ML070710332
| ML070710332 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 03/09/2007 |
| From: | Ogle C R NRC/RGN-II/DRS/EB1 |
| To: | |
| References | |
| PNO-II-07-002 | |
| Download: ML070710332 (1) | |
Text
March 9, 2007PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-II-07-002This preliminary notification constitutes EARLY notice of events of possible safety or public interestsignificance. The information is as initially received without verification or evaluation, and is basically all that isknown by Region II staff (Atlanta, Georgia) on this date.FacilityLicensee Emergency ClassificationSouthern Nuclear CompanyXNotification of Unusual EventVogtle Unit 2Alert Waynesboro, GeorgiaSite Area Emergency Docket/License: 50-425/NPF-81General EmergencyNot Applicable
SUBJECT:
VOGTLE UNIT 2 NOTIFICATION OF UNUSUAL EVENT (NOUE) DUE TO REACTORCOOLANT SYSTEM (RCS) LEAKAGE IN EXCESS OF 10 GALLONS PER MINUTE (GPM)At 2:23 p.m., EST on March 9, 2007, the licensee declared an NOUE for indication of Unit 2 RCS leakage inexcess of 10 gpm. Unit 2 had been shutdown for a scheduled refueling outage and an RCS draindownevolution was in progress. This declaration was based on control room operators detecting a mismatchbetween charging flow into the RCS and letdown flow out of the RCS of approximately 30 gpm. At the time ofthe event, the RCS was being cooled by the residual heat removal system, RCS temperature wasapproximately 90 degrees F, and the pressurizer was vented to the containment atmosphere.The NRC entered the Monitoring Mode at 3:08 p.m., and the Region II Incident Response Center was staffed.
The licensee attributed the mismatch between charging and letdown to a gas pocket that formed in the reactorvessel head during the shutdown evolution. The gas pocket was released into the containment atmosphere,after the reactor vessel head vent was opened during the draindown evolution. The licensee stated that noleakage from the RCS was detected and that no unplanned radiological exposure to personnel occurred fromthe venting of the RCS. The unit will remain shutdown until the completion of the refueling outage. The resident inspectors we re in theplant and monitored the licensee's actions associated with this event. The licensee terminated the NOUE at 5:51 p.m., at which time the NRC exited the Monitoring Mode.
The licensee has not received any inquiries from the media associated with this event and an NRC pressrelease is not planned.The information presented herein has been discussed with the licensee and is current as of 6:00 p.m., March 9, 2007.The State of Georgia has been notified of the event.Contact:Charles R. Ogle404-562-4605