ML20156A252
| ML20156A252 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/04/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1987-003-00 | |
| Download: ML20156A252 (4) | |
Text
B-129 PRECURSOR DESCRIPTION SHEET LER No.:
389/87-003 Event
Description:
4/9/87 Plant:
St. Lucie 2 EVENT DESCRIPTION Sequence While at 100% power, I&C personnel were testing the ESFAS.
The P-18 annunciator was found inoperative.
They made an error when con-necting a jumper to test the circuit and caused a MSIS actuation.
The MSIVs and MFW isolation valves closed causing a
LOFW and subsequent plant trip.
One SG MSRV failed to fully close after opening to relieve steam pressure.
Operators closed the valve 8 min after opening by open-ing an atmospheric dump valve to lower SG pressure and to let the MSRV reseat.
The open MSRV valve did not noticeably cause SG depressuriza-tion.
The 2C AFW pump tripped on overspeed but was restarted without problems.
Corrective Action Repairs were made and personnel were counseled.
Plant/Event Data Systems Involved:
Main feedwater Auxiliary feedwater Steam relief Components and Failure Modes Involved:
Pump fails on demand Component Unavailability Duration:
N/A Plant Operating Mode:
1 (100%)
Discovery Method:
Operational event Reactor Age:
3.8 y Plant Type:
PWR Comments None.
MODELINC CONSIDERATION AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient No recovery Event Identifier:
389/87-003
B-130 Branches Impacted and Branch Nonrecovery Estimate MFW 1.0 No recovery AFW Base case One of three trains unavailable (manual restart successful)
SSREL TERM 0.12 Valve is closed by operator action Plant Models Utilized PWR plant Class C Event Identifier:
389/87-003
B-131 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier:
389/87-003 Event
Description:
4/09/87.
Plant:
St Lucie 2 INITIATING EVENT NON-RECOVERABLE INITIATING EVENT TRANS SEQUENCE CONDITIONAL PROBABILITY End State/Initiator train fails and an MSRV sticks open PROBABILITIES
- 1. OE+00 Probability CO CV TRANS Total TRANS Total
- 7. 5E-05 7.5E-05 1.6E-04 1.6E-04 3.4E-05 3.4E-05 ATWS TRANS Total SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence 120 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress cond/rmfw 121 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open ss.depress 119 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress cond/mfw 109 trans -rt
-AFW -porv.or.srv.chall SS.RELEAS.TERM hpi 128 trans rt
- non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence 109 trans -rt
-AFW -porv.or.srv.chall SS.RELEAS.TERM hpi 119 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress -
cond/mfw 120 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress cond/rnfw 121 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open ss.depress 128 trans rt
- non-recovery credit for edited case SEQUENCE MODEL:
c:\\asp\\newmodel\\pwrgnew.cmp BRANCH MODEL:
c:\\asp\\newmodel\\iucie.new PROBABILITY FILE:
c:\\asp\\newmodel\\pwr_bnew.pro No Recovery Limit End State CD CD CV CV ATWS End State CV CV CD CD ATWS Prob
- 6. 6E-05 7.4E-06 1.3E-04 3.DE-05
- 3. 4E-05 Prob
- 3. OE-05
- 1. 3E-04
- 6. 6E-05
- 7. 4E-06
- 3. 4E-05 N Rec**
3.0E-02 8.8E-02 5.8E-02 1.0E-01 1.2E-01 N Rec**
1.DE-01 5.8E-02
- 3. OE-02 8.8E-02 1.2E-01 Event Identifier:
389/87-003
B-132 BRANCH FREQUENCIES/PROBABILITIES Branch System Non-Recov Opr Fail trans loop loca rt rt/loop emerg -power ep. rec AFW Branch Model:
1.OF.3+ser Train 1 Cond Prob:
Train 2 Cond Prob:
Train 3 Cond Prob:
Serial Component Prob:
afw/emerg.power MFW Branch Model:
l.OF.1 Train 1 Cond Prob:
porv.or.srv.chall porv.or.srv.reseat porv.or.srv.reseat/emerg.power SS. RELEAS.TERM Branch Model:
1.OF.l Train 1 Cond Prob:
ss.depress cond/mfw hpi hpi (f/b) porv.open hpr/-hpi csr 4.8E-04 4.6E-06 2.4E-06 2.8E-04
- 0. OE+00 2.9E-03
- 1. 0E+00 3.8E-04 > 2.3E-03 2.0E-02 1.0E-01 5.0E-02 > Failed 2.8E-04 5.0E-02 1.9E-01 > l.O+00 1.9E-01 > Unavailable 2.0E-02 1.0E-02 1.0E-02 1.5E-02 > 1.0E+00 1.5E-02 > Failed 3.6E-02 1.OE+00 3.0E-04 3.0E-04 1.0E+00 1.5E-04 2.0E-03 1.o0+00 3.9E201 4.3E-01 1.2E-01 1.0E+00 8.0E-01 1.7E-01 2.6E-01 3.4E-01 3.4E-01 1.0E+00 1.1E-02 1.0E+00 3.4E-01 > 1.2E-01 1.0E+00 3.4E-01 8.4E-01 8.4E-01 1.0E+00 1.0E+00 3.4E-01 1.0E-02 1.OE-02 O.OE+00 branch model file
- forced Minarick 05-16-1989 06:53:03 Event Identifier:
389/87-003