ML20161A158
| ML20161A158 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 06/09/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1988-029-00, LER 1988-030-00 | |
| Download: ML20161A158 (9) | |
Text
B-231 Accident Sequence Precursor Program Event Analysis LER No:
Event
Description:
Date of Event:
Plant:
344/88-029, -030 Both trains of safety injection and one emergency diesel generator inoperable September 17, 1988 Trojan Summnary Both trains of the safety-injection (SI) system and one train of the emergency power system (EPS) were inoperable for 16 min.
one train of SI and one train of EPS were inoperable for approximately 48 h, and both trains of SI were inoperable for a period of 29.5 h.
One train of SI was inoperable because of clam debris in the lube oil cooler of the injection pump.
The conditional core damage probability associated with the event is 8.6 x 10-5.
The relative significance of this event com-pared with other potential events at Trojan is shown below.
LER 344/88-029 1E-8 1 E-7 IE-6 I E-5 I1E-4 I E-3 I E-2 Trip 1
L EP nvi Trip w/1 AFW (360 hrs)
Train Unavail LOOP AFW Unavail (360 hrs)
Event Description Clam debris was found in the lube oil cooler of the SI train "A"l pump.
During the period when clam debris could have been in the lube oil cooler of train "A"l, the train "B" SI pump was inoperable on July 28-29 (28 h), August 26 (1.5 h), and August 29 (16 min).
The above informa-tion was provided by LER number 344/88-029.
In a related event (LER 344/88-030), two isolation valves in train "A" of the SI system were found in the wrong position.
The mispositioned isolation valves caused train "A" of the SI system to be out of service from June 3, 1988, until Sept. 17, 1988.
In addition, train "B" was out of service on July 13, 1988, Aug. 29 and 30, 1988, and Sept. 15 and 16, 1988.
The "B" train of emergency diesel generator was out of service on Aug. 29 and 30, 1988.
113-2 32 ASP Modeling Assumptions and Approach The event has been modeled as the sum of three periods.
The first period represents the 16 min on August 29 that both SI trains and one EDG train were inoperable.
The next period represents the approximately 48 h that one SI train and the opposite EDG train were inoperable on August 29 and 30.
The last period represents the period when both SI trains were unavailable for 29.5 h on July 28 and 29 and August 26.
In all cases, one train of SI was assumed failed because of the presence of clam debris in the lube oil coolers.
Analysis Results The conditional probability of severe core damage estimated for this event is 8.6 x 10-5.
The three segments that made up this event were (1) 2.8 x 10-7 for both SI trains and one EDG train inoperable, (2) 5.4 x 10-5 for one SI train and one EDG train inoperable, and (3) 3.2 x 1i-5 for both trains of SI inoperable.
The dominant sequence for all three cases involves a postulated small-break LOCA with unavailability of high-pressure injection and high-pressure recirculation.
This sequence is highlighted on the following event tree.
B3-233 LOCA IRT IAFW IMFW NmI HPR PORV SEQ END NO STATE 71 72 73 74 OK CD OK 00 CD OK 75 CD 76 CD 77 00 78 ATWS Dominant Core Damage Sequence for LER 344/88-029
B-234 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier:
344/88-029 Event
Description:
Both trains of SI and one DG Inoperable (calc 1)
Event Late:
09/17/88 Plant:
Trojan UNAVAILABILITY, DURATION=.25 NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS
- 1. 4E-04 LOOP 1.5SE-06 LOCA 2.6HE-07 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CO TRANS 9.5E-09 LOOP
- 2. 8E-07 Total
- 2. 8E-07 AIMS TRANS
- 0. 0E+00 LOOP
- 0. OE+00 LOCA
- 0. OE+00 Total 0.OE+00 SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence End State 72 71 53 17 loca -rt
-afw NPI boca -rt
-afw -NPI BPR/-NPI loop -rt/loop EMERG.PONER -afw/emerg.power -porv.or.srv.chall seal.loca ep.rec(sl) trans -rt afw mfw HPI(F/B)
CD CO CO CD P rob
- 2. 2E-07
- 4. IE-08
- 7. 2E-09 7.1lE-09 N Rects
- 3. 6E-01
- 8. 9E-02
- 2. 9E-01 2.OE-02
-* non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence End State 17 trans -rt afw mfw BPI(F/B)
CD 53 loop -rt/loop EMERG.POWER -afw/emerq.power -porv.or.srv.chall CO seal.loca ep.rec(sl) 71 loce -it
-afw -HPI NPRI-BPI CO 72 boca -rt -aiw NPI CD.
- non-recovery credit for edited case Mote:
For unavailabilities, conditional probability values are differential values added risk due to failures associated with an event.
Parenthetical values indicate compared to a similar period without the existing failures.
SEQUENCE MODEL:
c:\\asp\\seaimod\\pwrbseab.cmp BRANCH MODEL:
c:\\asp\\sealmod\\trojan.sll PROBABILITY FILE:
c:\\asp\\sealmod\\pwr bsll.pro No Recovery Limit BRANCH FREQUENCIES/PROBABILITIES P rob 7. 1E-0 9 7.2E-09 4. IE-08
- 2. 2E-07 N Rec t t 2. OE-02 2. 9E-01 6. 9-02 3.6E-01 which reflect the a reduction in risk Event Identifier: 344/88-029
B-235 Branch System trans loop 1 oca rt rtl loop EMERG. POWER Branch Model:
l.OF.2 Train 1 Cond Prob:
Train 2 Cond Prob:
afw afwlemerg.power mfw porv.or.srv.chall porv.or.srv. reseat porv.or.srv.reseat/emerg.power seal.boca ep. rec (si) ep. rec HPI Branch Model:
l.OF.2 Train 1 Cond Prob:
Train 2 Cond Prob:
HPI (F/B)
Branch Model:
1.OF.2+opr Train 1 Cond Prob:
Train 2 Cond Prob:
HPR/-HPI Branch Model:
1.OF.2+opr Train 1 Cond Prob:
Train 2 Cond Prob:
porv.open 5. 6E-04
- 1. 6E-05
- 2. 4E-06
- 2. 8E-04 0.OE+00 2.9E-03 > 5.01-02
- 5. OE-02 5.7E-02 > Unavailable 2.5E-03
- 5. 9E-01
- 6. 1E-02 1.OE-03 > 1.01+00 1.05-02 > Failed 1.0E-01 > Unavailable l.OE-03 > 1.05+00 1.05-02 > Failed 1.OE-01 > Unavailable 1.5E-04 > 1.OE+00 1.OE-02 > Failed 1.5E-02 > Unavailable 1.0E-02 Non -Recov 1.05+00 3.6E-01
- 4. 3E-01 1.2E-01 1.05+00 8.05-01 3.4E-01 3.4E-01 7.01-02 1.05+00
- 1. 11-02 1.01+00 1.05+00 1.05+00 1.05+00 8.4E-01 Opr Fail 8.4E-01 1.05E+00 1.05+00 1.05-02 1.05-03 4.OE-04
- branch model file
- forced 74inarick 11-13-1989 13:07:17 Event Identifier: 344/88-029
B-236 CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier:
Event
Description:
Event Date:
Plant:
344/88-029 Both trains of SI and one DO Inoperable (cain 2) 09/17/88 Trojan UNAVAILABILITY, DURATION= 48 NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS LOOP LOCA SEQUENCE CONDITIONAL PROBABILITY SUMS
- 2. 7E-02 2.8E-04
- 1. 8E-06 3.2E-06 4.9E-05 5.4E-05 S. BE+SS
- 0. DEs-S S.SE-s-C S. 5+500 TRANS LOOP LOCA Total SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence End State Prob N Rec' 5
72 71.
53 17 loac -rt -afw HPI loce -rt -afw -BPI BPR/-HPI loop -rt/loop EI4ERG.POWER -afw/emerg.power -porv.or.srv.chall seal.loca ep.reC(sl) trans -rt afw mfw HPI(F/B)
CD CD CD CD 4.2E-05 3.6E-01 7.9E-56 6.9E-02 1.4E-06 2.9E-01 1.3E-06 2.SE-02
-non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER) 17 53 71 72 Seqoence trans -rt afw mfw BPI(F/B) loop -rt/loop EMERG.POWER -efw/emerg.power -porv.or.srv.chall seal.loce ep.rec(sl) lone -rt
-efw -HPI HPR/-HPI lone -rt
-afw HPI End Stete Prob N Rec*"
CD CD CD CD 1.3E-06 2.SE-02 1.4E-06 2.9E-01 7.9E-06 6.9E-02 4.2E-05 3.6E-01
'5non-recovery credit fot edited cese Note:
For unavailebilities, conditional probability values are differential values which reflect the added risk due to failures associated with en event.
Parenthetical values indicate a reduction in risk competed to a similar period without the existing failures.
SEQUENCE MODEL:
BRANCH MODEL:
PROBABILITY FILE:
n:\\eap\\seelmod\\pwrbseal.crnp n:\\asp~sealmod\\trojan.sll n: \\asp\\sealmod\\pwr bsll.pro No Recovery Limit BRANCH FREOUENCIES/PROBABILITIES Event Identifier: 344/88-029
B-237 Branch trans l oop inca rt rt/ loop EMER. POWER Branch Model:
1.OF.2 Train 1 Cond Prob:
Train 2 Good Prob:
a Sw afw/emerg.power mfw porv.or.srv.chall porv.or.srv. reseat porv.or.srv.reseat/emoorg.power seal.boca ep. tec (si) ep. rec HPI Branch Model:
1.OF.2 Train 1 Good Prob:
Train 2 Gond Prob:
HPI (F/B)
Branch Model:
l.OF.2+opr Train 1 Gond Prob:
Train 2 Good Prob:
HPR/-HPI Branch Model:
1.OF.2+opr Train 1 Good Prob:
Train 2 Good Prob:
porv.open
- branch model file
- forced Minarick 11-13-1989 13: 08 :30 System 5.6GE-04
- 1. 6E-05
- 2. 46-0 6 2.8E-04 0.06+00 2.9E-03 > 5.06-02 5.0E-02 5.7E-02 > Unavailable 2.56-03
- 2. 56-03 1.06+00 4.06E-02 2.0E-02 2.06E-02 2.36-01
- 5. 96-01
- 6. 16-02 1.06-03 > 1.06+00 1.06-02 > Failed 1.06-01 > Unavailable 1.06-03 > 1.06+00 1.06-02 > Failed 1.06-01 > Unavailable 1.56-04 > 1.06+/-00 1.06-02 > Failed 1.56-02 > Unavailable 1.06-02 Non -Re cox' 1.06+00 3.66-01
- 4. 3E-01 1.26-01 1.06+00 8.06-01 3.46-01
- 3. 4E-01 7.06E-02 1.06+/-00 1.16-02
- 1. OE+00 1.06+00 1.06+00 1.06+00 6.4 6-01 Opr Fail 8.46-01 1.06+00 1.06+00 1.06-02 1.06-03 4.06-04 Event Identifier: 344/88-029
B8-23 8 CONDITIONAL CORE DAN-ADI PROBABILITY CALCULATIONS Event Identifier:
344/88-029 Event
Description:
Both trains of SI and one DO Inoperable (cabc 3)
Event Date:
09/17/88 Plant:
Trojan UNAVAILABILITY, DURATION= 295.
NON-RECOVERABLE INITIATINC EVENT PROBABILITIES TRANS LOOP LOCA
- 1. 7E-02 1.7E-04 3-OE-05 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CD TRANS LOOP LOCA Total ATWS 1.11E-01 1.8SE-07
- 3. SE-IS 3.21-IS 0.01+00 0.01+/-00 0.Z01,I 0.01+00 TRANS LOOP LOCA Total SEQUENCE CONDITIONAL PROBABILITIES (PROBABILITY ORDER)
Sequence End State Prob N Rec**
72 71 17 boca -rt -afw BPI iota -rt -afw -HPI BPR/-NPI trans -rt afw mfw BPI(F/B)
CD CD CD 2.6E-05 3.6E-01 4.8E-06 6.9E-02 8.3E-07 2.01-02
- non-recovery credit for edited case SEQUENCE CONDITIONAL PROBABILITIES (SEQUENCE ORDER)
Sequence End State Prob N Rec-'
17 71 72 trans -rt nfw mnfw BPI(F/B) boca -rt -afw -BPS 8PR/-BPI loca -rt -afw BPS CD CO CD
-non-recovery credit for edited case 8.3E-07 2.01-02 4.8E-06 6.9E-02 2.61-IS 3.6E-01 which reflect the a reduction in risk Noteo:
Sot unavajiabilitins, conditional probability values are differential values added rink due to failures associated with an event.
Parenthetical values indicate compared to a similar period without the exstning failures.
SEQUENCE MODEL:
B3RANCH MODEL:
PROBABILITY FILE:
c:\\asp\\sealmod\\pwrbseal.cmnp c:\\asp\\sealmod\\rrojan.sl1 c:\\anp\\scalmnod\\pwr_bsll.pro No Recovery Limit BRANCH FREQUENCIES/PRDBABILITIES Branch trans System 5.8GE-04 Non-Recov Opt Fail 1.01+/-00 Event Identifier: 344/88-029
B3-239 loop loca rt rt/loop erserg.power afw afw/emerg.power mfw porv.or.srv.chall porv.or.srv. reseat porv.or.srv.reseat/erserg.power seal. loca ep. rec (si) ep. rec B(PI Branch Model:
l.oF.2 Train 1 Cond Prob:
Train 2 Cond Prob:
((PT(FIB)
Branch Model:
1.OF.2+opr Train 1 Cond Prob:
Train 2 Cond Prob:
HPRI-HPI Branch Model:
l.OF.24opr Train 1 Cond Prob:
Train 2 Cond Prob:
porv.open 1. 6E-0 5 2.4E-0 6
- 2. BE-04
- 0. OE+00
- 2. 3E-01
- 5. 9E-01
- 6. 1E-02
- 1. OE-0 3
.1. OE+00
- 8. CE-Cl 3. 4Z-01
- 3. 4E-01 7. OE-02
- 1. 06+/-00 1.1lE-02
- 1. 06+/-00
- 1. 06+00 1.06+00 1. OE+00 86.4 E-01
- 8. 4-01 1.06+/-00
- 1. 06+00 1. OE+00 1.06-02 > Failed l.OE-0l > Failed l.OE-03 > l.OE+/-00 1.06-02 > Failed 1.06-01 > Failed 1.5E-04 > l.OE+00 1.OE-02 > Failed 1.5E-02 > Failed 1. OE-02 1.0E-02 1.0E-0 3 4.0E-04
- branch model file
- forced Minarick 11-13-1989 13:09:58 Event Identifier: 344/88-029