ML20156A137
| ML20156A137 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/04/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1985-027-00 | |
| Download: ML20156A137 (5) | |
Text
PRECURSOR DESCRIPTION SHEET LER No.: 293/85-027 Event
Description:
LPCI Made Inoperable for Modifications Date of Event: September 19, 1985 Plant: Pilgrim 1 EVENT DESCRIPTION Sequence The LPCI was out of service for equipment qualification work when the loop "B" injection valve failed to open in a test because of a failed motor. The motor failed from aging and wear.
Corrective Action The valve was repaired.
Plant/Event Data Systems Involved:
LPCI Components and Failure Modes Involved:
Injection valve - failed in test Component Unavailability Duration: 32.5 h Plant Operating Mode: 1 (100% power)
Discovery Method: Testing Reactor Age: 13.3 years Plant Type: BWR Comments The LER indicates the "LPCI system" was inoperable and that only RHR train A and LPCS were available, which implies RHR B train B was inoperable. Therefore, LPCI injection capability and RHR train B were assumed unavailable.
Event Identifier: 293/85-027 E-130
MODELING CONSIDERATIONS AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient, LOOP, Base case small LOCA (postulated event)
Branches Impacted and Branch Nonrecovery Estimate LPCI 1.0 Not recoverable iqithin --30 min (as sumed)
RHR Base case One train unavailable Plant Models Utilized BWR plant Class C Event Identifier: 293/85-027 E- 131
CONDITIONAL CORE DAMAGE CALCULATIONS LER Number: 293/85-027 Event
Description:
LPCI Made Inoperable for Modifications Event Date: 9/19/85 Plant. Pilgrim UNAVAILABILITY, DURATION= 32.5 NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS 3.712E-02 LOOP 1.442E-04 LOCA 3.591E-05 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CV TRANS 2.225E-13, LOOP 9.005E-14 LOCA 4.503E-15 Total 3.250E- 13 CD TRANS 1.39BE-06 LOOP 3.260E-08 LOCA B.109E-09 Total 1.439E-06 ATWS TRANS 0.OOOE+00 LOOP 0.OO0E+00 LOCA 0.OOOE+0O Total 0.OOOE+00 DOMINANT SEQUENCES End State: CV Conditional Probability: 1.046E-11 135 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FWIPCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS -COND/F Event Identifier: 293/85-027 E- 132
W.PCS RHR(SDC) -RHR(SPCOOL)I-LPCI.RHR(SDC)
End State: CD Conditional Probability: l.243E-06 101 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE -FW/PCS.TRANS RHR(SDC) RHR(SPCOOL)/-LPCI.RH R(SDC) C.I.AND.V/RHR(SDC).RHR(SPCaOL)
SEQUENCE CONDITIONAL PROBABILITIES Sequence End State Seq. Prob Non-Recov*f 101 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAN -SRV.CLOSE -FW CD 1.243E-06
- 1.073E-01
/PCS.TRANS RHR(SDC) RHR(SPCOOL)I-LPCI.RHR(SDC) C.I.AND.
V/RHR(SDCI .RHR(SPCOOL) 102 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS. -SCRAM -SRV.CLOSE FW CD 1.282E-07 3.82BE-02
/PCS.TRANS -HPCI RHR(SDC) RHR(SPCOOL)/-LPCI.RHR(SDC) C.
I.AND.V/RHR(SDC) .RHR(SPCOOL) 135J TRANS SCRAM -SLC.OR.RODS PCSITRANS -SRV.CLOSE FWIPCS.TRANS CV 1.046E-11 *2.2W5-02 HPCI RCIC/TRANS.OR.LOOP -SRV.ADS -COND/FW.PCS RHR(SDC) -
RHR(SPCOOL) /-LPCI.RHR(SDC) 139 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS 5.385E-*12 1.177E-02 HPCI RCIC/TRANS.OR.LOOP -SRV.ADS COND/FW.PCS -LPCS RHR(
SOC) -RHR(SPCOOL) /-LPCI.RHR(SDC) 156 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLO SE FW/PCS.LOCA CV 5.055E-13 4.OOBE-02 HPCI RCIC/LOCA -SRV.ADS -COND/FW.PCS RHR(SDC) -RHR(SPCOO L)/-LPCI.RHR(SDC) 227 LOOP -EMERG.POWER SCRAM -SLC.OR.RODS HPCI RCIC/TRANS.OR.LOO CV 3.782E-12 3.461E-02 P -SRV.ADS -LPCS RHR(SDC) -RHR(SPCOULI /-LPCI.RHR(SDC)
- dominant sequence for end state 1*non-recovery credit for edited case Note:
Conditional probability values are differential values which reflect the added risk due to observed failures.
Parenthetical values indicate a reduction inrisk compared to a similar period without the existing failures.
MODEL- b:bwrctree.cmp DATA- b:pilgprob.cep No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES Branch System Non-Recov Opr Fail TRANS 1.142E-03 1.000E+00 LOOP 1.305E-05 3.400E-01 LOCA 3.250E-06 3.400E-01 SCRAM 4.IOOE-04 1.OOOE+00 Event Identifier: 293/85-027 E-1 33
SLC.OR. RODS 1.OOOE-02 1.OOOE+00 4.O0OE-02 PCS/TRANS 1.700E-01I 1.O0OE+00 PCS/LOCA 1.OOOE+00 1.O00E+00 SRV. CHALL/TRANS. -SCRAM 1.OO0E+00 1.OOOE+00 SRV. CHALL/TRANS. SCRAM 1.OOOE+O0 1.OOOE+00 SRV. CHALL/LGOP. -SCRAM 1. OOOE+00 1.OOOE+00 SRV.CHALL/LOOP. SCRAM 1.000E+00 1.OOOE+00 SRV. CLOSE 1.320E-02 1.OOOE+00 EMERG. POWER 2. 850E-03 5.IOOE-01 FW/PCS. TRANS 2. 900E-01 3.400E-01 FW/PCS. LOCA 4. OOOE-02 3.400E-01 HPC I 1.OOOE-01 5.700E-01 RCIC/TRANS. OR. LOOP 6.7100E -02 5.7O0E-01 RCIC/LOCA 1.OOOE+00 1.OOOE+00 CR0 1.OOOE-02 1.OOOE+00 4.OOOE-02 SRV. ADS 6.700E-03 1.000E+00 4.OOOE-02 COND/FW. PCS 1.000E+00 3.400E-01 LPCS 3.OOOE-03 31.
400E-01I LPCI (RHR) /LPCS 4.OOOE-04 >1.0OOE+00 3.400E-01 > 1.000E+00 Branch Model: 1.OF.2 Train 1 Cond Prob: 4.O00E-03 > Unavailable Train 2 Cond Prob: 1.000E-01 ) Unavailable RHRSI4/LPCS. LPCI. TRANS 5.OOOE-01 1.000E 400 4. OOOE-02 RHRSW/LPCS. LPCI .LOOP 5.000E-01 1. OO0E+00 4.OOOE-02 RHRSW/LPCS. LPCI.LOCA 5. OOOE-01 1. OOOE+00 4.OOOE-02 RHR (SDC) 2.039E-02 > 1.180E-01 3.400E-01 Branch Model: 1.OF.2+5er Train 1 Cond Prob: 4.OOOE-03) ) Failed Train 2 Cond Prob: 1.000E-01 Serial Component Probability: 2. 000E-02 RHR(SDC) /-LPCI 2. 000E-02 3.400E-01 RHR(SDC)/LPCI 1.000E+00 1.OOOE+00 RHR(SPCOOL) /-LPCI.RHR (SDC) 2.000OE-02 1.OOOE+0O RHR (SPCOOL) /LPCI .RHR (SDC) 5. 200E-01 1.OOOE+00 C.I.AND.Y/RHR(SDC) .RHR(SPCOOL) 1.0O0E+00 3.400E-01 f** forced Austin 08-14-1986 13: 28:41 Event Identifier: 293/85-027 E- 134