ML19253C895
| ML19253C895 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 11/30/1979 |
| From: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7912120319 | |
| Download: ML19253C895 (5) | |
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November 30, 1979 Mr. A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors Nuclear Regulatory Commission Washington, D. C. 20555
Dear Mr. Schwencer:
SUBJECT:
Trojan Nuclear Plant Loss of Offsite Power Attached is the response to your request concerning information on partial /
complete loss of offsite power. As indicated in your request, there were two additional instances when partial loss of of fsite power occurred, one which was reported as Licensee Event Report 77-10 and one which did not warrant a Licensee Event Report. The appropriate information concerning these two instances is also submitted. One Licensee Event Report, 77-09 of April 26, 1977, which your letter referenced concerned not performing the required surveillance while one source of offsite power was secured for maintenance, is not commented upon because it was a planned maintenance item, not a partial / complete loss of offsite power.
Sincerely, r
C. Goodwin, Jr.
/
Assistant Vice President Thermal Operations & Maintenance v.gf.
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CG/ASC:na Attachment 1541 34I Aoo/
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7912120 C
ATTACHMENT A.
For losses of offsite power where less than all offsite power was lost:
Event No. 1 1.
How many circuits to the of fsite network are normally available and how many were lost during the event?
Two circuits are normally available. One circuit was deenergized during the event.
2.
What was the cause of the event?
A disconnect switch in the 230-kV switchyard was not properly closed which resulted in arcing at the disconnect switch. The circuit was remotely deenergized to stop the arcing.
3.
Why did the other lines not fail when some did fail?
The 230-kV switchyard has two independent offsite power supplies and a fault with one disconnect switch did not necessitate securing both sources of offsite power.
4.
Was any voltage increase or decrease experienced just prior to or during the outage?
No voltage transients were noted just prior to or during the outage.
5.
Was any frequency decay experienced just prior to or during the outage?
No frequency decay was noted just prior to or during the outage.
6.
How long was power unavailable from the circuit?
Power was unavailable for approximately 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> 47 minutes.
7.
Date of event.
Event Date - 4/16/76 Licensee Event Report 76-35 Event No. 2 1.
How many circuits to the offsite network are normally available and how many were lost during the event?
Two circuits are normally available. One circuit was deenergized during the event.
2.
What was the cause of the event?
Following a reactor trip, a fast transfer to offsite power was not completed satisfactorily because of an improperly set differential current relay which caused loss of one source of offsite power.
1541 342
5 Event No. 2*(Contd.)
3.
Why did the other lines not fail when some did fail?
The 230-kV switchyard has two i dependent of fsite power supplies, thus an improperly set differential current relay on one power source did not effect the other independent power source.
4.
Was any voltage increase or decrease experienced just prior to or during the outage?
No voltage transients were noted just prior to or during the outage.
5.
Was any frequency decay experienced just prior to or during the outage?
No frequency decay was noted just prior to or during the outage.
6.
How long was power unavailable from the circuit?
Power was unavailable approximately 16 minutes.
7.
Date of event.
Event Date - 1/23/77 Licensee Event Report 77-03 Event No. 3 1.
How many circuits to the offsite network are normally available and how many were lost during the event?
Two circuits are normally available. One circuit was deenergized during the event.
2.
What was the cause of the event?
While transferring plant electrical loads from the Unit Auxiliary Transformer to Startup Transformer No. 1, a high phase differential current relay actuated resulting in a partial loss of offsite power.
The high phase differential current trip was due to improperly completing maintenance on the current transformer which supplied the phase differential current relay.
Partial loss of offsite power occurred twice due to this cause.
3.
Why did the other lines not fail when some did fail?
The 230-kV switchyard has two independent offsite power supplies and a fault with one current transformer will not effect both power supplies.
4.
Was any voltage increase or decrease experienced just prior to or during the outage?
No voltage transients were noted just prior to or during the outage.
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' Event No. 3 (Contd.)
5.
Was any frequency decay experienced just prior to or during the outage?
No frequency decay was noted just prior to or during the outage.
6.
How long was power unavailable from the circuit?
Power was unavailable for approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> 52 minutes.
7.
Date of event.
Event Date - 4/29/77 and 4/30/77 Licensee Event Report 77-10 Event No. 4 1.
How many circuits to the offsite network are normally available and how many were lost during the event?
Two circuits are normally available. One circuit was deenergized during the event.
2.
What was the cause of the event?
Following a reactor trip, electrical power was not automatically shifted to both sources of offsite power due to an improperly functioning breaker. Maintenance had recently been conducted on a breaker but when it was returned to service, one of the control stabs was not fully connected to the breaker housing which resulted in the loss of control power to the breaker. When the automatic signal was sent to the breaker to close following the reactor trip, the lack of control power prevented the breaker from closing as required.
3.
Why did the other lines not fail when some did fail?
The offsite power system has two independent supplies to the plant of which only one source was made inoperable due to the breaker malfunction.
4.
Was any voltage increase or decrease experienced just prior to or during the outage?
No voltage transients were noted just prior to or during the outage.
3.
Was any frequency decay experienced just prior to or during the outage?
No frequency decay was noted just prior to or during the outage.
6.
How long was power unavailable from the circuit?
Power was unavailable approximately 30 minutes.
1541 344 7.
Date of event.
Event Date - 10/18/77 Licensee Event Report 77-40
. Event No. 5 1.
How many circuits to the offsite network are normally available and how many were lost during the event?
Two circuits are normally available, each supplied by two 230-kV transmission lines, and a total of three transmission lines were damaged leaving one circuit supplying offsite power.
2.
What was the cause of the event?
A light aircraft crashed into three 230-kV lines outside of the plant's exclusion area boundary.
3.
Why did the other lines not fail when some did fail?
The aircraft crashed into three of the four 230-kV transnission lines leaving one line intact. One line continued to supply offsite power to the plant.
4.
Was any voltage increase or decrease experienced just prior to or during the outage?
No voltage transients were noted just prior to or during the outage.
5.
Was any frequency decay experienced just prior to or during the outage?
No frequency decay was noted just prior to or during the outage.
6.
How long was power unavailable from the circuit?
Power was unavailable approximately 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> 23 minutes.
7.
Date of event.
Event Date - 9/14/78 Licensee Event Report - Report not submitted because plant was in Mode 5 at the time of the event which does not require two sources of offsite power.
B.
For losses of all offsite power:
There have been no complete losses of offsite power.
C.
Were there any other loss of offsite events other than we have liste?
See Section A, Events No. 3 and 5.
1541
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Docket No. 50-344 npg g._ cv
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esst. Vica pmg IDR res e%,4 Mr. Charles Goodwin, Jr.
fcs 4,. c c. s c, Assistant Vice President CJr Portland General Electric Company ort (
121 S. W. Salmon Street V
Portland, Gregon 97204 nws DJT
Dear Mr. Gocdwin:
Ocp ic/,iln RE: TROJAN NUCLEAR FLANT FILE Ne,' 2
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v 4I. 3 We are currently reviewing the adecuacy of the offsite ::ower systems of nuclear power clants and in particular, the loss of offsite power events at your fac 4 i t ty. One ascect of this review concerns the history of experienced total and partial power outages and attendant degraded voltage or frecuency ccnditions of the grid.
In our review of this matter we are drawing ucon the information you provided in Licensee Event Reports (LERs) and folicwup letters to the NRC.
Our review of a numcer of these LERs indicates that less of offsite power.-
f has occurred at your, facility on Aoril 16, 1976, January 23, 1977, April 26, 1977 and October it,' 1977.
In order to c::melete our review of loss of offsite power events we require response to the enclosed recuest for infomation.
s We request that you provide your response M of the receipt of this letter.
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/, I9 po Sincerely /
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($h A. Schwencer, Chief Ooerating Reactors Branch #1 Division of Goerating Reactors
Enclosure:
Request for Infomation 1541 346 cc: w/enclasure See next cage C.: pied for '/.assrs: Wm
- ma/Lindblad, 3rcehl, Ourhan, '41thers, 6 Lantsch, O' ernan, Christensen, Gaides, Heider, SM ran, Danen (3echtal),
C;megnas (W), '4eisloggi (??SL),.brall (TJE3), Nyland (3PA),.helrad, g
Leading File i j
Mr. Charles Gecdwin, Jr.
Portland General Electric Ccmpany cc: Mr. H. H. Phillips Rober-M. Hunt, Chairman Portland General Electric Ccacany 3 card of County Ccmmissioners 121 S.W. Salmen Street Columoia County Porti and, Oregen 97204 St. Helens, Oregen 97051 Warren Hastings, Esquire Counsel for Partiand General Electric Company 121 S.W. Salmon Street Portland, Oregon 97204 Mr. Jack W. Lantsch, Manager Generation Licensing and Analysis Por:1and General Electric Ccmpany 121 S.W. Salmen Street Per:1and, Oregon 97204 Columbia County Cour-hcuse Law Library, Circuit Cour* Rocm St. Helens, Oregen 97501 Director, Oregen Depar=ent of Energy Labor and Industries Building, Recm 111 Salem, Gregen 97310 Richard M. Sandvik, Esquire Counsel for Gregon Energy Facility Siting Counsel and Oregon Department of Energy 5C0 Pacific Building 520 S.W. Yamhill
?crtiand, Oregon 97204 Michael Malmrose U. S. Nuclear Regulatory Ccemission Trojan Nucl ear P1 ant P. O. Scx 0 Rainier, Oregen 97048 Mr. Ocnald W. Gcdard, Superviser Siting and Regul ation Organ Decar=ent of Energy Labor and Incustries Suilding, Recm lli 1541 3g Salem, Oregon ;7310
ATTACHMENT For losses of offsite pcwer wherehthan all offsite ocwer was lost:
A.
1.
Mcw many circuits to the offsite. network are nomally available and how many were lost during the event?
2.
What was the cause of the event?
Why did the other lines not fail when some did fiil?
3.
Was any voltage increase or decrease experier.:ad just prior to or during 1
the cutage?
If so, please give details, voltages reached, affects, etc.
5.
Was any frequency decay ex:erienced just prior to or during the cutage?
If so, please give de:sils, icwes frequency reached, decay rate, affec s on equipmen cpera:1ca, e :.
5.
Mcw long was pcwer unavailable frcm the circui:?
7.
Date of Event.
3.
Fce lesses of EiIleffsite power:
1.
Mcw icng was the pcwer off? Mcw icng for partial recovery? Please give details.
2.
If turbine trip cc urred, how scen after did less of offsite pcwer occur?
3.
If pcwer was recovered promptly (10 minutes er less), was tt due to aut:matic or manual actions?
4 Was any voltage increase or decreasc excerienced just prior to or during the cutage?
If so, please. give details, voltages reached, affects, etc.
5.
Was any frequency decay experienced just prior to or during the cutace?
If so, please give details, lowest frequency reached, decay rate, affects on equipment cperation, etc.
5.
Cate of Event.
C.
Were there any other loss of offsite pcwer events other than we have listed?
It so, please give details of eacn even.
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