|
---|
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
[Table view] |
Text
.
DUKE POWER GOMPANY v.o.nox canso guantorre, N.c. 28242 HALH.TUCKEH .' *C
. T PN m.......
g gn4 u December 1, 1986 Dr. J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Commission - Region II 101 Marietta St. NW, Suite 2900 Atlanta, Georgia 30323
Subject:
McGuire Nuclear Station, Unit 2 Docket Nos. 50-370 Technical Specification 3.4.9.3/6.9.2 PORV Opening Special Report
Dear Dr. Grace:
Pursuant to Technical Specifications 3.4.9.3, please find attached a Special Report pursuant to T.S. 6.9.2 regarding the opening of a PORV at McGuire on October 30, 1986.
The event was considered to be of no significance with respect to the health and safety of the public.
Very truly yours, f,
Hal B. Tucker JBD/130/j gm xc: INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, GA 30339 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. W.T. Orders 8703240504 861201 NRC Resident Inspector ADOCK 0500 0 hDR McGuire Nuclear Station ll0 reaA
, DUKE POWER COMPANY McGUIRE NUCLEAR STATION Pressurizer Power Operated Relief Valve INC-34A Opened Due to Inadequate Instrumentation On October 30,1986, at 2147, Pressurizer Power Operated Relief Valve (PORV)
INC-34A automatically opened while in the low pressure overpressurization protection mode. Operators had increased Reactor Coolant (NC) system pressure to approximately 360 psig to increase the differential pressure (D/P) across the Reactor Coolant Pump (RCP) seals. Immediately after PORV INC-34A opened, the Pressurizer heater controls were adjusted to augment NC system depressurization.
PORV INC-34A closed 29 seconds after opening and NC system pressure stabilized at approximately 325 psig.
Unit I was in Mode 5, Cold Shutdown, with NC system temperature at approximately 180*F and cooling down at the time of this incident.
This incident has been attributed to a Design Deficiency, because control room instrumentation was inadequate to accurately monitor NC system pressures near the Pressurizer PORVs low pressure trip setpoint.
Background
The Pressurizer PORVs provide low pressure overpressurization protection during periods of water solid operation during unit startup and shutdown. This protection prevents the NC system from exceeding pressure and temperature limits specified in 10CFR50, Appendix G, as defined in McGuire Technical Specifications Figures 3.4-2 and 3.4-3. Analyses have shown that one PORV is sufficient to prevent violation of these limits due to anticipated mass and heat input transients. However, redundant protection is provided through the addition of low pressure setpoints for two PORVs, NC-34A and NC-32B. The low pressure setpoints are enabled at NC system temperatures below 300*F, The low pressure setpoints are interlocked with NC system temperature to minimize the possibility of inadvertent actuation.
Pressurizer PORVs INC-34A and INC-32B automatically open on high pressure signals generated by wide range pressure transmitters (0-3000 psig) INCPT5120 and INCPT5140, respectively. Pressure transmitter INCPT5120 monitors pressure on the NC Loop D Hot Leg and INCPT5140 monitors pressure on the NC Loop C Hot Leg. The low pressure mode setpoints on these transmitters are calibrated such that actuation signals are generated at NC system pressures between 365 and 400 psig.
Both wide range pressure transmitters have corresponding control room indicators and INCPT5140 also provides an analog computer point on the Operator Aid Computer (OAC). Additional NC Loop C Hot Leg pressure indication is provided by a control room indicator and an OAC analog computer point, both of which receive signals from low range pressure transmitter (0-800 psig) INCPT5141.
Description of Incident On October 30, 1986, Unit I was in Mode 5 with NC system temperature and pressure at approximately 180*F and 300 psig, respectively. Operators were cooling down the NC system and the NC system overpressurization protection was in the low pressure mode.
F
". Page 2 As NC system temperature decreased, the D/P across the RCP seals dropped and was approaching 200 paid. An RCP seal D/P between 200 and 300 psid is required to ensure adequate cooling of the pump seals. The Pressurizer heater manual controls were adjusted to increase NC system pressure and RCP seal D/P. Operators used the OAC wide range pressure indication provided by 1NCPT5140 to monitor NC system pressure because they knew the Pressurizer PORVs were actuated by wide range pressure signals. NC system pressure increased to approximately 360 psig as indicated by the OAC.
At 2147, a Hi NC System Wide Range Pressure alarm was received in the control room and a wide range pressure of 376 psig on the NC Loop C Hot Leg was recorded on the alarm typer. Three seconds later, Pressurizer PORV INC-34A automatically opened.
Operators immediately adjusted the Pressurizer heater manual controls to augment NC system depressurization. PORV INC-34A automatically closed 29 seconds after it opened and NC system pressure stabilized at approximately 325 psig. Operators continued cooling down the NC system without further problems.
Conclusion Pressurizer PORVs INC-34A and INC-32B open on high wide range pressure signals from the NC system Loop D and C Hot Legs, respectively. However, only the wide range pressure on Loop C can be accurately monitored in the control room at low NC system pressures. The wide range pressure indicator for Loop D has insufficient resolution to accurately monitor lower pressures. Therefore, as NC system pressure increased, operators had no accurate indication of wide range pressure on Loop D. Also, operators knew that the maximum low pressure mode setpoint on the PORVs was 400 psig, but were unaware the PORVs could open at pressures as low as 365 psig. Loop D wide range pressure apparently exceeded the low pressure mode setpoint and PORV INC-34A automatically opened. The exact pressure at which PORV INC-34A opened is unknown. However, Loop D wide range pressure instrumentation was tested on August 18, 1986, and was found to generate a low pressure actuation signal at a pressure of 388 psig.
This incident has been attributed to a Design Deficiency, because control room instrumentation is inadequate to accurately monitor NC system pressures near the Pressurizer PORV low pressure actuation setpoint.
A review of past incidents at McGuire found one other incident (report dated April 15, 1986, amended September 5,1986) in which inadequate instrumentation caused a Pressurizer PORV to pen with the NC system in the low pressure overpressurization protection mode. Therefore this incident is considered recurring.
Corrective Actions Immediate: The Pressurizer heater manual controls were adjusted to augment NC system depressurization.
Subsequent: None
.. Page 3 Planned: 1) Station Problem Reports (SPRs) for Units 1 and 2 will be written to add NC system Loop D computer points on the OAC.
. Safety Analysis Pressurizer PORV INC-34A apparently opened and closed as designed with the NC system overpressurization protection in the low pressure mode. The low pressure mode setpoints on the PORVs protect the NC systen during periods of water solid operation. The NC system was not water solid at any time during this incident; therefore, the Pressurizer was capable of accommodating any design basis transients without pressure relief from the PORVs.
Section 15.6.1 of the McGuire Final Safety Analysis Report (FSAR), entitled Inadvertent Opening of a Pressurizer Safety or Relief Valve, analyzes an accidental depressurization of the NC system assuming reactor power and NC system pressure and temperature are initially at their nominal values. This incident occurred with the unit in Mode 5 at low NC system pressure and temperature.
Therefore, in the event that Pressurizer PORV INC-34A had not closed properly the resulting NC system transient would be bounded by the FSAR Section 15.6.1 accident analysis.
The health and safety of the public were not affected by this incident.
i I
_ _ . _ _ _ . __