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| Facility Chance 1 g charge check valve was disasse= bled, cleaned, and reassembled.- | | Facility Chance 1 g charge check valve was disasse= bled, cleaned, and reassembled.- |
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| ' equest 78-211 has been prepared to request removal of the check ' valve internals on | | ' equest 78-211 has been prepared to request removal of the check ' valve internals on f |
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| mql both Hydrogen Dilution Blowers to prevent recurrence. 80 7 8 9 of RY ol3CoVERY oESCRIPTioN oTHER STATUS l 3 jgl Surveillance Test ST 5065.05 h POWER l I1 15llEl@ l0l6l8lglE 10 12 31 44 l | | mql both Hydrogen Dilution Blowers to prevent recurrence. 80 7 8 9 of RY ol3CoVERY oESCRIPTioN oTHER STATUS l 3 jgl Surveillance Test ST 5065.05 h POWER l I1 15llEl@ l0l6l8lglE 10 12 31 44 l |
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| 7 4 9 9 NRC USE CNLY l 7.d..a*v ll lII\l III I I l 1l | | 7 4 9 9 NRC USE CNLY l 7.d..a*v ll lII\l III I I l 1l |
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| ,it- = J .oN - #. | | ,it- = J .oN - #. |
| ~ :- " l j l 'i I" '* i U.*s C3 69 2'J $l 0 | | ~ :- " l j l 'i I" '* i U.*s C3 69 2'J $l 0 |
| To: Isley pga.;g; ' 19-23 9-5000. Ext. Do I'7 N , v g - e s.,p u s, | | To: Isley pga.;g; ' 19-23 9-5000. Ext. Do I'7 N , v g - e s.,p u s, |
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| DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION | | DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION |
| * SUPPLD! ENTAL INFORMATION FOR LER NP-33-78-43 4 | | * SUPPLD! ENTAL INFORMATION FOR LER NP-33-78-43 4 |
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| | ; DATE OF EVENT: April 8, 1978 FACILITY: Davis-Bessa Unit l' IDENTIFICATION OF OCCURRENCE: Hydrogen Dilution Blower 1-1 Trip 4 |
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| | Conditions Prior to Occurrence: The unit was in Mode 1 vith Power (MWT) ranging from 1720 to 885, and Load (MWE) ranging from 560 to 625. |
| ; DATE OF EVENT: April 8, 1978 FACILITY: Davis-Bessa Unit l' | | ' Description of Occurrence: On April 8, 1978, Hydrogen Dilution Blower 1-1 was running for Surveillance Test ST 5065.05 " Hydrogen Purge Filter 18 Month or Special Test". After about ih hours of run time, the blower motor breaker tripped on overload. The technician at the blower had noticed no unusual noise while the blower was running. Shortly after the blower motor breaker tripped, j the operator attempted to reset the breaker but was unable to do so. This l blower being inoperable placed the unit in the Action Statement of Technical , |
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| IDENTIFICATION OF OCCURRENCE: Hydrogen Dilution Blower 1-1 Trip 4 | |
| Conditions Prior to Occurrence: The unit was in Mode 1 vith Power (MWT) ranging | |
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| from 1720 to 885, and Load (MWE) ranging from 560 to 625. | |
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| ' Description of Occurrence: On April 8, 1978, Hydrogen Dilution Blower 1-1 was running for Surveillance Test ST 5065.05 " Hydrogen Purge Filter 18 Month or Special Test". After about ih hours of run time, the blower motor breaker tripped on overload. The technician at the blower had noticed no unusual noise while the blower was running. Shortly after the blower motor breaker tripped, j | |
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| the operator attempted to reset the breaker but was unable to do so. This l blower being inoperable placed the unit in the Action Statement of Technical , | |
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| - Specification 3.6.4.3, which requires both Hydrogen Dilution Systems to be op' era- ; | | - Specification 3.6.4.3, which requires both Hydrogen Dilution Systems to be op' era- ; |
| ble while in Modes 1 and 2. The Action Statement requires the inoperable Hydro-gen Dilution System to be returned to operable status within 30 days or the unit be in Hot Standby within the next 6 hours. , , | | ble while in Modes 1 and 2. The Action Statement requires the inoperable Hydro-gen Dilution System to be returned to operable status within 30 days or the unit be in Hot Standby within the next 6 hours. , , |
| l On* April 18, 1978, Hydrcgen Dilution Blower 1-1 was again being operated for additional investigation of the previous failure. It was determined that the discharge check valve was not open and Hydrogen Dilution Blower 1-1 was again l declared inoperable at 1515 hours on April 18, 1978, returning the unit to the | | l On* April 18, 1978, Hydrcgen Dilution Blower 1-1 was again being operated for additional investigation of the previous failure. It was determined that the discharge check valve was not open and Hydrogen Dilution Blower 1-1 was again l declared inoperable at 1515 hours on April 18, 1978, returning the unit to the Action Statement of Technical Specification 3.6.4.3. |
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| | Designation of Apparent Cause of' Occurrence: The cause of both of these occur-rences is component failure. The suction check valve not fully opening was thought to be the cause of the first occurrence. Af ter further investigation, the discharge check valve was found to be not fully opening, causing the second occurrence. |
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| Action Statement of Technical Specification 3.6.4.3. | |
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| Designation of Apparent Cause of' Occurrence: The cause of both of these occur-rences is component failure. The suction check valve not fully opening was thought | |
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| to be the cause of the first occurrence. Af ter further investigation, the discharge check valve was found to be not fully opening, causing the second occurrence. | |
| t Analysis of Occurrence: There was no danger to the health and safety of the public or unit personnt.1. Hydrogen u:Liution Blower 1-2 was operable if an inci-dent requiring the Hydrogen Dilution 9ystem had occurred. | | t Analysis of Occurrence: There was no danger to the health and safety of the public or unit personnt.1. Hydrogen u:Liution Blower 1-2 was operable if an inci-dent requiring the Hydrogen Dilution 9ystem had occurred. |
| Corrective Action: On April 11, 1978, a heater in the breaker for Hydrogen Dilu-tion Blower 1-1 was replaced and the suction check valve was found to be stick-ing. On April 11, 1978, the velded bonnet suction check valve was disassembled, cleaned, and reassembled. Surveillance Test ST 5065.02, Hydrogen Dilution System Quarterly Test, was successfully perfor=ed for the Hydrozen Dilution Blower 1 which removed the unit from the Action Statenent of Technical Spefication 3.6.4.3. | | Corrective Action: On April 11, 1978, a heater in the breaker for Hydrogen Dilu-tion Blower 1-1 was replaced and the suction check valve was found to be stick-ing. On April 11, 1978, the velded bonnet suction check valve was disassembled, cleaned, and reassembled. Surveillance Test ST 5065.02, Hydrogen Dilution System Quarterly Test, was successfully perfor=ed for the Hydrozen Dilution Blower 1 which removed the unit from the Action Statenent of Technical Spefication 3.6.4.3. |
| v LER #78-035 | | v LER #78-035 |
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| | TOLEDO EDISON C0!!PANY PAGE 2 DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLCIENTAL INFORMATION FOR LER NP-33-IS-43 i |
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| | On April 24, 1978, the velded bonnet discharge check valve was disassembled, cleaned and, reassembled. |
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| TOLEDO EDISON C0!!PANY PAGE 2 DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLCIENTAL INFORMATION FOR LER NP-33-IS-43 | |
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| i On April 24, 1978, the velded bonnet discharge check valve was disassembled, cleaned and, reassembled.
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| Facility Change Request 78-211 has been prepared to request removal of the 1 | | Facility Change Request 78-211 has been prepared to request removal of the 1 |
| check valve internals on both Hydrogen Dilution Blowers to prevent recurrence. | | check valve internals on both Hydrogen Dilution Blowers to prevent recurrence. |
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| l Failure Data: Although there has been no previous reportable occurrences, momentary sticking of these check valves has been experienced in'the past. | | l Failure Data: Although there has been no previous reportable occurrences, momentary sticking of these check valves has been experienced in'the past. |
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Category:LICENSEE EVENT REPORT (SEE ALSO AO
MONTHYEARML20046C0661993-07-30030 July 1993 LER 92-009-01:on 920910,deficiencies Discovered During Dynamic Testing of Motor Operated Valves in Response to Generic Ltr 89-10.MOVs W/Deficiencies Modified or Repaired. W/930730 Ltr ML20046B6011993-07-26026 July 1993 LER 93-004-00:on 930428,plant Entered Mode 2 W/Afw Pump Turbine Main Steam Line Crossover Check Valve MS735 in Open Position.Caused by Inappropriate Use of Engineering Judgement.Valve MS735 closed.W/930726 Ltr ML20045D2451993-06-17017 June 1993 LER 93-003-00:on 930520,plant Experienced Trip from Approx & Continuity Between Fuse & Fuseholder Lost,Resulting in Loss of Selected RCS Average Temp Input to Ics.Faulty Fuse Cap & Fuse replaced.W/930617 Ltr ML20044B1681990-07-10010 July 1990 LER 90-002-01:on 900126,reactor Coolant Pump Current Monitor Inputs to Sfrcs ACH1 & Reactor Pressure Sys Channel 1 Experienced Reactor Trip.Probably Caused by Inadequate Test Switches & Isolation plug.W/900710 Ltr ML20043H3201990-06-18018 June 1990 LER 90-010-00:on 900518,station Experienced Inadvertent Safety Features Actuation Signal Level 1-4 Actuation W/Injection of 1,000 Gallons of Borated Water.Caused by Loss of 120-volt Ac Bus Y3.W/900618 Ltr ML20043B5711990-05-25025 May 1990 LER 90-008-00:on 900425,safety Features Actuation Sys Level 1 Actuation Occurred,Resulting in Trip of Containment Radiation Monitors.Caused by High Radiation Fields While Lifting Core Support Assembly.Mod initiated.W/900525 Ltr ML20043B8051990-05-25025 May 1990 LER 90-009-00:on 900426,source-check of Station Vent Radiation Monitors Not Performed Per Tech Spec 3.3.3.10. Caused by Use of Outmoded Light Emitting Dioide as Check Source.Source Check Procedures revised.W/900525 Ltr ML20042F2811990-05-0303 May 1990 LER 90-007-00:on 900403,inadvertent,inconsequential Safety Features Actuation Signal Occured While Defueled.Caused by Incidental Contact W/Monitor in Containment.Temporary Barriers Built Around monitors.W/900503 Ltr ML20042F2791990-05-0303 May 1990 LER 90-006-00:on 900403,station Experienced Safety Features Actuation Sys Levels 1 Through 5 Actuation.Caused by Contact W/Breaker Switch HAAE2 in High Voltage Switchgear Room 2. Meetings Held W/Craft personnel.W/900503 Ltr ML20042E4891990-04-16016 April 1990 LER 90-005-00:on 900314,determined That Some Class 1E Circuits That Pass Through Containment Electrical Penetrations Do Not Have Adequate Backup Fault Protection. Caused by Inadequate Design control.W/900416 Ltr ML20012D0341990-03-19019 March 1990 LER 90-004-00:on 900217,fuel Assembly Moved in Spent Fuel Pool While Emergency Ventilation Inoperable.Caused by Personnel Error.Personnel Involved Counseled & Subj LER Part of Required reading.W/900319 Ltr ML20012C7151990-03-14014 March 1990 LER 90-003-00:on 900212,station Entered Mode 6,refueling,w/o Operable Audible Source Range Indication.Caused by Personnel Error.Individual counseled.W/900314 Ltr ML20012B4851990-03-0606 March 1990 LER 83-039/03X-2:on 830726,discovered That Handwheel for Inner Door of Personnel Airlock in Shut Position & Partially Opened.Caused by Excessive Use of Door During Outages.Door Repaired & Returned to Operable status.W/900306 Ltr ML20011F3831990-02-26026 February 1990 LER 90-002-00:on 900126,reactor Tripped from 73% Power. Caused by Spurious Reactor Coolant Pump Monitor Signal Indicating Only One Pump Running in Each Loop.Pump Seal to Be Replaced During Sixth Refueling outage.W/900226 Ltr ML20006E6861990-02-20020 February 1990 LER 90-001-00:on 900118,reactor Protection Sys Channel 2 Bypassed Temporarily During Performance of DB-MI-03207. Caused by Inadequate Procedure Re Inoperable Channel Removal.Procedure SP1105.02 revised.W/900220 Ltr ML20011E2251990-01-30030 January 1990 LER 86-032-01:on 860802,inadvertent Start of High Pressure Injection Pump 1-2 Occurred.Caused by Open Relay Coil. Failed Relay Replaced & Procedure Change Initiated. W/900130 Ltr ML20005G1091990-01-0909 January 1990 LER 89-015-01:on 891026,concluded That Transmitter Was Out of Tolerance When Reactor Protection Sys Channel 2 Returned to Operable Status on 890924.Caused by leak-by in Instrument Manifold.Transmitter Recalibr successfully.W/900109 Ltr ML20042D4011990-01-0202 January 1990 LER 89-010-01:on 890612,control Room Ventilation Sys Declared Inoperable Due to Compressor High Pressure Trips. Caused by Tripping of Refrigerant Pressure Switch on High Pressure.Switch Reset & Sys retested.W/900102 Ltr ML19354D7361989-12-22022 December 1989 LER 89-018-00:on 891123,hydrogen Dilution Blower 1-1 Casing Drain Line Broke Off at Casing,Declaring Blower Inoperable. Caused by Drain Line Being Accidentally Stepped On.Drain Removed & Pipe Plug installed.W/891222 Ltr ML19332F8951989-12-13013 December 1989 LER 89-017-00:on 891113,containment Spray Pump 1-1 Inadvertently Started During Monthly Functional Test in Safety Features Actuation Sys (Sfas) Channel 1.Caused by Failed Relay in Sfas Channel 3.Relay replaced.W/891213 Ltr ML19332E7521989-12-0404 December 1989 LER 89-016-00:on 890917,unplanned Release of Radioactive Resin to Onsite Settling Basin Occurred.Caused by Personnel Error.Standing Order 89-051 Generated on 890920 to Direct Use of Working Copy of procedures.W/891204 Ltr ML19332D3111989-11-27027 November 1989 LER 89-015-00:on 890924,RCS Flow Transmitter Out of Tolerance When Reactor Protection Sys Channel 2 Returned to Operable Status.Caused by leak-by in Instrument Manifold Seen as Zero Shift.Transmitter recalibr.W/891127 Ltr ML19324C2081989-11-10010 November 1989 LER 89-014-00:on 891011,plastic Sheeting Blocked Off Fire Detectors in Auxiliary Feedwater Pump 1-1 Room & High Voltage Switchgear Room B,Making Fire Detectors Inoperable. Caused by Personnel Oversight.Event reviewed.W/891110 Ltr ML19325D4671989-10-16016 October 1989 LER 89-004-01:on 890411,determined That Circulating Water Line Break Would Result in Loss of Svc Water as Result of Concerns Raised on 890206.Cause Unknown.Standing Order 89-026 in Place to Plug Floor drains.W/891016 Ltr ML19325C8531989-10-13013 October 1989 LER 89-013-00:on 890913,hourly Fire Watch Patrol Exceeded Allowed Interval,Violating Tech Spec 3.7.10,Action a.2. Caused by Personnel Error.Individual Counseled & Event Info Distributed to Fire Watch personnel.W/891013 Ltr ML20024E2591983-08-0101 August 1983 LER 83-033/03L-0:on 830620,fire Detection Zone Reactor Coolant Pump 1-2,containment Level 603 Ft Alarmed & Could Not Be Reset.Caused by Faulty Detector String.Zone Will Be Restored During Next Refueling outage.W/830801 Ltr ML20024B8351983-07-0101 July 1983 LER 83-028/03L-0:on 830603 & 17,fuel Handling Area Radiation Monitors RE8446 & 7 Found Deenergized.Caused by Blown Radiation Monitoring Cabinet Fuse.Fuse replaced.W/830701 Ltr ML20024B0471983-06-21021 June 1983 LER 83-026/03L-0:on 830524,one Half Channel Trip in Steam & Feedwater Rupture Control Sys (Sfrcs) Channel 2 Received. Caused by Component Failure.Input Buffer replaced.W/830621 Ltr ML20024A3621983-06-0909 June 1983 LER 83-024/03L-0:on 830511,while Starting Up from 830510 Reactor Trip,Quadrant Power Tilt in Quadrant Yz Exceeded Tech Spec steady-state Limit.Caused by Inherent Design of B&W NSSS & Negative Moderator Temp coefficient.W/830609 Ltr ML20024A5341983-06-0808 June 1983 LER 83-023/03L-0:on 830510,120-volt Ac Essential Bus Y4 Lost,Resulting in Deenergizing Reactor Protection & Safety Features Actuation Sys Channel 4.Caused by Blown Fuse in Inverter YV4.Power Restored to bus.W/830608 Ltr ML20024A5481983-06-0707 June 1983 Revised LER 83-002/03X-2:on 830115,18,0409,10 & 0510,RCS Dose Equivalent I-131 Exceeded Tech Spec Limit.Caused by Slight Fission Product Leakage Through Fuel Cladding.Level of I-131 monitored.W/830607 Ltr ML20023D9051983-05-26026 May 1983 LER 83-027/03L-0:on 830428,valve RC240B Would Not Close W/O Repeated Signals from Control Room.Caused by Valve Operator Torquing Out Due to Dirty & Improperly Lubricated Stem.Stem Cleaned & Torque Switch reset.W/830526 Ltr ML20023C3241983-05-0505 May 1983 LER 83-016/03L-0:on 830407,determined That Amplifier of Startup Level Transmitter LT-SP9A3 for Steam Generator 1-2 Failed.Caused by Component Failure within Amplifier. Amplifier Replaced ML20023C3021983-05-0505 May 1983 Revised LER 83-002/03X-1:on 830115,RCS Dose Equivalent I-131 Exceeded Tech Spec Limit of 1.0 Uci/Gm.Caused by Leakage of Fission Products Through Fuel cladding.I-131 Monitored Until Level Dropped ML20028E9581983-01-19019 January 1983 LER 82-068/03L-0:on 821220,core Imbalance Vs Core Power Limit Computer Alarm C963 Inoperable.Caused by Mistake in Alarm Subroutine.Alarm Statement Corrected So Limits & Value for Imbalance Scaled Same ML20028D2291983-01-0707 January 1983 Revised LER 81-045/03X-1:on 810730,after Unit Trip,Three Action Statements Entered.Auxiliary Feedwater Pump 1-2 Did Not Operate Properly.Shield Bldg Integrity Lost When Panel Blown Out.Main Steam Safety Valve Lifted at Low Setpoint ML20028C1231983-01-0303 January 1983 LER 82-064/03L-0:on 821129,decay Heat Cooler Component Cooling Water Outlet Valve on CCW Train 1 Would Not Open. Caused by Mfg Error.Flanged Bearing Missing from Actuator Mounting Plate.Flanged Bearing Installed on 821215 ML20028C3111982-12-30030 December 1982 Revised LER 81-031/03X-6:on 810512,following Reactor Trip, RCS Sample Level Peaked Above Microcurie Limit.Other Iodine Spikes Occurred 810730,0902,1016 & 23 & 1228.Caused by Slight Leakage of Fission Products Through Fuel Cladding ML20028C1971982-12-30030 December 1982 Revised LER 82-045/03X-1:on 820904 & 1203,auxiliary Feedwater Pump 1-1 Suction Valve FW786 Closed for No Apparent Reason W/O Operator Touching Close Button.Cause Unknown.Valve FW786 Reopened Upon Discovery ML20028C2591982-12-30030 December 1982 LER 82-065/03L-0:on 821201,discovered That Control Room Not Placed in Recirculation Mode within 1 H of Ventilation Sys Chlorine Detector Being Taken Out of Svc.On 821203,chlorine Detector Failed.Caused by Personnel Error ML20028B0291982-11-19019 November 1982 LER 82-054/03L-0:on 821021,Door 107 to Radiation Equipment Found Partially Open & Blocked by Hose When Personnel Attempted to Perform Routine Flush on RE-1878.Caused by Personnel Error.Personnel Counseled ML20028B2281982-11-16016 November 1982 LER 82-053/03L-0:on 821018,half Trip Alarm on Steam & Feedwater Rupture Control Sys Channel 2 Received Due to Failure of Steam Generator Level Instrument Cabinet Channel 2,24-volt Dc Power Supply.Caused by Component Failure ML20027E7891982-11-0404 November 1982 Revised LER 82-052/03X-1:on 820928,reactor Quadrant Power Tilt in Wx Quadrant Exceeded Tech Specs.Caused by Xenon Oscillation Producing Large Negative Imbalance.Control Rod Group 7 Borated Out to Reduce Negative Imbalance ML20027C9551982-10-19019 October 1982 LER 82-049/03L-0:on 820920 & 22,Channels 2 & 3 on Containment post-accident Radiation Monitor Re 4597BA Were Reading High.Caused by Problem in Microprocessor Software. New Set of Software Installed & Faulty Actuator Replaced ML20027C5381982-10-0404 October 1982 LER 82-045/03L-0:on 820904,auxiliary Feedwater Pump 1-1, Suction Valve FW786 Observed Closed for No Apparent Reason W/O Operator Touching Close Button.Cause Unknown. Valve Reopened ML20027A9471982-09-0707 September 1982 LER 82-036/03L-0:on 820808,hole Discovered in Fire Barrier Wall Above Door 309.Caused by Snubber EBD125R43 Penetrating Wall Through Pipe Shell.Hole Left by Workers After Work on Snubbers.Fire Watch Established & Hole Filled ML20052G6651982-05-0707 May 1982 LER 82-020/03L-0:on 820409,while in Mode 6,station Experienced Loss of 120-volt Ac Distribution Panel Y2.Caused by Blown YV2 Inverter Fuse When Short to Ground Occurred During Maint on Control Room Emergency Ventilation Sys ML20052E6231982-04-30030 April 1982 LER 82-019/01T-0:on 820426,some Steam Generator Tubes Adjacent to Auxiliary Feedwater Header Showed Potential Interaction W/Header Support Sys.Header Found Insecurely Fastened & Damaged.Cause & Corrections Being Investigated ML20052E8761982-04-29029 April 1982 LER 82-016/03X-1:on 820312,door 108 Found W/Both Door Closure Mechanisms Broken.Caused by Improper Operation of Door Closure Mechanisms by Personnel.Mechanisms Temporarily Repaired & New Parts Ordered ML20052C4151982-04-23023 April 1982 LER 82-018/03L-0:on 820326,electrician Cut High Voltage Cable on Source Range Detector NI-2,while Working in Containment Penetration Box P1L1L1.Caused by Problem in Coordination of Work Performed.Cut Cable Reconnected 1993-07-30
[Table view] Category:RO)
MONTHYEARML20046C0661993-07-30030 July 1993 LER 92-009-01:on 920910,deficiencies Discovered During Dynamic Testing of Motor Operated Valves in Response to Generic Ltr 89-10.MOVs W/Deficiencies Modified or Repaired. W/930730 Ltr ML20046B6011993-07-26026 July 1993 LER 93-004-00:on 930428,plant Entered Mode 2 W/Afw Pump Turbine Main Steam Line Crossover Check Valve MS735 in Open Position.Caused by Inappropriate Use of Engineering Judgement.Valve MS735 closed.W/930726 Ltr ML20045D2451993-06-17017 June 1993 LER 93-003-00:on 930520,plant Experienced Trip from Approx & Continuity Between Fuse & Fuseholder Lost,Resulting in Loss of Selected RCS Average Temp Input to Ics.Faulty Fuse Cap & Fuse replaced.W/930617 Ltr ML20044B1681990-07-10010 July 1990 LER 90-002-01:on 900126,reactor Coolant Pump Current Monitor Inputs to Sfrcs ACH1 & Reactor Pressure Sys Channel 1 Experienced Reactor Trip.Probably Caused by Inadequate Test Switches & Isolation plug.W/900710 Ltr ML20043H3201990-06-18018 June 1990 LER 90-010-00:on 900518,station Experienced Inadvertent Safety Features Actuation Signal Level 1-4 Actuation W/Injection of 1,000 Gallons of Borated Water.Caused by Loss of 120-volt Ac Bus Y3.W/900618 Ltr ML20043B5711990-05-25025 May 1990 LER 90-008-00:on 900425,safety Features Actuation Sys Level 1 Actuation Occurred,Resulting in Trip of Containment Radiation Monitors.Caused by High Radiation Fields While Lifting Core Support Assembly.Mod initiated.W/900525 Ltr ML20043B8051990-05-25025 May 1990 LER 90-009-00:on 900426,source-check of Station Vent Radiation Monitors Not Performed Per Tech Spec 3.3.3.10. Caused by Use of Outmoded Light Emitting Dioide as Check Source.Source Check Procedures revised.W/900525 Ltr ML20042F2811990-05-0303 May 1990 LER 90-007-00:on 900403,inadvertent,inconsequential Safety Features Actuation Signal Occured While Defueled.Caused by Incidental Contact W/Monitor in Containment.Temporary Barriers Built Around monitors.W/900503 Ltr ML20042F2791990-05-0303 May 1990 LER 90-006-00:on 900403,station Experienced Safety Features Actuation Sys Levels 1 Through 5 Actuation.Caused by Contact W/Breaker Switch HAAE2 in High Voltage Switchgear Room 2. Meetings Held W/Craft personnel.W/900503 Ltr ML20042E4891990-04-16016 April 1990 LER 90-005-00:on 900314,determined That Some Class 1E Circuits That Pass Through Containment Electrical Penetrations Do Not Have Adequate Backup Fault Protection. Caused by Inadequate Design control.W/900416 Ltr ML20012D0341990-03-19019 March 1990 LER 90-004-00:on 900217,fuel Assembly Moved in Spent Fuel Pool While Emergency Ventilation Inoperable.Caused by Personnel Error.Personnel Involved Counseled & Subj LER Part of Required reading.W/900319 Ltr ML20012C7151990-03-14014 March 1990 LER 90-003-00:on 900212,station Entered Mode 6,refueling,w/o Operable Audible Source Range Indication.Caused by Personnel Error.Individual counseled.W/900314 Ltr ML20012B4851990-03-0606 March 1990 LER 83-039/03X-2:on 830726,discovered That Handwheel for Inner Door of Personnel Airlock in Shut Position & Partially Opened.Caused by Excessive Use of Door During Outages.Door Repaired & Returned to Operable status.W/900306 Ltr ML20011F3831990-02-26026 February 1990 LER 90-002-00:on 900126,reactor Tripped from 73% Power. Caused by Spurious Reactor Coolant Pump Monitor Signal Indicating Only One Pump Running in Each Loop.Pump Seal to Be Replaced During Sixth Refueling outage.W/900226 Ltr ML20006E6861990-02-20020 February 1990 LER 90-001-00:on 900118,reactor Protection Sys Channel 2 Bypassed Temporarily During Performance of DB-MI-03207. Caused by Inadequate Procedure Re Inoperable Channel Removal.Procedure SP1105.02 revised.W/900220 Ltr ML20011E2251990-01-30030 January 1990 LER 86-032-01:on 860802,inadvertent Start of High Pressure Injection Pump 1-2 Occurred.Caused by Open Relay Coil. Failed Relay Replaced & Procedure Change Initiated. W/900130 Ltr ML20005G1091990-01-0909 January 1990 LER 89-015-01:on 891026,concluded That Transmitter Was Out of Tolerance When Reactor Protection Sys Channel 2 Returned to Operable Status on 890924.Caused by leak-by in Instrument Manifold.Transmitter Recalibr successfully.W/900109 Ltr ML20042D4011990-01-0202 January 1990 LER 89-010-01:on 890612,control Room Ventilation Sys Declared Inoperable Due to Compressor High Pressure Trips. Caused by Tripping of Refrigerant Pressure Switch on High Pressure.Switch Reset & Sys retested.W/900102 Ltr ML19354D7361989-12-22022 December 1989 LER 89-018-00:on 891123,hydrogen Dilution Blower 1-1 Casing Drain Line Broke Off at Casing,Declaring Blower Inoperable. Caused by Drain Line Being Accidentally Stepped On.Drain Removed & Pipe Plug installed.W/891222 Ltr ML19332F8951989-12-13013 December 1989 LER 89-017-00:on 891113,containment Spray Pump 1-1 Inadvertently Started During Monthly Functional Test in Safety Features Actuation Sys (Sfas) Channel 1.Caused by Failed Relay in Sfas Channel 3.Relay replaced.W/891213 Ltr ML19332E7521989-12-0404 December 1989 LER 89-016-00:on 890917,unplanned Release of Radioactive Resin to Onsite Settling Basin Occurred.Caused by Personnel Error.Standing Order 89-051 Generated on 890920 to Direct Use of Working Copy of procedures.W/891204 Ltr ML19332D3111989-11-27027 November 1989 LER 89-015-00:on 890924,RCS Flow Transmitter Out of Tolerance When Reactor Protection Sys Channel 2 Returned to Operable Status.Caused by leak-by in Instrument Manifold Seen as Zero Shift.Transmitter recalibr.W/891127 Ltr ML19324C2081989-11-10010 November 1989 LER 89-014-00:on 891011,plastic Sheeting Blocked Off Fire Detectors in Auxiliary Feedwater Pump 1-1 Room & High Voltage Switchgear Room B,Making Fire Detectors Inoperable. Caused by Personnel Oversight.Event reviewed.W/891110 Ltr ML19325D4671989-10-16016 October 1989 LER 89-004-01:on 890411,determined That Circulating Water Line Break Would Result in Loss of Svc Water as Result of Concerns Raised on 890206.Cause Unknown.Standing Order 89-026 in Place to Plug Floor drains.W/891016 Ltr ML19325C8531989-10-13013 October 1989 LER 89-013-00:on 890913,hourly Fire Watch Patrol Exceeded Allowed Interval,Violating Tech Spec 3.7.10,Action a.2. Caused by Personnel Error.Individual Counseled & Event Info Distributed to Fire Watch personnel.W/891013 Ltr ML20024E2591983-08-0101 August 1983 LER 83-033/03L-0:on 830620,fire Detection Zone Reactor Coolant Pump 1-2,containment Level 603 Ft Alarmed & Could Not Be Reset.Caused by Faulty Detector String.Zone Will Be Restored During Next Refueling outage.W/830801 Ltr ML20024B8351983-07-0101 July 1983 LER 83-028/03L-0:on 830603 & 17,fuel Handling Area Radiation Monitors RE8446 & 7 Found Deenergized.Caused by Blown Radiation Monitoring Cabinet Fuse.Fuse replaced.W/830701 Ltr ML20024B0471983-06-21021 June 1983 LER 83-026/03L-0:on 830524,one Half Channel Trip in Steam & Feedwater Rupture Control Sys (Sfrcs) Channel 2 Received. Caused by Component Failure.Input Buffer replaced.W/830621 Ltr ML20024A3621983-06-0909 June 1983 LER 83-024/03L-0:on 830511,while Starting Up from 830510 Reactor Trip,Quadrant Power Tilt in Quadrant Yz Exceeded Tech Spec steady-state Limit.Caused by Inherent Design of B&W NSSS & Negative Moderator Temp coefficient.W/830609 Ltr ML20024A5341983-06-0808 June 1983 LER 83-023/03L-0:on 830510,120-volt Ac Essential Bus Y4 Lost,Resulting in Deenergizing Reactor Protection & Safety Features Actuation Sys Channel 4.Caused by Blown Fuse in Inverter YV4.Power Restored to bus.W/830608 Ltr ML20024A5481983-06-0707 June 1983 Revised LER 83-002/03X-2:on 830115,18,0409,10 & 0510,RCS Dose Equivalent I-131 Exceeded Tech Spec Limit.Caused by Slight Fission Product Leakage Through Fuel Cladding.Level of I-131 monitored.W/830607 Ltr ML20023D9051983-05-26026 May 1983 LER 83-027/03L-0:on 830428,valve RC240B Would Not Close W/O Repeated Signals from Control Room.Caused by Valve Operator Torquing Out Due to Dirty & Improperly Lubricated Stem.Stem Cleaned & Torque Switch reset.W/830526 Ltr ML20023C3241983-05-0505 May 1983 LER 83-016/03L-0:on 830407,determined That Amplifier of Startup Level Transmitter LT-SP9A3 for Steam Generator 1-2 Failed.Caused by Component Failure within Amplifier. Amplifier Replaced ML20023C3021983-05-0505 May 1983 Revised LER 83-002/03X-1:on 830115,RCS Dose Equivalent I-131 Exceeded Tech Spec Limit of 1.0 Uci/Gm.Caused by Leakage of Fission Products Through Fuel cladding.I-131 Monitored Until Level Dropped ML20028E9581983-01-19019 January 1983 LER 82-068/03L-0:on 821220,core Imbalance Vs Core Power Limit Computer Alarm C963 Inoperable.Caused by Mistake in Alarm Subroutine.Alarm Statement Corrected So Limits & Value for Imbalance Scaled Same ML20028D2291983-01-0707 January 1983 Revised LER 81-045/03X-1:on 810730,after Unit Trip,Three Action Statements Entered.Auxiliary Feedwater Pump 1-2 Did Not Operate Properly.Shield Bldg Integrity Lost When Panel Blown Out.Main Steam Safety Valve Lifted at Low Setpoint ML20028C1231983-01-0303 January 1983 LER 82-064/03L-0:on 821129,decay Heat Cooler Component Cooling Water Outlet Valve on CCW Train 1 Would Not Open. Caused by Mfg Error.Flanged Bearing Missing from Actuator Mounting Plate.Flanged Bearing Installed on 821215 ML20028C3111982-12-30030 December 1982 Revised LER 81-031/03X-6:on 810512,following Reactor Trip, RCS Sample Level Peaked Above Microcurie Limit.Other Iodine Spikes Occurred 810730,0902,1016 & 23 & 1228.Caused by Slight Leakage of Fission Products Through Fuel Cladding ML20028C1971982-12-30030 December 1982 Revised LER 82-045/03X-1:on 820904 & 1203,auxiliary Feedwater Pump 1-1 Suction Valve FW786 Closed for No Apparent Reason W/O Operator Touching Close Button.Cause Unknown.Valve FW786 Reopened Upon Discovery ML20028C2591982-12-30030 December 1982 LER 82-065/03L-0:on 821201,discovered That Control Room Not Placed in Recirculation Mode within 1 H of Ventilation Sys Chlorine Detector Being Taken Out of Svc.On 821203,chlorine Detector Failed.Caused by Personnel Error ML20028B0291982-11-19019 November 1982 LER 82-054/03L-0:on 821021,Door 107 to Radiation Equipment Found Partially Open & Blocked by Hose When Personnel Attempted to Perform Routine Flush on RE-1878.Caused by Personnel Error.Personnel Counseled ML20028B2281982-11-16016 November 1982 LER 82-053/03L-0:on 821018,half Trip Alarm on Steam & Feedwater Rupture Control Sys Channel 2 Received Due to Failure of Steam Generator Level Instrument Cabinet Channel 2,24-volt Dc Power Supply.Caused by Component Failure ML20027E7891982-11-0404 November 1982 Revised LER 82-052/03X-1:on 820928,reactor Quadrant Power Tilt in Wx Quadrant Exceeded Tech Specs.Caused by Xenon Oscillation Producing Large Negative Imbalance.Control Rod Group 7 Borated Out to Reduce Negative Imbalance ML20027C9551982-10-19019 October 1982 LER 82-049/03L-0:on 820920 & 22,Channels 2 & 3 on Containment post-accident Radiation Monitor Re 4597BA Were Reading High.Caused by Problem in Microprocessor Software. New Set of Software Installed & Faulty Actuator Replaced ML20027C5381982-10-0404 October 1982 LER 82-045/03L-0:on 820904,auxiliary Feedwater Pump 1-1, Suction Valve FW786 Observed Closed for No Apparent Reason W/O Operator Touching Close Button.Cause Unknown. Valve Reopened ML20027A9471982-09-0707 September 1982 LER 82-036/03L-0:on 820808,hole Discovered in Fire Barrier Wall Above Door 309.Caused by Snubber EBD125R43 Penetrating Wall Through Pipe Shell.Hole Left by Workers After Work on Snubbers.Fire Watch Established & Hole Filled ML20052G6651982-05-0707 May 1982 LER 82-020/03L-0:on 820409,while in Mode 6,station Experienced Loss of 120-volt Ac Distribution Panel Y2.Caused by Blown YV2 Inverter Fuse When Short to Ground Occurred During Maint on Control Room Emergency Ventilation Sys ML20052E6231982-04-30030 April 1982 LER 82-019/01T-0:on 820426,some Steam Generator Tubes Adjacent to Auxiliary Feedwater Header Showed Potential Interaction W/Header Support Sys.Header Found Insecurely Fastened & Damaged.Cause & Corrections Being Investigated ML20052E8761982-04-29029 April 1982 LER 82-016/03X-1:on 820312,door 108 Found W/Both Door Closure Mechanisms Broken.Caused by Improper Operation of Door Closure Mechanisms by Personnel.Mechanisms Temporarily Repaired & New Parts Ordered ML20052C4151982-04-23023 April 1982 LER 82-018/03L-0:on 820326,electrician Cut High Voltage Cable on Source Range Detector NI-2,while Working in Containment Penetration Box P1L1L1.Caused by Problem in Coordination of Work Performed.Cut Cable Reconnected 1993-07-30
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217K1231999-10-14014 October 1999 Revised Positions for DBNPS & Pnpp QA Program ML20217D5441999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Davis-Besse Nuclear Power Station.With ML20211R0811999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Davis-Besse Nuclear Power Station,Unit 1.With ML20211B0271999-08-13013 August 1999 SER Accepting Second 10-year Interval Inservice Insp Requests for Relief RR-A16,RR-A17 & RR-B9 for Plant, Unit 1 ML20210Q8541999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Davis-Besse Nuclear Power Station,Unit 1.With ML20209E6231999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Davis-Besse Nuclear Power Station,Unit 1.With ML20195K2871999-06-16016 June 1999 Safety Evaluation Accepting Licensee Response to GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves ML20195F4871999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Davis-Besse Nuclear Power Station,Unit 1.With ML20207E8011999-05-19019 May 1999 Non-proprietary Rev 2 to HI-981933, Design & Licensing Rept DBNPS Unit 1 Cask Pit Rack Installation Project ML20207F4351999-05-0404 May 1999 Rev 1 to DBNPS Emergency Preparedness Evaluated Exercise Manual 990504 ML20206M6341999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Davis-Besse Nuclear Station,Unit 1.With ML20205M2931999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Davis-Besse Nuclear Power Station.With ML20207J1461999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Davis-Besse Nuclear Power Station,Unit 1.With ML20199H5931999-01-20020 January 1999 Safety Evaluation Accepting Thermo-Lag Re Ampacity Derating Issues for Plant ML20204J6751998-12-31031 December 1998 1998 Annual Rept for Dbnps,Unit 1,PNPP,Unit 1 & BVPS Units 1 & 2 ML20199E2501998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Davis-Besse Nuclear Power Station,Unit 1.With ML20206B0101998-12-31031 December 1998 1998 Annual Rept for Firstenergy Corp, for Perry Nuclear Power Plant & Davis-Besse Nuclear Power Station.Form 10-K Annual Rept to Us Securities & Exchange Commission for Fiscal Yr Ending 981231,encl ML20205K5781998-12-31031 December 1998 Waterhammer Phenomena in Containment Air Cooler Swss ML20197J3441998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Davis-Besse Nuclear Power Station,Unit 1.With ML20195D0001998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Davis-Besse Nuclear Power Station,Unit 1.With ML20155B6781998-10-28028 October 1998 Safety Evaluation Accepting Proposed Reduction in Commitment Changes in QA Program Matl Receipt Insp Process ML20154H5801998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Davis-Besse Nuclear Power Station,Unit 1.With ML20151W1611998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Dbnps.With ML20237E3171998-08-21021 August 1998 ISI Summary Rept of Eleventh Refueling Outage Activities for Davis-Besse Nuclear Power Station ML20237B1681998-07-31031 July 1998 Monthly Operating Rept for July 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20236U5011998-07-23023 July 1998 Special Rept:On 980624,Unit 1 Site Damaged by Tornado & High Winds.Alert Declared by DBNPS Staff,Dbnps Emergency Response Facilities Activiated & Special Insp Team Deployed to Site by Nrc,As Result of Event ML20236R1441998-07-15015 July 1998 SER Related to Quality Assurance Program Description Changes for Davis-Besse Nuclear Power Station,Unit 1 ML20236N7451998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20236K3981998-06-30030 June 1998 SER Accepting in Part & Denying in Part Relief Requests from Some of ASME Section XI Requirements as Endorsed by 10CFR50.55a for Containment Insp for Davis-Besse Nuclear Power Station,Unit 1 ML20236K5131998-06-29029 June 1998 Safety Evaluation Accepting Proposed Alternate Emergency Operations Facility Location for Davis-Besse Nuclear Power Station,Unit 1 ML20248F7441998-05-31031 May 1998 Reactor Vessel Working Group,Response to RAI Regarding Reactor Pressure Vessel Integrity ML20249A4121998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20196B5221998-05-23023 May 1998 10CFR50.59 Summary Rept of Facility Changes,Tests & Experiments Dbnps,Unit 1 for 960602-980523 ML20236E7581998-05-19019 May 1998 Rev 0 to Davis-Besse Unit 1 Cycle 12 Colr ML20236N7501998-04-30030 April 1998 Rev 2 to Monthly Operating Rept for Apr 1998 for Davis-Besse Nuclear Power Station,Unit ML20247F6721998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Davis-Bess Nuclear Power Station,Unit 1 ML20249A4141998-04-30030 April 1998 Revised Monthly Operating Rept for Apr 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20217P8041998-04-0707 April 1998 11RFO OTSG ECT Insp Scope ML20216B4041998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20216C5131998-02-28028 February 1998 Monthly Operating Rept for Feb 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20202D3721998-01-31031 January 1998 Monthly Operating Rept for Jan 1998 for Davis-Besse Nuclear Power Station,Unit 1 ML20199G6321998-01-26026 January 1998 Rev 1 to Davis-Besse Unit 1,Cycle 11,COLR ML20198R4771998-01-13013 January 1998 SER Approving Second 10-year Interval Inservice Inspection Program Plan Requests for Relief for Davis-Besse Nuclear Power Station,Unit 1 ML20198K7931997-12-31031 December 1997 Monthly Operating Rept for Dec 1997 for Davis-Besse Nuclear Power Station,Unit 1 ML20217K6401997-12-31031 December 1997 1997 Annual Rept First Energy ML20203A3931997-11-30030 November 1997 Monthly Operating Rept for Nov 1997 for Davis-Besse Nuclear Power Plant,Unit 1 ML20198S5371997-10-31031 October 1997 Monthly Operating Rept for Oct 1997 for Davis-Besse Nuclear Power Station ML20217H7701997-09-30030 September 1997 Monthly Operating Rept for Sept 1997 for Davis-Besse Nuclear Power Station,Unit 1 ML20216H3261997-08-31031 August 1997 Monthly Operating Rept for August 1997 for DBNPS ML20217K0241997-07-31031 July 1997 Monthly Operating Rept for Jul 1997 for Davis Besse Nuclear Power Station,Unit 1 1999-09-30
[Table view] |
Text
. - _ _ - . _-_____ _________
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, LICENSEE EVENT MhPUM V ..,
IPLEAiiE PRINT OR TYT* L REQUIREO INFORMATIONI COiTROL SLOCaC: l l l l l 'I l 8 6 i l@
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EVENT oATg 1410 1817 18REPORT 34 75 ]@lo ATE0 l 510 80 l4I7l 3 3 63 61 coCKETAW.igER EVENT CESCRIPTION AND PROBABLE CONSEQUENCES h for testing when after about ik l lo t a l l On 4/8/78,. Hydrogen Dilution Blower 1-1 was running This olaced the unitj
[o ;3; [
hours of run ti=e the blower motor breaker tripped on overload.
I io 6 A1 l in the Action Statenent of Tech Spec 3.6.4.3, which requiree both Evdrocen Dilution On 4/18/78 Hydrogen Dilution Blower l lo t s j l Systems to be operable while in Modes 1 and '
the discharee check valve I lo is i ] l-1 was again being operated when it was determined that bydrogen Dilution Blower l
[o l 7 l l vas not open, returning the unit to the Action Statenent.
l-2 was operable if an incident occurred requiring hydrocen dilution. CIP-33-78-43') 1 80 Io #a1 I j COMP. VALVE SYSTEM CAU$E CAUSE 'U8CooE SUSCooC CooE SUSCooE COMPONENT CooE CooE lc)9l l S l E l@ {@ l B l@ I V I A I L l V l E l X l@ l 19C l@ [A_j 18 20 @
10 1: 12 13 REVIS3cN 3 8 9 00CURRENCE REPORT '
St oVENTI AL TYPE No.
P REPohT No. CooE
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41 l4Al@ 64 47 33 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS The suction check valve I
,I go;l The cause of both of th ue occurrences is ce=ponent failure.
The dis- I g,,ij l vas found to be sticking and was disassenbled, cleaned, and reassembled.
Facility Chance 1 g charge check valve was disasse= bled, cleaned, and reassembled.-
j
' equest 78-211 has been prepared to request removal of the check ' valve internals on f
,,,3j l J
l
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mql both Hydrogen Dilution Blowers to prevent recurrence. 80 7 8 9 of RY ol3CoVERY oESCRIPTioN oTHER STATUS l 3 jgl Surveillance Test ST 5065.05 h POWER l I1 15llEl@ l0l6l8lglE 10 12 31 44 l
45 46 80 7 8 9 ACTIVITY CONTENT LoCATloN oF RELEASE RELEASED oF RELEASE AMOUNT OF ACTIVITY l1 l6 l l El NA i' lM 80 44 45 7 8 9 10 11 PERioNNEL EXPOSURES NU .' E R TY'E oESCRl* Tion .l l1 l 7] l 0l l Z jA IO 11 12 13 7 8 9 PER$oNNE L INJVRIES y **s ga Ici,0l0]@!n o!$0RIPTioN **
80 Il ;
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TOLEDO EDISON COMPANY -
DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION
- SUPPLD! ENTAL INFORMATION FOR LER NP-33-78-43 4
}
- DATE OF EVENT
- April 8, 1978 FACILITY: Davis-Bessa Unit l' IDENTIFICATION OF OCCURRENCE: Hydrogen Dilution Blower 1-1 Trip 4
Conditions Prior to Occurrence: The unit was in Mode 1 vith Power (MWT) ranging from 1720 to 885, and Load (MWE) ranging from 560 to 625.
' Description of Occurrence: On April 8, 1978, Hydrogen Dilution Blower 1-1 was running for Surveillance Test ST 5065.05 " Hydrogen Purge Filter 18 Month or Special Test". After about ih hours of run time, the blower motor breaker tripped on overload. The technician at the blower had noticed no unusual noise while the blower was running. Shortly after the blower motor breaker tripped, j the operator attempted to reset the breaker but was unable to do so. This l blower being inoperable placed the unit in the Action Statement of Technical ,
- Specification 3.6.4.3, which requires both Hydrogen Dilution Systems to be op' era- ;
ble while in Modes 1 and 2. The Action Statement requires the inoperable Hydro-gen Dilution System to be returned to operable status within 30 days or the unit be in Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. , ,
l On* April 18, 1978, Hydrcgen Dilution Blower 1-1 was again being operated for additional investigation of the previous failure. It was determined that the discharge check valve was not open and Hydrogen Dilution Blower 1-1 was again l declared inoperable at 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br /> on April 18, 1978, returning the unit to the Action Statement of Technical Specification 3.6.4.3.
Designation of Apparent Cause of' Occurrence: The cause of both of these occur-rences is component failure. The suction check valve not fully opening was thought to be the cause of the first occurrence. Af ter further investigation, the discharge check valve was found to be not fully opening, causing the second occurrence.
t Analysis of Occurrence: There was no danger to the health and safety of the public or unit personnt.1. Hydrogen u:Liution Blower 1-2 was operable if an inci-dent requiring the Hydrogen Dilution 9ystem had occurred.
Corrective Action: On April 11, 1978, a heater in the breaker for Hydrogen Dilu-tion Blower 1-1 was replaced and the suction check valve was found to be stick-ing. On April 11, 1978, the velded bonnet suction check valve was disassembled, cleaned, and reassembled. Surveillance Test ST 5065.02, Hydrogen Dilution System Quarterly Test, was successfully perfor=ed for the Hydrozen Dilution Blower 1 which removed the unit from the Action Statenent of Technical Spefication 3.6.4.3.
v LER #78-035
TOLEDO EDISON C0!!PANY PAGE 2 DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLCIENTAL INFORMATION FOR LER NP-33-IS-43 i
On April 24, 1978, the velded bonnet discharge check valve was disassembled, cleaned and, reassembled.
Facility Change Request 78-211 has been prepared to request removal of the 1
check valve internals on both Hydrogen Dilution Blowers to prevent recurrence.
A modification has been made to Surveillance Test ST 5065.02 to verify oper-ability of the check valves until they can be removed.
i l -
l Failure Data: Although there has been no previous reportable occurrences, momentary sticking of these check valves has been experienced in'the past.
P Iza #78-035 O
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