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 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION III DEC. 07, 2000 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 BWR/GE-3 Subject: Scram of Unit 1 From Low Water Level Due to Feedwater Regulating Valve Malfunction Discussion: 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 Wednesday, March 24, 2021
Page Last Reviewed/Updated Wednesday, March 24, 2021