ML20149K398
| ML20149K398 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/28/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1984-054-00, LER 1984-056-00, LER 1984-060-00, LER 1984-062-00 | |
| Download: ML20149K398 (5) | |
Text
PRECURSOR DESCRIPTION SHEET LER No.:
373/84-054, -056, -060, -062 Event
Description:
Scram, ROIC Failures, and RHR Unavailability Within
+15 d Date of Event:
S-eptember 21, 29, and 30, 1984 Plant:
LaSalle 1 EVENT DESCRIPTION Sequence While the reactor was at 23% power on September 21, 1984, operator error caused a reactor scram and MSIV closure.
This caused a Group I isolation during the performance of an MSIV isolation calibration and functional test.
Later, on the same day, RCIC was found failed during a test; again on September 29, RCIC isolated on high steam flow when an attempt was made to open the RCIC outboard isolation valve.
On Septem-ber 30, with the unit in hot shutdown, the RHR inboard suction isolation valve failed to open on demand, rendering RHR unavailable for almost 9 h.
Due to the nature of the events, RCIC and RHR may have been un-available simultaneously with the scram.
Corrective Action Following the September 21 trip, a warning sign was posted to pre-vent bumping of the instrument rack that caused the trip.
The first RCIC failure was corrected by flushing the RCIC oil system and replacing clogged oil filters.
The second RCIC failure only required resetting of the outboard isolation valve.
The RHR suction valve inoperability was investigated, and a training procedure for declutching motor operators was issued.
Plant/Event Data Systems Involved:
RCIC, RHR Components and Failure Modes Involved:
RCIC pump -
isolated during test RCIC pump -
tripped during test RHR suction valve -
failed on demand Event Identifier:
373/84-054 D-207
Component Unavailability Duration:
NA Plant Operating Mode:
24%, 1%, 23%, and 0%
Discovery Method:
See sequence description Reactor Age:
2.2 years Plant Type:
BWR Comments None MODELING CONSIDERATIONS AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient 1.0 Nonrecoverable Branches Impacted and Branch Nonrecovery Estimate RCI C 1.0 Nonrecoverable in required time; pump-governor oil system required flushing RHR (SDC) 0.34 Recovered within 9 h, SDC is not required in the short term PCs 1.0 Unavailable due to MSIV closure MFW 1.0 Unavailable due to MSIV closure; considered nonrecoverable Plant Models Utilized BWR plant Class C Event Identifier:
373/84-054 D-208
CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier: 373/84-054 Event
Description:
Scram with RCIC Failure and RHR Unavailability W4-15 days)
Event Date:
9/21/84 Plant-LaSalle 1 INITIATING EVENT NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator 1
.OE+00 Probabil ity CV TRANS Total 2.4E-0~6 2
.4E-06 CD TRANS Total 2.3E-03 2.3E-03 ATWS TRANS Total 2,0OE-05 2
.OE-05 DOMINANT SEQUENCES End State: CV Conditional Probability:
1.OE-06 134 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS
End State: CO Conditional Probability:
2.2E-03 102 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE FW/PCS.TRANS -HPCI RHR(SDC)
RHR(SPCOOL)
C.I.AND.V/RHR(SDC).RHR(SPCOOL)
Event Identifier: 373/84-054 D,-20 9
End State: ATWS EndStae: TWSConditional Probability:
2.OE-05 173 TRANS SCRAM SIC.0R.RODS SEQUENCE CONDITIONAL PROBABILITIES Sequence End State
- Prob, N Rec**
102 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE FW
/PCS.TRANS -HPCI RHR(SDC) RHR(SPCOOL)/-LPCI.RHR(SDC) C.
I.AND.VIRHR(SBC).RHR(SPCOOL)
III TRANS -SCRAM P05/TRANS SRV.CHALL/TRANS.-SCRAM SRV.CLOSE -FW
RHRCSPCOOL)/-LPCI.RHR(SDC) 0.1.AND.V
/RHR(SDC).RHR(SPCOOL) 134 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LODP -SRV.ADS -COND/FW.PCS
-RHR(SDC) 135 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS -COND/FW.PCS RHR(SDC) -
RHR(SPCOOL) /-LPCI.RHR(SDC) 138 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.GR.LOOP -SRV.ADS COND/FW.PCS -LPCS -RHR(
500) 139 TRANS SCRAM -SLC.OR.RODS P05/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS CONO/FW.PCS -LPCS RHR(
500) -RHR(SPCOOL)/-LPCI.RHR(SDC) 173 TRANS SCRAM SLC.OR.R0DS CD CD Cv CV CV Cv 2.2E-03
- 1.2E-01 9.2E-05 7.6E-02 1.OE-06
- 1.5E-01 5.2E-07 7.6E-02 5.3E-07 7.6E-02 2.7E-07 3.9E-02 Z.OE-05 I
.OE+00 ATWS
- dominant sequence for end state
- 1non-recovery credit for edited case MODEL:
DATA:
b :\\bwrctree.cmp b:\\laslprob.cmp No Recovery Limit BRANCH FREQUENCIESIPROBABILITIES Branch System TRANS LOOP LOCA SCRAM SLC.OR.RODS PCS/TRANS Branch Model:
1.OF.1 Train 1 Cond Prob:
PCS/LGCA SRV.CHALL/TRANS.-SCRAN Event Identifier: 373/84-054 1.1E-03 1.3E-05 3.3E-06
- 4. 1E-04 I.OE-02 1.7E-01 > 1.OE+00 1.7E-01 > Failed 1.OE+00 I.OE+0Q Non-Recov I.OE+00 3.4E-01 3.4E-01I 1.OE+00 I.OE+00 1.0E+00 Opr FailI 4.OE-02 I.OE+00 1.OE+Q0 D>-2 10
SRV.CHALL/TRANS.SCRAM SRV.CHALL/LOOP.-SCRAM SRV.CHALL/LOOP.SCRAtI SRV.CLDSE EMERG.POWER FW/PCS.TRANS Branch Model:
1.OF.1 Train I Cond Prob:
FW/PCS SLOCA HPCI RCIC/TRANS.OR.LOOP Branch Mode):
1.7F.1 Train I Cond Prob:
RCIC/LGCA CRD SRY.ADS COND/FW.PCS LPCS LPCI (RHR) /LPCS RHRSW/LPCS.LPCI.rRANS RHRSW/LPCS.LPCI.LOOP RHRSW/LPCS.LPCI.LOCA RHR (SDC)
Branch Model:
1AJF.2+ser Train 1 Cond Prob:
Train 2 Cond Prob:
Serial Component Prob:
RHR(SDC) /-LPCI RHR (SDC) /LPCI RHR(SPCOOL) /-LPCI.RHR(SDC)
C.I.AND.V/RHR(SDC).RHR(SPCOOL) 1.OE+00 I
.OE+OO 1
.OE+0O 6.OE-02 2.9E-03 4.6E-01 > L.OE+OO 4.6E-01 > Failed 1
.OE+OO 24.OE-02 6.7E-02 > 1.OE+OO 6.7E-02 > Failed 1.OE+0O 1.OE-02 6.7E-03 1
.OE+OO 2.OE-02 6.OE-04 I.OE+OO 1
.OE400 1
.OE+OO 2.1E-02 > 1.OE+0O 1.1E-02 > Failed 1.OE-O1 > Failed 2.OE-02 2.OE-02 1.OE+0O 2.OE-02 5.2E-01 1
.OE+OO 1
.OE+OO 1.OE+OO 1.OE+0O 1 AO+00 5.1E-O1 3.4E-01 > 1,OE+OO 3.4E-01 3.4E-01 5.7E-01 > 1.OE+OO 1
.OE+OO 1.OE+OQ I
.OE+00 3.4E-O1 3A.E-O1 3A.E-O1 I.OE+OO 1.OE+OO 1.OE+00 3.4E-O1 3.4E-01 I
.OE+OO 1.OE+OO 1.OE+OO 3.4E-01 U.E-02 4.E-02 forced Minarick 04-12-1987 11-14:55 Event Identifier: 373/84-054 D-211I