ML072640494
| ML072640494 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| 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
1 TMI-2 Transient - 3/28/79 The Lessons Learned
2 Comparisons
TMI-1 TMI-2
Gilbert Associates Burns & Roe
GE Turbine Westinghouse
2568 MWt 2772 MWt
870 Mwe (UP RATE) 880 Mwe
Runback at that time from full power for turbine trip, not a reactor trip.
PORV setpoint 2255 vice 2355 psig.
3 Sequence
Trouble with resin transfer 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 seconds
Reactor trip on high RCS pressure
Pzr 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 seconds
Condenser hotwell low level alarm received
EFW 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)
Pzr low level alarms at 200(setpoint).
Pzr level reaches a minimum of 158
7
>1 minute
Pzr safety valve outlet temperature alarmed high.
Condenser hotwell high water level alarm received.
Both OTSGs 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 Minutes
IC-P-1A was started to prepare for max letdown flow.
Letdown flow off scale high
Pressurizer 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 Chronology
05:51 Pressurizer level goes off scale high.
08:18 EFW block valves 12A &B were opened.
09:23 Letdown flow isolation valve re-opened
10:15 Pressurizer level back on scale.
10:48 Rx Building sump high level alarm was received.
11 Chronology
13:13 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 Chronology
02:22:00 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 changes
ESAS status panel
Thermal Hydraulic Panel
PT plot
WR NIs
RCITs
Alarm System Reformat
Additional RMS
15 Lessons Learned TMI-2 Accident Organization Changes - Administrative processes
Emergency Planning
Lesson Learned-PRV behavior
INPO established
Site Organizational Realignment. GPU established to run nuclear units.
Radiation protection
16 Lessons Learned TMI-2 Accident Process changes
Symptom Based Procedures
Additional Training for Operators
Simulators BWOG
SPIP -improve safety system performance
- Control system power supply reliability
- Instrument air system upgrades