United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for December 7, 2000

                       Headquarters Daily Report

                         DECEMBER 07, 2000

                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

HEADQUARTERS                           X
REGION I                               X
REGION II                              X
REGION III          X
REGION IV                              X

Licensee/Facility:                     Notification:

Commonwealth Edison Co.                MR Number: 3-00-0043
Quad Cities 1                          Date: 12/07/00
Cordova,Illinois                       E-Mail
Dockets: 50-254

Subject: Scram of Unit 1 From Low Water Level Due to Feedwater Regulating
         Valve Malfunction


On December 6, 2000, the Unit 1 reactor tripped from full power on a low
reactor water level (+14.8 inches setpoint compared to +30 inches normal
operating level). The licensee traced the potential cause of the lowering
reactor water level to a cold solder joint in the master feedwater
controller. The suspected intermittent operation of the master controller
caused both feedwater regulating valves to start to close initially, then
continued to close the 1A feedwater regulating valve after operators took
manual control of the 1B feedwater regulating valve. The plant and
personnel properly responded to the trip, as designed.

The licensee repaired the master controller and completed other repairs
which had been previously identified. In addition, the licensee
identified discrepancies in the annunciator response procedures which may
have hindered rapid operator response to the original feedwater
perturbations. Procedures were changed to guide operators to reduce power
more quickly on a feedwater transient, to initiate a manual reactor trip
at +22 inches level, and to allow operators to take actions in a
transient condition without waiting for independent verification.
(Previous guidance was for a manual trip once level reached +20 inches,
but the reactor tripped automatically at about + 20 inches in this
instance due to acceptable instrument tolerance inaccuracies.)

The licensee plans to maintain the unit in Mode 3 pending final results
of the root cause investigation into this event and to complete procedure
changes and operator training. The licensee plans to start up the unit
directly following successful completion of the above activities. Start
up is expected later today.

Regional Action:

The resident inspectors were on site and monitored trip response and
plant recovery operations.

Contact:  M. RING                    (630)829-9703
Page Last Reviewed/Updated Thursday, March 29, 2012