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Category:ABNORMAL OCCURRENCE REPORTS (SEE ALSO LER & RO)
MONTHYEARML19210A1511976-02-12012 February 1976 Abnormal Occurrence 76-7/1P:on 760212,empty Snubber Fluid Reservoir Found at Location DHH-198.Leakage Due to Damaged Seal.Snubber Removed & Replaced ML19322A4301976-02-0505 February 1976 Abnormal Occurrence 76-6/1P on 760204:radiation Leak Detection Sys Out of Svc for 22-h.No Reactor Bldg Atmospheric Samples Taken.Caused by Cover Plate to Monitor Left Open Following Insp.Procedures Reviewed W/Personnel ML19210A1581975-12-26026 December 1975 Abnormal Occurrence 50-289/75-43:on 751218,one of Six Pressure Switches Tripped at Less Conservative Limits than Tech Specs During Channels Surveillance Test.Caused by Calibr Drift in Associated Pressure Switch PS-290 ML19343C2181975-12-23023 December 1975 AO 50-219/75-33:on 751212,during 6-month Load Test on Station a batteries,125 Volt Dc Distribution Ctr de-energized.Caused by Personnel Error in Following Procedure.Distribution Ctr re-energized ML19210A1451975-12-19019 December 1975 Abnormal Occurrence 50-289/75-42:on 751210,outside Containment Isolation Valve for Steam Generator Sample Line CA-V5B Failed to Close.Caused by Valve Manual Operator Inadvertently Left Open by Reactor Personnel ML20090C9991975-12-12012 December 1975 AO 75-33:on 751212,125-volt Dc Distribution Ctr of Station a Battery Inadvertently de-energized.Caused by Failure to Establish Proper Breaker Lineup Preparation for Conducting Battery Load Test.Procedure changed.W/751219 Memo ML19343C2191975-12-11011 December 1975 AO 50-219/75-32:on 751203,during Testing,Emergency Diesel Generator 1 Failed to Start When Simulated Loss of Power Condition Applied to Fast Start Logic Circuit.Caused by Failure of Relay to Operate Due to Varnish on Armature ML20126E8281975-12-0303 December 1975 AO 50-219/75-31:on 751124,during Operability Test of Torus to Drywell Vacuum Breakers,Alarm Sys 2 Failed to Annunciate in Control Room When V-26-4 Opened.Caused by Failure of Relay Due to Contacts Being Detective.Relay Replaced ML20090D0071975-11-25025 November 1975 AO 75-31:on 751124,drywell Vacuum Breaker Alarm Sys II Failed to Annunciate When Vacuum Breaker V-26-4 Opened. Caused by Component Failure.Corrective Action Under Investigation ML19210A1731975-11-25025 November 1975 Abnormal Occurrence 50-289/75-40:on 751112,stuck Contacts on Diesel Generator 1A Voltage Relays Threatened Function of Engineered Safety Feature.Caused by Pitting of Relay Contact.Relays Checked at Each Startup Pending Design Mods ML19261F1481975-11-24024 November 1975 Abnormal Occurrence 50-289/75-41:on 751114,personnel Failed to Strictly Follow Drain & Blanketing Procedure.Vented Center Control Rod Drive Mechanism Allowed Radioactive Gas Into Reactor Bldg.Personnel Counseled on Proper Procedures ML19210A1831975-11-21021 November 1975 Abnormal Occurrence 50-289/75-39:on 751112,control Rod 4 in Group 7 Dropped Into Core,Resulting in Asymmetrical Rod Signal & Automatic Power Reduction.Caused by Failure of Stator Winding.Stator Winding Replaced & Tested ML20090D0161975-11-0707 November 1975 AO 75-30:on 751106,low Reactor Pressure Core Spray Valve Permissive Pressure Switches Re 17 a & C Tripped at Pressure Less than Min Required Value.Caused by Switch Repeatability.Pressure Switches Recalibr ML20090D0601975-11-0606 November 1975 AO 75-29:on 751027,torus Drywell Vacuum Breakers Alarm Sys II Failed to Annunciate When Vacuum Breaker V-26-8 Opened. Caused by Sticking Microswitch ML19210A1911975-10-31031 October 1975 Abnormal Occurrence 50-289/75-37:on 751021,blocked Strainer on Outlet to Boric Acid Mixtank Decreased Flow Rate.Plant Shutdown Followed to Replace Strainer.Improper Design Allowing for One Strainer W/No Bypass Caused Blockage ML19210A1891975-10-31031 October 1975 Abnormal Occurrence 50-289/75-38:on 751021,control Rod Verification Program Not in Compliance W/Tech Specs.Caused by Procedure Misinterpretation.Revised Surveillance Program Will Clearly State Requirement of Individual Rod Movement ML19210A2021975-10-29029 October 1975 Abnormal Occurrence 50-289/75-36:on 751019,auxiliary Operator Failed to Obtain Radiation Work Permit & Carry Monitoring Device.Caused by Improper Administrative Procedures ML20090D0761975-10-28028 October 1975 AO 75-29:on 751027,torus to Drywell Vacuum Breaker Alarm Sys II Failed to Annunciate When Vacuum Breaker V-26-8 Opened.Caused by Component Failure.Corrective Action Under Investigation ML20090D0941975-10-24024 October 1975 AO 75-28:on 751015,standby Gas Treatment Sys 1 Inoperable. Caused by Air Solenoid Valve Coil Failure.Defective Solenoid Coil Replaced ML19210A1971975-10-21021 October 1975 Abnormal Occurrence 75-37:on 751021,blocked Strainer on Outlet of Boric Acid Mixtank Decreased Flow Rate.Plant Shutdown Followed to Replace Strainer.Plant Returned to Svc in 15 Minutes ML19210A2151975-10-20020 October 1975 Abnormal Occurrence 50-289/75-35:on 751010,improper Mix of Boric Acid Crystals Caused Blockage in Mix Tank.Crystals Settling to Bottom of Tank Clogged Line to Reclaimed Boric Acid Storage Tank.Mixture Mod Should Correct Failures ML20090D1141975-10-17017 October 1975 AO 75-27:on 751008,low Reactor Pressure Core Spray Valve Permissive Pressure Switches RE17B & D Tripped at Pressure Less than Min Required Value.Caused by Switch Repeatability. Pressure Switches Recalibr ML20090D1041975-10-16016 October 1975 AO 75-28:on 751015,standby Gas Treatment Sys 1 Inoperable. Caused by Air Solenoid Valve Coil Failure.Defective Solenoid Coil replaced.W/751016 ML19210A2211975-10-10010 October 1975 Abnormal Occurrence 75-37:on 751010,during Transfer of Boric Acid from Storage Tank to Reclaim Tank,Blockage Noticed in Outlet Line.Caused by Boric Acid Crystals Settling to Drain Due to Improper Mixture ML19210A2241975-10-0808 October 1975 Abnormal Occurrence 50-289/75-34:on 750928,inoperative Hydraulic Shock Suppressor Threatened Function of Engineered Safety Feature.Low Fluid Level in Snubber Caused Failure. All Other Snubbers Checked Satisfactorily ML20090D1341975-10-0808 October 1975 AO 75-27:on 751008,low Reactor Pressure Core Spray Valve Permissive Pressure Switches RE17B & D Tripped at Pressures Less than Min Required Value.Caused by Switch Repeatability. Pressure Switches Recalibr ML19322A4371975-09-30030 September 1975 Abnormal Occurrence 75-34 Re Disconnected Hydraulic Snubber within Reactor Bldg Secondary Shield.Investigation of Circumstances Incomplete.Snubber Replaced During Ongoing Seal Replacement Program ML19210A2461975-09-26026 September 1975 Abnormal Occurrence 50-289/75-31:on 750917,core Flood Tank Water Level Below Tech Specs Requirements.Caused by Incorrect Reading on Lower Reading Channel CF2-LT3.Channel Will Now Be Monitored & Personnel Informed on Procedures ML19210A2411975-09-26026 September 1975 Abnormal Occurrence 50-289/75-33:on 750917,de-ice Makeup Valve NR-V-4A Failed in Open Position.Failure Caused by High Resistance Contact in Closing Control Circuit Not Fully Energizing.All Control Contacts to Be Checked & Cleaned ML19210A2391975-09-26026 September 1975 Abnormal Occurrence 50-289/75-32:on 750918,incorrect Open Position of Air Supply Valves PP-V-47 & 179 Could Have Prevented Proper Functioning of Door Seals in Event of Emergency Safeguards Actuation.Jj Colitz 750919 Ltr Encl ML20090D1501975-09-23023 September 1975 AO 75-26:on 750923,emergency Svc Water Pump 52C Failed to Start Automatically During Routine Surveillance Test of Containment Spray Sys Ii.Caused by Failure of Contact Switch in Time Delay Relay 16 K4B.Relay Replaced ML19210A2451975-09-19019 September 1975 Abnormal Occurrence 75-33 Re Failure of de-ice Makeup Valve NR-V-4A to Close Using Control Room Remote Pushbutton.Caused by High Resistance Contact in Closing Control Circuit. Contact Cleaned,Tested & Returned to Svc ML19322A4361975-09-18018 September 1975 Abnormal Occurrence 75-31 Re Low Borated Water Level in Core Flood Tank B.Caused by Improper Level Channel Transmitter LT3 Readout.Transmitter Adjusted ML19291C2641975-09-0808 September 1975 AO 73-19:when Closing Signal Was Applied to Breaker S1A,loss of Power Occurred at 4160-volt Ac Bus 1A Causing Trip of Various Pumps.Caused by Incorrect Setting of Current Transformer Ratio Matching Taps.Taps Set Properly ML20090D2071975-09-0808 September 1975 AO 75-24:on 750829,electromatic Relief Valve Pressure Switches 1A83C & 1A83D Tripped at Pressures in Excess of Max Allowable Value.Caused by Instrument Setpoint Repeatability. Switches Reset ML20090D1941975-09-0808 September 1975 AO 75-25:on 750829,stack Gas Sample Sys Failed to Monitor Stack Releases Continuously While Reactor Was in Unisolated Condition.Caused by Malfunctioning Pump Lubricator.Thermal Overload Protection Reset ML19210A2251975-09-0505 September 1975 Abnormal Occurrence 50-289/75-30:on 750827,valve CF-V-2B of Core Flood Tank B Sample Line Isolation Failed to Close Upon Receipt of Engineered Safeguards Actuation Signal.Caused by Valve Binding Against Valve Stem ML19210A1791975-09-0505 September 1975 Abnormal Occurrence 50-289/75-29:on 750827,reactor Bldg Purge Supply Valve AH-V-1D Failed to Close Prior to Engineered Safeguards Test.Caused by Corroded Robotarm Actuator.Robotarm Actuator Lubricated ML20090D2151975-09-0202 September 1975 AO 75-24:on 750829,electromatic Relief Valve Pressure Switches 1A83C & 1A83D Tripped at Pressures in Excess of Max Allowable Value.Caused by Instrument Setpoint Repeatability. Switches Reset ML20090D2011975-09-0202 September 1975 AO 75-25:on 750829,stack Gas Sample Sys Failed to Monitor Stack Releases Continuously While Reactor Was in Unisolated Condition.Caused by Malfunctioning Pump Lubricator.Thermal Overload Protection Reset ML19210A1811975-09-0202 September 1975 Abnormal Occurrence 50-289/75-28:on 750823,MS-V-13A Valve Turbine Drive Emergency Feed Pump Failed to Remain Open. Caused by Control Circuit Pressure Switch Failure,Due Possibly to High Ambient Temp ML19210A1871975-08-29029 August 1975 Abnormal Occurrence 50-289/25-27:on 750821,crack & Leak Found in Auxiliary Makeup Pump a Suction Vent.Caused by Fatigue Due to Vibration.Cracks Repaired & Hydrostatically Tested.Failed Pipe Section Replaced ML19322A4351975-08-28028 August 1975 Abnormal Occurrence 75-30:on 750827,core Flood Tank B Sample Line Isolation Valve CF-V2B Failed to Close Following Engineered Safeguards Signal.Valve Manually Closed Using Handwheel ML19210A1861975-08-27027 August 1975 Abnormal Occurrence 75-29:on 750827,reactor Bldg Supply Valve AH-V-1D Failed to Fully Close.Investigation Into Cause Underway ML19210A1841975-08-23023 August 1975 Abnormal Occurrence 75-28:on 750820,during Test of Turbine Drive Emergency Feed Pump,Associated Valve Failed to Remain Open.Caused by Failed Pressure Switch ML20090D2241975-08-21021 August 1975 AO 75-23:on 750817-20,stack Effluent for Iodine & Particulates Not Monitored.Caused by Personnel Error.Filter Installed in Operating Stack Gas Sampling Train ML19210A1901975-08-21021 August 1975 Abnormal Occurrence 75-27 on 750821:leaks Found in Socket Weld Joint at Makeup Pump a & Suction Line Connection W/Pump Suction Header.Cause of Problem Under Investigation ML20090D2261975-08-11011 August 1975 Preliminary AO-50-219/75-22:on 750810,stack Gas Sample Line Low Flow Alarm Received.Caused by Stack Gas Sample Pump a Not Running.Thermal Overload Protection Reset ML20090D2471975-08-0404 August 1975 Preliminary AO-50-219/75-21:on 750801,during Routine Surveillance on B Isolation Condensor Sys,Steam Line Valve V-14-32 Failed to Close on Simulation of Steam Line High Flow.Caused by Low Torque Switch Setting.Torque Increased ML19210A1941975-08-0101 August 1975 Abnormal Occurrence 50-289/75-26:on 750724,high Reactor Coolant Pressure Trip Set Points Less Conservative than Tech Specs.Caused by Calibr Drift.Specs Will Be Changed to Account for Instrument Error 1976-02-05
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217K4451999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Oyster Creek Nuclear Generating Station.With ML20217K4701999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for TMI-1.With ML20211P6731999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Oyster Creek Nuclear Generating Station.With ML20211H5111999-08-31031 August 1999 Non-proprietary Rev 1 to MPR-1820(NP), TMI Nuclear Generating Station OTSG Kinetic Expansion Insp Criteria Analysis ML20211Q3551999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Tmi,Unit 1.With ML20210R4791999-08-13013 August 1999 Update 3 to Post-Defueling Monitored Storage SAR, for TMI-2 ML20211A7051999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Oyster Creek Nuclear Station.With ML20210U4791999-07-31031 July 1999 Monthly Operating Rept for July 1999 for TMI-1.With ML20209G0011999-07-0909 July 1999 Staff Evaluation of Individual Plant Exam of External Events Submittal on Plant,Unit 1 ML20210K7651999-07-0909 July 1999 Rev 2 to 86-5002073-02, Summary Rept for Bwog 20% Tp Loca ML20209H8251999-07-0101 July 1999 Provides Commission with Evaluation of & Recommendations for Improvement in Processes Used in Staff Review & Approval of Applications for Transfer of Operating Licenses of TMI-1 & Pilgrim Station ML20209H1421999-06-30030 June 1999 Monthly Operating Rept for June 1999 for TMI-1.With ML20209G0631999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Oyster Creek Nuclear Generating Station.With ML20212H5491999-06-18018 June 1999 Non-proprietary Rev 4 to HI-981983, Licensing Rept for Storage Capacity Expansion of Oyster Creek Spent Fuel Pool ML20195H0751999-06-0808 June 1999 Drill 9904, 1999 Biennial Exercise for Three Mile Island ML20209G0351999-05-31031 May 1999 TER on Review of TMI-1 IPEEE Submittal on High Winds,Floods & Other External Events (Hfo) ML20195H9261999-05-31031 May 1999 Monthly Operating Rept for May 1999 for TMI-1.With ML20195E7961999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Oyster Creek Nuclear Generating Station.With ML20207B6621999-05-27027 May 1999 SER Finding That Licensee Established Acceptable Program to Periodically Verify design-basis Capability of safety-related MOVs at TMI-1 & That Util Adequately Addressed Actions Required in GL 96-05 ML20206R0571999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Tmi,Unit 1.With ML20206N7431999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Oyster Creek Nuclear Generating Station.With ML20206D4201999-04-20020 April 1999 Safety Evaluation Granting Exemption from Technical Requirements of 10CFR50,App R,Section III.G.2.c for Fire Areas/Zones AB-FZ-4,CB-FA-1,FH-FZ-1,FH-FZ-6,FH-FZ-6, IPSH-FZ-1,IPSH-FZ-2,AB-FZ-3,AB-FZ-5,AB-FZ-7 & FH-FZ-2 ML20205K6851999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Tmi,Unit 1.With ML20205P5401999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Oyster Creek Nuclear Generating Station.With ML20209G0071999-03-31031 March 1999 Submittal-Only Screening Review of Three Mile Island,Unit 1 Individual Plant Exam for External Events (Seismic Portion) ML20210C0161999-03-0101 March 1999 Forwards Corrected Pp 3 of SECY-98-252.Correction Makes Changes to Footnote 3 as Directed by SRM on SECY-98-246 ML20207M8461999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for TMI-1.With ML20204C8201999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Oyster Creek Nuclear Generating Station.With ML20196K3561999-01-22022 January 1999 Safety Evaluation Concluding That Although Original Licensee Thermal Model Was Unacceptable for Ampacity Derating Assessments Revised Model Identified in 970624 Submittal Acceptable for Installed Electrical Raceway Ampacity Limits ML20207A9291998-12-31031 December 1998 1998 Annual Rept for TMI-1 & TMI-2 ML20199E4671998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Oyster Creek Nuclear Generating Station.With ML20196G4661998-12-31031 December 1998 British Energy Annual Rept & Accounts 1997/98. Prospectus of British Energy Share Offer Encl ML20195E8321998-12-31031 December 1998 10CFR50.59(b) Rept of Changes to Oyster Creek Sys & Procedures, for Period of June 1997 to Dec 1998.With ML20196F6861998-12-0202 December 1998 Safety Evaluation Accepting Licensee Second 10-yr Interval ISI Program Plan Request for Alternative to ASME B&PV Code Section XI Requirements Re Actions to Be Taken Upon Detecting Leakage at Bolted Connection ML20198B8641998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for TMI-1.With ML20198D2091998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Oyster Creek Nuclear Generating Station.With ML20195J8591998-11-12012 November 1998 Rev 11 to 1000-PLN-7200.01, Gpu Nuclear Operational QA Plan ML20195C6921998-11-12012 November 1998 Safety Evaluation Supporting Amend 52 to License DPR-73 ML20195C4271998-11-0606 November 1998 Safety Evaluation Supporting Proposed Ocnpp Mod to Install Core Support Plate Wedges to Structurally Replace Lateral Resistance Provided by Rim Hold Down Bolts for One Operating Cycle ML20155J3021998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Oyster Creek Nuclear Generating Station.With ML20196B7191998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for TMI-1.With ML20203G1211998-10-30030 October 1998 Informs Commission About Staff Preliminary Views Concerning Whether Proposed Purchase of TMI-1,by Amergen,Inc,Would Cause Commission to Know or Have Reason to Believe That License for TMI-1 Would Be Controlled by Foreign Govt ML20154R4981998-10-20020 October 1998 Core Spray Sys Insp Program - 17R ML20155E7511998-10-15015 October 1998 Rev 1 to Form NIS-1 Owners Data Rept for Isi,Rept on 1997 Outage 12R EC Exams of TMI-1 OTSG Tubing ML20154L3051998-10-14014 October 1998 Safety Evaluation Accepting Licensee Request to Defer Insp of 79 Welds from One Fuel Cycle at 17R Outage ML20154L5541998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for TMI Unit 1.With ML20154L5571998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Oyster Creek Nuclear Generating Station.With ML20154Q3371998-09-30030 September 1998 Rev 8 to Oyster Creek Cycle 17,COLR ML20153A9941998-09-16016 September 1998 Safety Evaluation Denying Request to Remove Missile Shields from Plant Design ML20151U8821998-09-0808 September 1998 SER on Revised Emergency Action Levels for Gpu Nuclear,Inc, Three Mile Island Nuclear Plant Units 1 & 2 1999-09-30
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Deputy Director for Reactor Projects
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Directorate of Licensing f United States Atomic Energy Commission _
Washington, D. C. 20545
Dear Mr. Giambusso:
Subject:
Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/74-48 The purpose of this letter is to forward to you the attached Abnormal Occurrence Report in compliance with paragraph 6.6.2.a of the Technical Specifi-cations.
Enclosed are forty copics of this submittal.
Very truly yours, AG' Donald A. Ross w
Manager, Nuclear Generating Stations cs Enclosures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region 1 s
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- 201539-6111 na-,,, or tw General hjj',} Pubhc Utilities Corporation OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74-48 .
Report Date October 4,1974 Occurrence Date September 25, 1974 Identification of Occurrence
- Inoperability of the A and B isolation condensers due to high flow as sensed by the condensate line break sensors. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D.
Conditions Prior to Occurrence The plant was in post scram stabilization operations. Conditions prior to the scram were:
Power: Reactor, 1902 MWt -
Electric, 665 MWe Flow: Recirculation, 60.2 x 10 6 lb/hr Feedwater, 7.11 x 10 6 lb/hr Reactor Pressure: 1020 psig Stack Gas: 12,600 pCi/sec Description of Occurrence On September 25, 1974, a generator load rejection scram occurred which resulted in closure of the main steam isolation valves approximately 45 seconds after the scram due to low main steam line pressure. In order to remove the reactor decay heat and to control reactor pressure, an attempt was made to initiate the B isola-tion condenser. Approximately one-half minute after initiation, the B isolation condenser rupture alarm sounded and the condenser isolated. Since there were 10373 1
F 0 0 5
Abnormal Occurrence No. 50-219/74-48 Page 2 no indications of line rupture, the operator on duty immediately pushed the isolation condenser reset button and reinitiated the condenser which again isolated after about one-half minute. The operator then initiated the A isola-tion condenser which also isolated approximately one-half minute after initiation.
Instrument department personnel were dispatched to the area of the line break instrumentation to verify high AP signals. Differential pressures of approximately 22 inches water were observed at this time. Recirculation flow was then reduced from rated flow after which the isolation condensers reset. Since the condensers were operabic for half-minute periods due to the action of an isolation bypass time delay relay, which is started when the isolation signal occurs, the operator was abic to initiate and reset alternately the condcaser isolations. This pro-vided a heat sink for the reactor decay heat until the effects of the reduction in recirculation flow allowed the isolation condensers to reset.
Apparent Cause of Occurrence This occurrence was caused by the tripping of line break sensors which was due to the effects of rated recirculation flow.
Analysis of Occurrence The isolation condensers are considered to be part of the engineered safeguards system referred to in the emergency core cooling system analysis submitted in Amendment 67 to the Oyster Creek FDSAR. Automatic initiation of the isolation condensers occurs on low-low water level which also results in the tripping of the recirculation pumps. It was demonstrated during this event that when recirculation flow was reduced, differential pressures of approximately 10 inches water were observed. Since this value is close to that expected with tripped recirculation pumps, both isolation condensers would have functioned as heat sinks during a loss of coolant accident.
Corrective Action Surveillance testing was performed on all isolation condenser condensate line .
break sensors. "As found" set points for the sensors were approximately 24 inches water. This is the set point that had been previously chosen due to sensor set point drift problems. During this testing, the line break sensors were adjusted to trip at 27 inches water. The 27 inches trip point corresponds to a minimum reset point of 23.5 inches water. Since this minimum observed reset point is above the AP noted at rated recirculation flow (22 inches water), the 27 inches trip point is considered to be adequate for isolation condenser operation under all recirculation flow conditions.
Based upon the dependence of isolation condenser operation on recirculation flow conditions demonstrated in this occurrence, this relationship and applicable plant procedures will be reviewed in the on-going operator training program.
Failure Data l
I Not applicabic.