PNO-III-02-032, Shutdown to Determine and Correct the Cause of Fluctuations in Main Steam Line Parameters (Flow, Pressure, Carryover)
| ML021960455 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 07/15/2002 |
| From: | Ring M, Karla Stoedter NRC/RGN-III |
| To: | Exelon Nuclear |
| References | |
| PNO-III-02-032 | |
| Download: ML021960455 (2) | |
July 15, 2002 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-III-02-032 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 Quad Cities Notification of Unusual Event Exelon Nuclear Generation Company Alert Cordova, Illinois Site Area Emergency Docket: 50-265 General Emergency License: DPR-30 X Not Applicable
SUBJECT:
SHUTDOWN TO DETERMINE AND CORRECT THE CAUSE OF FLUCTUATIONS IN MAIN STEAM LINE PARAMETERS (FLOW, PRESSURE, CARRYOVER)
DESCRIPTION:
At 2:41 a.m. CDT on July 11, 2002, the licensee began shutting down of the Unit 2 reactor due to irregular indications in steam flow, reactor pressure and level, and moisture carryover in the main steam lines.
As required by Technical Specifications 3.0.3., the licensee shut down the reactor when it was determined that reasonable assurance of operability of safety system components, such as steam flow indication in the main steam lines, could not be supported.
Unit 2 first began experiencing fluctuations in steam flow, pressure, level and moisture carryover in steam lines on June 7, 2002. After more fluctuations in June and July, the licensee conducted an engineering evaluation of one of the recent fluctuations, which occurred on July 6, and concluded that the steam flow difference could be caused by loose parts in the steam line and that this could impair proper functioning of safety systems.
The licensee initially believed the loose parts may be baffle plates, which were installed during the March 2002 refueling outage, as a modification to the steam dryer to reduce moisture carryover. However, subsequent to shutting down the unit, when the licensee removed the vessel head and examined the dryer on July 13, a dryer cover plate, located on the outer periphery of the steam dryer was found to have broken loose. The plate appears to have broken into 3 pieces. One was found on the steam separator, one on the top of the dryer, and one piece lodged in the venturi area of the A main steam line. Licensee efforts to recover the pieces, evaluate the condition of Unit 2, and determine the cause of the damage are continuing.
The resident inspectors are monitoring the licensees investigation.
The State of Illinois will be informed. The information in this preliminary notification has been reviewed with licensee management.
The licensee notified the NRC Operations Center of the shutdown at 4 a.m. CDT on July 11, 2002. This information is current as of 11 a.m. CDT on July 15, 2002.
CONTACTS: Mark Ring Karla Stoedter (630)829-9703 (309)654-2227