PNO-I-10-001, Calvert Cliffs Dual-Unit Trip Due to Partial Loss of Offsite Power
| ML100501188 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/19/2010 |
| From: | Glenn Dentel Reactor Projects Branch 1 |
| To: | |
| Dentel, G RGN-I/DRP/BR1/610-337-5233 | |
| References | |
| PNO-I-10-002 | |
| Download: ML100501188 (2) | |
DCS No.: 05000317/31802192010 Date:
February 19, 2010 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE ~~ PNO~I~10~001 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 Constellation Energy Nuclear Group, Inc.
Licensee Emergency Classification Calvert Cliffs Nuclear Power Plant Notification of Unusual Event Lusby, MD Alert Docket: 50-3171318 Site Area Emergency General Emergency
-1L Not Applicable
SUBJECT:
CALVERT CLIFFS DUAL~UNIT TRIP DUE TO PARTIAL LOSS OF OFFSITE POWER At 8:24 a.m. on February 18, 2010, Calvert Cliffs experienced a loss of one of the two electrical power distribution buses for the site. Loss of this power source resulted in a Unit 2 trip and all four Unit 2 reactor coolant pumps (RCPs) tripping. The loss of this bus caused a loss of power to one of the two safety buses on each unit; the Unit 2 2B emergency diesel generator (EDG) initially started, but tripped and failed to supply power to the affected Unit 2 safety bus. The Unit 1 1 B EDG started as expected upon the loss of power and supplied power to the affected Unit 1 safety bus. Plant operators cross-tied the de-energized Unit 2 safety bus with another power source to return power to Unit 2 safety~related loads. At approximately the same time as the loss of power, Unit 1 experienced an unexpected trip of one of the RCPs, resulting in a Unit 1 trip.
All other safety systems responded as appropriate. Both units are currently stable in hot standby.
Due to the partial loss of power, Unit 2 sustained a loss of normal heat removal due to a loss of the main condenser cooling and the loss of secondary pumps. Unit 2 is currently removing decay heat using auxiliary feed water pumps and steam generator atmospheric dump valves; two RCPs are currently running. Unit 1 is removing decay heat via normal means using main feed pumps and steam bypass to the main condenser. The licensee is investigating the cause of the partial loss of power, the cause for the trip of the Unit 1 RCP, and the trip of the Unit 2 2B EDG.
The NRC resident inspectors, supplemented by regional inspectors, responded to the control room and are providing event follow~up. In addition, Region I will be conducting a special inspection beginning the week of February 22, 2010, to review the event causes as well as operator and equipment response.
State and local officials have been informed.
The information presented herein has been discussed with Constellation and is current as of February 19, 2010, at 10:00 a.m.
Region I Public Affairs is prepared to respond to media inquiries.
ADAMS Accession Number: ML100501188 CONTACT:
Glenn Dentel (610) 337~5233
DISTRIBUTION: (by email: RI-DL-PN; PN_Distribution)
Chairman Jazcko Comm.
Klein Comm.
Svinicki OIP OCA OGC OPA EDO OE NRR SECY IRO NMSS ACRS OIG RES NSIR NRO PDR RSLO Regional 011'ices By Fax:
DOT:Trans INPO NSAC RI Resident Office Licensee:
Constellation Energy Nuclear Group, Inc.
ADAMS Accession Number: ML100501188 SUNSI Review Complete:
GTD (Reviewer's Initials)
DOCUMENT NAME: G:\\DRP\\PNS\\PNO-I-10-001.DOC To receive a copy of this document, indicate in the box: "C°-Copy without attachment/enclosure "E"=Copy attachment/enclosure °N"= No copy OFFICE RI/DRP RIIORA RIIPAO RIIDRP RIIDRS NAME GDentel/GD RBarkle IRB DScrencilDS PWilson/PW DATE 02/19/10 02119110 02/19/10 02/19/10 Region I Form 83 (Rev. July 2, 2003)