Similar Documents at Surry |
---|
Category:ABNORMAL OCCURRENCE REPORTS (SEE ALSO LER & RO)
MONTHYEARML20086S5861984-09-10010 September 1984 SR-S1-74-03:on 740403,safety Injection Experienced Due to Spurious High Steam Flow Signals in Conjunction W/Low Temp Average or Low Steam Line Pressure Signals.Caused by Fluctuations of Steam Flow Signals Above Setpoint ML20087B9541975-10-17017 October 1975 Telecopy AO:751011,containment Leak Rate Tests Revealed Containment Leakage Rate Greater than Acceptable Criteria ML20087B9651975-10-16016 October 1975 Telecopy AO:on751015,recirculation of Boron Injection Tank 2 Interrupted for Period of 15 Minutes.Caused by Failure of Boric Acid Transfer Pump D Motor ML20087C0771975-10-0101 October 1975 Telecopy Ao:On 750928,during Refueling Performance Test 18.2,safety Injection Master Relay Failed to Latch,Violating Tech Spec 3.3 ML20087C1041975-09-25025 September 1975 Telecopy Ao:On 750924,loop a Instrumentation Drifted Low Resulting in Safety Sys Setting Being Less Conservative than Tech Spec Limit ML20087B8501975-08-25025 August 1975 Telecopy Ao:On 750823,channel of Protection Found Unconservative Due to Failure of Resistance Temp Detector ML20087B7821975-08-25025 August 1975 Telecopy Ao:On 750823,leak Developed in Boric Acid Transfer Sys Decreasing Level in Boric Acid Storage Tank C Below Tech Spec Limit ML20087B8921975-08-22022 August 1975 Telecopy Ao:On 750822,channel of Protection Found Unconservative Due to Failure of Resistance Temp Detector ML20087B9321975-08-0707 August 1975 Telecopy Ao:On 750807,boron Injection Tank Recirculation Valves TV-2884 A,B & C Found in Closed Position ML20087C1461975-07-30030 July 1975 Telecopy Ao:On 750729,boron Concentration in Boron Injection Tank 2 Found to Be 11.4% ML20087C1691975-07-21021 July 1975 Telecopy Ao:On 750720 Low Level Amplifier Failed Causing One Temp Change Protection Channel to Be Unconservative ML20087C2041975-07-0707 July 1975 Telecopy Ao:On 750706,reactor Trip Occurred.Caused by Sudden Closure of Trip Valve in Main Steam Line B.Investigation Underway to Determine Cause of Malfunction & Corrective Action ML20087C2241975-07-0101 July 1975 Telecopy Ao:On 750630,discovered That Undervoltage Reactor Trip Circuit Inoperable ML20086Q3091975-05-21021 May 1975 Notifies That AO Reported on 750514 Re Perforation of Fuel Assembly During Fuel Operation in Error.Perforation Occurred During Normal Operation.Rept No Longer Considered AO ML20086Q2891975-05-16016 May 1975 Telecopy Ao:On 750516,chemical Addition Tank Valve MOV-CS-10IB Failed to Operate Properly ML20086Q3261975-05-14014 May 1975 Telecopy Ao:On 750513,manipulator Crane Stopped Due to Overload.Caused by Perforation in Fuel Clad ML20086Q3681975-05-0101 May 1975 Telecopy Ao:On 750430,emergency Diesel Generator 3 Failed While in Svc Due to Internal Problem in turbo-blower ML20086Q5871975-04-28028 April 1975 Telecopy Ao:On 750427,consequence Limiting Safeguards Channel 3,Train B Matrix Relay Coil Found to Be Open Circuit During Performance Test 8.5A ML20086Q6211975-04-28028 April 1975 Ao:On 750427,sample Sys Trip Valve on Pressurizer Relief Tank Failed to Stroke on Initiation of Safety Injection During Performance Test 18.2 ML20086Q5111975-04-28028 April 1975 Telecopy Ao:On 750427,circulating Water Sys Valve MOV-CW-206D Failed to Shut After Receiving Close Signal ML20086S4491975-03-26026 March 1975 Corrections to AO-S2-74-09 Re Steam Generator Support Couplings.Studs Not Welded to Encl Plate as Previously Reported Due to Potential Welding Problems ML20086R0291975-02-24024 February 1975 AO-S1-75-01:on 750118,boron Concentration Observed to Be 1,842 Ppm & Primary Grade Water Flow Controller 1114A Found in Manual Mode of Operation W/Demand Position Corresponding to Full Open Position of Valve FCV-1114A ML20086Q9391975-02-24024 February 1975 AO-S1-75-02:on 750118,containment Isolation Valves 2-IA-446 & 2-IA-447 Found Open.Caused by Operator Error.Operators Advised of Importance of Following Procedures & Verifying Actions ML20086Q9291975-02-24024 February 1975 AO-S1-75-03:on 750115,process Vent Particulate Monitor Alarm Occurred Followed by Ventilation Vent Particulate Monitor Alarm.Caused by Pressure Control Valve PCV-GW-107 Stuck Open Causing Relief Valve RV-GW-107 to Lift ML20086Q7671975-02-18018 February 1975 Telecopy Ao:On 750217,core Quadrant Tilt of 2.2% Existed W/Reactor at 100% Power ML20086Q8181975-02-18018 February 1975 Telecopy Ao:On 750215,overpower Low Level Amplifier Failed Causing Inoperable Overpower Protection ML20086Q7801975-02-14014 February 1975 Telecopy Ao:On 750214,steam Generator Narrow Range Level Detector Drifted High.Cause Not Determined ML20086S4261975-02-14014 February 1975 AO-S2-74-10:on 741129,unsatisfactory Leakage Ovserved While Performing Periodic Test 16.4.Caused by Stress to Four Keyways of Rockshaft Due to Valve Closure.Counterweights Modified & Repositioned on Weight Lever ML20086Q8771975-02-14014 February 1975 Telecopy Ao:On 750214,pressurizer Pressure Comparator Failed.Caused by Setpoint Drift.Comparator Replaced ML20086Q8941975-02-0303 February 1975 Telecopy Ao:On 750201,steam Generator Blowdown Activity Not Continuously Recorded & Monitored by Steam Generator Blowdown Sample Monitor Sys ML20086R0801975-01-24024 January 1975 AO-S2-75-02:on 750110,channel 1 of Steam Generator C Level Instrumentation Indication Drifted Beyond Allowable Limits. Caused by Packing Leak at Isolation Valve.Replacement of Packing Will Be Performed as Necessary to Minimize Leakage ML20086R1891975-01-24024 January 1975 AO-S2-75-01:on 750109,discovered High Water Level Existed in Sump Area of High Pressure Heater Drain Pump.Caused by Turbine Bldg Sump Pumps Shut Off for Test.Test Instructions Revised to Require Surveillance ML20086S3061975-01-23023 January 1975 AO-S1-74-16:on 741220,radiation Monitor Alarm Accurred on RM-SW-107 Which Monitors Svc Water Leaving Component Cooling Hxs.Caused by Pin Holes in Component Cooling HX 1-CC-E-1C Tubes.Hx Isolated from Svc Water Sys ML20086S3171975-01-23023 January 1975 AO-S1-74-15:on 741219,abnormal Degradation Found of One of Several Boundaries Designed to Contain Radioactive Matls Resulting from Fission Process.Caused by Sheet Sludge Deposits & Deleterious Effects of Sodium Phosphate Control ML20086Q9471975-01-20020 January 1975 Telecopy Ao:On 750119,two Valves in Station Instrument Air Supply to Containment Instrument Air Sys Found Open.Valves Shut & Locked ML20086Q9671975-01-20020 January 1975 Telecopy Ao:On 750118,chemical Vol & Control Sys Found Open Causing Dilution of Primary Coolant Sys ML20086S3471975-01-10010 January 1975 AO-S1-74-13:on 741107,tube Rupture Occurred in Component HX 1-CC-E-1D.Caused by Equipment Malfunction.Hx Isolated & Component Cooling Surge Tank Refilled & Observed to Verify No Further Leakage ML20086R0961975-01-10010 January 1975 Telecopy Ao:On 750110,control Room Log Readings Indicated Level Transmitter 2-1T-494 Drifted Above Prescribed Limits. Transmitter Trip Bistables Deenergized ML20086S4301975-01-10010 January 1975 Telecopy Ao:On 750109,valve Pit Containing Svc Water Valves MOV-SW-203 A-D Became Flooded.Condition May Have Temporarily Incapacitated Heat Removal Feature of Recirculation Spray Sys ML20086S3321975-01-0303 January 1975 AO-S1-74-14:on 741119,magnetic Amplifiers for Low Level Alarm LS-CW-1018 & Turbine Trip LS-CW-101C Found Out of Calibr.Caused by Changes in Temp & Humidity & Aging of Components.Test Initiated to Verify Calibr ML20086S2931974-12-31031 December 1974 Ao:On 741230,crack Found in Containment Spray Check Valve. Containment Spray Check Valve & All Cracked Rackshafts Being Replaced ML20086S3611974-12-20020 December 1974 Telecopy Ao:On 741219,tube Leaks in Component Cooling HX Resulted in Low Level Release of Radioactive Component Cooling Water Into James River.Source of Leakage Located & Repaired.Hx Isolated ML20086S3691974-12-19019 December 1974 Ao:On 741218,steam Generator Tube Wall Deterioration Found in Excess of 50% in 137 Tubes ML20086S4371974-12-16016 December 1974 AO-S2-74-09:on 741017,cracks Discovered in Some Steam Generator Lower Ring Support Swivel End Couplings.Caused by Lateral Load in Direction of Reactor Pressure Vessel.Support Couplings Redesigned ML20086S4621974-10-25025 October 1974 AO-S2-74-09:on 741017,cracks Found in Concrete Supporting Steam Generator A.All Couplings Being Removed to Be Radiographed & Inspected.Rept Will Be Submitted by 750103 ML20086S8821974-10-22022 October 1974 AO-S2-74-06:on 740803,during Six Degree Freedom of Movement Portion of PT-14,no Response Received from Any of Three Valves.On Second Test of TV-MS-201B W/Air Bled from Cylinders,Valve Went Fully Closed ML20086S5731974-10-0101 October 1974 AO-S2-74-08:on 740912,neither Fuel Oil Supply Flow Paths for Emergency Diesel Generator 2 Operable.Caused by Solenoid Valves Disconnected in Terminal Box.Personnel Instructed in Procedure ADM-37 ML20086S5761974-09-26026 September 1974 AO-S2-74-07:on 740810,summator TM-2-412G Drift Allowed Overpower Trip Setpoint to Be Approx 5% High.Caused by Defective Summator.Summator Removed & Replaced & Module Calibr ML20086S5781974-09-26026 September 1974 AO-S1-74-11:on 740820,during Depressurization Procedure, Alarm Indicated High Surge Tank Pressure Received in Control Room.Cause Not Listed.Overhead Gas Compressor Stopped & Pressure within Gas Stripper Surge Tank Reduced ML20086S5841974-08-21021 August 1974 AO-S1-74-10:on 740802,one Spent Fuel Pit to Boron Recovery Sys Temporary Hose Line Connection Separated from Fitting, Spraying Primary Grade Pump House Interior.Caused by Inadequate Design of Clamping Arrangement 1984-09-10
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML18152A2811999-10-12012 October 1999 Technical Basis for Elimination of Nozzle Inner Radius Insps (for Nozzles Other than Reactor Vessel),Technical Basis for ASME Section XI Code Case N-619. ML18152B3531999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for Surry Power Station,Units 1 & 2.With 991012 Ltr ML18152B6651999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for Surry Power Station Units 1 & 2.With 990915 Ltr ML18152B4421999-08-27027 August 1999 LER 99-006-00:on 990802,determined That Plant Was Outside of App R Design Basis Due to Fire Barrier Deficiencies. Caused by Original Plant Design Deficiencies.Fire Watches Were Established & Mods Have Been Completed.With 990827 Ltr ML18152B4411999-08-27027 August 1999 LER 99-005-00:on 990731,effluent Radiation Monitors Were Declared Inoperable.Caused by Degraded Heat Trace Circuits for Monitors Sample Suction Line.Degraded Heat Trace Circuit Was Replaced & Addl Heat Trace Is Being Installed ML18151A3981999-08-13013 August 1999 SPS Unit 2 ISI Summary Rept for 1999 Refueling Outage. ML18152B3771999-08-13013 August 1999 LER 99-004-00:on 990714,TS Violation Due to non-safety Related Fans Effect on CR Boundary Was Noted.Cause of Event Has Not Yet Been Determined.Cable Spreading Room Doors Were Operned to Reduce Pressure in Rooms ML18152B3791999-07-31031 July 1999 Monthly Operating Repts for July 1999 for Surry Power Station,Units 1 & 2.With 990811 Ltr ML18152B3911999-06-30030 June 1999 Monthly Operating Repts for June 1999 for Surry Power Station,Units 1 & 2.With 990713 Ltr ML18152B4341999-05-31031 May 1999 Monthly Operating Repts for May 1999 for Surry Power Station,Units 1 & 2.With 990614 Ltr ML20195E2401999-05-31031 May 1999 Rev 2 to COLR for SPS Unit 2 Cycle 16 Pattern Ag ML18152B4181999-05-18018 May 1999 LER 99-002-00:on 990425,MSSVs Tested Out of Tolerance for as Found Setpoint.Caused by Minor Setpoint Drift.No Immediate Action Required.Deviation Rept Submitted for Each Valve.With 990518 Ltr ML18152B4161999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for Surry Power Station Units 1 & 2.With 990512 Ltr ML18152B4111999-04-28028 April 1999 LER 99-003-00:on 990331,potential Loss of Charging Pumps Was Noted.Caused by Main CR Fire.Station Deviation Was Issued on 990331.With 990428 Ltr ML18152B6511999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for Surry Power Station Units 1 & 2 ML18153A2741999-03-29029 March 1999 LER 99-002-00:on 990301,prematurely Released Fire Watches Resulted in Violation of TS 3.21.B.7.Caused by Inadequate Procedure.Procedure for Opening & Sealing Fire Stops Was Revised on 990212 ML18153A2681999-03-19019 March 1999 LER 98-013-01:on 981122,turbine/reactor Tripped on High Due to Short Circuit in Summator for MSL C Loop Channel III Flow Transmitter.Replaced 1-MS-FT1494 Summator & Module Repair Procedure Revised.With 9903190 Ltr ML18152B7331999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for Surry Power Station,Units 1 & 2.With 990310 Ltr ML18152B5421999-01-31031 January 1999 Monthly Operating Repts for Jan 1999 for Surry Power Station,Units 1 & 2.With 990210 Ltr ML18151A3031999-01-29029 January 1999 ISI Summary Rept for 1998 Refueling Outage,Including Form NIS-1, Owners Rept for ISIs & Form NIS-2, Owners Rept for Repairs & Replacements. ML18152B7261999-01-21021 January 1999 LER 99-001-00:on 981222,auxiliary Feedwater Pipe Support Missed Surveillance.Caused by Personnel Error.Station Deviation Rept Was Submitted.Two Supports in Question Received Required Code Insp & Were Found Acceptable ML18152B6011998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for Surry Power Station,Units 1 & 2.With 990115 Ltr ML18152B5781998-12-16016 December 1998 LER 98-014-00:on 981126,manual Reactor Trip in Response to Main Feedwater Regulating Valve Failure Occurred.Caused by Dislocation of Retaining Clip in Positioner.Control Room Operators Placed Unit in Safe,Shutdown Condition ML18152B5811998-12-16016 December 1998 LER 98-013-00:on 981122,turbine/reactor Trip on High SG Level Occurred.Caused by Instrument Failure.Control Room Operators Placed Unit in Safe,Shutdown Condition ML18152B7121998-12-0404 December 1998 LER 98-S01-00:on 981105,noted Failure to Deactivate Station Access Badge.Caused by Human Error.Licensee Will Now Deactivate Station Badges Before Clearance Is Revoked & Process for Badge Deactivations Have Been Strengthened ML18152B7041998-12-0101 December 1998 LER 98-012-00:on 981102,noted That EDGs Were Concurrently Inoperable.Caused by Required Testing Per TS 3.16.B.1.a.2. Redundant EDG Was Returned to Svc within Two Hour Period, Following Satisfactory Testing.With 981201 Ltr ML18152B7081998-11-30030 November 1998 Rev 0 to COLR for Surry 1 Cycle 16,Pattern Un. ML18152B5721998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for Surry Power Station,Units 1 & 2.With 981214 Ltr ML18152B6161998-11-0606 November 1998 LER 98-011-00:on 981008,diesel Driven Fire Pump Failed to Start During Performance of Monthly Operability Test.Caused by Faulty Overspeed Trip Device Failure.Diesel Driven Fire Pump Declared Inoperable ML18152B6241998-10-31031 October 1998 Monthly Operating Repts for Oct 1998 for Surry Power Station Units 1 & 2.With 981111 Ltr ML18152B6081998-10-23023 October 1998 LER 98-010-01:on 980715,intake Canal Level Probes Were Inoperable Due to Marine Growth.Caused by Design of Canal Level Instrumentation.Canal Level Probes Will Continue to Be Monitored More Closely ML18152B6881998-09-30030 September 1998 Monthly Operating Repts for Sept 1998 for Surry Power Station Units 1 & 2.With 981012 Ltr ML18153A3271998-08-31031 August 1998 Monthly Operating Repts for Aug 1998 for Surry Power Station,Units 1 & 2 ML18152B7811998-07-31031 July 1998 LER 98-010-00:on 980715,low Intake Canal Level Instrument Channel I Was Declared Inoperable to Allow Testing of Intake Canal Level Probe 1-CW-LE-102.Subject Probe Was Cleaned by Diver,Tested & Channel I Was Returned to Operable Status ML18153A3161998-07-31031 July 1998 Monthly Operating Repts for July 1998 for Surry Power Station Units 1 & 2.W/980807 Ltr ML18152B7621998-06-30030 June 1998 Monthly Operating Repts for June 1998 for Surry Power Station,Units 1 & 2.W/980707 Ltr ML18153A2581998-06-0303 June 1998 LER 98-009-00:on 980509,nonisolable Leak of Reactor Coolant Pump Seal Injection Line Weld,Was Discovered.Caused by Lack of Fusion or Thermal Fatigue Coupled W/Vibration Stress Due to Loose Rod Hanger.Rcp Seal Injection Line Removed ML20248F7441998-05-31031 May 1998 Reactor Vessel Working Group,Response to RAI Regarding Reactor Pressure Vessel Integrity ML18153A3141998-05-31031 May 1998 Monthly Operating Repts for May 1998 for Surry Power Station,Units 1 & 2.W/980610 ML18152B8241998-05-22022 May 1998 LER 98-008-00:on 980228,auxiliary Ventilation Fans Were Noted in Condition Outside of Design Basis.Caused by Failure to Recognize Potential Impact of Certain Design Basis Accident Scenarios.No Corrective Actions Needed ML18152B8161998-04-30030 April 1998 Monthly Operating Repts for Apr 1998 for Surry Power Station Units 1 & 2.W/980508 Ltr ML18152B7951998-04-29029 April 1998 LER 98-007-00:on 980330,radiation Monitors Were Declared Inoperable.Caused by Change in Operating Temperature Range. Preplanned Alternate Method of Monitoring Was Initiated IAW TS Table 3.7-6 ML18153A2511998-04-22022 April 1998 LER 98-006-00:on 980324,unisolable Through Wall Leak of RCP Thermowell Was Noted.Cause of Leak Is Unknown.Rtd Will Be Replaced ML18153A2521998-04-22022 April 1998 LER 98-005-01:on 980212,fire Watch Insp Exceeded One Hour. Caused by Lack of Attention to Detail by Individual Involved.Individual Involved Was Coached on Requirement to Perform Fire Watch Patrols within Required Time Frame ML20217P9941998-04-0707 April 1998 Safety Evaluation Granting Licensee Third 10-yr Inservice Insp Program Relief Requests SR-018 - Sr-024 ML18153A2951998-03-31031 March 1998 Monthly Operating Repts for Mar 1998 for Sps,Units 1 & 2.W/ 980408 Ltr ML18153A2391998-03-13013 March 1998 LER 98-005-00:on 980212,fire Watch Insp Frequency Exceeded One H Occurred.Category 2 Root Cause Evaluation Being Conducted to Determine Cause of Event.Station Deviation Issued ML18153A2341998-03-0909 March 1998 LER 98-003-00:on 980226,no Procedural Guidance for Maintaining EDG Minimum Fuel Supply During Loop,Was Identified.Caused by Absence of Procedural Instructions. Deviation Rept Submitted to Document Deviating Condition ML18153A2301998-03-0606 March 1998 LER 98-004-00:on 980206,fire Watch Was Released Prematurely Resulting in Violation of Ts.Caused by Inadequate Planning of Repair Activity.Work Orders Will Include Ref to Applicable Procedures Developed to Assist in Repairs ML18153A2251998-03-0404 March 1998 LER 98-002-00:on 980202,automatic Turbine Trip Resulted in Automatic Reactor Trip.Caused Degraded Generator Voltage Regulator sub-component Failure.Placed Plant in Safe Hot SD & Replaced Intermittent Relay & Relay Socket 1999-09-30
[Table view] |
Text
. _ . _ . _
o
.. O o
. /,y\ f~~~j' n
'[,
V1uG1NIA ELucrate ANo Pownu CO PANYnry Rtcnxoxo.VtuorwsA 20201 f January 3', 1975 6] dAh8 1975 > [3 k.
, tL[ ~;r yh g L .
kn . .s:.: a
- ' %QTjf Mr. Norman C. Moseley, Director Serial No. 360 Directorate of Reculatory Operations P0&M/JTB:c1w United States Atomic Energy Commission Docket No. 50-280 Region II - Suite 818 50-281 230 Peachtree Street, Northwest 30303 License No. DPR-32 Atlanta, Georgia DPR-37
Dear Mr. Moseley:
d Pursuant to Surry Power Station Technical Specification 6.6.B.1, the Virginia Electric and Power Company hereb'r submits forty (40) copies of Abnormal Occurrence Report No. A0-SI-74-14.
The substance of this report has been reviewed by the Station Nuclear Safety and Operating Committee and will be placed on the agenda for the next meeting of the System Nuclear Safety and Operating Committee.
Very truly yours,
$$ ' f C. M. Stallings Vice President-Power Supply and Production Operations 1
Enclosures 40 copies of A0-SI-74-14 cc: Mr. K. R. Goller, Assistant Director for Operating Reactors e
S "17 s
COPY SENT REGION
.. O O ABNORMAL OCCURRENCE REPORT REPORT NO. A0-SI-74-M INTAKE CANAL LEVEL MAGNETIC AMPLIFIERS NOVEMBER 29, 1974 DOCKET NOS. 50-280 50-281 LICENSE NOS. UPR-32 DPR-37 SURRY POWER STATION VIRGINIA ELECTRIC AND POWER COMPANY L ___;
O_ Os I. INTRODUCTION In accordance with Technical Specification 6.6.B.1 for Surry Power Station, Operating License Nos. DPR-32 and DPR-37, this report describes an abnormal occurrence which was identified on November 19, 1974. The Directorate of Regulatory Operations, Region II, was notified on Nov-ember 19, 1974.
The occurrence reported herein is classified as an abnormal occurrence pursuant to Technical Specification 1.0.I.6 which states that: "An abnormal occurrence is defined as: Engineered Safeguard System malfunction or other component or system malfunction which rendered or could render the engineered safeguard system incapable of performing its intended safety function." The occurrence described herein could have permitted the intake canal level to fall below the +18 foot elevation during reactor operation without energizing the turbine trip solenoid or closing the circulating water condenser valves.
II.
SUMMARY
OF OCCURRENCE On November 19, 1974, both reactors were in a cold shutdown condition.
The instrument technicians were checking the calibration of the intake canal level magnetic amplifiers. It was determined that the Unit No. I magnetic amplifiers for the low level alarm (LS-CW-1018) and turbine trip (LS-CW-101C) wer'e out of calibration. The low level alarm would have activated at 15'-4" instead of 20'-0". The turbine trip solenoid would not have been activated regardless of the canal water level. The Unit No. 2 magnetic amplifier for the low level alarm (LS-CW-2018) was within the tolerance and would have been activated at approximately 20 feet. The turbine trip magnetic amplifier (LS-CW-201C) was out of calibration and
o O
would not have been activated rebardless of the canal water level.
Remotely operated butterfly valves are installed at the four inlets and outlets of each main condenser and in the supply lines to the re-circulating spray heat exchangers. The circulating water condenser valves are designed to close autormically with a low level alarm for an intake canal level of +18 foot elevation. Due to the instrumentation not being in calibration, the condenser valves of both units would not have closed automatically regardless of the canal water level.
III. ANALYSIS OF THE OCCURRENCE The intake canal level transmitters measure the water level of the canal over a range of 0 to 144 inches. The zero point of the level transmitter corresponds to a canal water level of +15 feet elevation and the 144 inch point corresponds to a canal water level of +27 feet elevation.
The output of the level transmitters to the magnetic amplifiers is a current which varies f rom 4 to 20 mil 11 amperes. Zero inches on the trans-mitter range (15 feet elevation) produces 4 milliamperes and 144 inches (27 f eet elevation) produces 20 mil 11 amperes.
This output current is fed into the magnetic amplifier through a 250 ohm resistor which produces a voltage of 1 to 5 volts depending on the current. Because the minimum current output of the level transmitters is 4 mil 11 amperes, the minimum voltage developed across the magnetic amplifier input resistors will be one volt. A potentiometer in the circuit with other components is utilized to adjust the setpoint at-which the output relay will trip. A change in value of-these components due to temperature, humidity or aging will change the level of input voltage l
In l
to the magnetic amplifiers which is required to trip the output relays.
this particular instance, the magnetic amplifier output relays should trip l
f
. .. . O O
,on a decreasing voltage of 2.666 volts for the low level alarm, 2.000 volts for the turbine trip solenoid and for the circulating water condenser valves. It was found that the Unit No. I relays tripped at 1.113 volts and 0.822 volts and Unit No. 2 relays tripped at 3.645 volts and 0.890 volts, respectively. Because the minimum current of 4 milli-amperes output from the level transmitters produces a minimum of one volt across the input resistor of the magnetic amplifier, the turbine trip relays would never trip due to intake canal low level, nor would the con-denser valves of both units close automatically, due to intake canal low level.
The Unit No. 1 magnetic amplifiers were last calibrated on July 29, 1971 and the Unit No. 2 magnetic amplifiers on January 20, 1972. The ef fect of the changes in temperature and humidity and the aging of the components caused the various component values to change which changed the relay trip setpoint.
IV. CORRECTIVE ACTION TO PREVENT RECURRENCE The immediate corrective action to prevent a recurrence was to initiate a periodic test to verify the calibration of the level transmitters and the setpoints of the magnetic amplifiers. Electronic components usually change values due to aging at a very slow rate. Therefore, an annual periodic test of the system has been instituted.
V. ANALYSIS AND EVALUATION OF SAFETY IMPLICATION OF THE OCCURRENCE Both reactors were in a cold shutdown condition at the time of this incident. However, it is possible the magnetic amplifiers were out of calibration for some indeterminate period of time during which the reactors
}
\'v1 vere operational. This fact notwithstanding, the possibility of the canal' falling below the +18 foot level during reactor operations was remote.
In addition to the two low level alarms, one of which would have functioned to alert the operators of a low canal level, each operator has a visual canal water level display which is closely monitored during reactor operations. Each of the displays is prominently marked to attract the operator's attention to a falling water level situation. If the situation cannot be corrected, the operator can manually trip the turbines and/or reactor when the canal water level falls to +18 feet.
If the intake canal fell below the +18 foot level during reactor operations, the Technical Specification 3.14A requirement for 25,000,000 gal. of water in the intake canal for critical services would be violated.
Gravity flow between the high level intake canal and discharge canal seal pit supplies service water to parallel flow loops through four (4) re-circulation spray heat exchangers per un t. i The recirculation spray system of one unit requires 24,400 gpm.
Since the water in the intake canal is required only under accident conditions, there were no safety Laplications associated with the occurrence.
VI. CONCLUSIONS The licensee concludes that :
- 1. The magnetic amplifiers were out of calibration due to the normal aging of electronic components.
- 2. The occurrence described herein did not affect the safe operation of the station.
- 3. The occurrence described herein did not affect the health and saf ety of the general public.
b