ML20156A122
| ML20156A122 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 06/04/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1985-003-00 | |
| Download: ML20156A122 (5) | |
Text
PRECURSOR DESCRIPTION SHEET LER No.: 27 7/85-003 Event
Description:
Loss of One RHR and LPCI Train Date of Event: June 3, 1985 Plant: Peach Bottom 2 EVENT DESCRIPTION Sequence On June 1 during a test, the "A" residual heat removal (RUR) system outboard injection valve (154A) failed in mid-position. This failure was not detected.
On June 3, the ERR loop A injection valve failed to open in a test and could not be opened manually at the valve. This failure also affected LPCI system train A operation. The valve's lock nut and yoke nut had been damaged in a May 29 hydro test. A trust bearing was also found damaged.
Corrective Action The valve was repaired.
Plant/Event Data Systems involved:
LPCI and RHR Components and Failure Modes Involved:
Injection valve - failed in test twice Component Unavailability Duration: 96 h Plant Operating Mode: 6 (0% power)
Discovery Method: Testing Reactor Age: 11.8 years Plant Type: BWR Comments None Event Identifier: 277/85-003 E-101
MODELING CONSIDERATIONS AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient, LOOP, small LOCA (Postulated event)
Base case Events are conservatively assumed to occur at power Branches Impacted and Branch Nonrecovery Estimate LPCI base case one train failed RHR (shutdown base case One train failed coding mode)
Plant Models Utilized BWR plant Class C Event Identifier: 277/85-003 E- 102
CONDITIONAL CORE DAMAGE CALCULATIONS LER Number: 277/85-003 Event Description- Loss of One RHR and One LPCI Train Event Date: 6/3/B5 Plant: Peach Bottom 2 UNAVAILABILITY, DURATION= 9b NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS 1.096E-01 LOOP 4.L5BE-04 LOCA 1.061lE-04 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CV TRANS 1.575E-12 LOOP 8.480E-14 LOCA 1.777E-13 Total 1.037E- 12 CD TRANS 3.984 E-06 LOOP 9.604E-09 LOCA 2. 393E-08 Total 4.104E-06 ATWS TRANS 0.OOOE+00 LOOP 0.OOOE+OO LOCA 0.OOOE+00 Total 0.OO0E+00 DOMINANT SEQUENCE.S End State: CV Conditional Probability: 9.905E-11 156 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA -SRV.ADS -COND/FW.PCS RHR Event Identifier: 277/85-003 E-103
(SDC) -RHRiSPCOOL)/-LPCI.RHR(SDC)
End State; CD Conditional Probability: 3.237E-06 101 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE -FW/PCS.TRANS RHR(SDC) RHR(SPCDOL)/-LPCI.RH R(SDC) C.1.AND.V/RHR(SDC).RHR(SPCOOL)
SEQUENCE CONDITIONAL PROBABILITIES Sequence End State Seq. Prob Non-RecoVtt 101 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLUSE -FW CD 3.237E-06 t 1.015E-01
/PCS.TRANS RHR(SDC) RHR(SPCOOL)/-LPCI.RHR(SDC) C.1.AND.
V/RHR(SDC) .RHRiSPCOOL) 102 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE FN CD 5.66b0E-07 3.82SE-02
/PCS.TRANS -HPCI RHR(SDC) RHR(SPCOOL)/-LPCI.RHR(SDC) C.
I.AND.V/RHR(SDC) .RHR(SPCDOL) 135 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLDSE FW/PCS.TRANS CV 4.619E-11 2.285E-02 HPCI RCIC/TRANS.OR.LOOP -SRV.ADS -CONDIFW.PCS RHR(SDC) -
RHR(SPCDDL) I-LPCI .RHR(SDC) 139 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FWIPCS.TRANS CV 2.377E-11 1.177E-02 HPCI RCIC/TRANS.OR.LOOP -SRV.ADS CDND/FW.PCS -LPCS RHR(
SDC) -RHRISPCOOL)/-LPCJ.RHR(SDC) 156 TRANS SCRAM -SLC.OR.RDDS PCS/TRANS SRV.CLOSE FW/PCS.LOCA CV 9.905E-11 I 4.008E-02 HPCI RCIC/LOCA -SRV.ADS -CDND/FW.PCS RHR(SDC) -RHR(SPCOO L)/-LPCI.RHR(SDC) 160 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLDSE FN/PCS.LDCA CV 5.097E-11 2.065E-07 HPCI RCIC/LDCA -SRV.ADS COND/FW.PCS -LPCS RHRfSDC) -RHR (SPCOOL) /-LPCI.RHR(SDC) 227 LOOP -EMER6.PIJWER SCRAM -SLC.DR.RODS HPCI RCIC/TRANS.OR.LDD CV iJI1BE-11 3.461E-02 P -SRV.ADS -LPCS_ RHR(SDC) -RHR(SPCDOL)/-LPCI.RHR(SDC) 315 LOCA SCRAM -SLC.OR.RODS PCS/LOCA FW/PCS.LDCA HPCI -SRV.ADS CV 1.640E-11 1.363E-02
-COND/FW.PCS RHR(SDC) -RHR(SPCODL)/-LPCI.RHR(SDC) 319 LOCA SCRAM -SLC.DR.RODS PCS/LOCA FW/PCS.LDCA HPCI -SRV.ADS CV 8.43BE-12 7.020E-03 COND/FW.PCS -LPCS RHR(SDC) -RHR(SPCDOL)/-LPCI.RHR(SDC)
I dominant sequence for end state Itnon-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 in risk compared to a similar period without the existing failures.
MODEL: b:bvrctree. cup DATA: b:peachpro.cmp No Recovery Limit BRANCH FREgUENCIES/PRDBABILITIES Event Identifier: 277/B5-003 E-104
Branch System BrachSysemNon-Recov Opr Fail TRANS 1.142E-03 l.0O0E+00 LOOP 1.305E-05 3.400E-01 LOCA 3.250E-06 3.400E-O1 SCRAM 4.1OOE-04 1.000E+00 SLC. OR. RODS 1.OOOE-02 1.OOOE+00 4.OOOE-02 PCS/IRANS 1.700E-01 1.OOOE+00 PCS/LOCA 1.OOOE+00 1.000E+00 SRV. CHALLITRANS. -SCRAM 1.OOOE+00 1.O00E+00 SRV. CHALL/TRANS. SCRAM 1.000E+00 I.000E+00 SRV. CHALL/LOOP. -SCRAM I.O0OE+00 1.OOOE+00 SRV. CHALL/LOOP. SCRAM 1.OOOE+00 1.000E+00 SR?. CLOSE 3.630E-02 1.000E+00 EMERG. POWER 2.708E-04 5.1IOOE-0 I FW/PCS. TRANS 4.600OE-01 3.400E-01 FW/PCS.LOCA 1.OOOE+00 3.400E-01 HPCI 1.000OE-01 5.700E-01 RCIC/TRANS. OR. LOOP 6.700E-02 5.700E-01 RCIC/LOCA 1.OOOE+00 1.OOOE+00 CRD 1.000E-02 1.000E+00 4.OOOE-02 SRV. ADS 6.700E-03 I.000E+00 4.OOOE-02 COND/FW. PCS 1.000E+00 3.400E-01 LPCS 3.000E-03 3.400E-01 LPCI (RHR) /LPCS 4.OOOE-04 > 1.000E-01 3.400E-01 Branch Model: I.OF.2 Train I Cond Prob: 4.OOOE-03 > Failed Train 2 Cond Prob: I.OOOE-01 RHRSWILPCS. LPCI .TRANS 5.OOOE-01 1.000E+00 4.OOOE -02 RHRSW/LPCS. LPCI .LOOP 5.OOOE-01 1.000E+00 4.OOOE-02 RHRSW/LPCS.LPCI .LOCA 5.OOOE-01 1.OO0E+00 4.OOOE-02 RHR (SDC) 2.039E-02 ) I.180E-01 3.400E-01 Branch Model: I.OF.2+ser Train 1 Cond Prob: 4.OOOE-03 > Failed Train 2 Cond Prob: 1.00OOE-01 Serial Component Probability: 2.OOOE-02 RHR(SDC) /-LPCI 2.OOOE-02 3.400E-01 RHR(SDC) /LPCI 1.000E+00 1.000OE+00J RHR (SPCODL) I-LPCI .RHR (SDC) 2.OOOE-02 1.000OE+00 RHR(SPCOOL) /LPCI.RHR(SDC) 5.200E-01 1.OOOE+00 C.I.AND.V/RHR(SDC).RHR(SPCOOL) 1.0OO0E+00 3.400E-01 111 forced-JD HARRIS 10-07-1986 14:54:34 Event Identifier: 277/B5-003 E-105