ML20156A209
| ML20156A209 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 06/04/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1984-017-00 | |
| Download: ML20156A209 (5) | |
Text
PRECURSOR DESCRIPTION SHEET LER No.: 272/84-017 Event
Description:
Unavailability of High-Head Charging Pumps Date of Event: July 16, 1984 Plant: Salem 1 EVENT DESCRIPTION Sequence While performing surveillance testing of charging pump 12, the pump-seized after running for -.30 s. Charging pump 12 was declared inoper-able; the redundant charging pumps remained operable. Upon disassembly' of the pump, a small amount of resin particles and metal filings were discovered in the pump casing. As a result of these findings, an in-vestigation ensued to determine the source and extent of the problem.
Similar material was found in the common suction line of all charging pumps.
It has been assumed (because of the extremely close internal tolerances in the centrifugal charging pumps) that the other charging pumps would also have failed as a result of the metal filings.
Corrective Action Replaced rotating element in the charging pump. Suction lines were cleaned and temporary strainers installed.
Plant/Event Data Systems Involved:
RHI S Components and Failure Modes Involved:
Charging pump 12 - failed on demand Remaining charging pumps - potentially failed on demand Component Unavailability Duration: 360 h (postulated)
Plant Operating Mode: 6 (0% power)
Discovery Method: During testing Reactor Age: 3.9 years Plant Type: PWR Comments This unavailability possibly could have been discovered during startup checks; however, it is being conservatively modeled as if it could have rendered HPI unavailable at power.
Event Identifier: 272/84-017 D-7 3
MODELING CONSIDERATIONS AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Postulated tran- Base case sient, LOOP, and LOCA Branches Impacted and Branch Nonrecovery Estimate HPI 1.0 No recovery is assumed possible Bleed and feed 1.0 No recovery is assumed possible Plant Models Utilized PWR plant Class B Event Identifier: 272/84-017 D- 74
CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier: 272/84-017 Event
Description:
Unavailability of High-Head Charging Pumps Event Date: 7/16/84 Plant: Salem 1 UNAVAILABILITY, DURATION= 360 NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS 3.E-01 LOOP 2.8E-03 LOCA 5.IE-04 SEQUENCE CONDITIONAL PROBABILITY SLIMS End State/Initiator Probability CV TRANS 1.6E-03 LOOP 6.2E-07 LOCA 4.BE-04 Total 2.1E-03 CD TRANS 2.OE-06 LOOP 7.OE-07 LOCA 4.5E-06 Total 7.3E-06 ATWS TRANS 0.OE+O0 LOOP 0.OE+00 LOCA 0.OE+00 Total 0.OE+00 DOMINANT SEQUENCES End State: CV Conditional Probability: 1.5E-03 Event Identifier: 272/84-017 Dý-75
109 TRANS -RT -AFW -PORV.JR.SRV.CHALL SS.RELEAS.TERM HPI End State: CD Conditional Probability:-- 1.8E-05 307 LOCA -RT -AFW HPI SS .DEPRESS SEQUENCE CONDITIONAL PROBABILITIES Sequence End State Prob, N-Rec*f 101 TRANS -RT -AFW PORV.OR.SRV.CHALL -PORV.OR.SRV.RESEAT SS.RELE CV 6.3E-05 3.4E-01 AS.TERM HPI 109 TRANS -RT -AFW -PORV.OR.SRV.CHALL SS.RELEAS.TERM Ff1 CV 1.5E-03 *~3.4E-01 126 TRANS -RT AFW OFW HPI (F/B) -56 .DEPRESS COND/MFW CD 1.9E-06 3.1E-02 214 LOOP -RT/LOOP -EMERG.POW'ER AFW HPI(F/B) CD 7.3E-07 9.2E-02 304 LOCA -RT -AFW HP! -SS.DEPRESS -LPI/HPI -LPR/HPI CV 4.9E-04 3.4E-01 307 LOCA -RT -AFW HPI 95 .DEPRESS CD 1.BE-05 -3.4E-01
- dominant sequence for end state
- non-recovery credit for edited case Note: For unavailabilities, conditional probability values are differential values which refflectthe added risk due to failures associated with an event. Parenthetical values indicate a reduction inrisk compared to a similar period without the existing failures.
MODEL: b:\pwrbtree.cmp DATA: b:\salempro.cmp No Recovery Limit BRANCH FREQUJENCIES/PROBABILITIES Branch System Non-Recov Opr Fail TRANS 1.OE-03 1.0E+00 LOOP 2.3E-05 3.4E-01 LOCA 4.E-06 3.4E-01 RT 2.5E-04 1.2E-01 RT/LOOP 0.OE+00 1.0E+00 EMERS .POWER 5.4E-04 5.1E-01 AFW 1.OE-03 2.7E-01 AFW/EMERS .POWER 5.OE-02 3.4E-01 MFW 2.OE-01 3.4E-01 PORV .OR .SRV .CHALL 4 .E-02 1.OE+00 PORV .OR .SRV .RESEAT 2.OE-02 5.OE-02 PORV.OR .61W.RESEAT/EMERS .POWER 2.OE-02 5.OE-02 66 .RELEAS .TERM 1.5E-02 3.4E-01 SB .RELEAS .TERM/-MFW 1.5E-02 3.4E-01 HP! 1.0E-03 > 1.OE+00 5.2E-01 > 1.0E+00 Event Identifier: 272/84-017 1)-76
Branch Model : 1.OF.2 Train 1 Cond Prob: 1.0E-02 > Failed Train 2 Corid Prob: 1.OE-01 > Failed WPI (F/B) 1.OE-03 ) 1.0E+00 5.2E-01 > 1.OE+O0 4.OE-02 Branch Model: l.OF.2+opr Train 1 Cond Prob: 1.OE-02 > Failed Train 2 Cond Prob: 1.OE-01 > Failed 3.OE-03 5.6E-01 4 OE-02 PORV.WE 1.0E-02 1.OE+00 SS.DEPRESS 3.6E-02 1.OE+00 COND/MFW 1.OE+00 3.4E-01 LPI/WIf 1 OE-03 3A.E-01 LPR/-WIHPI~R 6.7E-01 1.OE+00 LPR/HPI 1.OE-03 1.OE+00
- forced Minarick 04-11:-1987 14:26:35 Event Identifier: 272/84-017 D-77