ML20147A366
| ML20147A366 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/26/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1984-014-00 | |
| Download: ML20147A366 (6) | |
Text
PRECURSOR DESCRIPTION SHEET LER No.:3/801 Event
Description:
Trip and LOFW with HPCI Unavailable' Date of Event:
August 1, 1984 Plant:
Brunswick 1 EVENT DESCRIPTION Sequence At 1417 h while the reactor was-at 95% power, an instrument upscale trip of the reactor average power range monitor (APRM) system caused the reactor protection system to automatically initiate a reactor scram.
In addition, the HPCI system was out of service, pending periodic testing.
A scram recovery was carried out.
Reactor level, with the lowest recorded value of 142.8 in., was controlled through the RCIC system., A Group 1 isolation occurred, as per design, when the reactor pressure decreased to the low-pressure set point while the mode switch was in mode 1.
Reactor pressure, which peaked at 997 psig, was controlled by manual opening of the unit reactor SRVs A, B, E, and J.
Following the isolation, the control operator discovered that inboard MSIV 1-B21-F022A did not automatically close.
An attempt to close the valve manually proved unsuccessful.
The MSIV failed when its ac/dc, three-way, air-operated solenoid valve failed.
The subject APRM system upscale trip resulted, f rom. the 'reactor' s
recirculation-loop-f low instrumentation's receiving erroneous input 's~ig-nals.
These signals caused the instruments to sense simultaneous decreasing flow spikes in each reactor recirculation loop (A and B).
This resulted in an automatic reduction of the AFRM system high-reactor-power scram set point to less than the actual reactor power, thereby causing the APRM system upscale trip.
The cause of the erroneous input signals to the recirculation-loop-f low instrumentation was electronic keying of two-way radios in use in the immedi -ate vicinity of the s ubj ect instrumentation in the unit reactor building.
Plant auxiliary operators were using the two-way radios in the performance of an annual periodic test of the reactor building fire protection sprinkler systems.
Event Identifier:
325/84-014 D-1 125
Corrective Action The F022A three-way ac/dc solenoid pilot valve was replaced, and the removed component was subsequently bench tested.
No evident signs of failure were noted during testing of the three-way solenoid pilot valve.
As a result of this event, various types of communication radios utilized in both units will be electronically keyed in the vicinity of the Unit 2 instrumentation racks in the reactor building to determine if control room instrumentation is adversely affected.
This testing of plant communication radios was planned to be complete by September 14, 1984.
Following this testing, signs prohibiting the use of plant com7-municatjlon radios within specific identified plant areas were to be appropriately posted in those areas.
In addition, plant Engineering was to be requested to evaluate the apparent failure of the MSIV F022A solenoid pilot valve to determine applicable corrective action.
Plant/Event Data Systems Involved:
HPCI Components and Failure Modes Involved:
HPCI -
out of service for testing MFW -
failed by Group I isolation Component Unavailability Duration:
NA Plant Operating Mode:
1 (94% power)
Discovery Method:
Operational event Reactor Age:
7.8 years Plant Type:
BWR Comments None MODELING CONSIDERATIONS AND DECISIONS Initiators Modeled and Initiator Nonrecovery Estimate Transient 1.0 No recovery Event Identifier:
325/84-014 D-126
Branches Impacted and Branch Nonrecovery Estimate PCs 1.0 Unavailable following Group I isola-tion HPCI 0.34 Assume potential recovery from testing status MFW 1.0 Unavailable following Group I isola-t ion Plant Models Utilized BWR plant Class C Event Identifier:
325/84-014 D-127
CONDITIONAL CORE DAMAGE PROBABILITY CALCULATIONS Event Identifier: 325/84-014 Event
Description:
Trip and LOFW with HPCI Unavailable Event Date:
8/1/84 Plant:
Brunswick 1 INITIATING EVENT NON-RECOVERABLE INITIATING EVENT PROBABILITIES TRANS 1.0E+00 SEQUENCE CONDITIONAL PROBABILITY SUMS End State/Initiator Probability CV TRANS 5
.9E-06 Total 5.9E-06 CD TRANS 1
.2E-04 Total 1.2E-04 ATWS TRANS 2
.0E-05 Total 2.OE-O5 DOMINANT SEQUENCES End State: CV Conditional Probability:
3.1E-06 134 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.AOS
End-State: CD Conditional Probability:
4.3E-05 119 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM SRV.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA SRV.ADS End State: ATWS Conditional Probability:
2.OE-05 Event Identifier: 325/84-014 ID-128
173 TRANS SCRAM.
SLC.OR.RODS SEQUENCE CONDITIONAL PROBABILITIES SequnceEnd State Prob N Rec**
102 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE FN
C.
I.AND.YIRHR(SDC).RHR(SPCOOL) 103 TRANS -SCRAM PCSITRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE FW
/PCS.TRANS HPCI -RCIC/TRANS.OR.LOOP RHR(SDC) RfIR(SPCOOL
)/-LPCI.RHR(SDC) C.I.AND.V/RHR(SDC).RHR(SPCOOL) 110 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM -SRV.CLOSE FW
/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP CRD SRV.ADS 119 TRANS -SCRAM PCS/TRANS SRV.CHALL/TRANS.-SCRAM SRV.C.LOSE Fw
/PCS.LOCA HPCI RCIC/LOCA SRV.ADS 121 TRANS -SCRAM PCS/TRANS -SRV.CHALL/TRANS.-SCRAM FW/PCS.TRANS
C.I.AND.V/RHR (SDC).RHR (SPCOOL) 122 TRANS -SCRAM PCSITRANS -SRV.CHALL/TRANS.-SCRAM FW/PCS.TRANS HPCI -RCIC/TRANS.OR.LOOP RHR (SDC)
C.!.AND.Y/RHR(SDC).RHR(SPCOOL) 129 TRANS -SCRAM PCS/TRANS -SRV.CHAL/TRANS.-SCRAM FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP CRD SRV.ADS 134 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS -COND/FW.PCS -RHR (SDC) 138 TRANS SCRAM -SLC.OR.RODS PCS/TRANS -SRV.CLOSE FW/PCS.TRANS HPCI RCIC/TRANS.OR.LOOP -SRV.ADS COND/FW.PCS -LPCS -RHR~
SDC) 155 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRY.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA -SRV.ADS -COND/FW.PCS -RHR(SDC) 159 TRANS SCRAM -SLC.OR.RODS PCS/TRANS SRV.CLOSE FW/PCS.LOCA HPCI RCIC/LOCA -SRV.ADS COND/FW.PCS -LPCS -RHR(SDC) 173 TRANS SCRAM SLC.OR.RODS CD CD CD CD 9.1E'-06 7.6E-02 4.5 E-06 3
.9E-02
.CD CD Co CV CV CV CV 8.7E-06 1.9E-01 4.3E-05
- 1.2E-01 2.2E-05 7.6E-02 idIE-05 3.9E-02 2.1E-O5 1.9E-01 3.1E-.06 *1.3E-01 1.6E-06 6.6E-02 7.6E-07 7.6E-02 3.9E-07 3.9E-02 2.E-05
- 1.0E+00 ATWS
- dominant sequence for' end state
- 1non-recovery credit for edited case MODEL:
b:\\bwrctr'ee.cmp DATA:
b :\\brunprob.cmp No Recovery Limit BR ANC H FREQUENCIES/PROBABILITIES Branch Syst TRANS 1.1E em Non-Rectov Opr Fail
~-03
.IOE+00 Event Identifier: 325/84-014 D-129
LOO P LOCA SCRAMNý,
Branch Model:
1.0F.1 Train 1 'Cond Prob:
PCS/LOCA SRV.CHALL/TRANS.-SCRAtI SRV.CKALL/TRANS.SCRAM SRV SCHALL/LOOP.-SCRAM SRV.CHALL/LOOP.SCRAM SRY.CLOSE EMERGS OWER FW/PCS.STRANS Branch Model:
1.OF.1 Train 1 Cond Prob:
FW/PCS.LOCA HPCI Branch Model-1.F.1 Train I Cond Prob:
RCIC/TRANS.OR.LDOP RCIC/LOCA CRD SRY ADS COND/FW.PCS LPCS LPCI (RHR) /LPCS RHRSW/LPCS.LPCI.TRANS RHRSI'/LPCS.LPCI SLOOP RHRSW/LPCS.LPCI SLOCA RHR (SDC)
RHR(SDC) /-LPCI RHR(SDC) /LPCI RHR (SPCOOL) /-LPCI.RHR (SBC)
C.I.AND.V/RHR(SDC).RHR(SPCOOL) 1.3E-05 3.3E-06
- 4. 1 E-04 I.OE-02 1.7E-01 ) 1.OE+00 1.7E-01 > Failed 1.OE+00 3.OE-O1 I.0E400 3.OE-01 1.OE+00 2.7E-02 2.9E-03 4.6E-01 > 1.OE+00 4.6E-01 > Unavailable 1.OE+00 1.OE-01 > 1.OE+00 1.OE-O1 > Failed 6
.7E-02 1
.OE+00 1,OE-02 6
.7E-03 1.OE+00 3
.OE-03 4 OE-04 S
.OE-01 5.OE-01 5
.OE-01 2.OE-02 2
.OE-02 1
.OE400 2.OE-02 5.2E-01 1
.OE+00 3.4E-01 3.4E-01 1.OE+00 1.OE+00 1.OE+00 I.OE+00 1.OE+O0 I.OE+0O I.OE+00 1.OE400 I.OE+00 5.1E-01 3.4E-01 > 1.0E400 3.4E-01 5.7E-01 > 3.4E-01 5.7E-01 1.OE+00 1.OE+00 1.OE+00 3.4E-01 3A.E-01 3.4E-01 1.OE+O0 1.OE+00 1.OE+00 3.4E-01 3.4E-01 1.OE+00 1.OE+00 1.OE.00 3A.E-01 4 OE-02 4 OE-02 4.OE-02 4.OE-02 4 OE-02 4 OE-02
- forced Minarick 04-11-1987 17:12:32 Event Identifier: 325/84-014 D-130