United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for December 28, 1999

                       Headquarters Daily Report

                         DECEMBER 28, 1999

***************************************************************************
                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

HEADQUARTERS                           X
REGION I                               X
REGION II           X
REGION III                             X
REGION IV                              X
PRIORITY ATTENTION REQUIRED  MORNING REPORT - REGION II  DEC. 28, 1999

Licensee/Facility:                     Notification:

Duke Power Co.                         MR Number: 2-99-0016
Oconee 3                               Date: 12/28/99
Seneca,South Carolina
Dockets: 50-287
PWR/B&W-L-LP

Subject: OCONEE UNIT 3 NOTICE OF UNUSUAL EVENT UPDATE

Discussion:

This morning report supplements information regarding a Notice of Unusual
Event (NOUE) which occurred on Oconee Unit 3 on December 27, 1999 (Event
Notification 36543).

The NOUE was terminated at 8:42 p.m., on December 27, 1999, following
isolation of reactor coolant system letdown.  Isolating letdown resulted
in an increasing pressurizer level.  At 9:01 p.m., pressurizer level
exceeded the high level limit specified in Technical Specification (TS)
3.4.9.  The licensee isolated and unisolated letdown, and entered and
exited the pressurizer level TS, for several hours while controlling
pressurizer level.  After establishing an alternate letdown flowpath, the
licensee exited the pressurizer level TS for the final time at 2:23 a.m.
on December 28.  Manual control of pressurizer level has been maintained
satisfactorily since that time.  The diversion of reactor coolant system
water to the bleed holdup tank has stopped.  Power level was reduced
first to 50 percent power and then to 35 percent during this event.

Licensee troubleshooting identified a failure in the mechanical coupling
between the actuator and the letdown bypass valve (3HP-14) stem.  The
licensee is currently fabricating a replacement component for the valve
and intends to install this component with the unit online later today.


Regional Action:

The residents are following this issue.

Contact:  Charles R. Ogle            (404)562-4510
_
Page Last Reviewed/Updated Thursday, March 29, 2012