PNO-III-09-008, A: LaSalle Unit 2, Unplanned Shutdown Greater than 72 Hours
| ML092320637 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 08/20/2009 |
| From: | Kenneth Riemer, Nirodh Shah NRC/RGN-III |
| To: | |
| References | |
| PNO-III-09-008A | |
| Download: ML092320637 (1) | |
PRELIMINARY NOTIFICATION - REGION III August 20, 2009 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-III-09-008A This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.
Facility Licensee Emergency Classification LaSalle Station, Unit 2 Notification of Unusual Event Exelon Generation Co. Alert Marseilles, Illinois Site Area Emergency Docket: 50-373 General Emergency License: DPR-22 x Not Applicable
SUBJECT:
UPDATE--LASALLE UNIT 2 UNPLANNED SHUTDOWN GREATER THAN 72 HOURS DESCRIPTION:
At 1606 on Saturday, August 15, 2009, the Unit 2 reactor tripped after the turbine tripped during the performance of a weekly turbine overspeed surveillance test. Prior to the reactor trip, Unit 2 was operating at 100 percent power. All control rods inserted during the scram, reactor water level was being maintained by the main feedwater system and decay heat was being removed via the turbine bypass valves.
The turbine trip occurred after two of the three turbine overspeed channels were in a trip condition. One of the channels was placed in the trip condition as part of the ongoing surveillance testing. The second channel had apparently been in the trip condition since August 9, unknown by the licensee. Both Unit 1 and Unit 2 have installed a digital electro-hydraulic control system for turbine control.
The licensee is investigating the cause of the turbine over-speed logic trip signal that existed starting on August 9, and which was present during the surveillance testing. Additionally, the licensee is reviewing other anomalies that occurred during the scram. These anomalies did not significantly challenge the licensees response and they are being evaluated by the resident inspectors.
On August 19, Unit 2 was restarted and synched to the grid. The Unit is expected to be returned to full power by August 21.
ADAMS Accession Number: ML092320637 CONTACT: Ken Riemer Nirodh Shah 630-829-9628 630-829-9821