ML20156A127
| ML20156A127 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 06/04/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1987-009-00 | |
| Download: ML20156A127 (3) | |
Text
B-172 PRECURSOR DESCRIPTION SHEET LER No.: 440/87-009 Event
Description:
Two diesel generators inoperable Date of Event: 2/27/87 Plant: Perry I EVENT DESCRIPTION Sequence Two control air solenoid valves failed (leaked) and caused the two emergency diesel generators to be inoperable. No conclusive cause of failure was identified. Both solenoid valves had been previously identified for replacement. The high-pressure core spray diesel generator and system were operable during this time frame.
Corrective Action The air solenoid valves were replaced.
Plant/Event Data Systems Involved:
Emergency power Components and Failure Modes Involved:
Two diesel generators inoperable Component Unavailability Duration: 360 h (assumed)
Plant Operating Mode: 1 (29% power)
Discovery Method: Surveillance test Reactor Age: 0.72 y Plant Type: BWR Comments None.
MODELING CONSIDERATION AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Postulated LOOP Base case nonrecovery Branches Impacted and Branch Nonrecovery Estimate Emergency power 1.0 Assumed nonrecoverable EP recovery 0.04 (HPCS DC operable)
Plant Models Utilized BWR plant Class C Event Identifier: 440/87-009
B-173 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier: 440/87-009 Event
Description:
Two diesel generators inoperable Event Date: 02/27/87 Plant: Perry I UNAVAILABILITY, DURATION= 360 NON-RECOVERABLE INITIATING EVENT PROBABILITIES LOOP 2.OE-03 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CD LOOP 2. 3E-04 Total 2.3E-04 CV LOOP 9.9E-09 Total 9.9E-09 ATWS LOOP 6. 7E-07 Total 6.7E-07 SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence End State Prob N Rec**
274 loop EMERG.POWER -scram EP.REC CD 2.3E-04 3. BE-02 256 loop EMERG.POWER -scram -EP.REC srv.chall/loop.-scram -srv.clo CV 2. 3E-08 8.2E-02 se -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v -rhrsw (c.i.and.v) 263 loop EMERG.POWER -scram -EP.REC srv.chall/loop.-scram srv.clo CV 1.5E-09 8.2E-02 se -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v -rhrsw (c.i.and.v) 221 loop -EMERG.POWER -scram srv.chall/loop.-scram srv.close -hpci CV 1.8E-09 4.7E-02 rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v -rhrsw(c.i.and.v 202 loop -EMERG.POWER -scram srv.chall/loop.-scram -srv.close -hpci CV 5.4E-09) 1.BE-02 rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v rhrsw(c.i.and.v 201 loop -EMERG.POWER -scram srv.chall/loop.-scram -srv.ciose -hpci CV 2.6E-08 4. 7E-02 rhr(sdc) rhr(spcoal)/-lpci.rhr(sdc) -c.i.and.v -rhrsw(c.i.and.v 841 loop EMERG.POWER scram ATWS 6.8E-07 3.2E-01
-* non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence End State Prob N Rec**
201 loop -EMERG.POWER -scram srv.chall/loop.-scram -srv.close -hpci CV 2.6E-08 ) 4.7E-02 rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v -rhrsw(c.l.and.v 202 loop -EMERG.POWER -scram srv.chall/loop.-scram -srv.close -hpci CV 5.4E-09 ) 1.BE-02 rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v rhrsw(c.i.and.v Event.Identifier: 440/87-009
B-174 221 loop -EMERG.POWER -scram srv.chall/loop.-scram srv.close -hpci Cv ( 1.BE-09 ) 4.7E-02 rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v -rhrsw(c.i.and.v 256 loop EMERG.POWER -scram -EP.REC srv.chall/loop.-scram -srv.clo Cv 2.3E-08 8.2E-02 se -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v -rhrsw (c.i.and.v) 263 loop EMERG.POWER -scram -EP.REC srv.chall/loop.-scram srv.clo Cv 1.5E-09 8.2E-02 se -hpci rhr(sdc) rhr(spcool)/-lpct.rhr(sdc) -c.i.and.v -rhrsw (c.i.and.v) 274 loop EMERG.POWER -scram EP.REC CD 2.3E-04 3.BE-02 841 loop EMERG.POWER scram ATWS 6.8E-07 3.2E-01
- non-recovery credit for edited case Note: For unavailabilities, conditional probability values are differential values which reflect the added risk due to failures associated with an event. Parenthetical values indicate a reduction in risk compared to a similar period without the existing failures.
SEQUENCE MODEL: c:\asp\newmodel\bwr_cnew.cmp BRANCH MODEL: c:\asp\newmodel\perry.new PROBABILITY FILE: c:\asp\newmodel\bwrcnew.pro No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES Branch System Non-Recov Opr Fail trans S. 6E-04 1.OE+O0 loop 1. 7E-05 3.2E-01 loca 3.3E-06 5.OE-OI scram 3.5E-04 1.OE+O0 slc.or.rods i.OE-02 1.OE+O0 1.OE-02 pcs/trans 1.7E-01 1.OE+00 srv.chall/trans.-scram I.OE+00 1.OE+00 srv.chall/loop.-scram 1.OE+OO l.OE+O0 srv.close 6.3E-02 1.OE+O0 EMERG.POWER 2.9E-03 > I.OE+O0 8.OE-O1 > I.OE+00 Branch Model: l.OF.2 Train 1 Cond Prob: 5.OE-02, > Failed Train 2 Cond Prob: 5.7E-02 > Failed EP.REC 1.OE+00 > 1.0E+O0 1.7E-01 > 1.2E-01 Branch Model: 1.OF.I Train 1 Cond Prob: 1.OE+O0 fw/pcs.trans 4.6E-01 3.4E-01 fw/pcs.loca 1.OE+00 3.4E-01 hpci 2.OE-02 3.4E-01 rcic 6.OE-02 7.OE-01 crd 1.OE-02 1.OE+00 1.OE-02 srv.ads 3.7E-03 ,7.1E-O1 1.OE-02 cond/fw.pcs 1.OE+00 3.4E-01 I.OE-03 lpcs 2.OE-02 3.4E-01 lpci(rhr)/lpcs 6.OE-04 7.1E-01 rhr(sdc) 2.3E-02 3.4E-01 1.OE-03 rhr(sdc)/-lpci 2.OE-02 3.4E-01 1.OE-03 rhr(sdc)/lpci 1.OE+O0 1.OE+O0 1.OE-03 rhr(spcool)/-lpci.rhr(sdc) 2.OE-03 I.OE+O0 rhr(spcool)/lpci.rhr(sdc) 5.2E-01 1.OE+00 c.i .and.v 1.OE-03 1.OE+00 1.OE-02 rhrsw 2.OE-02 3.4E-01 2.OE-03 rhrsw(c.i.and.v) 5.OE-01 3.4E-01
- branch model file
- forced Minarick 05-16-1989 07:03:53 Event Identifier: 440/87-009