05000348/LER-2021-001, Automatic Reactor Trip Due to Turbine Generator Trip
| ML21172A303 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/21/2021 |
| From: | Kharrl C Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-21-0561 LER 2021-001-00 | |
| Download: ML21172A303 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iv)(B), System Actuation |
| 3482021001R00 - NRC Website | |
text
- Southem Nudear June 21, 2021 Docket No.:50-348 NL-21-0561 U.S.Nuclear RegulatoryCommission ATTN:Document Control Desk Washington, D.C.20555-0001 JosephM. Farley NuclearPlant
- - Unit 1
LicenseeEvent Report 2021-001-00 A
Ladies andGentlemen:
inaccordance withtherequirements of10CFR50.73(a)(2)(iv)(A),
Southern Nuclear Company issubmitting theenclosed Licensee EventReport for Unit 1.
Thisletter contains noNRCcommitments.
lfyouhaveanyquestions regarding this submittal, please contact GeneSurber at(334) 661-2265.
Respectfully submitted, mj f//CUN Charles Kharri VicePresident
- - Farley CK/rgs/cbg
Enclosure:
Unit1Licensee EventReport 2021-001-00 Cc:Regional Administrator, Region 11 NRRProject Manager
- - Farley Nuclear Plant Senior Resident inspector
- - Farley Nuclear Plant RTYPE:CFA04.054 A
Joseph M.Farley Nuclear Plant
- - Unit1 Licensee EventReport 2021-001-00 AutomaticReactor TripduetoTurbine Generator Trip Enclosure Unit1Licensee Event Report2021001-00
Abstract
(Umit to1560spaces ie approximately 15single-spaced typewntten hnes)
At1450CDTonApril 22,2021,with Farley Nuclear Plant(FNP)
Unit 1inMode1at48%poweranautomatic reactor trip occurred duetoamainturbine trip.
Themainturbine
/generator trip wasduetodatainput error intheexciter switchgear software during exciter testing.
Thetrip wasnotcomplex withall systems responding normally.
Operations stabilized theplant in Mode3.Duetolowdecayheatload, theMainSteamIsolation valves wereclosed tominimize cooldown andtheAtmospheric Relief Valves wereusedtoremove decayheat.
This eventwasinitially reported aseventnotification 55206.
Corrective Actions included correcting thedataentry intheexciter switchgear control software andperforming causal analysis on thehumanperformance aspectofthis event.
This eventisreportable under10CFR50.73(a)(2)(iv)(A) duetotheautomatic actuation ofasystemlisted in10CFR50.73(a)(2)
(B).
FNPUnit2wasnotaffected during this event.
A.EVENT/CAUSE
DESCRIPTION
At1450CDTonApril 22,2021, withFarley Nuclear Plant(FNP)
Unit 1inMode1at48%poweranautomatic reactor trip [EEIS:
JC) occurred duetoamain turbine [EEIS: TA) trip.
Unit 1hadjust recently completed arefueling outage andwas ascending inpower.
Theunit wasat48% power with exciter switchgear[EEIS:TL) powerascension testing inprogress by ABBcontractors under thesupervision ofFNP Site Projects personnel.
TheABBcontractor updating thesoftware madea humanperformance error andinserted anincorrect setpoint value within theexciter switchgear software.
This caused the exciter todrive theexcitation voltage andcurrenton the generator tonear zero.Thiscausedacorresponding rise in generator current onall three phases.
Ultimately, this sequence wassecured whenthedistance relay [EEIS:
TB/21) provided agenerator trip.
Thisresulted inacascadingturbine trip andsubsequent automatic reactor trip.
B.SAFETYASSESSMENT
/REPORTABILITY:
Therewerenosafety consequences asresult ofthis event.Theoperating crewresponded correctly totheevent.
The applicable abnormal
/emergency operating procedures wereproperly entered anddocumentation metexpectations.
This eventwaswithin theanalysis oftheUFSARChapter 15.Additionally, no radiological release occurred duetothis event.
This event isreportable under10CFR50.73(a)(2)(iv)(A) duetotheautomatic actuation oftheReactor Protection System (RPS) asidentified in10CFR50.73(a)(2)(iv)(B).
C.CORRECTIVE ACTIONS:
Corrective Actions included correcting thedataentry intheexciter switchgear control software andperforming causal analysis onthehumanperformance aspect ofthis event.
Causal analysis determined there was alack ofrisk recognition andoverreliance onvendor expertise.
D.PREVlOUSSIMILAR EVENTS:
Thefollowing similar events werereported, however these similar events arecomponent related andare not human performance related:
LERU22019-00200, Manual Reactor Trip duetoMisaligned Rodduring LowPowerPhysics Testing LERU22019-003-00, Manual Reactor Tripdueto2CReactor Coolant PumpHighVibration indication E.OTHERSYSTEMSAFFECTED:
Noother systems wereaffected bythis event.
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