ML20149K401

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Final ASP Analysis - LaSalle 2 (LER 374-84-017)
ML20149K401
Person / Time
Site: LaSalle 
Issue date: 05/28/2020
From: Christopher Hunter
NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1984-017-00, LER 1984-018-00
Download: ML20149K401 (5)
v • d • e


Text

PRECURSOR DESCRIPTION SHEET LER No.:

374/84-017, -018 Event

Description:

LOFW While Shutting Down and HPCS Fails in Test Within +15 d of LOFW Date of Event:

May 3 and 17, 1984 Plant:

LaSalle 2 EVENT DESCRIPTION Sequence On May 3, 1984, while the reactor was at 10% power and shutting down, it was scrammed manually following failure to restart the motor-driven FW pump.

The pump had tripped due to a clogged strainer follow-ing a valving. error.

The tu 'rbine-driven FW pumps had been valved out due to the shutdown in progress..On May 17, with the reactor at 30%

power, the HPCS system failed in testing when the HPCS pump breaker failed to close and start the pump.

Faulty position switch contacts were found, and certain breaker/switch components had not been in-stalled.

Due to the nature of these events, HPCS may have been unavail-able during the May 3 LOFW.

Corrective Action The motor-driven FW pump was repaired and steps were taken to pre-vent a similar valving error from recurring.

The breaker position switch that caused the HPCS breaker failure was replaced.

In addition, all of the Division III 4160-V switchgear were inspected and cleaned before being returned to service.

Plant/Event Data Systems Involved:

MEW, HPCS Components and Failure Modes Involved:

Motor-driven FW pump -

tripped due to operator error HPCS pump -

failed to start on demand (breaker failure)

Component Unavailability Duration: NA Plant Operating Mode:

10%, 30% power Discovery Method:

See sequence description Reactor Age:

0.2 year Plant Type:

BWR Event Identifier:

374/84-017, -018 Dý-212

Comment s None MODELING CONSIDERATIONS AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient 1.0 Nonrecoverable Branches Impacted and Branch Nonrecovery Estimate PGs 1.0 Failed due to LOFW Main feed-0.34 Motor-driven train was not recover-water able; possible recovery through use of turbine-driven feed pump HPCS 0.34 Potential recovery at breaker Plant Models Utilized BWR plant Class C Event Identifier:

374/84-017, -018 D-213

CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Evenit Identifier: 374/84-017 Event

Description:

LOFW 'While Shutting Dawn and HPCS Fails in Test (4/-15 days)

Event Date:

5/3/84 Plant:

LaSalle 2 INITIATING EVENT NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS 1

.0E+00 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CV TRANS

4.

1E-06 Total

4. 1E-06 CD TRANS 3.8E-04 Total 3.BE-04 ATWS TRANS 2.OE-05 Total 2

.OE-05 DOMINANT SEQUENCES End State: CV Conditional Probability:

1.7E-06 155 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA -SRV.ADS -COND/FW.PCS

-RHR(SDC)

End State: CD Conditional Probability-3.2E-04 119 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM SRV.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA SRV.ADS End State: ATWS Conditional Probability:

2.OE-05 Event Identifier: 374/84-017 D-2 14

173 TRANS SCRAM SLC.OR.RODS SEQUENCE CONDITIONAL PROBABILITIES Sequence End State Prob N Rec**

101 TRANS -SCRAM PGS/TRANS SRV.DHALL/TRANS.-SCRAM -SRV.CLOSE -FW

/PCS.TRANS RHR(SDC). RHR(SPCOOL)/-LPCI.RHR(SDC)

C.i.AND.

W/RHR (SDC).RHR (SPCOOL) 102 TRANS -SCRAM PCS/TRANS SRY.CHALL/TRANS.-SCRAM -SRV.CLOSE FW

/PCS.TRANS -HPCI RHR(SDC) RHR(SPCOOL)/-LPCI.RHR(SDC) C.

I

.AND.V/RHR(SDC).RHR(SPCOOL) 119 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM SRV.CLOSE FW

/PCS.LOCA HPCI RCIC/LOCA SRV.ADS 134 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LQOP -SRV.ADS -COND/FW.PCS -RHR(SDC) 138 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/F125. TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS COND/FW.PCS -LPCS -RHR(

SDC) 155 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLOSE FN/PCS.LOCA HPCI RCIC/LOCA -SRV.ADS -COND/FW.PCS -RHR(SDC) 159 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA -SRV.ADS COND/FW.PCS -LPCS -RHR(SDC) 173 TRANS SCRAM SLC.OR.RODS CO CD CD CV Cv CV CV 3.OE-05 7.6E-02 1.OE-05 2.6E-02 3.2E-04

  • 1.2E-01 1.OE-06 4.3E-02 5.2E-07 2.2E-02 1.7E-06
  • 7.6E-02 8.6E-07 3.9E-02 2.OE-05
  • dominant sequence for end state
    • non-recovery credit for edited case MODEL:

DATA:-

b :\\bwrctree.cmp b: \\1asl prob.cmp No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES Branch System TRANS LOOP LOCA SCRAM SLC.OR.RODS PCS/TRANS Branch Model:

1.OF.1 Train 1 Cond Prob:

PCS/LOCA SRV.CHALL/TRANS.-SCRAM SRV.CHALL/TRANS.SCRAM Event Identifier: 374/84-017 1.1E-03 1.3E-05 3.3E-06

4.

1 E-04 1

.OE-02 1.7E-01 > 1.OE+00 1.7E-01 > Failed I

.OE+00 1.0E+00 1.0E+00 Non-Recov 1.0E+00 3.4E-01 3.4E-01 1.0E+00 1.0E+00 1

.OE+00 1.0E+00 1.0E+00 1

.OE+00 Opr Fail 4.OE-02 1)-2 15

SRY.CHLLILOOP.-SCRAMi SRV.CHALL/LOOP.SCRAM SRY.CLOSE EMERG.POER FW/PCS.TRANS Branch Model:

1.0F.1 Train 1 Cond Prob:

FW/PCS.LOCA HPCI Branch Model:

1.OF.1 Train I Cond Prob:

RCIC/TRANS IR

.LOOP RCIC/LOCA CRD SRV.ADS COND/FW.PCS LPCS LPC.I(RHR) /LPPS RHRSW/LPCS.LPCI.TRANS RHRSW/LPCS.LPCI.LOOP RHiRSW/LPCS.LPCI SLOCA RHR (SDC)

RHR (SDC) /-LPCI RHR (SDC) /LPCI RHR(SPCOOL) /-LPCI.RHR(SDC)

RHR(SPCOOL)/LPCI.RHR(SDC)

C.I.AND.V/RHR(SDC).RHR(SPCOOL)

    • forced Minarick 04-12-1987 12:02:46 Event Identifier: 374/84-017 I

.0E+00 I OE+00 6.OE-02 2.9E-03 4.6E-01 > 1.OE+0O 4.6E-01 > Failed 1

.OE+00 2.OE-02 > 1.OE+00 2.OE-02 > Failed 6.7E-02 1

.OE+00 1

.0E-02 6.7E-03 1.OE+00 2.OE-02 6.OE-04 1.0E+00 1

.OE+00 1

.OE+00 4.1E-02 2.OE-02 I

.OE+00 2.OE-02 5.2E-01 1.OE+00 1.OE+00 1

.OE400 I

.OE+00 5.1E-01 3.4E-01 3.4E-01 3.4E-01 5.7E-01 1.OE+00 1.OE+00 1

.0E+00 3A.E-01 3A.E-01 3.4E-01 1

.OE+00 1.0E+O0 1.OE+00 3A.E-01 3.4E-01 1.OE+00 1

.OE+00 I.OE+00 3.4E-01

4.

.E-0*22

4.

OE-02 D-216

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