ML20147A475
| ML20147A475 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/26/2020 |
| From: | Christopher Hunter Office of Nuclear Regulatory Research |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1987-001-02 | |
| Download: ML20147A475 (4) | |
Text
B-7 1 PRECURSOR DESCRIPTION SHEET LER No.:
324/87-001 R2 Event
Description:
Reactor trip with HPCI and RCIC unavailable Date of Event:
1/5/87 Plant:
Brunswick 2 EVENT DESCRIPTION Sequence While at 100% power, problems with holding main generator voltage caused a grid voltage fluctuation and a reactor scram.
A low RCS level signal initiated RCIC and HPCI;
- however, the systems did not inject because the signal duration was too brief to permit seal-in of each system's injection valve opening logic (per design).
RCS pressure peaked at 1189 psig, and MSRVs opened to relieve steam.
Operators opened additional valves to lower RCS pressure.
Several SRVs lost valve position indication, but the loss of indication did not affect relief function.
Operators monitored tailpipe temperature to confirm opera-bility.
Operators attempted to use RCIC to restore vessel inventory, but this was ineffective because of a 50% open full-flow test valve.
When operators tried to use HPCI again, its injection valve would not open due to its valve motor having failed.
A control rod drive pump and RCIC (degraded) were employed to maintain vessel level.
Corrective Action Repairs were made.
Plant/Event Data Systems Involved:
HPCI Components and Failure Modes Involved:
HPCI isolation valve motor fails on demand, RCIC valve stem anti-rotation device failed.
Component Unavailability Duration:
N/A Plant Operating Mode:
1 (100%)
Discovery Method:
Operational event Reactor Age:
11.8 y Plant Type:
BWR Comments The event has been modeled assuming RCIC inoperability and the use of the CRD pumps for injection.
Event Identifier:
324/87-001 R2
B-72 MODELING CONSIDERATION AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient No recovery Branches Impacted and Branch Nonrecovery Estimate HPCI 1.0 No recovery RCIC 1.0 No recovery (CRD pumps utilized)
PCS 1.0 No recovery Plant Models Utilized BWR plant Class C Event Identifier:
324/87-001 R2
B-73 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier:
324/87-001R2 Event
Description:
Reactor trip with HPCI and RCIC unavailable Event Date:
01/05/87 Plant:
Brunswick 2 INITIATING EVENT NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator
- 1. OE+00 Probability CD CV TRANS Total TRANS Total 2.4E-04 2.4E-04
- 1. 3E-04 1.3E-04 7.OE-06 7.OE-06 ATWS TRANS Total SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence 145 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close fw/p cs.loca HPCI srv.ads 125 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CS.TRANS HPCI RCIC crd srv.ads 913 trans scram -slc.or.rods PCS/TRANS -srv.close FW/PCS.TRANS H
PCI RCIC -srv.ads -cond/fw.pcs -rhr(sdc) 917 trans scram -slc.or.rods PCS/TRANS -srv.close FW/PCS.TRANS H
PCI RCIC -srv.ads cond/fw.pcs -lpcs -rhr(sdc) 101 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close -FW/P CS.TRANS rhr(sdc) rhr(spcool)/-ipci.rhr(sdc)
-c.i.and.v
-rhrsw (c.i.and.v) 110 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CS.TRANS HPCI RCIC -crd rhr(sdc) rhr(spcool)/-lpci.rhr(sdc)
-c.i.and.v 941 trans scram -slc.or.rods PCS/TRANS srv.close fw/pcs.loca HP CI -srv.ads -cond/fw.pcs -rhr(sdc) 963 trans scram slc.or.rods non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence 101 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close -FW/P CS.TRANS rhr(sdc) rhr(spcool)/-lpci.rhr(sdc)
-c.i.and.v
-rhrsw (c.i.and.v) 110 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CS.TRANS HPCI RCIC -crd rhr(sdc) rhr(spcool)/-lpci.rhr(sdc)
-c.i.and.v End State CD CD Prob
- 1. 6E-04 8.2E-05 7.3E-05 3.7E-05 8.4E-06 N Rec**
- 2. 4E-01 2.4E-01 2.2E-01 1.1E-01
- 1. 9E-01 CV CV CV CV CV 5.1E-06 1.2E-01 2.7E-06 2.2E-01 7.OE-06 1.OE+00 ATWS End State CV Prob N Rec**
8.4E-06 1.9E-01 5.1E-06 1.2E-01 CV Event Identifier:
324/87-001R2
B-74 125 145 913 917 941 963 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CS.TRANS HPCI RCIC crd srv.ads trans -scram PCS/TRANS srv.chall/trans.-scram srv.close fw/p cs.loca HPCI srv.ads trans scram -slc.or.rods PCS/TRANS -srv.close FW/PCS.TRANS H
PCI RCIC -srv.ads -cond/fw.pcs -rhr(sdc) trans scram -slc.or.rods PCS/TRANS -srv.close FW/PCS.TRANS H
PCI RCIC -srv.ads cond/fw.pcs -ipcs -rhr(sdc) trans scram -slc.or.rods PCS/TRANS srv.close fw/pcs.loca HP CI -srv.ads -cond/fw.pcs -rhr(sdc) trans scram slc.or.rods CD CD Cv Cv Cv 8.2E-05 2.4E-01 1.6E-04 2.4E-01 7.3E-05 2.2E-01 3.7E-05 1.1E-01 2.7E-06 2.2E-01 7.0E-06 1.0E+00 ATWS
- non-recovery credit for edited case SEQUENCE MODEL:
BRANCH MODEL:
PROBABILITY FILE:
c:\\asp\\newmodel\\bwrcnew.cmp c:\\asp\\newmodel\\brunswck.new c:\\asp\\newmodel\\bwr_cnew.pro No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES Branch System Non-Recov Opr Fail trans loop loca scram slc.or.rods PCS/TRANS Branch Model:
l.OF.1 Train 1 Cond Prob:
srv.chall/trans.-scram srv.chall/loop.-scram srv.close emerg.power ep.rec FW/PCS.TRANS Branch Model:
l.OF.l Train 1 Cond Prob:
fw/pcs.loca HPCI Branch Model:
1.OF.l Train 1 Cond Prob:
RCIC Branch Model:
l.OF.I Train 1 Cond Prob:
crd srv.ads cond/fw.pcs lpcs lpci(rhr)/lpcs rhr(sdc) rhr(sdc)/-lpci rhr (sdc) /lpci rhr(spcool) /-lpci.rhr(sdc) rhr(spcool)/lpci.rhr(sdc) c.i.and.v rhrsw rhrsw(c.i.and.v) branch model file
- forced Minarick 05-16-1989 06:52:21
- 8. 6E-04 1.7E-05
- 3. 3E-06 3.5E-04 1. 0E-02 1.7E-01 > 1.OE+00 1.7E-01 > Unavailable 1.OE+00 1.OE+00 3.6E-02 2.9E-03 1.OE+00 4.6E-01 > 1.0E+00 4.6E-0l > Unavailable 1.OE+00 2.9E-02 > 1.OE+00 2.9E-02 > Failed 6.OE-02 > l.OE+00 6.OE-02 > Failed 1.OE-02 3.7E-03 1.0E+00 3.OE-03 I.OE-03 2.1E-02 2.OE-02 1.OE+00 2.OE-03 5.2E-01 1.OE-03
- 2. OE-02 5.OE-01 1.OE+00 3.2E-01 5.OE-01 I.OE+00 1.OE+00 1.OE+00 1.OE+00 1.OE+00 1.OE+00 8.0E-01 1.7E-01
- 3. 4E-01 3.4E-01 7.OE-0
> l.OE+00 7.OE-01 > 1.OE+00 1.OE+00 7.1E-01 3.4E-01 3.4E-01 7.1E-01 3.4E-01 3.4E-01 1.OE+00 1.OE+00 1.OE+00 1.OE+00 3.4E-01 3.4E-01 1.OE-02 1.OE-02 1.OE-02 1.OE-03 1.OE-03 I.OE-03 1.OE-03 1.OE-02 2.OE-03 Event Identifier:
324/87-001R2