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Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO LER)
MONTHYEARML20148S3141997-06-30030 June 1997 Ro:On 970422,Oconee Unit 2 Was Shut Down Due to Leak in Rcs. Leak Was Caused by Crack in Pipe to safe-end Weld Connection at RCS Nozzle for HPI Sys A1 Injection Line.Unit 1 Was Shut Down to Inspect Hpis Injection Lines & Implement Ldst Mods ML20117A5981992-11-23023 November 1992 Special Rept:On 921119,ability of Control Battery Racks to Withstand Seismic Event Could Not Be Confirmed & Batteries Declared Inoperable.Batteries Expected to Be Restored in TS Required Time ML20236T0791987-11-25025 November 1987 Advises LER 269/87-09,re Degradation of More than One Functional Unit of Emergency Power Switching Logic for Units 2 & 3,in Preparation & Will Be Submitted by 871215. Incident Originally Discussed in Special Rept ML20210J6671987-02-0303 February 1987 Special Rept:On 861113-14,1206 & 23,spurious Fire Alarms Annunciated in Control Room.On 870118,unit Shut Down Due to Problems W/Detectors.Cause Undetermined.Technicians Investigating Potential Problem W/Detectors ML20215N4011986-10-20020 October 1986 Special Rept:On 860808,during Shutdown for Maint,Found Unidentified Wires in Environmentally Qualified Limitorque motor-operated Valves.Caused by Mfg Deficiency.Wires Replaced ML20209C1871986-08-13013 August 1986 Special Rept:On 860707,fire Barrier Penetration Nonfunctional.Caused by Design Deficiency Due to Ineffective Communication Between Design Groups.Fire Watch Established. Notice Initiated Requiring Installation of Fire Wall ML20212D2221986-07-29029 July 1986 Special Rept:On 860606,determined That Inadequate Assurance Existed Re Use of Qualified Grease in All Limitorque Operators.Appropriate Programs Not Updated to Reflect Revs. Lubrication Records Reviewed ML20210N5641986-04-14014 April 1986 Special Rept:On 860206,fire Wall Determined to Be Degraded. Caused by Personnel Failure to Recognize That Removing Small Amount of Pyrocrete Would Degrade Fire Wall.Fire Wall Repaired & Declared Fully Functional.Part 21 Related ML20137D6481985-11-22022 November 1985 Ro:On 851119,Keowee Hydro Unit 2 Inoperable Beyond Oconee Tech Spec Limit Due to Burned Out Laminated Copper Connection Between Two Coils.Caused by Cracked Brazement. Connector & Field Coils Will Be Replaced ML20135D7781985-08-21021 August 1985 Ro:On 850722,CRD Dc Breaker CB-1 Failed Trip Time Requirement During Channel C Reactor Protective Sys on-line Test.Cause of Failure Could Not Be Determined.Failed CB-1 Breaker Placed in Tripped Position ML20129G0441985-05-24024 May 1985 Ro:On 850425,batch of Powdex Resin from Powdex Cells 1A & 1D Transferred to Chemical Treatment Pond 2 Instead of Powdex Backwash Tank.Caused by Misalignment of Valve CTP-7.Valve Correctly Positioned ML20108E5341985-02-14014 February 1985 Special Rept:On 850114,CRD Dc Breaker Failed Slow During Channel D Reactor Protective Sys on-line Test.Caused by Sticking Trip Latch Roller Bearings & Excessive Trip Latch Operating Torque.Breaker Front Frame Replaced ML20112D0771984-12-14014 December 1984 Special Rept:On 841109,many Fire Barriers Did Not Meet Surveillance Insp Acceptance Criteria & Declared Inoperable. Caused by Const/Installation Deficiency,Component Failure/ Malfunction & Some Unknown Causes.Firestops Repaired ML20099E0241984-10-24024 October 1984 Special Rept:On 840927,discovered That Contaminated Oil Shipped to Lee Steam Station for Disposal by Incineration. Caused by Misinterpretation of Regulations.Shipments of Contaminated Oil Halted ML20093F1911984-10-0808 October 1984 RO 269/83-16,revising 831107 Commitment Re Completion Date of 850101 to Relocate Hydrogen Purge Unit Connection Near Permanent Hookup Connections on Each Unit for Hydrogen Recombiner ML20093L5061984-10-0505 October 1984 Special Rept:On 840906,batch of Powdex Resin from Powder Cells 2D & 2E Transferred from Plant to Chemical Treatment Pond 1 Instead of to Powdex Backwash Tank.Caused by Misalignment of Valves of Chemical Treatment Ponds 5 & 6 ML20106B4791984-10-0303 October 1984 Special Rept:On 840928,power Circuit Breaker 22 Explosively Short Circuited,Causing Power Circuit Breaker 9 to Open, Isolating 230 Kv Overhead Line from Primary OL Power Source. Breaker Reclosed ML20096A1061984-08-22022 August 1984 Suppl to Rev 1 to RO-287/83-13:containment Isolation Valve 3CS-5 Declared Inoperable Due to Leakage Past Seat. Investigation Into Valve Failure Conducted & Diaphragm Replaced ML20094N8601984-07-27027 July 1984 RO 269/83-20 Re Trip Shaft & Bearing Assembly Portions of CRD Breaker Front Frame Assemblies.Nine of 17 GE Frames Defective.Util Awaiting Schedule for Delivery of New Frames ML20092A4291984-06-0606 June 1984 Special Rept:On 840419,during Fuel Reshuffling for Cycle 8, Fuel Assembly FA 0297 Became Stuck in Fuel Location E-10 During Insertion & Fuel Assembly FA 029Q Damaged.Caused by Inadequate Procedure Change ML20092A3841984-04-30030 April 1984 Updated RO-269/83-20 Submitted on 840111 Re Two CRD Breakers Experiencing Delay During Testing.Ge Will Ship CRD Breaker Front Frame Assemblies on 840514.Installation Will Be Complete on All Three Units by 840731 ML20084G4851984-04-18018 April 1984 Updated RO 269/83-17:seals at Conduit Connections Defective. Scotchcast 9 Epoxy Resin Will Be Utilized to Seal Conduit Connections,Dow Corning RTV 3145 Applied to Conduit Fittings & Conduit/Cable Seals Will Be Upgraded ML20082R7561983-12-0202 December 1983 Ro:On 831015-16,standby Bus 2 Deenergized to Verify Emergency Power Path & CT-3 Startup Transformer Locked Out. Caused by Failure of Two Insulators Causing Short to Ground. Info Supersedes 831101 Rept ML20082H5161983-11-21021 November 1983 Ro:Re Loss of Power on Both Standby Buses W/Both Units Out of Svc.Investigation Incomplete.Necessary Info Will Be Submitted by 831202 ML20082C6081983-11-14014 November 1983 Ro:On 831109,while Units Out of Svc for Planned Maint,Lee 6C Gas Turbine Tripped off-line,deenergizing Standby Buses & Placing Units in Degraded Mode Beyond Tech Spec Limit.Cause Undetermined.Next Rept by 831118 ML20078P9651983-11-0202 November 1983 Ro:On 831028,while Unit Out of Svc,Lee 6C Gas Turbine Tripped & Deenergized Both 4,160-volt Standby Buses.Cause Unknown.Lee 5C Turbine Placed on-line to Sys Grid. Investigation Continuing ML20081K0951983-11-0101 November 1983 Ro:On 831015-16,w/Unit 1 Out of Svc,Standby Bus 2 Deenergized to Allow Operability Verification of Underground Emergency Power Path in Accordance W/Tech Specs.On 831015, CT-3 Underwent Lockout.Caused by Bad Insulators ML20078P8841983-10-31031 October 1983 Ro:On 831026,w/unit Out of Svc for Maint,Lee Steam Station Gas Turbine Tripped,Deenergizing Both Standby Buses.Cause Not Determined.Redundant Buses Available ML20081B2521983-10-17017 October 1983 Ro:On 831012,standby Buses Deenergized to Allow for Operability Performance Testing of Standby Bus Breakers Per Tech Specs.Testing Caused Degraded Mode Beyond Tech Spec Limit ML20078H4121983-10-0404 October 1983 Ro:On 830929,while Energizing 4,160-volt Standby Buses,Lee 6C Gas Turbine Tripped off-line,deenergizing Both Standby Buses & Placing Two Operating Units in Degraded Mode.Cause Undetermined Since Unit Has No Event Recorder ML20080P3271983-09-27027 September 1983 Ro:On 830922,w/both Keowee Hydro Units Out of Svc for Planned Maint,Lee 6C Gas Turbine,Being Used to Energize Buses,Tripped Off Line.Both Standby Buses Deenergized & Units 1 & 3 Placed in Degraded Mode ML20080M0261983-09-16016 September 1983 Updated RO 287/83-07.Investigation Incomplete.Next Rept Expected by 831030 ML20080G2351983-09-0606 September 1983 RO 270/83-09:on 830802,hydraulic Snubber Noted Technically Inoperable for More than 72 H.Investigation Incomplete.Next Rept Will Be Submitted by 830912 ML20076C3291983-08-15015 August 1983 RO 287/83-07:followup to Rept Submitted on 830708. Investigation Incomplete.Supplemental Rept Expected by 830915 ML20072J2031983-06-24024 June 1983 Ro:On 830527,certain Containment Isolation Valves May Have Failed in non-ES Position Due to Loss of Dc Power. Investigation & Rept Will Be Completed & Reviewed by 830708 ML20073Q0121983-04-19019 April 1983 Corrected RO 269/83-07:on 830303,during Insp of Manual Containment Isolation Valves,Valve CF-19 Discovered Open. Caused by Personnel Error.Valve Closed.Core Flood Procedure & Reactor Bldg Manual Checklist Changed ML20069K4141983-04-15015 April 1983 Updated ROs 287/83-04,269/83-05 & 269/83-10:repts Being Reviewed & Will Be Submitted No Later than 830419 ML20072T7011983-03-30030 March 1983 RO-287/83-04 Will Not Be Submitted by 830331 as Planned.Rept Re Open Valve on Emergency Hatch Leak Rate Test Pressurization Line Incomplete.Rept to Be Submitted by 830414 ML20072T6971983-03-30030 March 1983 RO-269/83-10 Will Be Delayed Due to Continuing Investigation of Incident Re Partially Opened Interpersonnel Emergency Door Following Testing.Rept Should Be Submitted No Later than 830415 ML20073C4071983-03-25025 March 1983 Informs That RO-287/83-04 Not Reportable.Results of Seismic Analysis Indicate Letdown Line Was Seismically Operable W/Lead Blankets Attached.Pipe Stress,Support Restraint & Equipment Nozzle Loads within Allowable Limits ML20069E3741983-03-11011 March 1983 Ro:On 830225,reactor Protective Sys Pump Power Monitor Sys Failed to Meet Operability Requirements.Investigation Incomplete at Present Time.Rept Will Be Submitted by 830325 ML20070K5851982-12-23023 December 1982 Ro:On 821213,Region 2 Informed of Two Manual Containment Isolation Valves Discovered Open.Rept Providing Details Delayed Due to Investigation.Rept Will Be Completed & Submitted by 821231 ML20070K7311982-12-23023 December 1982 RO 287/82-14:primary to Secondary Leak Discovered in Steam Generator 3B.Rept Will Not Be Submitted Until 830107 Contrary to Previous Commitment ML20065L7761982-10-14014 October 1982 Ro:On 821014,Unit 2 Core Relief Valves Declared Inoperable Due to Analysis Prompted by B&W Safety Concern.Unit 3 Valves Were Offsite Undergoing Ring Adjustment.Immediate Shutdown of Unit 2 Commenced ML20063N2791982-09-0707 September 1982 Informs That RO-269/82-15 Re Electrically Inoperable Valve CCW-8 Will Be Submitted by 820921.Investigation Incomplete ML20063M0851982-09-0303 September 1982 Advises That RO-269/82-16 Re Separation of safety-related Cables Will Not Be Filed.Review & Evaluation Determined That Separation of Specified Cables Conforms to Established Criteria.No Further Action Required ML20063M1031982-09-0101 September 1982 Ro:On 820818,five Reactor Coolant Pump Closure Studs Determined to Be Degraded in Size Below Acceptable SAR limits.RO-287/82-09 Will Be Completed,Reviewed & Submitted by 820910 ML20062J1721982-08-0505 August 1982 RO 270/82-10:on 820722,util Informed NRC That Upper Surge Tank Indicator Read Below Tech Spec Min Required Water Level.Investigation & Preparation of Rept Incomplete.Final Review & Rept Expected by 820819 ML20071K3471982-07-20020 July 1982 RO 269/82-13:on 820706,emergency Feedwater Pump Declared Inoperable When Required Surveillance Testing Discovered Not Performed.Investigation & Rept Will Be Completed,Reviewed & Submitted by 820803 ML20058D8291982-07-16016 July 1982 RO 270/82-09:on 820616,valve 2FDW-316 Would Not Close Completely After Sampling & Affected Flow Path Declared Inoperable.Investigation & Rept Will Be Completed,Reviewed & Submitted on 820730 1997-06-30
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20206P1501999-01-0505 January 1999 LER 98-S03-00:on 981207,security Officer Discovered Uncontrolled Safeguards Info Drawing.Caused by Failure to Follow Established Procedures & Policies.Drawing Was Controlled by Site Security.With ML20216F9931998-12-31031 December 1998 Piedmont Municipal Power Agency 1998 Annual Rept ML20198E6381998-12-17017 December 1998 LER 98-S02-00:on 981130,security Access Was Revoked Due to Falsification of Criminal Record.Individual Was Escorted from Protected Area & Unescorted Access Was Restricted. with ML20153G4601998-09-30030 September 1998 USI A-46 Seismic Evaluation Rept, Vols 1-2 ML17354B0971998-09-0909 September 1998 Part 21 Rept Re Possible Machining Defect in Certain One Inch Stainless Steel Swagelok Front Ferrules,Part Number SS-1613-1.Caused by Tubing Slipping Out of Fitting at Three Times Working Pressure of Tubing.Notified Affected Utils ML15261A4681998-09-0404 September 1998 Safety Evaluation Supporting Amends 232,232 & 231 to Licenses DPR-38,DPR-47 & DPR-55,respectively ML20248F7441998-05-31031 May 1998 Reactor Vessel Working Group,Response to RAI Regarding Reactor Pressure Vessel Integrity ML20247L9041997-12-31031 December 1997 1997 Annual Rept for Duke Energy Corporation & Saluda River Electric Cooperative,Inc,Financial Statements as of Dec 1997 & 1996 Together W/Auditors Rept ML20198J7651997-10-15015 October 1997 Safety Evaluation Accepting 10-yr Interval Insp Program Plan Alternatives for Listed Plants Units ML20148S3141997-06-30030 June 1997 Ro:On 970422,Oconee Unit 2 Was Shut Down Due to Leak in Rcs. Leak Was Caused by Crack in Pipe to safe-end Weld Connection at RCS Nozzle for HPI Sys A1 Injection Line.Unit 1 Was Shut Down to Inspect Hpis Injection Lines & Implement Ldst Mods ML20148H2501997-06-0505 June 1997 Safety Evaluation Accepting Proposed Restructuring of Util Through Acquisition Of,& Merger W/Panenergy Corp ML20210E3591997-03-27027 March 1997 Part 21 Rept Re Sorrento Electronics Inc Has Determined Operation & Maint Manual May Not Adequately Define Requirements for Performing Periodic Surveillance of SR Applications.Caused by Hardware Failures.Revised RM-23A ML20134N7121997-02-20020 February 1997 Safety Evaluation Accepting Relief Request 96-04 for Plant ML20138L2151997-01-31031 January 1997 Monthly Operating Repts for Jan 1997 for Oconee Nuclear Station,Units 1,2 & 3 ML20138L2281996-12-31031 December 1996 Revised Monthly Operating Repts for Dec 1996 for Oconee Nuclear Station,Units 1,2 & 3 ML20133C1231996-12-23023 December 1996 Informs Commission of Staff Review of Request for License Amends from DPC to Perform Emergency Power Engineered Safeguards Functional Test on Three Oconee Nuclear Units ML20115F2471996-07-0303 July 1996 Part 21 Rept Re Piping (Small Portion of Unmelted Matl Drawn Lengthwise Into Bar During Drawing Process) Defect That Existed in Bar as Received from Mill.Addl Insp Procedure for Raw Matl Instituted ML20107M8931995-10-31031 October 1995 Nonproprietary DPC Fuel Reconstitution Analysis Methodology ML17353A4341995-10-31031 October 1995 Rev 1 to BAW-2245, Initial Rt of Linde 80 Welds Based on Fracture Toughness in Transition Range. ML17264A1181995-07-31031 July 1995 Response to Part (1) of GL 92-01,Rev 1,Suppl 1. ML20086M0851995-06-29029 June 1995 DPC TR QA Program ML20077R3631994-12-31031 December 1994 Monthly Operating Repts for Dec 1994 for Bfnpp ML20236L5971994-12-29029 December 1994 SER in Response to 940314 TIA 94-012 Requesting NRR Staff to Determine Specific Mod to Keowee Emergency Power Supply Logic Must Be Reviewed by Staff Prior to Implementation of Mod ML20064L2001994-01-31031 January 1994 Final Rept EPRI TR-103591, Burnup Verification Measurements on Spent-Fuel Assemblies at Oconee Nuclear Station ML20062K7481993-12-0101 December 1993 ISI Rept for Unit 2 McGuire 1993 Refueling Outage 8 ML20056E5171993-08-31031 August 1993 Technical Review Rept, Tardy Licensee Actions ML20046C1291993-08-0202 August 1993 LER 93-007-00:on 930701,determined That Unit 1 Ssf Rc Makeup Sys Inoperable in Past Due to Design Deficiency.Operations Procedures Revised to Reflect Newly Calculated Operating Limits for Rc Makeup Pump,Rcps & RCS.W/930802 Ltr ML20056G0131993-07-27027 July 1993 Rev 0 to ISI Rept Unit 2 Oconee 1993 Refueling Outage 13 ML20044G5311993-05-26026 May 1993 Suppl to 921207 Part 21 Rept Re Declutch Sys Anomaly in Certain Types of Valve Actuators Supplied by Limitorque Corp.Limitorque Designed New Declutch Lever Which Will Be Available in First Quarter 1993 ML20126J5961992-12-31031 December 1992 Part 21 Rept Re Potential Loss of RHR Cooling During Nozzle Dam Removal.Nozzle Dams May Create Trapped Air Column Behind Cold Leg Nozzle Dam.Mod to Nozzle Dams Currently Underway. Ltrs to Affected Utils Encl ML20117A5981992-11-23023 November 1992 Special Rept:On 921119,ability of Control Battery Racks to Withstand Seismic Event Could Not Be Confirmed & Batteries Declared Inoperable.Batteries Expected to Be Restored in TS Required Time ML20097G0421992-05-31031 May 1992 Analysis of Capsule OCIII-D Duke Power Company Oconee Nuclear Station Unit-3 ML20077D0671991-11-15015 November 1991 Nonproprietary Version of Rev 0 to Boric Acid Corrosion of Oconee Unit 1 Upper Tubesheet ML20067A5241990-12-31031 December 1990 Final Submittal in Response to NRC Bulletin 88-011, 'Pressurizer Surge Line Thermal Stratification.' ML20042F3541990-04-30030 April 1990 Special Rept Re Failure to Prevent Performance Degradation of Reactor Bldg Cooling Units.Caused by Mgt Deficiency & Inadequate Program.Cooling Unit Declared Inoperable & Removed from Svc for Cleaning & Placed Back in Operation ML17348A1621990-03-27027 March 1990 Part 21 Rept Re Matls W/Programmatic Defects Supplied by Dubose Steel,Inc.Customers,Purchase Order,Items & Affected Heat Numbers Listed ML19332D5391989-10-31031 October 1989 Core Thermal-Hydraulic Methodology Using VIPRE-01. ML20042F2321989-08-31031 August 1989 Nonproprietary DCHF-1 Correlation for Predicting Critical Heat Flux in Mixing Vane Grid Fuel Assemblies. ML20205F3211988-10-10010 October 1988 Part 21 Rept Re Potential Deviation from Tech Spec Concerning Ry Indicators Due to Operating Temp Effect on Analog Meter Movement.Initially Reported on 881006.Customers Verbally Notified on 881006-07 ML20154K2091988-09-0909 September 1988 Rev 0 to Response to NRC Bulletin 88-005,Nonconforming Matls Supplied by Piping Supplies,Inc at Folsom,Nj & West Jersey Mfg Co.... Proprietary Procedure 1404.1, Leeb Hardness Testing (Equotip).... Encl.Procedure Withheld ML20245D9541988-09-0606 September 1988 Part 21 Rept Re Condition Involving Inconel 600 Matl Used to Fabricate Steam Generator Tube Plugs & Found to Possess Microstructure Susceptible to Stress Corrosion Cracking ML20245B6061988-08-31031 August 1988 Inadequate NPSH in HPSI Sys in Pwrs, Engineering Evaluation Rept ML20239A6991987-11-30030 November 1987 Addendum 1 to Rev 2 to Integrated Reactor Vessel Matl Surveillance Program (Addendum) ML20236T0791987-11-25025 November 1987 Advises LER 269/87-09,re Degradation of More than One Functional Unit of Emergency Power Switching Logic for Units 2 & 3,in Preparation & Will Be Submitted by 871215. Incident Originally Discussed in Special Rept ML20236Q9491987-10-31031 October 1987 Monthly Operating Repts for Oct 1987 ML20235W9611987-09-30030 September 1987 Monthly Operating Repts for Sept 1987 ML20234B1861987-08-31031 August 1987 Monthly Operating Repts for Aug 1987 ML20237K4761987-07-31031 July 1987 Monthly Operating Repts for Jul 1987 ML20236Y0221987-07-0808 July 1987 Safety Evaluation Clarifying Determination of Acceptability of Test Duration for Performance of Integrated Leak Rate Test at Plant ML20235S6311987-06-30030 June 1987 Monthly Operating Repts for June 1987 1999-01-05
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DUKE POWER GOMPAhT P.O. BOX 33180 CHARLOTTE, N.C. 28242 HAL B. TUCKER rzamenown
= r= ==s== =T (700 amaat NtitiLEAR PAostWTIOS February 3, 1987 U. S. Nuclear Regulatory Comunission Attention: Document Control Desk Washington, D. C. 20555
Subject:
- Oconee Nuclear Station, Unit 2 Docket No. 50-270 T.S. 3.17.1 Special Report
Dear Sir:
Please find attached a special report regarding inoperable fire detection instrumentation. This report is submitted pursuant to Oconee Nuclear Station Technical Specification 3.17.1 which concerns fire detection instrumentation which cannot be restored to operable status within 14 days, and describes an incident which is considered to be of no significance with respect to public health and safety.
Very truly yours, b w Hal B. Tucker PJN/04/sbn Attachment t
xc: Dr. J. Nelson Grace, Regional Administrator INPO Records Center U. S. Nuclear Regulatory Conamission Suite 1500 Region II 1100 circle 75 Parkway 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30339 Atlanta, Georgia 30323 Ms. Helen Pastis Mr. J. C. Bryant Office of Nuclear Reactor Regulation NRC Resident Inspector U. S. Nuclear Regulatory Cor ission Oconee Nuclear Station Washington, D. C. 20555 American Nuclear Insurers M&M Nuclear Consultants e/o Dottie Sherman, ANI Library 1221 Avenue of the Americas The Exchange, Suite 245 New York, New York 10020 270 Farmington Avenue Farmington, CT 06032 8702120127 870203 /
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ADOCK 05000270 PDR
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DUKE POWER COMPANY
.OCONEE NUCLEAR STATION SPECIAL REPORT ON. INOPERABLE FIRE DETECTORS Introduction On November 13 and 14, 1986, with. Unit 2 at 94% full power, spurious fire alarms annunciated in the control room for strings No. 2 and No. 15 respectively. These alarms were associated with the Pyr-A-Lara detection system in the Reactor Building. The alarms were investigated and it was determined that the detectors in alarm were inside the secondary shield wall and thus inaccessible.
This incident was caused by two fire detectors in the Reactor Building giving an erroneous indication of a fire, for unknown reasons.
Immediate corrective action was a once per hour fire watch using the installed TV camera in the Reactor Building. The affected detectors were replaced during a shutdown on January 18, 1987.
~ Since no fire was observed and appropriate compensatory action was taken to monitor the-Reactor Building for fire, the health and safety of the public were not affected by this incident.
Background
In the Unit 2 Reactor Building there are two fire zones. Each of these zones has redundant fire detection strings strategically located throughout the Reactor Building. Each string has 12 ionization type detectors with 11 in use. Four detectors on each string are located inside the secondary shield in close proximity to the reactor coolant pumps. The other 7 detectors are located outside of the secondary shield. The two strings are identified as string No. 2 for fire zone 2 i sud. string No.15 for fire zone 15. When a detector senses a combustible gas, the detector will send a signal to the Fire Indicating Un'it and a local indicating lamp will flash. The Fire Indicating Unit for Unit 2 is located in Unit I and 2 control room. The fire indicating unit sends a signal to the operator control board for that particular unit. Besides smoke or other combustible gases, the detectors can be actuated by small amounts of other conductive contaminants which accumulate in the area covered by the detectors.
Description of Occurrence On November 13, 1986 at 0828, with Unit 2 at 94% full power the control room i received a fire alarm on the Pyr-A-Larm fire detection system string No. 2.
. Technicians entered Unit 2 Reactor Building to investigate the spurious alarm and repair as necessary. The investigation included changing the detector lamps and visually verifying no alarm condition existed on any of the 7 accessible detectors located outside of the secondary shield. There were 4 detectors inside the secondary shield that are normally not accessible during reactor operation thus they were not checked.
On November 14, 1986 at 1210, Unit 2 control room received an alarm on string no.
- 15. With both strings in alarm, a once per hour fire watch is required to comply with technical specification 3.17.1. The fire watch is accomplished by i surveillance of the Reactor Building with a TV camera. The TV camera surveillance was initiated and no signs of fire were observed. ;
Operations personnel and technicians entered the Unit 2 Reactor Building to survey j for fires, and investigate and repair alarming detectors on string No. 15. During this surveillance no sign of fire was detected. No accessible detectors on string No.15 were found in alarm.
I On November 15 at 0445, the alarms on both string No. 2 and string No. 15 cleared.
There were no further alarms on these two strings and on November 17 at 1030, after 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> without alarms, strings No. 2 and 15 were declared operable.
At 0930 on December 6, alarms were again received on both strings No. 2 and No. 15.
These alarms annunciated and cleared several times. Unit 2 was again surveyed with i the TV camera for visible signs of fire. No signs of fire were observed during l surveillance. At 0945, string No. 15 alarmed and locked in. Technicians investigated the problem at the Unit 2 Fire Indicating Unit located in the Unit 1 :
and 2 control room. No Reactor Building entry was made at this time. No problem was found at the Fire Indicating Unit. At 1055, string 2 alarmed and then cleared.
At this time, the once per hour fire watch was reinitiated using the Reactor Building TV camera. There were no indications of fire observed during the TV surveillance. At 1300, the alarm on string No. 15 was reset. The alarm reset and did not come back in. The once per hour fire watch was secured at 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />.
On December 23 at 2250, alarms were received on both strings No. 2 and No. 15.
l Hourly surveillance was once again initiated using the Unit 2 Reactor Building TV camera. Technicians investigated the alarm problem at the fire indicating unit.
, The leads on string No. 15 were disconnected and reconnected in the Fire Indication Unit and the alarm was reset. On December 31, technicians further investigated the I
string No. 15 alarm problem. During this investigation, no accessible detectors on
- string No. 15 were found in alarm. The accessible detectors were set off and the alarms were reset. At this time, a 91K resistor was installed on string No. 2 and string No. 15 to protect the Fire Indicating Unit alarm circuit. Operations was informed of this installation of resistors on both strings which causes them to be inoperable. The hourly fire watch was continued.
On January 18, 1987 Unit 2 went to hot shutdown. The loss of redundant fire detection strings was not a factor in the unit shutdown.
On January 18, 1987 technicians entered the Unit 2 Reactor Building to investigate the potential problem with the inaccessible detectors. Detectors 2F (string No. 2) and 15F (string No.15) which are inside the secondary shield and inaccessible at power, were found in alarm with no indication of fire present. These detectors were replaced and the resistors were removed from the circuits. The two strings were functionally verified the Reactor Building fire detection system was declared operable.
Cause of Occurrence The root cause of this event cannot be determined from the available facts. An evaluation of the replaced detectors was performed. The two detectors that were
3-replaced are located inside "B" cavity containing 2 reactor coolant pumps and a steam generator. The cavity is normally inaccessible during reactor operation due
- to high radiation. The physical location of the detectors is on the bottom of beams or supports which inhibit a visual inspection from the top of the cavity. It is speculated that a buildup of dust, oil fumes, water vapor, and/or other '
conductive contaminants over a period of time caused the detectors to alarm.
This is not a recurring event.
Corrective Action The Immediate corrective actions included:
(1) Once per hour fire watch of the area covered by the two strings of detectors was established each time the redundant string of detectors alarmed.
. (2) The string circuit and accessible detectors were verified operable several times.
l (3) After December 31, 1986 once per hour fire watches were established with both l strings of detectors inoperable.
Supplemental corrective actions were to replace and functionally verify detectors 2F and 15F as soon as the area was made accessible.
Analysis of Occurrence Within the Reactor Building there exists several trains of fire detectors. These trains are strategically located so that specific areas of the building are monitored at all times. The area involved in this incident was the reactor coolant pump cavity. In this cavity, there are four locations that have two detectors from
, two separate strings. Each string alarms separately in the control room.
When this event started, both detectors in one location were in alarm. The operators promptly initiated action to verify whether a fire was in fact involved.
Use of the television camera in the cavity provided assurance that no fire was present.
i For the period of time that the two strings were out of service because of the installed resistors, Operations personnel kept an hourly' fire watch using the TV camera. This was in accordance with Technical Specification 3.17.1.
Since no fire was observed and appropriate monitoring of the cavity was performed so that any fire could be detected, the safety and health of the public was not affected.
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