At 1510, "[Watts Bar Nuclear (
WBN)] had identified
RCS leakage in excess of 25 gallons per minute (gpm). The leakage was estimated at 105 gpm. This is a report notification only and not a declaration. The
EAL that was exceeded was 2.6,
RCS identified leakage. While placing a mixed bed demineralizer in service
VCT level was observed to have dropped 10%. The demineralizer was immediately removed from service. This terminated the drop in
VCT level. In accordance with
WBN EPIP-1 Emergency Classification Flowchart, section 3.0 step 3.3.7, if an
EAL was exceeded but the emergency has been totally resolved (prior to declaration), the emergency condition that was appropriate shall not be declared but reported only. The duration of the leakage was approximately 15 minutes. The unit remains at mode 1 and 100% power. The cause for the unexpected level decrease is under investigation at this time. There were no radiological releases associated.
The licensee will notify the NRC Resident Inspector.
- * * UPDATE FROM MICHAEL BRANDON TO JOE O'HARA AT 1327 ON 1/15/08 * * *
The original report contains a typographical error. The leak duration was reported as 15 minutes. The correct time period is 1.5 minutes.
Notified R2DO(Moorman)
- * * RETRACTION ON 2/8/2008 AT 1710 FROM MICHAEL BRANDON TO MARK ABRAMOVITZ * * *
On January 11, 2008, TVA notified the NRC of the discovery of an after the fact unusual event. The reported event described potential RCS leakage in excess of 25 GPM that was approximately 1 and 1/2 minutes in duration. The estimated magnitude of this leak was based on a step change in Volume Control Tank (VCT) level that occurred when placing the 1A Mixed Bed Demineralizer in service. TVA's post-event investigation concluded the cause of the VCT level change was the filling of a void in the 1A Mixed Bed Demineralizer. The cause of the void was a procedural deficiency in the flush methodology used when returning the demineralizer to service. Based on the evaluation of this event, TVA has concluded that no actual RCS leakage occurred. The RCS pressure boundary remained intact throughout this evolution.
Based on the result of this evaluation and the subsequent successful alignment of the demineralizer without incident, TVA is retracting this event.
The licensee has notified the NRC Resident of this retraction.
Notified the R2DO (Munday) and
NRR EO (Brown).
