ML072640494

Unit 2 Accident - Presentation Slides

ML072640494
Person / Time
Site:	Three Mile Island
Issue date:	03/28/2007
From:	AmerGen Energy Co
To:	NRC/FSME
Widmayer D, ACNW, 301-415-7366
References
WL-130
Download: ML072640494 (16)

Text

1TMI-2 Transient -3/28/79 The Lessons Learned 2 ComparisonsTMI-1TMI-2Gilbert AssociatesBurns & RoeGE TurbineWestinghouse2568 MWt2772MWt870 Mwe (UP RATE)880 MweRunback at that time from full power for turbine trip, not a reactor trip.PORV setpoint 2255 vice 2355 psig.

3 SequenceTrouble with resin tr ansfer on condensate polisher.Pzr being cycled for boron equalization.

Spray valve in manual. Pzr heaters on.Condensate Pump 1A tripped.FW pumps 1A and 1B trip. (Low suction)Main Turbine Trip.

4 8 secondsReactor trip on high RCS pressurePzr heaters returned to automatic control.Pressure decreases below 2205 PORV closure setpoint.Pzr level peaks at 256" and begins a rapid decrease.Letdown flow was stopped 5 13 secondsCondenser hotwell low level alarm receivedEFW pump discharge indicated.OTSG A water level indicated 74 " on startup range.PORV and pzr safety valve outlet high temp alrm comes in.

6 30 seconds OTSG A water level decreased to 27.3"OTSG B water level decreased to 28.8"(41 sec) MUP-1A started (A & B running)Pzrlow level alarms at 200"(setpoint).Pzrlevel reaches a minimum of 158" 7>1 minutePzr safety valve outlet temperature alarmed high.Condenser hotwell high water level alarm received.Both OTSG's boiled dry(00:02:01) ESAS 1600# actuation.MU-P-1A ES starts / MUP-1B ES stops 8> 4 minutes RCDT relief valve lifts at 122 psig.RCDT high temperature alarm.Pressurizer high level alarm received.Operator stops MU-P-1C and throttles all high pressure injection valves.

9> 5 MinutesIC-P-1A was started to prepare for max letdown flow.Letdown flow off scale highPressurizer level lowers to reached 377".Condensate pump 1A was started to try to restore secondary cooling.T hot reaches saturation at 1340# and 582F.

10 Chronology05:51 Pressurizer level goes off scale high.08:18 EFW block valves 12A &B were opened.09:23 Letdown flow isolation valve re-opened10:15 Pressurizer level back on scale.10:48 Rx Building sump high level alarm was received.

11 Chronology13:13 DHR pumps are secured (running dead headed).14:18 RCDT rupture disc blows.20:00 SR-NI departed from normal shutdown

profile.01:13:29 RCP 2B stopped.01:13:42 RCP 1B stopped.01:40:37 RCP 2A stopped.01:40:45 RCP 1A stopped.

12 Chronology02:22:00 The PORV block valve (RC-V2) was closed.02:55:00 Site Emergency declared.

13 Estimated Final Condition of Core 14 Lessons Learned TMI-2 Accident Hardware changesESAS status panelThermal Hydraulic PanelPT plotWR NI'sRCIT'sAlarm System ReformatAdditional RMS 15 Lessons Learned TMI-2 AccidentOrganization Changes -Administrative processesShift Technical AdvisorEmergency PlanningLesson Learned-PRV behaviorINPO establishedSite Organizational Realignment. GPU established to run nuclear units.Radiation protection 16 Lessons Learned TMI-2 Accident Process changesSymptom Based ProceduresAdditional Training for Operators Simulators BWOGSPIP -improve safety system performance

• Control system power supply reliability

• Instrument air system upgrades