ML20147A499
| ML20147A499 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/26/2020 |
| From: | Christopher Hunter Office of Nuclear Regulatory Research |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1987-029-00 | |
| Download: ML20147A499 (4) | |
Text
B-157 PRECURSOR DESCRIPTION SHEET LER No.: 414/87-029 Event
Description:
Trip, LOFW, and TD AFW pump fails to run Date of Event: 11/3/87 Plant: Catawba 2 EVENT DESCRIPTION Sequence Personnel had initiated shutdown to fix a steam generator level instrument. This steam generator level instrument became increasingly erratic and caused a spurious steam generator level turbine trip, a main feedwater isolation, and a main feedwater pump trip. The reactor was then manually tripped in anticipation of a low steam generator level automatic trip. The turbine-driven auxiliary feedwater (AFW) pump started automatically but tripped within seconds. The motor-driven AFW pumps functioned normally. The governor for the turbine-driven AFW pump was adjusted incorrectly and caused the pump to trip on overspeed.
Corrective Action The instrument lines were repaired by fixing the leaks and the governor because the turbine-driven AFW pump was adjusted correctly.
Plant/Event Data Systems Involved:
Auxiliary feedwater system Main feedwater system Steam generator instrumentation system Components and Failure Modes-Involved:
Steam generator level instrument fails Turbine-driven AFW pump fails to run Component Unavailability Duration: N/A Plant Operating Mode: 1 (93% power)
Discovery Method: Operational event Reactor Age: 1.5 y Plant Type: PWR Comments None.
MODELING CONSIDERATION AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient 1.0 No recovery Event Identifier: 414/87-029
B-158 Branches Impacted and Branch Nonrecovery Estimate MFW Base case nonrecovery AFW Base case TD AFW fails to run Plant Models Utilized PWR plant Class F Event Identifier: 414/87-029
B- 59 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier: 414/87-029 Event
Description:
Trip, LOFW, and TD AFW pump fails to run Event Date: 11/03/87 Plant: Catawba 2 INITIATING EVENT NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS 1.OE+00 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CD TRANS 1.7E-06 Total 1.7E-06 CV TRANS 7.1E-06 Total 7.1E-06 ATWS TRANS 3.4E-05 Total 3.4E-05 SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence End State Prob N Rec**
126 trans -rt AFW MFW hpi(f/b) -ss.depress cond/mfw CD 7.3E-07 2.5E-02 120 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress CD 6.9E-07 3.0E-02 cond/mfw 127 trans -rt AFW MFW hpi(f/b) ss.depress CD 8.1E-08 7.4E-02 121 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open ss.depress CD 7.7E-08 8.8E-02 123 trans -rt AFW MFW -hpi(f/b) hpr/-hpi -ss.depress cond/mfw CD 7.6E-08 3.0E-02 109 trans -rt -AFW -porv.or.srv.chall ss.releas.term hpi CV 4.1E-06 2.9E-01 125 trans -rt AFW MFW hpi(f/b) -ss.depress -cond/mfw CV 1.4E-06 4.9E-02 119 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress - CV 1.3E-06 5.8E-02 cond/mfw 101 trans -rt -AFW porv.or.srv.chall -porv.or.srv.reseat ss.releas CV 1.7E-07 2.9E-01
.term hpi 122 trans -rt AFW MFW -hpi(f/b) hpr/-hpi -ss.depress -cond/mfw CV 1.4E-07 5.8E-02 128 trans rt ATWS 3.4E-05 1.2E-01
- non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence End State Prob N Rec**
101 trans -rt -AFW porv.or.srv.chall -porv.or.srv.reseat ss.releas CV 1.7E-07 2.9E-01
.term hpi 109 trans -rt -AFW -porv.or.srv.chall ss.releas.term hpi CV 4.1E-06 2.9E-01 119 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress - CV 1.3E-06 5.8E-02 cond/mfw 120 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open -ss.depress CD 6.9E-07 3.0E-02 cond/mfw 121 trans -rt AFW MFW -hpi(f/b) -hpr/-hpi porv.open ss.depress CD 7.7E-08 8.8E-02 122 trans -rt AFW MFW -hpi(f/b) hpr/-hpi -ss.depress -cond/mfw CV 1.4E-07 5.8E-02 Event Identifier: 414/87-029
B-160 123 trans -rt AFW MFW -hpi(f/b) hpr/-hpi -ss.depress cond/mfw CD 7. 6E-08 3.OE-02 125 trans -rt AFW MFW hpi(f/b) -ss.depress -cond/mfw Cv 1.4E-06 4. 9E-02 126 trans -rt AFW MFW hpi(f/b) -ss.depress cond/mfw CD 7.3E-07 2.5E-02 127 trans -rt AFW MFW hpi(f/b) ss.depress CD 8. 1E-08 7.4E-02 128 trans rt ATWS 3.4E-05 1.2E-O1
- non-recovery credit for edited case SEQUENCE MODEL: c:\asp\newmodel\pwr~bnew.cmp BRANCH MODEL: c:\asp\newmodel\cataw.new PROBABILITY FILE: c:\asp\newmodel\pwr_bnew.pro No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES Branch System Non-Recov Opr Fail trans 4. BE-04 I.OE+00 loop 4. 6E-06 3.9E-01 loca 2.4E-06 4.3E-01 rt 2.BE-04 1.2E-01 rt/loop O.OE+O0 1 .OE+00 emerg .power 2.9E-03 8.OE-01 ep. rec 1.0E+00 1.7E-01 AFW 3.BE-04 > 2.3E-03 2.6E-01 Branch Model: 1.OF.3+ser Train 1 Cond Prob: 2.OE-02 Train 2 Cond Prob: 1.OE-01 Train 3 Cond Prob: 5.OE-02 > Failed Serial Component Prob: 2.8E-04 afw/emerg .power 5.OE-02 3.4E-01 MFW 2.OE-01 > 1.OE+00 3.4E-01 Branch Model: l.OF.1 Train 1 Cond Prob: 2.OE-01 > Failed porv.or.srv.chall 4.OE-02 1.OE+00 porv.or. srv. reseat 3.OE-02 1.1E-02 porv.or. srv. reseat/emerg .power 3.OE-02 1.OE+O0 ss. releas .term 1.5E-02 3.4E-01 hpi I.OE-03 8.4E-01 hpi (f/b) 1.OE-03 8.4E-01 I.OE-02 hpr/-hpi 1.5E-04 1.OE+00 I.OE-03 porv. open 1.OE-02 1.OE+00 4.OE-04 ss. depress 3.6E-02 1.OE+00 cond/mfw I.OE+00 3.4E-01 1.OE-02 lpi/hpi 1.5E-04 3.4E-01 lpr/-hpi .hpr 6.7E-01 1.OE+00 lpr/hpi 1.5E-04 1.0E+00
- branch model file
- forced Minarick 05-16-1989 07:02:31 Event Identifier: 414/87-029