVENTS A.
For losses of off-site power where less than all off-site power was lost:
1.
How f circuits to the off-site network are normally available and how many were lost during the events?
Response
There was only ons. off-site power source (circuit) available up to March 1968 when a second olf-site power source was installed. Cur-rently, two off-site power sources (circuits) are available. There have been 10 trips of the 138 kV source while at power since 1965.
Three of these trips resulted in total loss of off-site power. Two of these trips occurred when only one off-s.te circuit was available and the other resulted in loss of both off-site circuits.
2.
What was the cause of the events?
Response
The cause of events was:
a.
Two relay malfunctions.
b.
Five due to ice or lightning or storm conditions.
c.
One due to vandalism.
d.
One switching error.
e.
One trip during modification of a substation.
3.
Why did the other lines not fail when some did fail?
Response
Protective relays isolate the affected line, thereby eliminating its affects from the other line. One of the trips included both lines due to storm and equipment failure.
4.
Was any voltage increase or decrease experienced just prior to or during the outages? If so, please give details, voltages reached, affects, etc.
Response
Voltage changes cannot be determined from available records.
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5.
Was any frequency decay experienced just prior to or during the outages? If so, please give details, lowest frequency reached, decay rate, affects on equipment operation, etc.
Response
Frequency changes cannot be determined from available records.
6.
How long was power unavailable from the circuit?
Response
Power was unavailable from the circuit during the trips from.2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 7.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> (see Table 1).
7.
Dates o.* ovents.
Response
Dates of the events were:
9/17/65 9/28/71 8/08/66 1/25/72 6/28/70 4/06/78 12/03/70 4/17/78 5/12/71 5/31/78 B.
For losses of off-site power:
1.
How long was the power off? How long for partial recovery? Please give details.
Response
For first two events when only one off-site power source existed, power was lost for.2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The third event resulted in total loss of off-site power for.6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. On all three occasions, the emergency diesel generator started in less than 30 seconds and furnished power to the essential bus.
2.
If turbi-- trip occurred, how soon after did loss of off-site power occur?
Response
Turbine trip did not precede lo s of power.
3 3.
It power was recovered promptly (10 mintues or less), war it due to at.matic or manual actions?
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Response
None of these trips recovered in less than 10 minutes.
4.
'n'as any voltage increase or decrease experienced just prior to or during the outages? If so, please give details, voltages reachel, affects, etc.
Respor.s e Voltage changes cannot be determined from available records.
4 5.
Was any frequency decay experienced just prior to or during the outages? If so, please give details, lowest frequency reached, decay rate, affects on equipment operation, etc.
Response
Frequency changes cannot be determined from available records.
i 6.
Dates of events.
Respotse Dates of events:
9/17/65 (One Off-Site Power Source in Existence) 8/08/66 (One Off-Site Power Source in Existence) 1/25/72 (Two Off-Site Power Sources in Existence) i j
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f' T AHt E 1 AT T ACllME N T I Of f-Site Power Sources flow Many Why Did Other Period unavailable Date of Event (Circuitsj Available L o g(__
Cause Lines Not fall flours 9/17/65 1
1 Relay Malfunction Additional Off-Site Powe r 0.2 Sources (Circuits) Not in Existence 8/08/66 1
1 Storm Additional Orr-Site Power 0.2 Sources (Ci rcul t' ) Not in Existence 6/28/70 2
1 Sto rm Relays isolated Problem to 7.1 Arrected Line Only 12/03/70 2
1 Ice Storm Relays isolated Problem to 5.7 Affected Lino Only 5/12/71 2
1 Vandalism Holays isolated Problem to 21.1 Arrected Line Only 9/28/71 2
1 Lightning Relays isolated Problem to 5.0 Arrected Line Only 1/25/72 2
2 Storm and Equipment Relay failure Caused Loss of 0.6 rallure Second Line 4/06/78 2
1 Relay Malfunction Relays isolated Problem to 1.0 Arrected Line Only 4/17/78 2
1 Switching Error at Relays isolated Problem to 2.3 Substation Arrected Line Only 5/31/78 2
1 Tripped 199 During Modi-Relays isolated Problem to 6.5 fication of Substations Arrected Line only nu0181-0072b-43 i