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Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO LER)
MONTHYEARML20205C4171999-03-25025 March 1999 Special Rept 99-02:on 801027,Commission Approved for publication,10CFR50.48 & 10CFR50 App R Delineating Certain Fire Protection Provisions for Nuclear Power Plants Licensed to Operate Prior to 790101.Team Draft Findings Reviewed ML20207K2051999-03-0505 March 1999 Special Rept 99-01:on 990128,DG Tripped After 2 H of Operation During Loaded Operation for Monthly Test.Caused by Several Components That Were Degraded or Had Intermittent Problems.Parts Were Replaced & Initial Run Was Performed ML20196D4171998-11-24024 November 1998 Special Rept 98-02:on 981112,failure to Implement Fire Watches in Rooms Containing Inoperable Fire Barrier Penetrations,Was Determined.Repair of Affected Fire Barriers in Progress ML20151W3521998-09-0808 September 1998 Special Rept 98-01:on 980819,maint Could Not Be Performed on FPS Due to Isolation Boundary Leakage.Caused by Inadequate Info Provided in Fire Impairment Plan.Isolated Portion of FPS Was Returned to Svc ML20148A9881997-05-0101 May 1997 Special Rept 96-04-02:on 970429,groundwater Level at Well Mk GWA-2 Was in Alarm for 7 Days.Caused by Precipitation During Previous Week.Verified That No Other Groundwater Monitoring Instruments Were in Alarm ML20137P0711997-04-0707 April 1997 Special Rept 97-01:on 970226,Peak Accelerometer,1MIMT-5030, Removed Under WO 95092624 as Part of SG Replacement Project. Accelerometer Will Return to Svc Prior to Unit 1 Startup ML20133L6051997-01-0909 January 1997 Special Rept 96-04,Rev 1,groundwater Level at Well Mk GWA-2 Monitored by 2WZLS5060 Was in Alarm for 7 Days.Verified That No Other Groundwater Monitoring Instruments in Alarm ML20134N0261996-11-14014 November 1996 Special Rept:On 961006,groundwater Alarm Was Received & Entered in TS Action Item List for Tracking.Field Survey of Surrounding Areas Was Performed to Verify That No Water Was Percolating to Surface That Would Indicate Pipe Leak ML20116K0331996-08-0909 August 1996 Special Rept 96-03:on 960611,identified Broken Secondary Contact Blocks.Caused by Mishandling of Breakers or over- Torquing of Mounting Bolts.Breaker 2BYA Repaired,Tested & re-installed in Cabinet ML20086G9601995-07-12012 July 1995 Special Rept 95-002:on 950612,turbocharger Failed,As Detected by Excessive Noise & Vibration.Engine Subsequently Secured.Damaged Components Replaced & DG 2A Returned to Operable Status ML20080G4421995-02-0303 February 1995 Special Rept 95-01:on 950104,personnel on Unit 2 Operating in Solid Condition During Fill & Vent of Nc Sys ML20078R7651994-12-15015 December 1994 Special Rept 94-06:on 941012,fatigue Usage to SI Sys Piping by Manually Initiating Flow Through B Cold Leg from Fwst During Testing for Valve 1NI-71 Intentionally Increased. Startup of Facility Discontinued to Repair Valve ML20078L6571994-11-22022 November 1994 Special Rept SR-94-05:on 941024,Channel 3 of Vibration & Loose Parts Monitoring Sys Declared Inoperable Due to Noise.Channel 3 of V&Lpm Will Be Repaired Under WR 94043758 or Replaced by Nsm MG-12096 During Outage 1EOC10 ML20073C2451994-09-14014 September 1994 Special Rept 94-004:on 940821,valid Failure of DG 1A Occurred Due to Failure of Series Boost exciter-regulator (Voltage Regulator).Isolation Transformer T54 & Current Transformers CT1,CT2 & CT3 Will Be Inspected ML20065K2501994-04-15015 April 1994 Special Rept 94-03:on 940210,during Testing PORV Observed to Hang Open in Absence of air-assisted Closure.Caused by Incomplete Testing of Porvs.Compensatory Measures Reanalyzed & Reestablished Addressing Fire & Security Issues ML20064K0311994-03-15015 March 1994 Special Rept 94-01:on 940215,DG 2A Tripped W/Low Lube Oil Pressure Indication During Routine Surveillance Test.Caused by Pressure Too Low in Bldg Up in Sensing Lines.Test Satisfactorily Repeated ML20058M4281993-09-27027 September 1993 Special Rept 93-09:on 930920,notifies of Alarm Condition Showing Alert on Ground Water Level Outside 1A DG Room.Work Order 93063348 Initiated by Wc Personnel to Have Iae Personnel Check Operation & Calibr ML20056F8561993-08-23023 August 1993 Special Rept 93-06:on 930405,discovered Debris on Unit 1 Lower Core Plate.Four Other Unidentified Objects Noted During Video Insp of Lower Core Plate ML20126B5051992-12-15015 December 1992 Inplant Review Rept 92-20,special Rept Re Postulated Scenario That Could Introduce Air Into AFW Suction Piping. Caused by Functional Design Deficiency.Setpoints of Affected Pressure Switches Increased ML20106D7401992-10-0909 October 1992 RO 92-19:on 920804,discovered That Drive Shaft on Pump 1MNVPU0046 Was Rotating in Opposite Direction than Specified on Pump Casing.Caused by Mgt Deficiency.Motor Leads of Subj Pump Reconfigured to Provide Correct Pump Shaft Rotation ML20127E0191992-09-0909 September 1992 Special Rept:On 920421,unusual Event Declared Because Unit 1 Train B of Ssps Inoperable Due to Defective Circuit Card within Ssps.Failed Train B Ssps Circuit Board Replaced & Appropriate Procedures to Be Evaluated ML20101T9441992-07-13013 July 1992 Special Rept for Inplant Review 92-10:on 920610 No Mention Made on Work List of Vent Path Through SG 1B for Incoming SG Crews.Caused by Deficient Communication.Turnover Sheet Established to Document Existing Vent Path Status ML20101P5581992-07-0303 July 1992 In-Plant Review Rept 92-09:on 920619,setpoint Problems Noted W/Ts & Selected Licensee Commitment Values for Listed Field Data.Caused by Discrepancies W/Groundwater Level Monitoring Portion of Wz Sys.Ts Monitor Logged in Unit 2 Logbook ML20086Q1101991-12-20020 December 1991 Voluntary Special Rept 91-23:on 911008,reactor Vessel Lower Internals Contacted Reactor Vessel During Removal.Caused by Inappropriate Operator Action & Mgt Deficiency.Recovery Plan Developed Re Insp of Lower Internals & Refueling Canal ML20086H9431991-12-0404 December 1991 Special Rept 91-24:on 911104-29,concerns Noted Re Possible Leakage of Containment Spray Sys Check Valves Into Annulus, Causing Offsite Radioactive Dose.Caused by Design Deficiency.Check Valve Installed Downstream of Piping ML20091C0851991-08-0101 August 1991 Special Rept PIR 1-M91-0113:on 910616,diesel Engine Cooling Water Leak Discovered on Diesel Generator 1A at Discharge Flange on Intercooler End Bell Cover.Caused by Poor Casting Quality.New Covers Will Be Installed ML20081F7371991-06-0404 June 1991 Rev 1 to Special Rept 91-11 Dtd 910411:on 910215,turbine Driven Auxiliary Feedwater Pumps Automatically Started. Caused by Deficient Communication & Lack of Attention to Detail.Pump Speed Reduced & Discharge Valves Closed ML20062E7991990-11-14014 November 1990 Special Rept:On 901011,turbine Driven Auxiliary Feedwater Pump Declared Inoperable W/O Having Made Security Notification.Caused by Inappropriate Action ML20055G2161990-07-12012 July 1990 Ro:On 900602,discovered That Channel 7 of Vibration & Loose Parts Monitor Sys Had Low Noise Level.Probably Caused by Bad or Damaged Sensor Cable.Definite Cause of Failure Undetermined.Sys Scheduled to Be Replaced ML20246F7081989-07-0303 July 1989 Special Rept:On 890601,diesel Generator 1A Shut Down Due to Lack of Oil Flow.Due to Test Being Performed,Normal Stop Would Not Shutdown Engine.New Oil Added & Pumps Primed. Turbocharger Mods Under Investigation ML20247N8841989-05-30030 May 1989 Special Rept:On 890418,vibration & Loose Parts Monitor Failed.Caused by Damaged Cables to Sensors on Each Affected Channel.Vibration & Loose Parts Monitor Will Be Repaired During Next Refueling Outage After New Replacement Received ML20244C6731989-04-0606 April 1989 Special Rept:On 890225,operations Personnel Discovered That Channel 8 of Vibration & Loose Parts Monitoring Sys Had Low Noise Level.Investigation Scheduled to Be Completed During Unit 1 Tube Leak Outage ML20196E8241988-12-0505 December 1988 Special Rept:On 881205,diesel Generator 1B Experienced Invalid Test Failure.Caused by Improper Adjustment of Voltage Regulator Due to Personnel Error.Operations Mgt Will Cover Incident W/Representative from Each Shift ML20196B5211988-11-29029 November 1988 Special Rept:On 881030,Diesel Generator 1B Experienced Invalid Test Failure During Start Attempt 602.Applicable Procedures for Diesel Generator Testing Reviewed & Revised If Necessary ML20195H4901988-11-16016 November 1988 Special Rept:On 881017,diesel Generator 1A Started for Operability Test & Subsequently Tripped.Caused by Loose Wire on Jacket Pump Discharge Pressure Switch.Wire Reterminated & Pressure Switch Calibr ML20205G3401988-10-24024 October 1988 Special Rept:On 880916,Tech Spec 3.7.14.a Violated.Caused by Standby Shutdown Facility Being Inoperable for More than 7 Days Due to Transfer Canal Isolating & Draining Utilizing Weir Gate.Special Order 88-13 Issued ML20151R0971988-07-27027 July 1988 Special Rept:On 880627,diesel Generator 1A Failed to Start within 11 S.Caused by Missing Drain Valve on Starting Air Filter Housing on Right Bank Side of Diesel Engine.Work Request Written to Replace Filter Housing ML20151F4911988-07-22022 July 1988 Special Rept:On 880519,diesel Generator 1A Started for Operability Test & After Operating for 10 Minutes, Automatically Stopped & Declared Inoperable.Caused by Failure to Maintain Lubricating Level in Valve 1LD-7 ML20195J3601988-06-22022 June 1988 Special Rept:On 880323,Train a Safety Injection & Main Steam Sys Isolation Signals Received from Unknown Fault Inside Train a Solid State Protection Sys Logic Cabinet.Cause of Fault Could Not Be Isolated.Cabinet Returned to Svc ML20195J6161988-06-20020 June 1988 Advises That Special Rept Re Diesel Generator 1A Incident on 880519 Will Be Submitted by 880708 Instead of 880620 Due to Unresolved Concerns ML20195G2171988-06-17017 June 1988 Special Rept:On 880518,diesel Generator 1B Experienced Valid Failure.Caused by Fuel & Vol of Trapped Air Shook Debris Loose from Engine Mounted Duplex Fuel Filter.Filter Cartridges Replaced.Preventative Maint Procedure Revised ML20151C7691988-04-0404 April 1988 Ro:Change of Commitment Submitted Re Diesel Generator Turbocharger Rotor Assembly Replacement.Turbocharger Inlet Casings Replaced on All Four Engines W/New Design.Dye Penetrant Testing Will Continue to Be Performed ML20147F4311988-03-0303 March 1988 Special Rept:On 880123,Channels 3,4 & 8 of Vibration & Loose Parts Monitor Had Unusual Noise Level.Cause Not Determined Due to Number of Possible Failures & Location of Components within Plants.Monitor Will Be Repaired During 1988 Outage ML20237D1341987-12-14014 December 1987 Special Rept:On 871108,safe Shutdown Facility RCS Wide Range Transmitter Out of Calibr.Instrument Could Not Be Calibrated.Requisition Initiated for Replacement Transmitter ML20236Q1621987-11-13013 November 1987 Special Rept:On 870816,malfunction of Main Turbine Generator Controls Caused Rapidly Decreasing Main Steam Line Pressure Triggering Safety Injection/Reactor Trip.Safety Injection & Unusual Event Terminated & Repairs Completed on 870821 ML20214S5421987-06-0808 June 1987 Special Rept:On 870503,pressurizer PORV 2NC-34A Automatically Opened Due to Pressure Transient in Rcs.Cause Not Determined.Charging & Letdown Flow Adjusted & Procedures Re Allowable Setpoint Range Revised ML20214G7301987-05-13013 May 1987 Special Rept:On 870407 & 08,complete 18-month Insp Required for Standby Shutdown Diesel Generator Determined Not to Have Been Performed on Time.Caused by Personnel Error.Work Request Will Be Issued Prior to 18-month Due Dates ML20213H0591987-05-0808 May 1987 Ro:On 870409,personnel Discovered Monthly Channel Checks on Reactor Vessel Level Instrumentation Sys Wide Range Instrumentation Not Performed,Per Tech Specs.Ler Will Be Submitted by 870518 ML20214J1591986-11-21021 November 1986 Ro:On 861029,valves in ECCS Declared Inoperable.Caused by Rotork Motor Switch Settings.Ler for Incident Will Be Delayed Until 861219 to Allow Testing & Evaluation of Units ML20203J6551986-07-28028 July 1986 Ro:On 860626 & 27,small Cylindrical Objects Observed on Upper Core Baffle & in Vicinity of Upender,Respectively.On 860629,objects Confirmed to Be Spent Fuel Pellets.Pellets Vacuumed from Core & Upender 1999-03-05
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217G7951999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for McGuire Nuclear Station,Units 1 & 2 ML20217F3661999-09-22022 September 1999 Rev 18 to McGuire Unit 1 Cycle 14 Colr ML20212D1911999-09-20020 September 1999 SER Accepting Exemption from Certain Requirements of 10CFR50,App A,General Design Criterion 57 Closed System Isolation Valves for McGuire Nuclear Station,Units 1 & 2 ML20216E8851999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for McGuire Nuclear Station,Units 1 & 2 ML20211B1281999-08-31031 August 1999 Dynamic Rod Worth Measurement Using Casmo/Simulate ML20217G8101999-08-31031 August 1999 Revised Monthly Operating Repts for Aug 1999 for McGuire Nuclear Station,Unit 1 & 2 ML20211G5261999-08-24024 August 1999 SER Accepting Approval of Second 10-year Interval Inservice Insp Program Plan Request for Relief 98-004 for Plant,Unit 1 ML20211F3441999-08-17017 August 1999 Updated non-proprietary Page 2-4 of TR DPC-NE-2009 ML20210S2371999-07-31031 July 1999 Monthly Operating Repts for July 1999 for McGuire Nuclear Station,Units 1 & 2 ML20216E8951999-07-31031 July 1999 Revised Monthly Operating Repts for July 1999 for McGuire Nuclear Station,Units 1 & 2 ML20209E4361999-07-0909 July 1999 SER Agreeing with Licensee General Interpretation of TS LCO 3.0.6,but Finds No Technical Basis or Guidance That Snubbers Could Be Treated as Exception to General Interpretation ML20196K6631999-07-0707 July 1999 Safety Evaluation Supporting Licensee 990520 Position Re Inoperable Snubbers ML20209H1631999-06-30030 June 1999 Monthly Operating Repts for June 1999 for McGuire Nuclear Station,Units 1 & 2 ML20210S2491999-06-30030 June 1999 Revised Monthly Operating Rept for June 1999 for McGuire Nuclear Station,Units 1 & 2 ML20209H1731999-05-31031 May 1999 Revised Monthly Operating Rept for May 1999 for McGuire Nuclear Station,Units 1 & 2 ML20206T4771999-05-31031 May 1999 Rev 3 to UFSAR Chapter 15 Sys Transient Analysis Methodology ML20196L1881999-05-31031 May 1999 Non-proprietary Rev 1 to DPC-NE-3004, Mass & Energy Release & Containment Response Methodology ML20195K3691999-05-31031 May 1999 Monthly Operating Repts for May 1999 for McGuire Nuclear Station,Units 1 & 2 ML20206N3511999-05-11011 May 1999 Safety Evaluation Accepting Licensee Response to GL 96-05, Periodic Verification of Design-Basis Capability of Safety- Related Movs ML20195K3761999-04-30030 April 1999 Revised MORs for Apr 1999 for McGuire Nuclear Station,Units 1 & 2 ML20206R0891999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205L2341999-04-0505 April 1999 SFP Criticality Analysis ML20206R0931999-03-31031 March 1999 Revised Monthly Repts for Mar 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205P8991999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205C4171999-03-25025 March 1999 Special Rept 99-02:on 801027,Commission Approved for publication,10CFR50.48 & 10CFR50 App R Delineating Certain Fire Protection Provisions for Nuclear Power Plants Licensed to Operate Prior to 790101.Team Draft Findings Reviewed ML20207K2051999-03-0505 March 1999 Special Rept 99-01:on 990128,DG Tripped After 2 H of Operation During Loaded Operation for Monthly Test.Caused by Several Components That Were Degraded or Had Intermittent Problems.Parts Were Replaced & Initial Run Was Performed ML20204C8911999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205P9021999-02-28028 February 1999 Revised Monthly Operating Repts for Feb 1999 for McGuire Nuclear Station,Units 1 & 2 ML20204C8961999-01-31031 January 1999 Revised Monthly Operating Repts for Jan 1999 for McGuire Nuclear Station,Units 1 & 2 ML20199E0301998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for McGuire Nuclear Station,Units 1 & 2 ML20216F9931998-12-31031 December 1998 Piedmont Municipal Power Agency 1998 Annual Rept ML20198A4481998-12-11011 December 1998 Safety Evaluation Concluding That for Relief Request 97-004, Parts 1 & 2,ASME Code Exam Requirements Are Impractical. Request for Relief & Alternative Imposed,Granted ML20198D7561998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for McGuire Nuclear Station,Units 1 & 2 ML20199E0491998-11-30030 November 1998 Revised Monthly Operating Rept for Nov 1998 for McGuire Nuclear Station,Units 1 & 2 Re Personnel Exposure ML20199E9651998-11-24024 November 1998 Rev 1 to ATI-98-012-T005, DPC Evaluation of McGuire Unit 1 Surveillance Weld Data Credibility ML20196D4171998-11-24024 November 1998 Special Rept 98-02:on 981112,failure to Implement Fire Watches in Rooms Containing Inoperable Fire Barrier Penetrations,Was Determined.Repair of Affected Fire Barriers in Progress ML20196G0581998-11-0606 November 1998 Rev 17 to COLR Cycle 13 for McGuire Unit 1 ML20196G0761998-11-0606 November 1998 Rev 15 to COLR Cycle 12 for McGuire Unit 2 ML20198D7771998-10-31031 October 1998 Revised Monthly Operating Rept for Oct 1998 for McGuire Nuclear Station,Units 1 & 2 ML20195E5961998-10-31031 October 1998 Monthly Operating Repts for Oct 1998 for McGuire Nuclear Station,Units 1 & 2 ML20154L6251998-09-30030 September 1998 Monthly Operating Repts for Sept 1998 for McGuire Nuclear Station,Units 1 & 2 ML20195E6021998-09-30030 September 1998 Revised Monthly Operating Rept for Sept 1998 for McGuire Nuclear Station,Units 1 & 2 ML20154B4131998-09-22022 September 1998 Rev 0 to ISI Rept for McGuire Nuclear Unit 1 Twelfth Refueling Outage ML20151W3521998-09-0808 September 1998 Special Rept 98-01:on 980819,maint Could Not Be Performed on FPS Due to Isolation Boundary Leakage.Caused by Inadequate Info Provided in Fire Impairment Plan.Isolated Portion of FPS Was Returned to Svc ML20154L6321998-08-31031 August 1998 Rev 1 to MOR for Aug 1998 for McGuire Nuclear Station,Unit 1 ML20153B3741998-08-31031 August 1998 Monthly Operating Repts for Aug 1998 for McGuire Nuclear Station,Units 1 & 2 ML20236U1601998-07-31031 July 1998 Non-proprietary DPC-NE-2009, DPC W Fuel Transition Rept ML20237B2381998-07-31031 July 1998 Monthly Operating Repts for July 1998 for McGuire Nuclear Station,Units 1 & 2 ML20153B3931998-07-31031 July 1998 Revised Monthly Operating Repts for Jul 1998 for McGuire Nuclear Station,Units 1 & 2 ML20236P0451998-07-0808 July 1998 Part 21 Rept Re non-conformance & Potential Defect in Component of Nordberg Model FS1316HSC Standby Dg.Caused by Outer Spring Valves Mfg from Matl That Did Not Meet Specifications.Will Furnish Written Rept within 60 Days 1999-09-30
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- DOrIbutt Company ; . T C Marwx . '
. AlcGuire Nudear Genemtion Department-- ~ Vicehesident 12700 Hogers ferry hbad(MG01A)-. (704)875-4890 Huntmeilie. NC28018-898S !?04)3IS-4809 Fa
. DUKEPOWER -
Februaryil2, 1993-U.S. Nuclear Regulatory Commission Document Control' Desk' WaFhington, D.C. 20555-Subject; McGuire Nuclear Station Unit 2 Safety Review Group Special Report No. 93-01 Gentlemen:
' Pursuant to Selected Licensee Commitment, Section 16.9-7, Remedial- .
' Action (c), attached is Special Report 93-01 concern'ng,the. Standby -
Shutdown System'being inoperable for'more than 7 days due'to an . 1 equipment failure. This event is considered to becof no-significance 1 with-respect to the health.and safety of the public. ,.
Very truly your ,
fC&M
-T.C. McMeekin TLP/bcb s.
Attachment xc: Mr. S.D. E'bneter .INPO Records Center-
'Administ.rator, Region II Suite 1500 U.S. Nuclear Regulatory Commission- 1100 Circle 75 Parkway.
1J1 Marietta St., NW, Suite 2900 Atlanta, GA'L30339' Atlanta, GA 30323 Mr. Tim Reed Mr. P.K.-Van Doorn U.S. Nuclear Regulatory-Commission NRC Resident Inspector Office of Nuclear Reactor Regulation. McGuire Nuclear Station
. Washington, D.C. 20555 220CS1 9302220342 930212 PDR S ADOCK 03000370 PDR w --- /h}[f(
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- i,
MCGUIRE SAFETY REVIEW GROUP STATION PROBLEM REPORT
- 1. REPOT.T NUMBER: 93-01
- 2. DATE OF REVIEW: January 13 - February 9, 1993
- 3. SUBJECT DESCRIPTION: This 30 day report is submitted as a special report pursuant to Selected Licenree Commitment (SLC) Section 16.9-7, Remedial Action c. The Standby Shutdown System (SSS) was determined inoperable for more than 7 days when a problem developed with Unit 2 Chemical Volume and Control (NV) system Standby Makeup pump (2MNVPU0046) Discharge damper 2MNVAC0049. This report documents the related circumstances outlining the cause of inoperability, corrective actions taken, and the plan used to restore the system to operable status.
- 4. EVALUATION AND COMMENT:
Abstract On January 6, 1993, the SSS was removed from service for performance of several maintenance activities. On January 8, 1993, Maintenance personnel were performing maintenance activities on Discharge damper 2MNVAC0049 associated with Standby Makeup pump 2MNVPU0046. During the maintenance activities, a problem developed with disassembly of the damper. The damper housing threads galled to the connecting l flange. This kept the damper from being further disassembled or reassembled using the threaded joint. The damper was then removed from the system by cutting the connected piping. The damper was subsequently taken to a machine shop for repair, however, the damper was not restored to operable status within the 7 day limit specified by SLC section 16.9-7 (c). Problem Investigation Process (PIP) 2-M93-0017 was initiated to document and determine cause of the event, and corrective actions takt... Unit 2 the was in Mode 1 (Power Operation) at 100 percent power at the time of the event. The cause of this event is equipment
_ allure due to the galled threads on the discharge damper
4 DPC/MNS STATION PROBLEM REPORT No. 93-01 PAGE 2 of 6 housing. Subsequently, Discharge damper 2MNVAC0049 was repaired and re-installed in the system, and the SSS returned to operable status on January 15, 1993.
Background
The standby makeup subsystem of the NV system functions as part of the SSS to control reactor coolant volume should normal volume control be unavailable following a postulated fire or security event. The SSS serves as the last resort and is designed to be used when the preferred equipment has been rendered inoperable.
One standby makeup pump is located in the annulus of each Reactor building to supply makeup flow to the Reactor Coolant (NC) system. The pump provides a means of makeup to recover normal system leakage and NC pump seal leakage during SSS events. The pump is manually started within 10 minutes of the loss of preferred source to ensure the Reactor Coolant pump seals are not degraded. The pump should not be stopped until the NC system is at atmospher...
pressure or until the NV system charging pumps and a source of borated water are available for seal injection. The design basis operating time for this pump is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, however, the most probable event scenarios would expect the pump to be used for no more than 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
The standby makeup pump is of the positive displacement (PD) design, reciprocating plunger type, and adds a constant quantity (26 gpm) of borated water to the NC system. The pump discharge is connected through a tee fitting to a discharge damper. The discharge damper is provided to absorb or minimize the discharge flow pulsation inherent vith positive displacement reciprocating plunger type pumps.
The discharge damper consists of a 29 inch long outer casing which is threaded to a tee assembly and contains an inner fluid chamber and a gas chamber separated by a bellows assembly. The fluid chamber is exposed to system fluid and pressure. The gas chamber is filled with nitrogen gas and maintained at approximately 1900 pei. T'io total volume of the Standby Makeup Pump Discharge damper is approximately 2 gallons and it has a dry weight of approximately 270 pounds.
SLC 16.9.7, SSS, requires that the SSS be operable during Modes 1, 2 (Startup), and 3 (Hot Standby). If any SSS components, such as a standby makeup pump cr its associated water supply, are inoperable, the SSS shall be declared inoperable. Remedial Action paragraph c requires that with i
DPC/MNS STATION PROBLEM REPORT No. 93-01 PAGE 3 of 6 the SSS inoperable for more than 7 days, submit a specia' report to the NRC within the next 30 days outlining the cause of the inoperability, corrective actions being taken, and plans for restoring the system to operable status.
l Description Of Event On August 27, 1992, Component Engineer A was reviewing preventative maintenance records of the Unit 2 Standby Makeup pump 2MNVPU0049 and associated equipment. He determined that the Unit 2 Standby Makeup Pump Discharge damper 2MNVAC0049 did not maintain its gas charge as required. He suspected that the bellows inside the Discharge damper was defective and subsequently originated work order 92039489 to replace the bellows on Discharge damper 2MNVAC0049. He also initiated activity to procure the necessary parts for the job from the vendor, Parker Metal Bellows Corporation.
At 1000 on January 6, 1993, the SSS was removed from service for performance of several maintenance tasks associated with SSS subsystems. One of the jobs scheduled to be performed during the time the SSS was out of service was replacement of the bellows assembly in Discharge damper 2MNVAC0049.
On the morning of January 7, 1993, repair activities, as directed by work order 92039489, were initiated on Discharge damper 2MNVAC0049. Maintenance Technicians A and B were 7
assigned to repair the damper. They proceeded to the Unit 2 l
Reactor building annulus where Discharge damper 2MNVAC0049 is located and after verification of prerequisite conditions, began to disassemble the discharge damper.
Maintenance Technician A started to unscrew the dampar housing. After several turns, the housing froze in nlace and could not be screwed off the remaining threads on the connected flange. 'ubsequent attempts were made to remove the discharge dam _ housing by Maintenance Technicians A and B. They tried tapping the housing with a hammer and heating the housing but were unable to successfully remove it as planned. The Maintenance Technicians then consulted Component Engineers A and B for direction on how to proceed with the removal of the damper. The Engineers and Maintenance Technicians determined hat the threads had galled and further attempts to unscrew the housing would destroy the threads. It was then decided the best approach was to cut the Discharge Damper piping to remove the damper.
DPC/MNS STATION PROBLEM REPORT No. 93-01 PAGE 4 of 6 By late that afternoon, the damper piping was cut and Discharge damper 2MNVAC0049 was removed to a machine shop for further disassembly and repair of '.he threaded portion of the damper housing.
Maintenance and Engineering personnel determined a replacement housing was needed. Parker Metal Bellows was contacted; however, no. replacement housings were available.
Catawba Nuclear Station was also contacted for replacement parts; however, it was determined that they did not have an identical replacement housing. Maintenance and Engineering personnel then determined that a portion of the original housing could be used if a-new threaded ring was replaced in the housing. This approach was determined to be the most' cost effective and expeditious for returning Discharge damper 2MNVAC0049 to service. Component Engineer-A contacted the vendor for drawings to fabricate the replacement threaded ring to the orzginal manufacturers specifications.
During the evening
- January 8, 1993, Materials personnel began to search foi source for the SA36 material needed to fabricate the thrcausd ring. Maintenance personnel were also busy during this time machining the old housing to prepare it for the new threaded ring.
At 0100, on January 10, 1993, the SA36 material arrived on site. Maintenance personnel started machining the SA36 material as specified by Component Engineering personnel.
At 1000, on January 13, 1993, while recovery efforts were underway, the grace period for returning the SSS to operability expired.
At 1615, on January 13, 1993, Component Engineer A originated PIP 2-M93-007 to document the problem with the t dischargo damper housing and that the 7 day grace period for repairing it had been exceeded.
The discharge damper was subsequently repaired by addition of the fabricated ring and replacement of the new bellows assembly, re-installed in the system, and functionally tested. by 1339, January 15, 1993, the SSS was returned to operable status.
Conclusion This event is assigned a cause of Equipment Failure because the threads on the discharge damper housing galled when the
DPC/MNS STATION PROBLEM REPORT No. 93-01 PAGE 5 of 6 Maintenance Technicians tried to unscrew it. The galled threads resulted from localized seizing. Once this phenomena occurs, further attempts to rotate the threaded portion will only result in additional damage to the threads. Engineering personnel have stated that it is difficult to prevent galled threads from occurring. The most effective way to prevent galled threads is to apply a lubricant to the thread surfaces during assembly of the joint. A work history search of Discharge damper 2MNVAC0049 revealed that this component has not been disassembled since initial installation, which occurred prior to 1985. The investigation could not determine whether the threads for Discharge damper 2MNVAC0049 housing were initially lubricated. F vever, the environment the discharge damper is installed t and the long time the component remained assembled would tend to negate the anti galling effects contributed by any lubricant initially used. Current Maintenance practice is to apply lubricants, as appropriate, to threaded surfaces when assembling components.
Once the Maintenance Technicians recognized that the threads on the discharge damper had galled, they discontinued further disassembly efforts until more knowledgeable personnel could be consulted. After consultation with Engineering personnel, it was decided that the most prudent course of action was to remove the entire assembly from the system and machine the housing off the threaded flange.
This approach kept the flange portion of the discharge damper intact and allowed the housing portion to be repaired by first fabricating a replacement threaded ring, then welding the ring to the housing. The replacement bellows assembly was subsequently installed and the entire discharge
! damper assembly was returned to the system.
Had the problem with the galled threads not existed, the original task to replace the bellows assembly inside the discharge damper could have been completed well within the 7 l
dcy window. However, when the problem occurred, it was not possible to return the discharge damper to the original position and reschedule the task of replacing the bellows to l a time when a longer repair windcw was available.
Therefore, recovery efforts were expeditiously undertaken by Maintenance and Engineering personnel. However, the overall recovery effort exceeded the SLC requirement by 51 hours5.902778e-4 days <br />0.0142 hours <br />8.43254e-5 weeks <br />1.94055e-5 months <br />, 39 minutes.
There were no personnel injuries, radiation overexposures, or uncontrolled releases of radioactive material as a result
! of this event
6PC/MNS STATION PROBLEM REPORT No. 93-01 PAGE 6 of 6 Corrective Actions Immediate PIP 2-M93-0017 was initiated to document and correct the problem.
Subsequent 1. A new threaded ring was fabricated and welded to the original discharge damper housing.
- 2. The repaired discharge damper was returned to the system.
Planned None