ML091960486

From kanterella
Jump to navigation Jump to search
PNO-I-09-005: Exelon Generation Co. Llc., Oyster Creek Reactor Trip and Unusual Event Due to a Loss of Offsite Power and Shutdown Greater than 72 Hours
ML091960486
Person / Time
Site: Oyster Creek
Issue date: 07/15/2009
From: Bellamy R R
NRC/RGN-I/DRP/PB6
To:
bellamy rr
References
0500021907152009 PNO-I-09-005
Download: ML091960486 (2)


Text

DCS No.: 0500021907152009 Date: July 15, 2009

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-I-09-005 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 I staff on this date.

Facility Exelon Generation Company, LLC Oyster Creek Forked River, NJ Docket: 50-219 Licensee Emergency Classification X Notification of Unusual Event Alert Site Area Emergency General Emergency Not Applicable

SUBJECT:

OYSTER CREEK REACTOR TRIP AND UNUSUAL EVENT DUE TO A LOSS OF OFFSITE POWER AND SHUTDOWN GREATER THAN 72 HOURS On July 12, at 1:35 a.m., a lightning strike on the Whiting (Q121) line, a portion of the 34.5 KV offsite distribution system, caused a fault which resulted in a loss of offsite power (LOOP) at Oyster Creek. All control rods inserted during the scram. Both isolation condensers (ICs) actuated, two electro-magnetic relief valves (EMRVs) opened, and the reactor recirculation pumps tripped as designed in response to a high-pressure condition. In addition, the #2 EDG fast-started and loaded its emergency bus, while the #1 EDG started and loaded its bus 80 seconds later. A primary containment isolation (including main steam isolation valve closure) occurred due to reaching low-low reactor water level due to the loss of power to the main feedwater pumps. Plant operators used the Isolation Condenser System, EMRVs and Control Rod Drive flow to control reactor pressure and level. An Unusual Event (UE) was declared at 1:48 a.m. because the LOOP exceeded 15 minutes in duration. Offsite power was subsequently restored at 3:05 a.m. and the UE was terminated at 4:05 a.m. Oyster Creek achieved cold shutdown at 6:30 p.m. using the Isolation Condenser System and shutdown cooling.

Equipment anomalies observed during the transient included: 1) the Q121 breaker, which isolates the Whiting Line, failed to open to clear the fault which resulted in the LOOP that caused the reactor scram; 2) the #1 EDG required longer to start and load its respective emergency bus than expected; 3) the "B" isolation condenser level indication for the shell side exhibited anomalous readings. In addition, there were a number of non-safety systems that were affected by the loss of power.

The Resident Inspectors responded to the site and closely monitored licensee actions to stabilize the plant and restore offsite power. Troubleshooting of the plant systems continues prior to restart. The resident staff, supplemented by regional specialists, continues to monitor the plant status and is following the licensee's actions to address equipment issues before plant restart.

The State of New Jersey was informed at the time of the event.

The NRC Region I Public Affairs Office has responded to media inquiries.

The information presented herein has been discussed with Exelon Plant Manager, Pete Orphanos, and is current as of July 15, 2009 at 1:00 p.m.

NRC Region I will update this PN after plant restart.

ADAMS Accession Number: ML091960486 CONTACT: Scott Barber (610) 337-5232 DISTRIBUTION: (by email) Chairman Jazcko Comm. Klein Comm. Svinicki OIP OCA OGC OPA EDO OE NRR SECY IRO NMSS ACRS OIG RES NSIR NRO PDR RSLO Regional Offices By Fax: DOT:Trans INPO NSAC RI Resident Office Licensee: Exelon Generation Company LLC Oyster Creek Generating Station ADAMS Accession Number: ML091960486 SUNSI Review Complete: GSB (Reviewer's Initials)

DOCUMENT NAME: G:\DRP\PNs\PNO-I-09-005 - OC Rx Trip due to LOOP.doc After declaring this document "An Official Agency Record" it will be released to the Public.

To receive a copy of this document, indicate in the box:

" C" = Copy without attachment/enclosure, " E" = Copy with attachment/enclosure " N" = No copy OFFICE RI/DRP RI/ORA RI/PAO RI/DRP RI/DRP NAME SBarber/SB DTifft/DT DScrenci/DSDLew/DCLRBarkley/RB DATE 07/ 15/09 07/15 /09 07/15 /09 07/15 /09 07/15/09 OFFICIAL RECORD COPY