ML19345D445: Difference between revisions

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   @ l 0l Hl Dj Bl Sl 1l@l 0l 0l 0l 0l LICENSE                                          0l 0lNUVdEH0l 0l 0l 0l 0l@l      h 4l 1l
   @ l 0l Hl Dj Bl Sl 1l@l 0l 0l 0l 0l LICENSE                                          0l 0lNUVdEH0l 0l 0l 0l 0l@l      h 4l 1l
                                                                                                                                 ;t6 1l 1l 1l@l57 GAT LICENSE TvPE JJ l
                                                                                                                                 ;t6 1l 1l 1l@l57 GAT LICENSE TvPE JJ l
bd lQ 7            8 9            LICENSEE CODE              14        16 CON'T M                      SoE I L l@l 0 l 5 l 0 l- l 0 l 3 l 4 l646 j@l                        b9 1lEVENT 1l DATE 1l 2l 8l 0]@l 1lREPORT la      7b 2l 1lDATE0l 8l 0l@ 41J 7            8                    60          61                  DOCK ET NUMa g R EVENT OESCRIPTION AND PROB ABLE CONSEQUENCES h                                                                                                                l 10121 l (NP-33-80-105) On November 12, 1980, at 1403 hours, the unit experienced a loss of ihis bus powers RPS Channel 2 which was the source of RC3 flow to l l o 13 l l Essential Bus Y2.
bd lQ 7            8 9            LICENSEE CODE              14        16 CON'T M                      SoE I L l@l 0 l 5 l 0 l- l 0 l 3 l 4 l646 j@l                        b9 1lEVENT 1l DATE 1l 2l 8l 0]@l 1lREPORT la      7b 2l 1lDATE0l 8l 0l@ 41J 7            8                    60          61                  DOCK ET NUMa g R EVENT OESCRIPTION AND PROB ABLE CONSEQUENCES h                                                                                                                l 10121 l (NP-33-80-105) On November 12, 1980, at [[estimated NRC review hours::1403 hours]], the unit experienced a loss of ihis bus powers RPS Channel 2 which was the source of RC3 flow to l l o 13 l l Essential Bus Y2.
10141 I the Integrated Control System. The loss of flow indication started a series of event $
10141 I the Integrated Control System. The loss of flow indication started a series of event $
I c 151 I which resulted in a reactor trip on high RCS pressure. The Station entered the actio9 There was no danger to the health and                                l f Ts 1 I statement of TS 3.8.2.1 for the loss of Y2.
I c 151 I which resulted in a reactor trip on high RCS pressure. The Station entered the actio9 There was no danger to the health and                                l f Ts 1 I statement of TS 3.8.2.1 for the loss of Y2.
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Dm TremRmm                                                m (419) 259-5000 EXT. 235 {
Dm TremRmm                                                m (419) 259-5000 EXT. 235 {


TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-105 DATE OF EVENT: November 12, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of Essential Instrumentation Power Bus Y2 which resulted in a reactor trip Conditions Prior to Occurrence: The unit was in Mode 1 with Power (MWT) = 1092 and Load (Gross FME) = 330 Description of Occurrence: On November 12, 1980 at 1403 hours with the unit at approxi-mately 40 percent power, the unit experienced a loss of Essential Bus Y2. This bus powers the Reactor Protection System (RPS) Instrumentation Channel 2. This channel was providing Reactor Coolant System (RCS) flow indication to the Integrated Control System (ICS). When the bus was lost, ICS sensed a loss of flow indication and started running back feedwater flow on the secondary side. This loss of cooling to the RCS caused RCS pressure to go high, and the reactor tripp,ed on high pressure.
TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-105 DATE OF EVENT: November 12, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of Essential Instrumentation Power Bus Y2 which resulted in a reactor trip Conditions Prior to Occurrence: The unit was in Mode 1 with Power (MWT) = 1092 and Load (Gross FME) = 330 Description of Occurrence: On November 12, 1980 at [[estimated NRC review hours::1403 hours]] with the unit at approxi-mately 40 percent power, the unit experienced a loss of Essential Bus Y2. This bus powers the Reactor Protection System (RPS) Instrumentation Channel 2. This channel was providing Reactor Coolant System (RCS) flow indication to the Integrated Control System (ICS). When the bus was lost, ICS sensed a loss of flow indication and started running back feedwater flow on the secondary side. This loss of cooling to the RCS caused RCS pressure to go high, and the reactor tripp,ed on high pressure.
The loss of Y2 entered the station into the action statement of Technical Specification 3.8.2.1 which required the bus be restored to operable status within eight hours or be in at least hot standby (Mode 3) within the next six hours and in cold shutdown within the following thirty hours. Since the reactor tripped, and the station entered Mode 3, the conditions were met.
The loss of Y2 entered the station into the action statement of Technical Specification 3.8.2.1 which required the bus be restored to operable status within eight hours or be in at least hot standby (Mode 3) within the next six hours and in cold shutdown within the following thirty hours. Since the reactor tripped, and the station entered Mode 3, the conditions were met.
Designation of Apparent Cause of occurrence:    The cause was determined to be a personnel error. An Instrument and Control apprentice overlooked a precaution written on a work order, and used a grounded oscilloscope to record input voltage waveforms at the Steam Generator Level Instrument Cabinet Channel 2 of the Steam and Feedwater Rupture Control System (SFRCS). These wr/eforms were being recorded as aWhen  method  of troubleshoot-the oscilloscope ing past difficulties experienced with Sorenson power supplies.
Designation of Apparent Cause of occurrence:    The cause was determined to be a personnel error. An Instrument and Control apprentice overlooked a precaution written on a work order, and used a grounded oscilloscope to record input voltage waveforms at the Steam Generator Level Instrument Cabinet Channel 2 of the Steam and Feedwater Rupture Control System (SFRCS). These wr/eforms were being recorded as aWhen  method  of troubleshoot-the oscilloscope ing past difficulties experienced with Sorenson power supplies.
was connected, it caused a ground to feed back through the YV2 inverter and blew the inverter input fuse which caused the loss of Channel 2 of RPS, SFRCS, and Safety Features Actuation System (SEAS).
was connected, it caused a ground to feed back through the YV2 inverter and blew the inverter input fuse which caused the loss of Channel 2 of RPS, SFRCS, and Safety Features Actuation System (SEAS).
Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The loss of essential bus Y2 disabled only one of four safety system circuits still allowing three redundant safety circuits to perform their function as designed.
Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The loss of essential bus Y2 disabled only one of four safety system circuits still allowing three redundant safety circuits to perform their function as designed.
Corrective Action: The I&C apprentice involved was given further guidance in performing proper test practices. The inverter input fuse was replaced under Maintenance Work Order 80-3839 and essential 120 VAC power restored to Y2 at 1530 hours on November 12, 1980. Memorandum M80-2502 was issued to all 16C ap' prentices concerning the use of oscilloscopes in critical circuitry.
Corrective Action: The I&C apprentice involved was given further guidance in performing proper test practices. The inverter input fuse was replaced under Maintenance Work Order 80-3839 and essential 120 VAC power restored to Y2 at [[estimated NRC review hours::1530 hours]] on November 12, 1980. Memorandum M80-2502 was issued to all 16C ap' prentices concerning the use of oscilloscopes in critical circuitry.
LER #80-081
LER #80-081


Revision as of 10:28, 2 March 2020

LER 80-081/03L-0:on 801112,unit Experienced Loss of Essential Bus Y2.Caused by Use of Grounded Oscilloscope to Record Input Voltage Wave forms.YV2 Inverter Input Fuse Replaced & Essential 120-volt Ac Power Restored
ML19345D445
Person / Time
Site: Davis Besse Cleveland Electric icon.png
Issue date: 12/10/1980
From: Trautman D
TOLEDO EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19345D444 List:
References
LER-80-081-03L, LER-80-81-3L, NP-33-80-105, NUDOCS 8012150118
Download: ML19345D445 (3)
v • d • e


Text

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O. S. NUCLE AR REGULATORY CoMMISSloN NPC FORM 3:36' LICENSEE EVENT REPORT CONTROL BLOCC l l l l l l o

lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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10141 I the Integrated Control System. The loss of flow indication started a series of event $

I c 151 I which resulted in a reactor trip on high RCS pressure. The Station entered the actio9 There was no danger to the health and l f Ts 1 I statement of TS 3.8.2.1 for the loss of Y2.

l iTT71 I safety of the public or to Station personnel. The three redundant safety circuits 1

l3lsl l (channels) were operable during this time.

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l li l o l l The cause was the use of a grounded oscilloscope by I&C personnel to record input f TT1 I voltage waveforms at the SFRCS Ch. 2 Cabinet. The ground fed back to the YV2 invertett The fuse l

, , l input fuse which took out the Y2 bus 9hich caused the loss of RPS Ch. 2.

3 3 l was replaced under FMO 80-3839 and essential 120 VAC power restored to Y2 at 1530 l Memorandum M80-2502 concerning oscilloscopes was issued. g 3 4 l hours. so IS O RY DISCOV E Rt' O ESCRIPTION StA S  % POWER OTHER STATUS Operator Observation l l

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-105 DATE OF EVENT: November 12, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of Essential Instrumentation Power Bus Y2 which resulted in a reactor trip Conditions Prior to Occurrence: The unit was in Mode 1 with Power (MWT) = 1092 and Load (Gross FME) = 330 Description of Occurrence: On November 12, 1980 at 1403 hours58.458 days <br />8.351 weeks <br />1.922 months <br /> with the unit at approxi-mately 40 percent power, the unit experienced a loss of Essential Bus Y2. This bus powers the Reactor Protection System (RPS) Instrumentation Channel 2. This channel was providing Reactor Coolant System (RCS) flow indication to the Integrated Control System (ICS). When the bus was lost, ICS sensed a loss of flow indication and started running back feedwater flow on the secondary side. This loss of cooling to the RCS caused RCS pressure to go high, and the reactor tripp,ed on high pressure.

The loss of Y2 entered the station into the action statement of Technical Specification 3.8.2.1 which required the bus be restored to operable status within eight hours or be in at least hot standby (Mode 3) within the next six hours and in cold shutdown within the following thirty hours. Since the reactor tripped, and the station entered Mode 3, the conditions were met.

Designation of Apparent Cause of occurrence: The cause was determined to be a personnel error. An Instrument and Control apprentice overlooked a precaution written on a work order, and used a grounded oscilloscope to record input voltage waveforms at the Steam Generator Level Instrument Cabinet Channel 2 of the Steam and Feedwater Rupture Control System (SFRCS). These wr/eforms were being recorded as aWhen method of troubleshoot-the oscilloscope ing past difficulties experienced with Sorenson power supplies.

was connected, it caused a ground to feed back through the YV2 inverter and blew the inverter input fuse which caused the loss of Channel 2 of RPS, SFRCS, and Safety Features Actuation System (SEAS).

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The loss of essential bus Y2 disabled only one of four safety system circuits still allowing three redundant safety circuits to perform their function as designed.

Corrective Action: The I&C apprentice involved was given further guidance in performing proper test practices. The inverter input fuse was replaced under Maintenance Work Order 80-3839 and essential 120 VAC power restored to Y2 at 1530 hours63.75 days <br />9.107 weeks <br />2.096 months <br /> on November 12, 1980. Memorandum M80-2502 was issued to all 16C ap' prentices concerning the use of oscilloscopes in critical circuitry.

LER #80-081

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2,*

SUiPLEMENTAL INFORMATION FOR LER NP-33-80-105 Failure Data: One previous similar occurrence has been reported, see Licensee Event Report NP-33-80-70 (LER 80-056)

LER #80-081 O

S v

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