North Anna Unit 1 and Unit 2 ROOT CAUSE EVALUATION

8/3/2019 North Anna Unit 1 and Unit 2 ROOT CAUSE EVALUATION

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VIRGINIA ELECTRIC AND POWER COMPANYRICHMOND, VIRGINIA 23261 10 CFR 100, Appendix A

October 12, 2011U.S. Nuclear Regulatory CommissionAttention: Document Control DeskWashington, DC 20555

Serial No.:NL&OS/GDMDocket Nos.:License Nos.:

11-578R250-338/339NPF-4/7

VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)NORTH ANNA POWER STATION UNITS 1 AND 2ROOT CAUSE EVALUATIONDUAL UNIT TRIP FOLLOWING TH E AUGUST 23, 2011 EARTHQUAKEDuring a September 30, 2011 telephone conversation between Dominion personnel and NR Cstaff, the NRC requested information regarding the root cause evaluation (RCE) for NorthAnna Power Station that addressed the dual unit trip following the August 23, 2011 Mineral,Virginia earthquake. Pursuant to the NRC request, a summary of excerpted portions of theRCE is provided as an attachment to this letter along with selected attachments to the RCE.Separately, in regard to the "Sequence of Events Validation" discussion, unexpectedinstrumentation responses were evaluated, and an investigation determined that the alarmsreceived were valid for the existing plant conditions.If you have any questions or require additional information, please contact Mr. Gary D. Millerat (804) 273-2771.Sincerely,


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Serial Number 11-578Docket Nos. 50-338/339Page 2 of 2cc : Regional Administrator

U.S. Nuclear Regulatory Commission - Region IIMarquis One Tower245 Peachtree Center Ave. NESuite 1200Atlanta, Georgia 30303-1257NRC Senior Resident InspectorNorth Anna Power StationM. KhannaBranch Chief - Mechanical and Civil Engineering BranchU. S. Nuclear Regulatory CommissionOne White Flint NorthMail Stop 09 E-311555 Rockville PikeRockville, MD 20852-2738R. E. MartinNRC Project ManagerU. S. Nuclear Regulatory CommissionOne White Flint NorthMail Stop 08 G-9A11555 Rockville PikeRockville, MD 20852-2738P. G. BoyleNRC Project Manager


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Serial Number 11-578Docket Nos. 50-338/339

Attachment

Summary of Excerpted Portions of the Root Cause Evaluation - Dual Unit TripFollowing Magnitude 5.8 Earthquake


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*pV DominiionSummary of Excerpted Portions

Root Cause EvaluationRCEO01061Rev I

Dual Unit Trip Following Magnitude 5.8Earthquake


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Table of Contents

1.0 Executive Summary 41.1 Problem Statement 41.2 Root Causes 41.3 Contributing Cause(s) 41.4 Corrective Action 41.4.1 Corrective Action(s) to Prevent Recurrence (Not Included in Summary of

Excerpted Portions)1.4.2 Recommendation for Contributing Causes (Not Included in Summary of

Excerpted Portions)1.4.3 Compensatory or Short Term Corrective Action (Not Included in Summary of

Excerpted Portions)1.4.4 Other Insights That Warrant Corrective Action (Not Included in Summary of

Excerpted Portions)2.0 Detailed Report 42.1 Team Members (Not Included in Summary of Excerpted Portions)2.2 Event Investigation and Analysis 42.3 Organizational and Programmatic Review(Not Included in Summary of

Excerpted Portions)


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Attachment(s):Attachment 1:Attachment 2:Attachment 3:

Attachment 4:Attachment 5:Attachment 6:Attachment 7:

Attachment 8:

Attachment 9:

Attachment 10:Attachment 11:Attachment 12:Attachment 13:

Nuclear Instrumentation Core OrientationWhy ChartDual-Unit Seismically-Induced Reactor Trip - Indicated Nuclear PowerTransient Cause Matrix (Not Included in Summary of Excerpted Portions)Timeline of Events Unit 1Timeline of Events Unit 2Electrical TimelineFailure Mode Effects Analysis (FMEA) (Not Included in Summary ofExcerpted Portions)Organizational and Programmatic Deficiencies Fishbone (Not Included inSummary of Excerpted Portions)Cause To Corrective Action Matrix (Not Included in Summary of ExcerptedPortions)Analysis Of Dranetz Event Data vs Plant Computer SystemPurdue AssessmentResponse Time Assessment (Not Included in Summary of Excerpted Portions)1H Bus & Seismic Activity


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1.0 Executive Summary1.1 Problem Statement"On August 23, 2011 at 1351 North Anna Power Station experienced a magnitude 5.8earthquake followed by a dual unit trip and a loss of offsite power. The purpose of this RootCause Evaluation is to:0 Identify the cause for the reactor trips on NAPS Unit 1 and Unit 2."1.2 Root Causes1.2.1 "The Direct Cause for the both the Unit 1 and Unit 2 reactor trip was the initiation ofthe rate Nuclear Instrument (NIs) Power (PWR) Range Hi Flux Rate Reactor Trip. Both Unit1 and Unit 2 met the required coincidence of 2 out of 4 Power Range Nuclear Instruments(PRNI) with greater than a 5 % change in 2.25 seconds.(RC1) The Root Cause of this event was a synergistic combination of seismically inducedconditions which include core barrel movement, detector movement, and small reactivityeffects from core movement and thickening of the thermal-boundary layer along the fuelrods. The additive effects of the combined conditions resulted in momentary undermoderated core conditions as evidenced by the oscillatory bu t overall decreasing flux profilesfrom both Unit 1 and Unit 2."1.3 Contributing Cause(s):1.3.1 "N o Contributing Causes are applicable to this event. All potential candidates forContributing Causes were investigated in detail and determined to not be credible."


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Trip". The "First Out" turbine trip signal for Unit 1 was "Main Transformer Lock Out". The"First Out" for Unit 2 was "Reactor Trip/Turbine Trip".To facilitate the investigation the following investigative techniques were used;1. Fault Diagram - "Why" chart (Attachment 2) ...2. Event Timeline (Attachments 4, 5 and 6) ...3. Analysis Of Dranetz Event Data vs Plant Computer System (Attachment 10)"

Detailed DiscussionIntroduction"The RCE Team began by gathering all available information already obtained by the EventReview Team as well as data that was not previously available. A critical source ofinformation made available to the RCE Team was the Transient Response Analysis (TRA)data which provides thirty-three sample points per second from one hour before the ReactorTrip Breakers opened until ten minutes after the start of data acquisition. The data capturesPlant Computer System (PCS) monitored points on a much higher than normal sampling rate.It is important to note that normal post trip analysis at NAPS would not routinely involvescrutinizing post trip data on a thirty-three times per second sampling interval. The normalsampling rate did not show a negative rate trip when reviewed. The period in question isextremely short in duration, approximately one second long. With the assistance of NuclearAnalysis and Fuels (NAF) the Unit 1 and 2 average PRNI traces were then plotted. The graphbelow (Figure 1) shows the results.

Unit 1 an d 2 Power vs Time During Earthquake(Average of 4 NI signals)


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Intermediate Range Nuclear Instrumentation (IRNI) traces and they also produced a similartrend when plotted (See Figures 2 and 3).105 -3100 U IR & PR Comparisons -3.05

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as the Gamma-metrics excore detector signals (-one second sampling rate) did not provideany useful data. The RCE Team concluded that the likelihood of an instrument failure/faultimpacting Unit 1 and 2 PRNIs as well as IRNIs at the exact same time and in the exact samemanner was deemed non-credible ... Based on this, the focus of the RCE Team was toidentify which seismic related events could impact either indicated or true reactor power.Several Short Term Corrective Actions (STCA) and Enhancements were created to verifythat the Nuclear Instruments were not damaged during this event."

RCE Team Methodology"The RCE Team postulated various theories to explain the shape of the PRNI traces... If thetheory was deemed plausible, every effort was made to quantify the impact on eitherindicated power or real power.Each theory was reviewed by the RCE Team, discussed with Dominion Nuclear Analysis andFuels (NAF) personnel and Westinghouse personnel brought on site to assist the RCE Team.Westinghouse personnel also requested support from their corporate support staff to assistwith the vetting process.

Specific Indicated Nuclear Power Transient Cause Discussion"Operating experience and testing associated with Japanese nuclear reactors indicates corereactivity changes can occur as a result of small changes in overall fuel geometry caused byearthquakes. This phenomenon would cause a down power created by seismic vibrationsdisrupting the laminar sub-layer along the cladding wall resulting in rapid and transitorybubble bursts that would add negative reactivity due to the void defect. The RCE Team notedthat the down power at the start of the event coincides with the start of seismic activity. Oncethe Reactor Trip Breakers opened there were several more oscillations which coincided withthe highest seismic peaks noted during the earthquake. Figure 4 and 5 show the correlationbetween the oscillations and seismic activity on both Units. Also plotted on the graphs is thetime that reactor trip breakers opened.


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Unit 1 PRNI vs Time During Earthquake(Average NIsignals)

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Time (mmms.s)

Figure 4Unit 2 PRNI vs Time During Earthquake

(Average NI signals)


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power oscillations 180 degrees out of phase with each other during some parts of the event.These PRNIs are located in a plane along the same axis in both Units (See Figure 6).

Figure 6

By overlaying the NI plots with the seismic motion recorded at NAPS a strong correlation is noted.(See Figures 7 and 8) .


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Another graph used to compare the difference between N-41/42 and N-43/44 is shown inFigures 9 and 10. It is a plot of the magnitude of the difference between these two sets of NIsat any given time. As an example Unit 1 shows that N-41 and N-42 were out of synch for themajority of the event. It also shows the predominate effect was in the east -west plane.

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CASMO calculation to determine the effect of reducing the assembly pitch shows thatmoving all assemblies in the core closer together by 31 mils (the inter-assembly gap) reducesreactivity by 50 pcm, which could produce a power reduction of 10%. A much smaller effectcould occur locally with a smaller set of assemblies. Secondary flow in the core may bepossible resulting in a possible explanation of the localization of thermal-boundary layers.Existing bubbles would grow or new bubble generation could occur. According to theresearch results in Japan, these bubbles can collapse significantly when the frequency ishigher than 10 Hz. The Purdue Assessment is included in this report (Attachment 11)."Core Compression"Movement of internal core components due to the earthquake could close the gaps betweenassemblies in the core which would add negative reactivity. The subsequent decompressionwould then add positive reactivity. Westinghouse Core Design experts estimated that thiscould add as much as 100 to 200 pcm. Subsequent evaluation determined that the corecompression during a seismic event would occur after the time of the reactor trip and couldnot explain the entire power behavior; however, it could be a minor contributor. Additionallythe Purdue Assessment also discusses the impact of fuel assembly motion on localizedchanges in the fuel rod thermal-boundary layer, which can produce bubble growth andbubble generation that could be a minor potential contributor to the power transient."Core Barrel Movement"Based on the fact that there was a correlation between PRNI and seismically induced motionthe RCE Team discussed what could cause indicated PRNI to change due to motion of thecore. One possible theory was that the gap between the core barrel and the vessel wallincreased by seismic motion, thereby decreasing the flux seen by the PRNI detectors due tomore moderation. The outer most fuel assemblies produce the majority of flux seen at thedetectors and if the moderator thickness was increased this would cause a down powerindication. This is due to the fact that the freedom of movement for core components is


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Figure 11Westinghouse reports that an analysis performed for Beaver Valley, a sister plant to NAPS,indicates that it is possible for detector movement within the wells to cause a 5% variation inindicated reactor power. Based on the analysis this was deemed possible but would not causethe trip by itself."

Rod Control Motor Generator Set Output Breakers"Initially it was thought that the event was caused by opening of the Rod Control MotorGenerator set output breakers. This was based on the fact that all four Rod Control MotorGenerator set output breakers had an instantaneous over current trip locked in and wereverified open as noted in post event walk downs. NAF reviewed the PRNI traces an d notedthat the rate of power decrease at the start of the event was not high enough to support thistheory based on computer modeling. At this point the RCE Team concluded that rodmovement started after the Reactor Trip Breakers opened and that in all likelihood the outputbreaker drops came after the breakers opened and therefore could not be the cause of theinitial down power excursion. Although the Rod Control Motor Generator output breakers


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NAPS Reactor Trips - Indicated Nuclear Power Profiles120

NOTE:Alldata synchronized to RTBopening

100 time. 2011 seismic trip data for Unit 1 1! * and Unit 2 artificially appear to be out-

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, *The overlay of the 1995 MG Se t event demonstrates__6o the earthquake events were not caused by

4the MG Output BreakereoThe 1995 Ul Dropped Rod events matches the earthquake eventshowever, Rod Drop has been refuted as a cause based on the FMEA40and investigation of ro d drop times.

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Time Relative to RTBOpening (sec)1995 U2 M-GSe t 1996 Ul Dropped Rod - 2011 U1 Seismic NFRT - 2011 U2Seismic NFRT

- - 1995 U2 M-G Set Shifted 2007 U2 SI - - - ReactorTrip Breaker

Figure 12Th e RCE Team also noted that had the output breaker indication been available on PC S orthe "Rod Control MG Sets Trouble" annunciator been recorded the exact time could havebeen fixed."


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"Unit 1Dranetz point 0031 - RWST CHEM ADD TK LO TEMPThe Trip for LO temperature is 25 degF, Reset is 26.5 degF. This may have been caused by aconnection issue with the field or cabinet wiring providing an intermittent partial short acrossthe RTD causing a low temperature input to the NRA card TM-QS201 (CF-121). I&C checksof wiring and calibration recommended.Dranetz point 0036/PCS point T0444A, T0497A - Loop 1C HI DELTA T DEVIATIONActual Delta T Deviation never exceeded the setpoint, so the reason for this actuation isUNKNOWN. Recalibration did not show any anomalous data. Same event on Unit 2.Additional I&C checks recommendedDranetz point 0041 - FIRE WATER SYSTEM INITIATEDFire system pressure changes during seismic event may have caused this indication. This isindicated by initial fast Init/Normal toggling time of < 400ms due to earthquake. No plant logentries found for Fire System Initiated on 08/23/2011. Although not indicated in plant logs,RCE team post trip discussion with Operations personnel indicated that the fire water systemactuated. Additional I&C checks recommended.

Unit 2Dranetz point 0031 - RWST CHEM ADD TK LO TEMPThe Trip for LO temperature is 25 degF, Reset is 26.5 degF. This may have been caused bya connection issue with the field or cabinet wiring providing an intermittent partial shortacross the RTD causing a low temperature input to the NRA card TM-QS101 (CF-121).Additional I&C checks recommendedDranetz point 0036/PCS point T0444A, T0497A - Loop 1C HI DELTA T DEVIATIONActual Delta T Deviation never exceeded the setpoint, so the reason for this actuation is


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2.5 Assessment of Safety Consequences"The observed negative and positive reactivity excursion of the event was postulated to haveoccurred due to synergistic effects of the seismic event. Core motion induced reactivitychanges resulted in a net negative reactivity addition and observed power decrease followedby a net positive reactivity addition and observed power increase. The power increase onUnit 1 was observed to peak and turn downward without rod motion, on Unit 2 the positivepeak was arrested by the control motion. At no time did reactor power increase above 100%following the initial decrease in power. There were no safety consequences as a result of thisevent and the reactor was shut down as a result of a negative flux rate trip. All protectionequipment responded as designed as documented in the OP-AA-105, Post Trip ReviewReport."Safety Analysis Summary of Reactor Trip Data"The Plant Computer System data was reviewed relative to the requirements of the NorthAnna UFSAR safety analyses. Based on a review of this data, the global RCS response isconsistent with a normal reactor trip from full power followed by an RCP trip coastdownfrom the loss of power to the supply buses. Although there are some core power variationsprior to full control rod insertion, power decreases from the initial value and at no timeexceeds 100% power. RCS temperatures trend smoothly toward hot zero power values asexpected with no perturbations. There were some variations in pressurizer pressure andlevel early in the event whose validity could not be confirmed; however, the overall trendswere reasonable and the magnitudes, even considering the variations, were well within safetyanalysis response values.Safety analysis events most applicable to this event include UFSAR 15.2.7 "Loss of ExternalElectrical Load and/or Turbine Trip" (LOEL), UFSAR 15.2.9 "Loss of Offsite Power to theStation Auxiliaries" (LOOP), and UFSAR 15.3.4 "Complete Loss of Reactor Coolant Flow"(CLOF). Since the reactor trip, turbine trip and reactor coolant pump trips occurred atessentially the same time during the plant event, the transient response was easily bounded


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2.8 Operating Experience"Note: Attempts were made to obtain Fukushima OE, however no data could beobtained that applied to this report.A search of internal and external OE which may be related to this event was conducted. TheOE which has been reviewed for the RCE report is listed below. None of the OperatingExperience reviewed could have predicted or prevented the reactor trips at North Anna. Themajor lesson learned was to improve our station procedure for responding to a seismic eventto meet industry standards. This specific issue will be addressed in the "Organizational andProgrammatic Review" section of the RCE. The specific response of the NuclearInstrumentation during the earthquake at NAPS was no t identified in other plant OE. Onepossible reason for this, which was brought up in calls with others, is that the resolution ofthe data which the ERT and RCE team looked at (33.3 times per second) is not obtainable atother sites with their installed computer systems. No internal and external events similar toNAPS in regards to initial plant response (RX trip on high flux rate) could be found either.Other sites have had seismic events. Some have resulted in reactor trips and others have not.For the OE looked at, those trips were a result of electrical issues, manual trips, or automatictrips as a result of trip signals keyed off of seismic activity."LER 87-075-00 Vogtle - Unit 1 Missing Screws in the Nuclear Instrumentation Drawers"O n December 22, 1987, at 1406, with Unit 1 at approximately 99 percent of rated thermalpower (RTP), an Instrumentation and Control (I&C) technician, while taking test readings ina power range Nuclear Instrumentation (NI) drawer, identified that the screws were missingfrom a hold down (cover) plate on a printed circuit (PC) card rack. The plate functions as ahold down plate for the card assemblies to aid in the restriction of card movement.The exact circumstances by which the screws came to be missing were not known. It isthought that this event occurred because a failure to initially install these screws was notdiscovered during the Construction Acceptance Test Program or during the subsequent


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Power Plant (DCPP). Ground motion was felt and recognized as an earthquake by the controlroom operators. The earthquake force monitor recorded greater than 0.01g for the seismicevent. Operations personnel declared an Unusual Event at 1122 PST. (Reference NRC EventNotification Number 40408.) On December 23,2003, at 1212 PST, the Unusual Event wasterminated upon confirmation that no damage to the plant occurred. There was no adverseeffect to public health and safety, or upon facility features important to safety.The main shock was felt in the Units 1 and 2 Control Room. It triggered the basic seismicsystem analog recorder (Kinemetrics SMA) in the Control Room and the Kinemetrics digitalrecorders (SSA) at the Unit 1 containment base, top of containment, the Auxiliary Building,and the free field pit locations (near the Fitness Trailer). The supplemental system was out ofservice at the time of the earthquake, however, three temporary accelerometers located in theAuxiliary and Turbine Buildings and a permanent instrument in the basement of the 500 kVSwitching Center triggered. The supplemental system was unavailable and replacement partsare obsolete; both the basic and supplemental systems are scheduled to be replaced inJanuary 2004 with new instrumentation.""This OE was evaluated as being applicable to this event. Two areas of concern in this OEare that at Diablo Canyon, the installed seismic supplemental system was unavailabledue tomaintenance and the main turbine experienced rotormovement during the event, and varioustank levels alarmed at Diablo Canyon. At NAPS, a portion of the installed seismicinstrumentation did not have power available from when the emergency bus was de-energized until it was restored by its respective Emergency Diesel Generator (EDG)...Temporary Modification #1845 will install an uninterruptible power supply (UPS) on theEarthquake Monitoring Panel 1-EI-CB-151 in the Control Room to address the poweringissue.

"This OperatingExperience could not have predictedorprevented the reactor rips at NorthAnna Power Station."


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"This OE was evaluated as being potentially applicable to this event. During the event,atNAPS, breakers were observed to have tripped and in addition there was a tripping of theA/B/C RSS due to sudden pressure relay actuations.Also, it was observed thatboth units roddrive motor generatorsets output breakers have phase over current trip flags and each ofthese breakers were determined to have tripped at some time during the event. The impactthat the actuationof the phase over currenttrips on the rod drive motor generatorset outputbreakers is being evaluated aspart of the RCE."

"This OperatingExperience could not have predictedor prevented the reactor trips at NorthAnna PowerStation."

OE6860 - Earthquake Near Humboldt Bay Power Plant"On September 1, 1994 at 8:16 a.m. a 7.2 magnitude Earthquake occurred off the north coastof California, approximately 90 miles from Humboldt Bay Power Plant. Unit 3 at this plant isa permanently shutdown BWR. All the fuel is off-loaded in a spent fuel pool. The seismicevent resulted in peak on-site accelerations up to 0.05 g. The peak acceleration at the fuelpool was 0.04 g. The acceleration generated 6 inch waves, which were fully contained withinthe pool. Follow-up inspections verified there was no fuel or fuel pool liner damage causedby this event. Note: this event is relatively minor compared to an April 1992 earthquakewhich generated peak acceleration at the plant of 0.24 g. This April 1992 Quake was ofsimilar magnitude, but was located much closer to the plant. The Design Basis Earthquakefor the plant is 0.25 g."

"Following the event at NAPS, a walkdown of the fuel building, spent fuel pool and spentfuel pool cooling systems was completed. It was reported- y individuals in the NAPS fuelbuilding at the time of the event that there was significantwave action in the spent fuel pooldue to the seismic event, but no apparentdamage was observedand all water was contained


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moved away from the core and safely placed back on its storage stand. A plant standbyemergency was declared that prompted activation of level-1 of the Emergency ResponseOrganization who reached Emergency Control and Technical Support Centers as perprocedure. A detailed inspection of all critical areas and safety equipment of the plant wascarried out and, after confirming normalcy, the "standby emergency" was terminated at 1213hrs the same day and maintenance work was allowed from 1400 hours onward. Fuelunloading operations however remained suspended for subsequent 48 hours in view ofcontinued intermittent aftershocks."

CONSEQUENCES:"Appearance of minor cracks in non-load-bearing walls, damage of an underwater light anddislocation of another in Refueling Water Pool, splash / loss of insignificant quantity ofRefueling Pool water through ventilation ducts, delay in Fuel unloading, and other workexecution.The fuel conveyor car got stuck on its railing inside transfer tube between Reactor and Fuelbuildings when it was tested functionally in the evening of 8th October, 2005. Some grindingwork on the anti-seismic cramp plates corrected the problem. Thereafter the empty conveyorcar got stuck once again inside the transfer tube during actual fuel unloading when it wasbeing moved back after completing unloading of 15th fuel assembly at 2140 hours on l1thOctober, 2005. Interference of one anti-seismic cramp plate, installed on front of the car, withthe railing was found to be the reason. Both anti seismic cramp plates from front of car(facing towards the Reactor building) were temporarily removed in consultation withdesigner to expedite completion of unloading as partial loaded core inside RPV was underrisk from aftershocks.""Following the event at NAPS, a walkdown of the fuel building, spent fuel pool and spent

fuel pool cooling systems was completed. It was reported by individuals in the NAPS fuelbuilding at the time of the event that there was significantwave action in the spentfuel pooldue to the seismic event, but no apparentdamage was observed and all water was contained


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"This OperatingExperience could not have predictedorprevented the reactortrips at NorthAnna Power Station."

OE5406 - Seismic Events, Seismic Ground Motion at SONGS"At 0458 on June 28 , 1992, strong ground motion, measured at .038g, was felt at SONGS, asthe result of an earthquake in Landers, CA (approximately 10 0 miles from the plant).Annunciator "Seismic Recording System Actuation", Seismic Alarm Annunciator Alarm"Strong Motion Acceleration System Activation" was received. Numerous plant alarms werereceived from various plant systems. At 0805 strong ground motion was once again felt,measured at .042g, and the same alarms as mentioned before were received. This was theresult of second earthquake in Big Bear, CA (approximately 70 miles from the plant).At 0502 an Unusual Event was declared after the first series of alarms were received andclosed out at 1035 upon completion of the required checks after the second one. Nosignificant abnormal plant conditions were noted. Unit 2's Spent Fuel Pool filter has beenplugging up frequently due to debris stirred up in the water. There was no significantdamage reported in the media within a 50 mile radius of the plant.""At NAPS, water clarity issues were identified in the spent fuel pool which requiredplacingthe spent uel pool purificationsystem and skimmer in service."

"This OperatingExperience could not havepredictedor prevented the reactor rips at NorthAnna Power Station."

SEN 269 Earthquake at Kashiwazaki-Kariwa"At 10:13 on July 16, 2007, an earthquake of magnitude 6.8 on the Richter scale shook thenorthwest coast of Japan in the Niigata Prefecture near Kashiwazaki City. The epicenter ofthe earthquake was 16 kilometers from Tokyo Electric Power Company's (TEPCO)


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" Seismic events can impact the integrity of radioactive waste storage drums or other itemsthat are stacked without restraints.

* Alternate means of personnel contamination monitoring may need to be establishedfollowing a natural disaster."

"EPRI Technical Report NP 6695, "Guidelines for Nuclear Plant Response to anEarthquake," which provides additional guidance for post-earthquake response actions iscited in the SEN. It is this report that is being used as the basis for our post earthquakeinspectionsand recovery plans."

"This OperatingExperience could not have predicted orprevented the reactor rips at NorthAnna PowerStation."

MER TYO 07-067 Reactor Manual Trip Due to Intensity Level V Earthquakes"On December 26, 2006, Maanshan Unit 1 & 2 were operating at 100% thermal power. At20:26, an earthquake of magnitude (ML) 7.0 occurred at about 25 km southwest of plant sitewith a depth of 44.1 km. At 20:34 (8 minutes later), a second earthquake of magnitude 7.0occurred at about 25 km west of plant site and 50.2 km in depth. The maximum intensity forboth quakes measured at station was level V. The intensity reached 0.25 g for local areanearby.

During the earthquakes, many alarms including turbine and reactor coolant pump highvibration alarms were actuated. But the trip set points were not exceeded. Due to intenseshaking in the control room and many alarms showing on the annunciator panel, unit 2 shiftsupervisor made a conservative decision and ordered a manual reactor trip. All safetysystems were actuated as designed and the unit was stabilized at hot shutdown condition.


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"According to plant procedure, manual reactor trip is required if the earthquake intensityexceeds the OBE settings. The OBE settings range from 0.25 g for containment base to 0.37g for higher level floor. The recorded maximum intensity for these earthquakes was 0.17 g atpower block. Determination of OBE by free-field response spectrum and accumulativeabsolute velocity (CAV) according to RG 1.166 need to be evaluated for applicability inresponse to the actual earthquake energy release."

CORRECTIVE ACTIONS:"In addition to the extensive inspection performed, a further investigation for all buildingstructures' response to the big earthquake was initiated.Further survey of control room non-safety panels and ceilings were completed.A task force was assigned to thoroughly review the procedures in response to the earthquake,post earthquake inspection program and determination criteria of an OBE."

"This OperatingExperience could not have predicted orprevented the reactortripsat NorthAnna PowerStation."

2.9 Extent of Cause"Object of Cause: Nuclear InstrumentationCause: Earthquake induced changesApplication: Reactor Critical Operations* Tier 1 - Same Object - Same Application: Are there other nuclear instrumentation issuesthat have the same cause during reactor critical operations? No. All potential effects onnuclear instrumentation as a result of an earthquake's were evaluated as part of this RCE.


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discussion, there were instrumentation fluctuations, but these fluctuations ceased followingthe earthquake. These same fluctuations could occur during other modes of operation."Extent of Cause Basis"The extent of cause was bounded only to the instruments that are used to monitor the reactorwhile at power or shutdown conditions since they may be affected by the earthquake. Duringthe reactor trip of both North Anna units, other equipment issues were observed which were aresult of the earthquake. This included affects on level instrumentation, spiking on radiationmonitors, failures of the sudden pressure relays for the reserve station transformers, andoperation of the 2H EDG (list no t all inclusive). Each of these and other issues will beevaluated outside of this RCE using the stations corrective action program."2.10 Equipment Reliability/PM Adequacy"Review of the Equipment Reliability and PM 's for the unit 1 & 2 Nuclear InstrumentationSystem Power Range channels and the reactor vessel internals has no t shown any concerns.The Power Range channels and the reactor vessels are properly classified and haveestablished maintenance strategies. There is no actual failure mode to consider as the neutronflux indications seen on the Power Range channels for each unit were an actual seismicinduced indication of flux. A review of the applicable components for equipmentclassification, performance monitoring, preventative maintenance, work practices,design/operation, parts/vendor quality, and aging/obsolescence has no t revealed areas thatwere determined to be inadequate or would have had an impact in mitigating the event."

2.13 Causal Factors"RC1: GVB, Vibration - Failure due to vibration of the equipment or components, oftenas a result of unbalanced loading, mechanical looseness, excessive clearances or

unexpected harmonics."


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/let

INCOFE TUN,.NEL

/ /SA"Loop OutletINCORE TUJNNEL IQ "A" oop InletNote: Those cells gray in olor are confirmed with 11716-FE-47A-1O and 12050-FE-47A-7Note: Akes (AR)(1-15) come fromthe onloadoffload core maps used in efueling, which are very good references, as the SR are clearly defined on these mapsNote: Regardless of unit#. thirn-le N-13 is inquadrant N-4e., C-13 is in 1*42, etc. Therefore Ceois configuration holds truefor QPTR even with U1 and U2 being 18Y out.

N-411 N-.tN-41 N-42

RCE 001061, Rev. 1Page 25 of 130


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Attachment 2HUnit 1/2 TripsF RN IFU AE R

IPWR RNG N42 HI FLUX BISTABLE (NEG) I IPWR RNG N41 HI FLUX BISTABLE (NEG) I

I Indicated Negative Neutron Flux

MG Set Bkr Opens

MG Set Output Over Current Loss of SSequip seismically Trip signal to pwr to MG setaffected MG Set

Output Bkr

Flywheel coastdown only

Breaker Rela Electrical maintainsFault voltage and HzI I for -I second

Not aqCaus-eSame style asRx Trip Bkr Not a causewhich is Flux proftie Not a causeSQUG overlay w/ TimelineQualified previous shows loss ofknown trip SS occurred

not a match after initial trip

Not a CauseFragility Testing Resultsdetermined seismicallyfragile. Flux profileoverlay wt previousknown trip not a match

I or more Dropped Rods

STEM

Gripperdisengages dueto seismicactivity

Not a causeDesign is robust.Statisticallyunlikely to haveboth Unitsexperience thesame mechanicalfailure of theCRDM at thesame time

loss ofvoltage tostationarygripper coils

T i i

Not a Cause Loose LOSS OF Blown fuses Power Cabinet FailuresPer Westinghouse, connections CONTACTpower cycling off and on the CRDM ON FUSEon induced logic errors, cable to head HOLDERSAT Results from 2- connection Not a cause Regulation Firing Card PhaseIPM-RCS-G-001B No blown Card Failure Control CardTesting will rule out fusesdefinitively

Not a cause NOTaRPI traces cause. NOT a NOT a NOT a cause.show no Visual cause, cause.abnormalities checks 2-IPM- 2-IPM- G-OO1B willJackshaft SAT. RCS-G- RCS-G- check fordrionned CARE 01B will OOIB wll proper phasefrom spider Testing by [ check check for control card9/20 will VEER to proper output firing

confirm determine if output voltages>6.2 VDC firing which feed the

Not a Cause Weight voltages firing cardchecks SAT

Logic Cabinetfailures

NOT acauseSAT testresults fromI-IPM-RCS-G-OOIAindicate noissues

PaCe02 6 of, Rev.IPage 26 of 130


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Attachment 2

Not a CauseNI traces indicate actualchange in flux.Equipment responded asexpected. SAT Resultsfrom ChannelOperational Testing willrule out definitively

Analyses performed forBeaver Valley 1 sisterplant in terms of NSSSand NSTdesign) showthat the maximumpossible variation inindicated power wouldbe 5%. This is for thecase of the detectortube contacting the wellwall and is believed tobe a very boundingestimate.

RCE 001061, Rev. 1Page 27 of 130


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Attachment 2

Not a CauseThe required reductionin moderation in thevessel downcomer gapto result in theobserveddecrease/increase inpower is estimated atbetween 0.5"(Westinghouse) and1.0" (NAF).Westinghouseinternals experts havequantified themaximum reduction inthe gap as being on theorder of 0.1".

Nota CauseSeismic motion increasesin magnitude during andafter the reactor trip. Itis difficult to explain whyvoids are formed due toseismic activity, thencease at the same time inboth units even thoughthe seismic motioncontinues to increase.

Not a CauseNAF analyses showedthat it would require onthe order of a 40%reduction in total RCSflow over 0.5 seconds tocause the powerreduction. A nmechanismto cause this reduction,followed by a nearinstantaneous increaseback to full flow (all notseen on high resolutionTRA (Transient ResponseAnalysis) flow data forany loop) is not plausible.

Seismic motion resulting inclosing assembly gaps wouldresult in a decrease in corereactivity in an undermoderatedlattice. Subsequent opening ofgaps when motion changes .direction would be expected toadd positive reactivity to core.

RCE 001061, Rev. 1Page 28 of 130


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Attachment 4 Timeline of Events Unit 1

F;781-1' I

1+ 7-jAR r c-1,0 A

t 'i!


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RCLOOP AS.- P, '0

1 977~

Id wJV'WF~~a'~? U W~I 1HA~SLU

Ihi' ~U~I ~

P AF.5':"

S;tu GrN'C HSTEAYF C W

31~ 1946


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5 " SurIPRESS RELAY5TM~ ~ 1 M-1A1 1~


35/133


UNURVLvTA1.44:


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t_

RC~ O~WA1rpp~J

4N0 N~~u~RArE RX125~lt ~


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Attachment 5 Timeline of Events Unit 2SW 08N BIlS1~M4F SThIGENCH~STh$MlTft~PPEII CHrV'351 11920 ~98PP~0*~St ti

WIS5OOP' C(>ill LOFICMONOT WMIPED1351 11982

nomt4C uS2


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Attachment 5 Timeline of Events Unit 2S&*4CPBUS~AUt~RVOLTAGETRPPED~5! I25&~


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Attachment 6 Electrical Timeline

Unit 1


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Attachment 6 Electrical Timeline

Unit 2


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Attachment 10

North Anna Power StationUnits 1 and 2Analysis of Dranetz event data

versus thePlant Computer System (PCS)For August 23, 2011


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Attachment 10Executive Summary

PurposeThe purpose of this analysis is to determine the validity of the Dranetz SOE Recorder events for North Anna Units 1 and 2during the earthquake that occurred on August 23, 2011. The following tables summarize the analysis of the sequence ofevents for Units 1 and 2, respectively. The Unit 1 analysis begins at time = 13:51:10.224 and ends at time =14:00:14.359. The Unit 2 analysis begins at time = 13:51:11.072 and ends at time = 14:16:18.714. To perform thisanalysis, the Unit 1 and Unit 2 Dranetz Sequence of Events (SOE) Recorder event times were normalized to the PlantComputer System (PCS). For Unit 1, 1.0 Minute and 20.703 Seconds was added to each Dranetz SOE event time. ForUnit 2, 3.0 Minutes and 26.327 Seconds was added to each Dranetz SOE event time. This normalization process wasnecessary because only PCS data sources were used to perform the analysis of the Dranetz SOE events.

Summary of ResultsNorth Anna Unit 1Valid Dranetz SOE Recorded events: 183Outlier Dranetz SO E Recorded events: 25 (8 items are Electrical Power Events)North Anna Unit 2Valid Dranetz SOE Recorded events: 231Outlier Dranetz SO E Recorded events: 38 (11 items are Electrical Power Events)The Unit 1 and Unit 2 Outlier Dranetz SO E Recorded events are addressed in Attachments 3 and 4, respectively. Th ereview of the Outliers by alternate means verification has eliminated many of them; however, some remain withrecommended actions as indicated in Attachments 3 and 4.

MethodologyThe PCS data source of choice was to use the PCS TRA (i.e., the PCS Transient data base) Analog and Digital Points to


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low pass filters embedded in their on-board circuitry. This means that trip setpoint accuracy for any given function will beaffected when the instrument loop is subjected to relatively high frequency input signals (i.e., between 3 and 7 hz for thisevent) and fast ramp rates (i.e., > 300 VD C / Minute "nominal" and > 2000 VDC / Minute in some cases for this event). Inaddition, a small lag component (i.e., = 10 milliseconds) is attributed to the Solid State Protection System for theprocessing of the digital point signals sent to the PCS and the Dranetz SOE Recorder.0When the inaccuracy of the 7300 trip signals is combined with the skewed PCS data sources, judgment had to be used insome cases to determine if the Dranetz event was valid or not. The justification for the determination of the validity of theevent function is contained in the Notes section for each line item in the tables.The rest of the Dranetz SOE event data was developed by individual plant switches and sensors that send on-offelectrical signals directly to SSPS, the Dranetz SOE Recorder, and/or to the PCS. In general, the Dranetz SOE eventdata developed by the Westinghouse 7300 Protection and Control System and the Solid State Protection System wasable to be accurately quantified in the attached analysis as compared to the inputs developed from individual plantswitches and sensors. The analysis of Dranetz SOE event data developed by individual plant switches and/or sensorswas based on the best available TR A or PCS Analog and/or Digital Point data.In the tables that follow, in the Valid Trip column, if a 'Yes" is entered then the Dranetz event function is considered valid,taking into account the limitations noted above. Ifa "No" is entered then the Dranetz event function is not considered validdue to PCS Data not supporting the event status or because no PCS or TR A Points were available that could be used todetermine the status versus the time stamp. All of the events designated with a "No" are considered to be Outliers andthey will be addressed in Attachment 3 (Unit 1) and Attachment 4 (Unit 2).

Attachment 10


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North Anna Power Station, Unit 1Analysis of Dranetz event dataversus thePlant Computer System (PCS)

For August 23, 2011

RC E 001061, Rev. 1Page 41 of 130

Attachment 10


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Time Point ID Point Description Message Valid Trip NotesNormalized to (Dranetz I PCS) (Status) (Yes / No )

PCS

13:51:10.224 0078/ PRZ HI LEVEL, BU HTRSON ON YES Between t = 13:51:10.224 and t = 13:51:11.784,LiRC001A/2A/3A Pressurizer Level was spiking between a low point of13:51:10.231 NORMAL YES 58% and a high point of 75%. (PZR HI LVL, BU HTRS

ON signal will be generated whenever Pressurizer13:51:10.786 ON YES Level exceeds 5% of program level which was at 64%

during this time period). Heaters turning on then13:51:10.800 NORMAL YES returning to normal during the time span are likely.13:51:11.059 ON YE S13:51:11.091 NORMAL YE S13:51:11.585 ON YE S13:51:11.617 NORMAL YE S13:51:11.685 ON YE S13:51:11.750 NORMAL YE S13:51:11.784 ON YE S

RCE 001061, Rev. 1Page 42 of 130

Attachment 10North Anna Power Station Unit 1


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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No )to PC S

13:51:11.801 0044 / F1 RC003A RC LOOP 1A LO FLOW CH III LO YES At t = 13:51:11.800 RCS flow was spiking down andreached a peak of 92% on the PCS (not the lowsetpoint of 90%). At t = 13:51:11.829, RCS flow was onan upward spike at t = 13:51:11.829 with level

13:51:11.829 0044 / F1RC003A NORMAL YES indication of 96% for Ch Ill.

13:51:11.840 0078/ PRZ HI LEVEL, BU HTRSON NORMAL YES At t = 13:51:11.840, Pressurizer Level was spikingLiRC001A/2A/3A downward with a minimum value of 56%. Heatersturning off during the time span are likely.

13:51:11.873 0005/ NIS PWR RG E HI FLUX RATE TRIP YES X1RD035D indicates trip a t = 13:51:12.024, Ni's showM1NM007A,8A,9A, RX TRIP negative rate event at approx t= 13:51:11.870 to10A, X1 RD035D 13:51:11.98213:51:11.888 0082 / MAIN TRANS SUD PRESS TRIP NO * There was not an electrical fault within the transformer.RELAY (63X ABC) The SPR (i.e., FPR) actuated due to the earthquakewhich it is not designed to intentionally detect.13:51:11.888 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES At t = 13:51:11.888 RCS flow was on a decreasing

trend to t = 13:51:11.950, CH III flow indication was at90%.

RCE 001061, Rev. 1Page 43 of 130



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Time Point ID Point Description Message Valid Trip NotesNormalized to (Dranetz / PCS) (Status) (Yes / No )PC S

13:51:11.892 0177/ MAIN TRANS LO RELAY TURB TRIP YE S 86 = Lockout Relay, Main Transformer 86T relayTRIP (86T) activates with 2 out of 3 SPR actuations (pertransformer) causing SST Lockout.

13:51:11.916 0041 / FIRE WATER SYSTEM INIT NO * No TR A or PCS Computer Points for this function.INITIATED13:51:11.918 0195/ MAIN REACTOR TRIP TRIP YES t = 13:51:12.008 BKR TrippedX1RD036D BREAKER B13:51:11.926 0196/ MAIN REACTOR TRIP TRIP YE S t= 13:51:12.024 BKR Tripped

XlRD035D BREAKER A13:51:11.927 0044/ RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:11.930 F1RC003A = 110%Fl RC003A13:51:11.935 0120 / Y0390D/ REACTOR TRIPPED-TURB TRIP YES "B" / "A" Rx Trip Breakers opened at t = 1-3:51:12.510Y0006D / TRIP with a Turbine Trip at t = 13:51:12.558.

Y0007D

13:51:11.944 0079/ SWYD PCB 1C TRIPPED YES Breaker G102-1 and G102-2 are the Unit 1 GeneratorX1SY001D / output breakers in the switchyard. These breakersXlSY002D tripped due to the GSU/SST SPR/FPR actuation, asI_ __ _desired.

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13:51:11.952 0072/ SWYD PCB 11 TRIPPED YES Breaker G102-1 and G102-2 are the Unit 1 GeneratorX1SV001D/ output breakers in the switchyard. These breakersXlSVO02D tripped due to the GSU/SST SPR/FPR actuation, asdesired.

13:51:11.971 0082/ MAIN TRANS SUD PRESS NORMAL NO * There was not an electrical fault within the transformer.RELAY (63X ABC) The SPR (i.e., FPR) actuated due to the earthquakewhich it is not designed to intentionally detect.

13:51:11.975 0041 / FIRE WATER SYSTEM NORMAL NO * No TRA or PCS Computer Points for this function.INITIATED13:51:11.991 0044/ RC LOOP 1A LO FLOW CH 111 LO YES t = 13:51:11.991 RCS flow was spiking downward withF1 RC003A a low flow indication at t = 13:51:12.063 of 93%. PC S

indication was not to the low flow setpoint of 90% bu tthe data was cut off at this point.

13:51:11.994 0096/ TRANS 1C SUD PRESS RELAY TRIP NO * There was not an electrical fault within the transformer.(63X-1) The SPR (i.e., FPR) actuated due to the earthquakewhich it is not designed to intentionally detect.

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13:51:12.000 0078/ PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:12.000, Pressurizer Level was on aL1RC001A/2A/3A downward spike with an immediate upward spike andPressurizer Level indicated 69% at t = 13:51:12.070.Heaters turning on during the time span are likely.

13:51:12.003 0176/ SS TRANS 1C LO RELAY TRIP YES 86 = Lockout Relay, Main Transformer 86T relayTURB TRIP activates with 2 out of 3 SPR actuations (pertransformer) causing SST Lockout.

13:51:12.015 0096/ SS TRANS 1C SUD PRESS NORMAL NO * There was not an electrical fault within the transformer.RELAY (63X-1) The SPR (i.e., FPR) actuated due to the earthquakewhich it is not designed to intentionally detect.

13:51:12.015 0044/ RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:12.014 F1RC003A = 99%F1 RC003A

13:51:12.033 0119 / Y0390D SOLENOID TURB TRIP TRIP YES This is the 7Y/AST Solenoid Position Indicator switch(window 1E-F1). It is valid, given the turbine trip onPCS at t = 13:51:12.558.

RCE 001061, Rev. 1Page 46 of 130



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13:51:12.047 0107/ RSS TRANS B SUD PRESS RELAY TRIP NO * There was not an electrical fault within the(63A) transformer. The SPR (i.e., FPR) actuated due tothe earthquake which it is not designed tointentionally detect.

13:51:12.050 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:12.050, Pressurizer Level wasLi RC001 A/2A/3A indicating 58% on the PCS. Heaters returning tonormal during the time span are likely.

13:51:12.055 0189/X1TGO02D GEN BKR G12 TRIPPED YES t = 13:51:12.114 PCS indicates Breaker Tripped

13:51:12.056 0058 / Y0390D/ TURBINE TRIP RX TRIP TRIP YES t = 13:51:12.557 PCS indicates TrippedXl RD035D /XlRD036D

13:51:12.058 0106/ RSS TRANS A SUD PRESS RELAY TRIP NO * There was not an electrical fault within the(63A) transformer. The SPR (i.e., FPR) actuated due tothe earthquake which it is not designed tointentionally detect.

RCE 001061, Rev. 1Page 47 of 130



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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No )

to PC S

13:51:12.079 0038/ ST M GE N 1A HI-HI LEVEL TURB TRIP YES At t = 13:51:12.080 Steam Generator Levels wereL1FW002N3A/1A TRIP on an increasing trend with max indications at 72%on CH II. At t = 13:51:12.172, Steam GeneratorLevels spiked upward with a max indication at 78%.(PCS data on CH II was cut off at 71% on

increasing spike.) SG 1A HI-HI LEVEL TURB TRIPsetpoint is 75% increasing levels.

13:51:12.082 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES At t = 13:51:12.080 RCS flow indication was on adecreasing trend to 87% at t = 13:51:12.143.

13:51:12.090 0078/ PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:12.096, Pressurizer Level was on anL1RC001A/2A/3A upward trend with max indication of 87%. Heatersturning on during the time span are likely.

13:51:12.094. 0038/ ST M GE N 1A HI-HI LEVEL TURB NORMAL YES At t = 13:51:12.094 Steam Generator LevelL1FW002A/3A/1A TRIP indications were at 51% which is below the HI-HILevel trip setpoint of 75%.

13:51:12.118 0044 / F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES At t = 13:51:12.119 F1RC003A = 97%

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Time Point ID (Dranetz Point Description Message Valid Trip NotesNormalized PCS) (Status) (Yes/ No )to PCS

13:51:12.120 0027/L1RC001A/2A/3A PRESSURIZER HI LEVEL RX TRIP TRIP YES Pressurizer Level spiked up with a peak reading of99% at t = 13:51:12.101 with a downward trend at t= 13:51:12.120. (PZR HI LVL RX TRIP setpoint =92%)

13:51:12.125 0045/X1RC001D RCP 1ACH 1 BK R OPEN YES t = 13:51:12.188 PCS indicates "A" RCP BreakerOpen

13:51:12.133 0076 /L1QS001A RWST CHEM ADD TK LO LEVEL LO NO* t = 13:51:12.132 L1QS001A = 88% (Low Level Tripsetpoint = 85%, RWST CA T Level did notchange/decrease below trip setpoint)

13:51:12.134 0027/L1RC001A/2A/3A PRESSURIZER HI LEVEL RX TRIP NORMAL YES At t = 13:51:12:132, Pressurizer Level Ch I, II, andIII were indicating 61%, 72%, and 68%. (PZR HILVL RX TRIP reset = 91% decreasing level)

13:51:12.144 0129/L1RC001A/2A/3A LOSS OF COOL FLOW PW R >30% TRIP YES At t = 13:51:12.120, RCS Flow was spiking/M1NMO07A/ downward, at t = 13:51:12.164 RCS flow reachedM1NM008A/ low peaks of 87% on CH III and 94% on CH II withM1 NMO09A NI Pw r > 30% (Loss of Cool Flow Pwr > 30% tripMlNMO10A setpoint is 2 out of 3 RC Low Flow Trips on 1 out of3 loops with Pw r greater than P8)

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13:51:12.158 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:12.158, Pressurizer Level Ch 1, 1, andL1RC001A/2A/3A III were indicating 67%, 63%, and 66% which are all

below the 5% above Program Level trip setpoint.Heaters returning to normal during the time spanare likely.

13:51:12.177 0044 /F1RC003A RC LOOP 1A LO FLOW CH III LO YES t = 13:51:12.180 F1RC003A = 87%

13:51:12.188 0076 / L1QS001A RWST CHEM ADD TK LO LEVEL NORMAL YES t = 13:51:12.188 L1QS001A = 88%, with a low levelreset setpoint of 86%. (Level did not change)

13:51:12.194 0134/ FEED WT R PP BKRS OPEN TURB TRIP YES t = 13:51:13.550 PCS indicates "B" & "C "X1 FW011D,012D, TRIP Feedwater pump breakers open013D,14D,01 5D,01 6D

13:5112.205 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:12.204 F1RC003A = 105%13:51:12.212 0078/ PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:12.211, Pressurizer Level Ch II and IIILI RC001 A/2A/3A were indicating 88% and 82%. Heaters turning on

normal during the time span are likely.

RCE 001061, Rev. 1Page 50 of 130



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to PC S

13:51:12.213 0041 / FIRE WATER SYSTEM INITIATED INIT NO * No TRA or PCS Computer Points for this function.13:51:12.242 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:12.240, Pressurizer Level minimum

Li RC001 A/2A/3A value was indicating 58%. Heaters returning tonormal during the time span are likely.

13:51:12.242 0013 / T0499A/ TAVG > < TREF DEV DEVIATION YES At t = 13:51:12.242, Tref = 580.6 and Tavg = 580.4T0496A (Diff of 0.2);

At t = 13:52:13.470 Tavg = 580.4 and Tref = 573.4(Diff of > 5 degrees). Tref starts trending down at t= 13:51:12.242

13:51:12.303 0078/ PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:12.301, Pressurizer Level signal wasLi RC001 A/2A/3A spiking up with a peak reading of 78%. Heaters

turning on during this time are likely.

13:51:12.352 0044/F1RC003A RCLOOP1ALOFLOWCHIII LO YES Loop A, Ch Ill, t = 13:51:12.421, Valley =90.6007%.

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to PC S

13:51:12.352 0038/ STM GE N 1A HI-HI LEVEL TURB TRIP YES At t = 13:51:12.352 Steam Generator Level CH IILi FW002A/3A/1A TRIP and III were on an increasing trend and indicating71% and 61% (while the HI-HI Level Trip setpoint is75%, the data for CH II and III were cut off at719%/61%).

0038 /13:51:12.369 L1FW002A/3A/1A STM GE N 1A HI-HI LEVEL TURB NORMAL YES SG Level indications were trending downward fromt = 13:51:12.364 to t = 13:51:12.382 with CH II andTRIP III indicating 71% and 65%.

13:51:12.380 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:12.388 F1RC003A = 104%

13:51:12.426 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:12.330, PZR Level spiked downwardLi RC001 A/2A/3A with a low peak of 30% and then spiked upwardswhere t = 13:51:12.426, max PZR Level was 88%.Heaters returning to normal during this time arelikely..

13:51:12.443 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES At t = 13:51:12.441 RCS flow was on a decreasingtrend with F1 RC003A indicating 90%. (PCS datawas cut off at 90%)

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to PC S

13:51:12.482 0078/ PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:12.482, Pressurizer Level max valueLi RC001 A/2A/3A was indicating 86%. Heaters turning on during thistime are likely.

13:51:12.482 0044 / F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES At t = 13:51:12.480 RCS flow was on an increasingtrend with F1 RC003A indicating 105%

13:51:12.509 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:12.510, Pressurizer Level minimumLiRC001A/2A/3A value indicated was 53%. Heaters returning tonormal during this time are likely.

13:51:12.516 0116/V0321D/ STASERV2OF3BUSESUV-RX TRIP YES 13:51:12.556 SS/RCP BU S 1A / 1B indicatedV0322D TRIP tripped

13:51:12.542 0044 / F1 RC003A RC LOOP 1A LO FLOW CH III LO YES t = 13:51:12.540 F1 RC003A = 84%13:51:12.558 0108/ RSS TRANS C SUD PRESS RELAY TRIP NO * There was not an electrical fault within the(63A) transformer. The SPR (i.e., FPR) actuated due tothe earthquake which it is not designed tointentionally detect.13:51:12.578 0044/F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:12.578 F1RC003A = 105%

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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No)to PCS

13:51:12.618 0078/ PRZ HI LEVEL, BU HTRSON ON YES At t = 13:51:12.600 Pressurizer Level spikedLiRC001A/2A/3A upwards with a max level indication of 74% with animmediate downward spike to t = 13:51:12.618 with

Pressurizer Level indication of 54%. Heatersturning on during this time are likely.

13:51:12.657 0002/ ST M GEN 1A LEVEL ERROR ERROR YES At t = 13:51:12.657 Ch I was 47.8%, Ch II wasLi FW002A/3A/1A 62.6% and Ch III was 56.2%. Level error is +/- 5%from program Level = 44%.

13:51:12.695 0004/C0099D, RPI ROD BOTTOM RO D DROP DROP NO * At RPI Rod Bottom/Rod Drop PCS point indicatesC0002A,C001 5A, Dropped at t = 13:51:13.520 with RP I PCS

C0026A, C0038A/ indications dropping to the Rod Bottom SetpointXlRD036D / after the alarm occurs. Alarm occurred at the sameV1EE019A time as "B" Rx Trip Breaker went open. MC C 1H1-1voltage source for the RP I was at 478.99 volts at

this time which shows a decrease in RP I sourcevoltage.

13:51:12.700 0031 / RWST CHEM ADD TK LO TEMP LO NO * No TRA or PCS Computer Points for this function.

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13:51:12.710 0078/ PR Z HI LEVEL, BU HTRS ON NORMAL YES Pressurizer Level was spiking between t =LiRC001A/2A/3A 13:51:12.700 to t = 13:51:12.884 with max low andhigh indications were 63% and 78%. Heaters

13:51:12.747 0078 / PRZ HI LEVEL, BU HTRS ON ON YES turning on then returning to normal during the timeL1 RC001 A/2N3A span are likely.

13:51:12.811 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YESLi RC001 A/2A/3A

13:51:12.827 0044 /F1 RC003A RC LOOP 1A LO FLOW CH III LO YES At t = 13:51:12.826 RCS flow was on a decreasingtrend indicating 91% (PCS indication did notdecrease below the low flow setpoint of 90%, butPCS data was cut off at 91%)

13:51:12.845 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES RCS flow was on an increasing trend from t =13:51:12.845 to t = 13:51:12.858 with indication of93%

1.3:51:12.883 0078/ PRZ HI LEVEL, BU HTRS ON ON YES Pressurizer Level was spiking, between t =Li RC001A/2A/3A 13:51:12.700 to t = 13:51:12.884 with max low andhigh indications were 63% and 78%. Heatersturning on during the time are likely.

13:51:12.886 0076 / L1QS001A RWST CHEM ADD TK LO LEVEL LO NO * t = 13:51:12.886 L1QS001A = 88% (Low Level Tripsetpoint = 85%, RWST CA T Level did notchange/decrease below trip setpoint)

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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No )to PCS

13:51:12.891 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:12.892, Pressurizer Level minimumLiRC001A/2A/3A value indication was 51%. Heaters returning to

normal during this time are likely.13:51:12.915 0044/F1RC003A RCLOOP1ALOFLOWCHIII LO YES Loop C, CH III, t = 13:51:12.972 Valley =

91.1806%, t = 13:51:12.991 F1RC003A =13:51:12.943 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES 92.0246% (R C LO FLOW TRIP = 90% decreasing,Reset = 90.8% increasing level)

13:51:12.964 0076 / L1QS001A RWST CHEM ADD TK LO LEVEL NORMAL YES At t = 13:51:12.964 L1QS001A = 88% (Low Levelreset point = 86%, Level did not change)

13:51:13.002 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES Loop C, CH III decreasing trend to 91.1806% at t =13:51:12.980, slight increasing trend to 92.0246%at t=13:51:13.002

13:51:13.010 0078/ PRZ HI LEVEL, BU HTRSON ON YES At t = 13:51:12.980, Pressurizer Level was on aLi RC001 A/2A/3A downward spike with max level indication of 78%.At t = 13:51:13.010, Pressurizer Level wasindicating 67%. Heaters turning on during this timeL____ are likely.

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13:51:13.034 0044 / F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:13.034 F1RC003A = 99%13:51:13.094 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES RCS flow was on a decreasing trend to 91% at t =13:51:13.08213:51:13.104 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES Between t = 13:51:13.001 and t = 13:51:13.104,LiRC001A/2A/3A Pressurizer Level spiking: Valley = 50% and Peak =

74%. Heaters returning to normal during this timeare likely.13:51:13.129 0044/ F1 RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t =13:51:13:128 FlRC003A=100%,

13:51:13.259 0021 /X2TGO01D EXCITATION LOSS OF POWER POWER YES Since SPR's activated and the 86T relay actuated(ALl -2, AL4-5) for the GSUs, the Exciter field breaker trippedcausing the Excitation Loss of Power to go fromNormal to Power (alarm condition).

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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No)to PC S

13:51:13.276 0044 / F1RC003A RC LOOP 1A LO FLOW CH III LO YES t = 13:51:13.264 RCS flow was spiking down thenreached an upward spike at t = 13:51:13.318. Note13:51:13.284 0043/ F1RC002A RC LOOP 1A LO FLOW CH II LO YES PC S indicates a low spike of 92% level (not to thelow flow setpoint of 90 %) but the PCS data was13:51:13.315 0129/ P0398A, LOSS OF COOL FLOW PWR > 30% NORMAL YES cutoff at this point. PCS indicates at t =P0399A 13:51:13.296 1 st stage pressure was 582 psig at t =13:51:13.529 1 st stage pressure was 342 psig.

13:51:13.316 0058 / Y0390D / TURBINE TRIP RX TRIP NO T TRIP YES t = 13:51:13.470 PCS indicates not trippedX1 RD035D /X1 RD036D

13:51:13.322 0043 / F1RC002A RC LOOP 1A LO FLOW CH II NORMAL YES t = 13:15:13.322 RCS flow was on an upward spikewith level indication 92.85% and 93.44% for Ch II13:51:13.323 0044 / F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES and II1.13:51:13.329 0078 / PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:1.322 Pressurizer Level started spikingLi RC001 A/2A/3A up from 53% level to a max peak of 81% level at t=13:51:13.371 PRZ HI LEVEL, BU HTRS ON NORMAL YES 13:51:13.424. Level then spiked down to 64% at t =0078/ 13:51:13.458. Heaters turning on then returning toL RC001 A/2A/3A normal during the time span are likely.

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13:51:13.383 0043 / F1RC002A RC LOOP 1A LO FLOW CH II LO YES t = 13:51:13.380 CH II and III were below the tripsetpoint of 90% flow with indication of a start of an13:51:13.398 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES upward trend. At t = 13:51:13.416 Ch II flow wasabove reset point i.e. 94.23%.

13:51:13.416 0043 F1RC002A RC LOOP 1A LO FLOW CH II NORMAL YE S

13:51:13.419 0078/ PRZ HI LEVEL, BU HTRS ON ON YES t = 13:51:13.414 Pressurizer Level was spiking upLiRC001A/2A/3A and reached it max value of 81% at t =13:51:13.424 which is 5% greater than programlevel.13:51:13.425 0047 / F1RC005A RC LOOP 1B LO FLOW CH II LO YES t = 13:51:13.390 Ch I and II of "B" RCS Flow was

on a downward spike with the trip setpoint being0130/ LOSS OFCOOL FLOW PWR > 10 % TRIP YES reached at approximately t = 13:51:13.498. PC S13:51:13.426 F1RC004A/5A/6A indicates at t = 13:51:13.296 1 st stage pressure was582 psig at t = 13:51:13.529 1 st stage pressure was13:51:13.428 0046/ F1RC004A RC LOOP 1B LO FLOW CH I LO YES 342 psig.

t = 13:51:13.428 top of upward spike with Ch III "A"RCS flow indicating 96%.13:51:13.429 0044/F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YE S

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13:51:13.446 0078/ PRZ HI LEVEL, BU HTRSON NORMAL YES t = 13:51:13.446 Pressurizer Level was spikingLi RC001A/2A/3A down and reached the programmed Level at t =13:51:13.458.

13:51:13.470 0043/F1 RC002A RC LOOP 1A LO FLOW CH II LO YES t = 13:51:13.470 "A" RCS flow was on a downwardspike below Low Flow setpoint of 90% for both Ch II13:51:13.481 0044/F1RC003A RC LOOP 1A LO FLOW CH III LO YES and I11. RCS flow was cycling above and below

setpoint until t = 13:51:13.600 at which time flow13:51:13.508 0043/ F1RC002A RC LOOP 1A LO FLOW CH II NORMAL YES was at the peak of an upward spike with anequivalent flow of 92.5% for Ch II and 95% for Ch13:51:13.521 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES Ill.

13:51:13.554 0043 / F1RC002A RC LOOP 1A LO FLOW CH II LO YES13:51:13.561 0044/ F1RC003A RC LOOP 1A LO FLOW CH Ill LO YES13:51:13.592 0048 / F1RC006A RC LOOP 1B LO FLOW CH Ill LO YES t = 13:51:13.568 Ch Ill "B" RCS flow was spiking

downward with the trip setpoint of 90% being13:51:13.599 0043 I F1RC002A RC LOOP 1A LO FLOW CH II NORMAL YES reached at t = 13:51:13.64413:51:13.600 0078/ PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:13.600 Pressurizer Level was at the

LiRC001A/2A/3A peak of a downward spike then started an upwardspike reaching the max peak 69.5% at t =_ __ _13:51:13.708 which could cause the ON status.

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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No)to PC S

13:51:13.608 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:13.606, F1RC003A = 92%

13:51:13.622 0078 / PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:13.708 Pressurizer Level was at a maxLi RC001 A/2A/3A peak of 69.5% then spiked down reachingprogrammed level at approximately t =13:51:13.714 and level of 63.89%.

13:51:13.637 0043/ F1RC002A RC LOOP 1A LO FLOW CH II LO YES t = 13:51:13.630 RCS flow was on a downwardtrend and reached the low flow setpoint of 90% at t13:51:13.649 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES = 13:51:13.640 and then started an upward trendand reached the peak of 91.4% on Ch II at t =

13:51:13.690 0043/ F1RC002A RC LOOP 1A LO FLOW CH II NORMAL YES 13:51:13.694.

13:51:13.691 0078/ PRZ HI LEVEL, BU HTRS ON ON YES From t = 13:51:13'672 to t = 13:51:13.758Li RC001 A/2A/3A Pressurizer Level was spiking from 65% to 73%

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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz I PCS) (Status) (Yes / No)to PC S

13:51:13.699 0044 / F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:51:13.694 RCS Flow was at a max peak of95.8% on Ch III and started a downward trend at

13:51:13.732 0043 / F1RC002A RC LOOP 1A LO FLOW CH II LO YES which the low peak was reached at t =13:51:13.728, where Ch II reached a value of13:51:13.743 0044 / F1RC003A RC LOOP 1A LO FLOW CH III LO YES 86.2% and Ch III was 84.83%.

13:51:13.773 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:13.772 Pressurizer Level was at a peakL1RC001A/2A/3A value of 72.19% going down and reached the resetvalue at approx. t = 13:51:13.794

13:51:13.793 0043 / F1RC002A RC LOOP 1A LO FLOW CH II NORMAL YES t = 13:51:13.790 RCS flow was on a upward spikewith flow starting below the trip setpoint of 90% for13:51:13.798 0044 / F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES both Ch II and Ill. RCS flow was cycling above andbelow setpoint with Ch I and Ch II staying below the13:51:13.801 0042 / F1RC001A RC LOOP 1A LO FLOW CH I LO YES trip setpoint until t = 13:51:13.910 at which timeflow for Ch III Was at the peak of an upward spike13:51:13.811 0043/ F1RC002A RC LOOP 1A LO FLOW CH II LO YES with an equivalent flow of 91.7%.13:51:13.827 0044 / F1RC003A RC LOOP 1A LO FLOW CH III LO YE S13:51:13.885 0044 / F1RC003A RC LOOP 1A LO FLOW CH Ill NORMAL YE S13:51:13.910 0044/F1RC003A RC LOOP 1A LO FLOW CH Ill LO YE S

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to PC S

13:51:13.960 0078 / PRZ HI LEVEL, BU HTRS ON ON YES At t = 13:51:13.902 Pressurizer Level appears to beLiRC001A/2A/3A steady at 62%, then starts a downward spike at t =

13:51:13.984 to a low value of 48% then spikesupward to a max value of 80% at t = 13:51:14.054

13:51:13.992 0044/ F1RC003A RC LOOP 1A LO FLOW CH III NORMAL YES t = 13:15:13.984 a rapid downward spike was notedon Ch II and Ch III and the minimum peak was13:51:13.996 0044/ F1RC003A RC LOOP 1A LO FLOW CH III LO YES reached at t = 13:51:14.010 with Ch III being at84.6% which is below the trip setpoint of 90%.

13:51:13.998 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:13.998 Pressurizer Level is spikingL1RC001A/2A/3A downward then starts an upward spike at t =13:51:14.010 reaching a peak value of 81% at t =13:51:14.085 0078 / PRZ HI LEVEL, BU HTRS ON ON YES 13:51:14.054. Level then spikes downward and at tLiRC001A/2A/3A = 13:51:14.100 LVL is at 57%.

13:51:14.099 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YESLi RC001 A/2A/3A13:51:14.279 0052/ F1RC009A RC LOOP 1C LO FLOW CH III LO YES t = 13:51:14.280 Ch III was on a downward trend

with Low flow setpoint being reached at t =13:51:14.342.

13:51:14.327 0051 / F1RC008A RC LOOP 1C LO FLOW CH II LO YES t = 13:51:14.320 Ch II was on a downward trendwith Low flow setpoint being reached at t =13:51:14.408.

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Time Point ID Point Description Message Valid Trip NotesNormalized (Dranetz / PCS) (Status) (Yes / No)to PCS

13:51:14.337 0078/ PRZ HI LEVEL, BU HTRSON ON YES Between t = 13:51:14.334 and t = 13:51:14:412,Li RC001 A/2A/3A Pressurizer Level was spiking with Valley = 58.4%and Peak = 71%.

0078 /13:51:14.376 L1RC001A/2A/3A PRZ HI LEVEL, BU HTRS ON NORMAL YES At t = 13:51:14.461, Pressurizer Level spikeddown, Valley = 56%.13:51:14.421 0050 / F1RC007A RC LOOP 1C LO FLOW CH I LO YES Ch I was trending downward with the trip setpoint

being reached at t = 13:51:14.48813:51:14.693 0078/ PRZ HI LEVEL, BU HTRSON ON YES At t = 13:51:14.680 Pressurizer Level reaches a

LiRC001A/2A/3A max value of 66% Level from an upward spike andthen the trace flattens out until t = 13:51:14.710 at

13:51:14.711 0078 / PRZ HI LEVEL, BU HTRS ON NORMAL YES which it starts trending downward reaching a peakLi RC001 A/2A/3A value of 57% at t = 13:51:14.874. Level then startsan upward spike to 70% at t = 13:51:15.058 then

13:51:14.947 0078/ PRZ HI LEVEL, BU HTRSON ON YES spikes down to 58% at t = 13:51:15.074 andL RC001 A/2A/3A continues spiking with the largest peak of 68.78%at t= 13:51:15.330.13:51:14.978 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YES

Li RC001 A/2A/3A

13:51:15.231 0078/ PRZ HI LEVEL, BU HTRS ON ON YESLi RC001A/2A/3A13:51:15.244 0078/ PRZ HI LEVEL, BU HTRS ON NORMAL YESLi RC001A/2A/3A

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Time Point ID Point Description Message Valid Trip NotesNormalized to (Dranetz / PCS) (Status) (Yes / No)PC S

13:51:15.530 0041 / FIRE WATER SYSTEM INITIATED NORMAL NO * No TRA or PCS Computer Points for this function.

13:51:15.703 0078/ PRZ HI LEVEL, BU HTRSON ON YES At t = 13:51:15.672 Pressurizer Level starts anLi RC001A/2A/3A upward spike from 57% to 65% at t = 13:51:15.710and then spikes downward to 55% at t =

13:51:15.721 0078 / PRZ HI LEVEL, BU HTRS ON NORMAL YES 13:51:15.730.Li RC001 A/2A/3A

13:51:15.820 0071/L1FW006A ST M GE N 1B LO-LO LEVEL CH I-I1-111 LO-LO YES At t = 13:51:15.818 all three S/G Level Channelswere 20% and spiking down with CH III spiking to16.7% at t = 13:51:15.868 and Ch I & II at 18% and19%.

13:51:15.827 0003 / L1FW006A STM GEN 1B LEVEL ERROR ERROR YES At t = 13:51:15.826 Ch I was 20%, Ch II was 20.6%and Ch III was 19%. Level error is +/- 5% fromProgram Level.

13:51:15.840 0062 / L1FW002A STM GEN 1A LO-LO LEVEL CH I-Il-Ill LO-LO YES At t = 13:51:15.840 S/G Level Ch I was 18.81% on adownward spike and reached 18% at t =

13:51:15.870 0062/L1FW002A ST M GE N 1A LO-LO LEVEL CH I-I1-111 NORMAL YES 13:51:15.844. The Level started an upward spike at t= 13:51:15.874 and reached a peak value of 20.33%13:51:15.930 0062 / L1FW002A ST M GE N 1A LO-LO LEVEL CH I-Il-Ill LO-LO YES at t = 13:51:15.900 then spiked downward to 17.73%at t = 13:51:15.944.

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Point ID Point Description Message Valid Trip Notes


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TimeNormalized (Dranetz / PCS) (Status) (Yes / No )to PCS

13:51:15.939 0029/ LIFW006A STN GEN 1B LO-LO LEVEL RX TRIP TRIP YES At t = 13:51:15.940 "B" S/G Level was CH I =17.8%, Ch II = 18.6% and Ch III = 17.7%

13:51:15.977 0062 / L1FW002A ST M GE N 1A LO-LO LEVEL CH I-I1-111 NORMAL YES At t = 13:51:15.944 CH I S/G Level was 17.73%and flat lining until t = 13:51:16.028 when. Levelstarts an upward spike to 18.87% at t =

13:51:16.013 0062 / L1FW002A ST M GE N 1A LO-LO LEVEL CH I-I1-111 LO-LO YES 13:51:16.084 then spikes down to 16.95% at t =13:51:16.10813:51:16.088 0062 / L1FW002A ST M GE N 1A LO-LO LEVEL CH I-I1-11 NORMAL YE S

13:51:16.103 0062 / L1FW002A ST M GE N 1A LO-LO LEVEL CH I-I1-111 LO-LO YE S

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Time Point ID Point Description Message Valid Trip Notes


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Normalized (Dranetz I (Status) (Yes ! No )to PCS PCS)

13:51:16.437 0073/ STM GEN 1C LO-LO LEVEL CH I-I1-111 LO-LO YES At t = 13:51:16.436 Ch I = 20%, Ch II = 21% and Ch IIl =L1FW01OA 22.7% with Ch III spiking down. At t = 13:51:16.470 Ch I& II peaked high at 20.9% and 22% with Ch III starting

13:51:16.466 0073/ ST M GE N 1C LO-LO LEVEL CH I-Il-Ill NORMAL YES an upward spike. At t = 16.504 Ch I, II, and Ill wereL1FW01OA spiking down with Ch I reading a low peak of 17.95% at t= 13:51:16.514. At t = 13:51:16.520 all 3 channels had13:51:16.505 0073/ STM GEN 1C LO-LO LEVEL CH I-I1-11 LO-LO YES spiked down to a low value of 17.95% Ch 1,20.2% Ch IIL1FW01OA and 19.6% Ch III at t = 13:51:16.564 Ch II & III were20.9% and 21.8% and at t = 13:51:16.610 Ch I was13:51:16.540 0124/ ST M GE N 1C LO-LO LEVEL RX TRIP TRIP YES 17.2% and Ch II & III were spiking down to approx. 19 %

LIFW01OA Level at t = 13:51:16.654 Level then spiked up and wasfalling and were indicating approx. 19.8% on Ch II and13:51:16.568 0124 / STM GEN 1C LO-LO LEVEL RX TRIP NORMAL YES 19.97% on Ch III.

L1FW01OA13:51:16.608 0124/ ST M GE N 1C LO-LO LEVEL RX TRIP TRIP YE S

L1 FW01OA13:51:16.651 0124/ STM GEN 1C LO-LO LEVEL RX TRIP NORMAL YE SL1FW01OA13:51:16.665 0028/ STM GEN 1A LO-LO LEVEL RXTRIP TRIP YES At t = 13:51:16.664 "A" CH I = 14.85% and Ch III is

Li FW002A spiking down to a value of 19.8%

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Normalized to (Dranetz I (Status) (Yes / No )PCS PCS)

13:51:16.669 0014/ ST M GE N 1C LEVEL ERROR ERROR YES At t = 13:51:16.670 Ch I = 15% Level, Ch II = 18.5%L1FW01OA Level and CH III = 19.79% Level and all three were13:51:16.672 ST M GE N 1C LO-LO LEVEL RX TRIP TRIP YES spiking down. The RX Trip setpoint was reached at t =0124/ 13:51:16.686L1EFW01OA

13:51:16.694 0028/ STM GEN 1A LO-LO LEVEL RXTRIP NORMAL YES At t = 13:51:16.694 CH I is 13.7% Level and CH IIILi FW002A spikes up to 21% Level.13:51:16.732 0124/ STM GEN 1C LO-LO LEVEL RXTRIP NORMAL YES At t = 13:51:16.732 Ch I = 16.9% and Ch II and III were

L1FW01OA 19.7% and 19.3%.13:51:16.736 0028/ ST M GE N 1A LO-LO LEVEL RXTRIP TRIP YES At t = 13:51:16.736 "A" CH I = 12.88% and Ch III isLi FW002A spiking down to a value of 18.6%13:51:16.756 0124/ ST M GE N 10 LO-LO LEVEL RX TRIP TRIP YES At t = 13:51:16.756 Ch I= 15.9%, Ch 11 = 18.3%, and ChL1FW010A III = 18%. At t = 13:51:16.812 Ch I = 15.6%, Ch II =18.8% and Ch III = 19.3% and all three channels were13:51:16.812 0124/ ST M GE N 1C LO-LO LEVEL RXTRIP NORMAL YES on an upward spike. At t = 13:51:16.836 Ch I = 14.9%,L1FW01OA Ch 11= 18.2% and Ch III = 18.4% and all three were on a

downward spike.13:51:16.836 0124/ STM GEN 1C LO-LO LEVEL RX TRIP TRIP YE S1FW01OA

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Normalized (Dranetz / PCS) (Status) (Yes / No )to PCS

13:51:16.867 0002/ L1FW002A ST M GE N 1A LEVEL ERROR ERROR YES At t = 13:51:16.867 CH I Level = 11.4%, CH II was20.66%, and CH III was 16.4%. All are < 5% of theprogrammed value of 33% Level.

13:51:16.907 0124/LiFW010A ST M GE N 1C LO-LO LEVEL RX NORMAL YES At t = 13:51:16.906 Ch II & III were on an upward spikeTRIP reading 17.2% and 16.6% at t = 13:51:16.920 peak ofupward spike Ch II and III were 19% and 18.6% then13:51:16.917 0124/LFW01OA ST M GE N 1C LO-LO LEVEL RX TRIP YES spiked down below the trip setpoint at t = 13:51:16.932TRIP

13:51:17.013 0041 / FIRE WATER SYSTEM INIT NO * No TRA or PCS Computer Points for this function.INITIATED

13:51:18.508 0001 / SMOKE DETECTION SYSTEM TROUBLE NO * No TR A or PCS Computer Points for this function.

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Normalized to (Dranetz! PCS) (Status) (Yes / No)PCS

13:51:19.452 0036 / T0444A, LOOP 1C HI DELTAT HI NO * At t = 13:51:19:466 Loop C Control = 85.13%, Loop CT0443A T0497A DEVIATION Protection = 97.73% and Median Delta T = 84.27%.

Protection to Median Delta T Difference was 13.46%,however, Control to Median Delta T Difference was only0.86%. The comparison of Protection to Median Delta Twould have actuated this alarm, however the differencebetween Control and Median would not have due to thedifference between Loop and Median Delta T DeviationTrip setpoint must be a +3.2% difference. There is adiscrepancy between the protection and control readingsduring this event.

13:51:20.141 0031 / RWST CHEM ADD TK LO TEMP NORMAL NO * Could not find a computer point to validate

13:51:20.623 0025 / Y0004D, MANUAL INITIATION RX TRIP TRIP YES t = 13:51:21:536 PCS indicates TRIPY0005D

13:51:21.609 0025 / Y0004D, MANUAL INITIATION RX TRIP NORMAL YES t = 13:51:22.546 PCS indicates No t TrippedY0005D13:51:22.740 0001 / SMOKE DETECTION SYSTEM NORMAL NO * No TRA or PCS Computer Points for this function.13:51:25.092 0001 / SMOKE DETECTION SYSTEM TROUBLE NO *

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Normalized to (Dranetz / PCS) (Status) (Yes / No )PC S

13:51:25.349 0132 / MANUAL INITIATION TURB TRIP TRIP NO * Could no t find a computer point to validate13:51:25.884 0132/ MANUAL INITIATION TURB TRIP NORMAL . NO *

13:51:27.657 0036 / T0443A, LOOP 1C HI DELTA T NORMAL YES At t = 13:51:27.660 Loop C Control = 35.53%, Loop CT0444A, DEVIATION Protection = 44.19% and Median Delta T = 34.06%. Th eT0497A Protection to Median Delta T Difference was 10.13%,however, Control to Median Delta T Difference was only

1.47%. The comparison of Protection to Median Delta Twould not have allowed the point to go to normal,however the difference between Control and Medianwould have gone back to normal condition. Thedifference between Loop and Median Delta T Deviationreset must be less than +1.7% difference. There is adiscrepancy between the protection and control readingsduring this event.

13:51:32.476 0013/ T0499A / TAVG >


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Normalized to (Dranetz I PCS) (Status) (Yes / No )PC S

13:51:33.151 0041 / FIRE WATER SYSTEM NORMAL NO * No TRA or PCS Computer Points for this function.INITIATED

13:51:38.218 0053 / RCP CH 3 BK R OPEN YES "C " RCP Breaker indicates OPEN at t = 13:51:38.284XlRC003D

13:51:43.494 0188/ AMSAC INITIATED YES At t = 13:51:43.256 AMSAC was not initiated per theX2RX004D/ PCS Computer . But between t = 13:51:45.420 andX2RX005D 13:51:46.506 AMSAC did initiate.(PCS scan rate isdifferent than Drantez)

13:51:44.531 0049 / RCP 1B CH 2 BK R OPEN YES "B" RCP breaker indicates open at t = 13:51:44.594XlRC002D

RCE 001061, Rev. 1Page 72 of 130


Time Point ID Point Description Message Valid Trip NotesNormalized to (Dranetz / PCS) (Status) (Yes / No )


76/133

PC S

13:52:09.867 0013 / T0499A/ TAVG > < TREF DE V DEVIATIO YE

North Anna Unit 1 and Unit 2 ROOT CAUSE EVALUATION

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