ML19312D206
| ML19312D206 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Oconee  |
| Issue date: | 03/14/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8003210496 | |
| Download: ML19312D206 (4) | |
Text
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. TENNESSEE VALLEY AOTHORITY
- CH ATT A NOCG A, TrNNESSEE 37.tcl
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.400 Chestnut Street 7ower II March 14, 1980-
- Director'of Nuclear Reactor. Regulation
! Attention: 'Mr. Thomas A'.-Ippolito, Chief Branch'No.'3
. Division of. Operating Reactors
'U.S. Nuclear Regulatory Commission Washington, DC 20555?
Dear Mr. Ippolito:
In'the Matter of the
)
Docket Nos. 50-259
.Tenneosee' Valley Authority-
)
50-260 50-296 Enclosed,is our response to your letter to H. G. Parris dated December 13, 1979, which requested.information regarding loss of offsite power events
.at the Browns. Ferry Nuclear Plant., Our review of operating records and
. licensee. event reports for incidents of partial or complete loss of offsite power included all~ events from,the initial startup of the first Browns Ferryfunit:in 1973. As detailed further in the enclosure, our review identified two events of partial loss of power. No events of complete
' loss of offsite' power.were' identified.
Very trul'y yours, TENNESSEE VALLEY NJTHORITY-
' ~~.
L. M. Mills, Manager '
Nuclear Regulation'and Safety
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! REQUEST FOR ADDITIONAL INFORMATION 77;: g
', ;5 -? N LOSS:0F!OFFSITE F0WER
- BROWNS.FERRYNUCLEARPLANTl UNITS 1.2,[N;D3
~(DOCKET;NOS L50-259, -260, -296)-
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- EVENT A:' Partial [lossofoffaitepower-L
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[ Ques' tion: 'How many circuitsLto:the.offsite network are normally.available
=and.how many~were lost during the event?-
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Response:?.Two offsite power sources are normally availableifrom the TVA
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1161-kVl grid)l~0ne of'these~was' lost during this event. Additionally,
- there are:six~500-kV transmission lines connected to the plant
- - distribution' buses.1 F10elof these were < lost during this event.
Question:'What was the cause'of~the e' vent?
Response: The causeiof.the event was tornado damage.
-Question:=.Whyldid the other lines not fail when some did fail?
~
Response: Other lines did not~ fail becau,e they were not in the path of the storm.- -This s'eparation istin plant design.'
- Qtiestion
- Was'any voltage increase-cr decrease experienced just prior to or during the outage? If so,.please give details, voltages
~.
. reached,-affects, etc.'
t' Response: Voltage _ values?for this event are net available; however, station
. electrical systems and.cquipment' continued to operate normally-1.: 1
>from the available offsite voltage.
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LQuestun: Was any. frequency decay experienced :just prior to or during outage? -
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- If so,: please4give idetails, lowest frequency reached, decay rate,.
affects,on equipment operation ;etc.
' Response::Th'e! station frequencyi,was not7affected by the event. _
a lQueStisn:!How long was power unavail5ble from:thelcircuit?
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' Response:;A'second offsite power' source was obtained by?b'ackfeeding:the
- 4 - _f 1500-kV; system to.a unit transformer within-approximately three gs-m f
- days. ' Thefoffsite~ power source was returned
- to normal within j six' days 6,
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/ ! Que'stion: c Date.oflEvent. l N
- Response
- The event dateiwasipri1^3, ?lN4.;[For;additionaldinformation
/refei to: report 50-259'BFAO: 7424W.-
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! EVE T.Bi1". Partial loss of.offsite power.
. Question: How ::iany-' circuits tr the of fsite network:are normally available and
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Jhow many;were-lost during the event?.
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JResponse:iTwofoffsite power sources are normally available from the TVA
- 161-kV grid, f"Botti of-these' were lost during the event. - The.
Athensl61-kV:line was' lost. from approximately.10:36 a.m. until 11:11Jain. on March _1,.1980;..the Trinity 161-kV'line tripped intermittently until approximately 11'a.m. on March 1, 1980.
-Additionally,:there are sixiS00-kV transmission lines connected to the: plant. distribution buses. One of these was lost during' the event..'The Davidson 500-kV line tripped at 3:42 p.m. on March 1,-1980, Land was not restored until.the afternoon hours of Harch 3,"1980.'
-Qnestion::What was-tihe cause of the event?.
~
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Response: LThe cause of the event was ice and wind conditions which caused
'several of.the transmission line conductors to fault'to each
..other or to' ground.
! Question:.Why'didjthe other lines'not' fail when some did fail?
Response: The reason the other lines did not-fail is unknown.
It is assumed that the localized weather conditions (in the. vicinity of each
^
transmission line) caused' random failures on each of the
.affeeted lines.-
-Question: Nas any ' voltage increase or decrease experienced just prior to or during'theloutage?..If so, please.~give details, voltages reached, affects, etc.-
' Response: There were no abnormal voltage' increases or decreases experienced
.as a result of the event. A total loss of voltage was experienced
~
on'the 4-kVcstart boards and the 4-kV bus-tie board.- Loss of the
[4-kV. start boards delayed:theistartup-of unit 2;(BFRO-50-260-8013).
Loss of thel 4-kV bus' tie board placed ; unit '3 -in a ' limiting
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condition'for operation-(BFRO-50-296-8007).
hQuestion:?Was - anyifrequency ' decay. experienced -just -prior to o'r during(the outage?' If ~so,. please. give; details, ; lowest f frequency' reached,
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1decaysrate,iaffects on-equipment; operation, etc.
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! esponse:'Thefstation? requency was not affected byfthe. event.
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. Questions:How longTwas power 1 unavailable-from the, circuit?-.
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JResponse:nTheidur.ation of..the power outageD.is.provided=inithe response'to r
' item:1..The; extended' outage;of the-500-kV Davidson line was:
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'- t Ques' tion: ' Date1of.: event,
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.MResponse: The: event rdate:was March l',;1980.
For additionalLinformation r<' 'i.-
refer (toLtheifollowingfreports:?
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W BFR0-.50.259/8020?
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p iS.r BFRO-50-296/8007
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