ML023580096
| ML023580096 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 03/11/2002 |
| From: | Gray K NRC/RGN-III |
| To: | NRC/OCM |
| References | |
| PNO-III-02-006 | |
| Download: ML023580096 (2) | |
Text
From:
PN1
.1 6
To:
EVENTS; FRONT; PN1 Date:
3/11/02 7:41AM
Subject:
PN302006; Davis-Besse - Significant Metal Loss Observed in Reactor Vessel Head Attached is PN302006 involving Davis-Besse - Significant Metal Loss Observed in Reactor Vessel Head.
Please distribute.
- Thanks, Kathy Gray
&C1O64.
r aY
March 8, 2002 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PNO-III-02-006 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 Davis-Besse Nuclear Power Plant Notification of Unusual Event FirstEnergy Corporation
- Alert Oak Harbor, Ohio
- Site Area Emergency Docket: 50-346 5
General Emergency x Not Applicable
SUBJECT:
SIGNIFICANT METAL LOSS OBSERVED IN REACTOR VESSEL HEAD DESCRIPTION:
During recent ultrasonic examination of vessel head penetration (VHP) nozzles required by NRC Bulletin 2001-01 "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles," dated August 3, 2001, the licensee identified that five VHP nozzles required repair due to cracking in the nozzle adjacent to the J-welds which attach the VHP nozzles to the vessel head. The repair procedure involved machining the cracked portion of the tubes and placing a new weld between the tube and the vessel head.
On March 5, 2002, during VHP nozzle repair activities, the licensee identified an unexpected rotation and lateral movement of one of the nozzles during the machining operation. On March 6, the licensee removed the VHP nozzle and discovered significant metal loss in the head adjacent to the VHP nozzle. The area of the metal loss is not easily observable because of permanent insulation on the exterior of the vessel head.
The licensee has begun to assess the extent of the damage and has formed a root cause team to investigate the cause of this phenomenon. Repair or replacement options are being considered.
The resident inspectors are monitoring the licensee's ongoing assessment activities. Region III (Chicago) will conduct follow-up inspections which will focus on extent of condition, causal factors, and repair or replacement activities.
The reactor is currently in a refueling outage, in Mode 6 (Refueling), and depressurized.
The State of Ohio will be notified. The information in this preliminary notification has been reviewed with licensee management.
There has been news media interest in the licensee's VHP nozzle inspection activities.
This information is current as of 4:00 p.m. (CST) on March 8, 2002.
CONTACTS:
Melvin Holmberg John Jacobson 630/829-9748 630/829-9736