ML20156A199
ML20156A199 | |
Person / Time | |
---|---|
Site: | River Bend |
Issue date: | 06/04/2020 |
From: | Christopher Hunter NRC/RES/DRA/PRB |
To: | |
Littlejohn J (301) 415-0428 | |
References | |
LER 1987-032-00 | |
Download: ML20156A199 (4) | |
Text
B-186 PRECURSOR DESCRIPTION SHEET LER No.:
458/87-032 Event
Description:
Low power scram with failed CRD pumps and MFW Date of Event:
12/19/87 Plant:
River. Bend 1 EVENT DESCRIPTION Sequence The plant was in startup at 0% power following a refueling out-age.
Due to an error in a written procedure and an operator's cognitive procedural error, the normally locked open isolation valve (V123) to the CST was closed during a test of the CRD system and was not reopened.
The CST is the alternate water supply for the CRD pumps when the normal condensate supply is unavailable.
On the following
- shift, a
leak occurred in the short cycle condensate line requiring the condensate system to be shut down (LOFW).
With V123 closed, the CRD pumps were unable to take suction from the CST and tripped off.
The operators manually scrammed the reactor.
The CST isolation valve was closed on a previous shift in accord-ance with the "Control Rod Drive Hydraulics" operating procedure.
In addition, the operator failed to obtain proper authorization to reposi-tion the valve (in violation of an administrative procedure and an operations procedure).
Corrective Action The CRD lineup was immediately restored and the pump restarted.
The deficient procedure was revised and the operator was counseled.
Plant/Event Data Systems Involved:
Condensate Control rod drive pump Main feedwater Components and Failure Modes Involved:
CST isolation valve closed in test Condensate line leaks in operation MFW fails in operation Component Unavailability Duration:
N/A Plant Operating Mode:
2 (0%)
Discovery Method:
Operational event Reactor Age:
2.1 y Plant Type:
BWR Event Identifier:
458/87-032
B-187 Comments None.
MODELING CONSIDERATION AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient 1.0 No recovery Branches Impacted and Branch Nonrecovery Estimate CRDS 0.34 Recoverable locally at CST valve MFW 1.0 No recovery Plant Models Utilized BWR plant Class C Event Identifier:
458/87-032
B-188 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier:
458/87-032 Event
Description:
Low power scram with failed CRD pumps and MFW Event Date:
12/19/87 Plant:
River Bend 1 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 5.9E-06 5.9E-06 ATWS 1.5E-05
- 1. 5E-05 7.0E-06 7-OE-06 TRANS Total SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence End State 105 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CD CS.TRANS -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v rhrsw(c.i.and.v) 145 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close fw/p CD cs.loca hpci srv.ads 125 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CD CS.TRANS hpci rcic CRD srv.ads 106 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CD CS.TRANS -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) c.i.and.v 127 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close -fw/p CD cs.loca rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v rhrsw(
c.i.and.v) 104 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CV CS.TRANS -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v
-rhrsw(c.i.and.v) 126 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close -fw/p CV cs.loca rhr(sdc) rhr(spcool)/-lpci.rhr(sdc) -c.i.and.v
-rhrsw(
c.i.and.v) 963 trans scram slc.or.rods ATWS
-- non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence End State 104 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CV CS.TRANS -hpci rhr(sdc) rhr(spcool)/-ipci.rhr(sdc) -c.i.and.v
-rhrsw(c.i.and.v) 105 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CD Prob N Rec**
2.8E-06 1.2E-01 1.5E-06 1.2E-06 1.8E-07 1.0E-07 8.2E-02 5.7E-02 3.4E-01
- 7. 6E-02 1.4E-05 2.9E-01 5.0E-07 1.9E-01 7.OE-06 1.OE+00 Prob N Rec*
1.4E-05 2.9E-01 2.8E-06 1.2E-01 Event Identifier:
458/87-032
B-189 CS.TRANS -hpci rhr(sdc) rhr(spcool)/-lpci.rhr(sdc)
-c.i.and.v rhrsw(c.i.and.v) 106 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CS.TRANS -hpci rhr(sdc) rhr(spcool)/-ipci.rhr(sdc) c.i.and.v 125 trans -scram PCS/TRANS srv.chall/trans.-scram -srv.close FW/P CS.TRANS hpci rcic CRD srv.ads 126 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close -fw/p cs.loca rhr(sdc) rhr(spcool)/-lpci.rhr(sdc)
-c.i.and.v
-rhrsw(
c.i.and.v) 127 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close -fw/p cs.loca rhr(sdc) rhr(spcool)/-lpci.rhr(sdc)
-c.i.and.v rhrsw(
c.i.and.v) 145 trans -scram PCS/TRANS srv.chall/trans.-scram srv.close fw/p cs.loca hpci srv.ads 963 trans scram slc.or.rods CD CD CV CD 1.8E-07 3.4E-01 1.2E-06 5.7E-02 5.OE-07 1.9E-01 1.OE-07 7.6E-02 1.5E-06 8.2E-02 7.OE-06 1.0E+00 CD ATWS
- non-recovery credit for edited case SEQUENCE MODEL:
BRANCH MODEL:
PROBABILITY FILE:
c:\\asp\\newmodel\\bwrcnew.cmp c:\\asp\\newmodel\\riverbnd.new c:\\asp\\newmodel\\bwrcnew.pro No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES Branch System Non-Recov Opr Fail trans loop loca scram slc. or. rods PCS/TRANS Branch Model:
1.OF.I Train I Cond Prob:
srv.chall/trans
.- scram srv.chall/loop.-scram srv.close emerg.power ep.rec FW/PCS. TRANS Branch Model:
1.OF.1 Train 1 Cond Prob:
fw/pcs.loca hpci rcic CRD Branch Model:
1.OF.l+opr Train 1 Cond Prob:
srv.ads cond/fw. pcs lpcs lpci (rhr)/lpcs rhr (sdc) rhr (sdc)/-ipci rhr(sdc)/lpci rhr (spcool)/-lpci.rhr (sdc) rhr(spcool)/lpci.rhr(sdc) c.i.and.v rhrsw rhrsw(c.i.and.v)
- 8. 6E-04 1.7E-05 3.3E-06 3.5E-04 1.OE-02 1.7E-01 > 1.0E+00 1.7E-01 > Failed 1.OE+00 1.OE+00 5.3E-02 2.9E-03 1.0E+00 4.6E-01 > 1.OE+00 4.6E-01 > Failed 1.OE+O0 2.OE-02 6.OE-02 1.OE-02 > 1.0E+00 1.OE-02 > Failed 3.7E-03 1.OE+00 2.OE-02 6.OE-04 2.3E-02 2.OE-02 1.OE+00 2.OE-03 5.2E-01 1.OE-03 2.OE-02 5.0E-01 1.OE+00 3.2E-01 5.OE-01 1.OE+00 1.OE+O0 1.0E+00 1.0E+00 1.OE+00 1.OE+00 8.OE-01 1.7E-01 3.4E-01 > 1.0E+00 3.4E-01 3.4E-01 7.OE-01 1.OE+00 > 3.4E-01 7.1E-01 3.4E-01 3.4E-01 7.1E-01 3.4E-01 3.4E-01 1.OE+00 1.OE+00 1.0E+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 1.OE-03 1.OE-03 1.OE-02 2.OE-03 branch model file forced Minarick 05-16-1989 06:55:37 Event Identifier:
458/87-032