05000425/LER-2004-001
| Docket Number(S) | |
| Event date: | 04-18-2004 |
|---|---|
| Report date: | 06-16-2004 |
| 4252004001R00 - NRC Website | |
FACILITY NAME (1)� � DOCKET ' 05000-425 20 (6) 04 -- 001 -- 00 LER NUMBER PAGE (3)
A. REQUIREMENT FOR REPORT
This event is reportable per 10 CFR 50.73 (a)(2)(iv) because an unplanned actuation of the Auxiliary Feedwater system occurred.
B. UNIT STATUS AT TIME OF EVENT
At the time of this event, Unit 2 was in Mode 3 (hot standby) at 0 percent of rated thermal power and was being shut down for a refueling outage. The reactor coolant system (RCS) was at 2235 psig and 557 degrees F. The auxiliary feedwater system (AFW) was in service supplying feedwater to the steam generators (SGs) while the unit was transitioning to cold shutdown. Other than that described herein, there was no inoperable equipment that contributed to the occurrence of this event.
C. DESCRIPTION OF EVENT
On April 18, 2004, the main feedwater pumps were out of service and AFW was supplying feedwater to the SGs. Personnel were performing SG feedwater pump turbine (SGFPT) testing per surveillance procedure 14236-2, "SGFPT A and B Trip TADOT." As the reactor coolant system (RCS) temperature and pressure decreased, a caution in the operating procedure required disabling of the AFW actuation signal that is initiated from a trip of both SGFPs, prior to breaking condenser vacuum. However, this would have prevented completion of the SGFPT testing, so the AFW actuation signal was not disabled at that time. Since problems were encountered, the testing was delayed as allowed by the surveillance procedure. Later, at 1238 EDT, the Unit Shift Supervisor (USS) directed the Balance-Of-Plant Operator (BOP) to break condenser vacuum. This was not in compliance with the caution in the unit operating procedure to ensure the AFW actuation signal was disabled. Condenser vacuum was broken, which resulted in a SGFPT low vacuum trip, generating an AFW actuation signal. The AFW discharge valves went fully open and control room operators acted to throttle these valves to control SG water levels. The NRC Operations Center was notified of this event at 1531 EDT, per the requirements of 10 CFR 50.72 (b)(3)(iv)(A).
D. CAUSE OF EVENT
The cause of this event was the failure of the control room staff to adequately sequence the work activities associated with the start of the refueling outage. Simultaneous activities distracted control room employees who failed to follow a procedural caution to disable the AFW actuation signal prior to breaking condenser vacuum. The occurrence of these human performance errors by DOCKETFACILITY NAME (1) 20 LER NUMBER (6 04 -- 001 -- 00 the licensee employees involved were not the result of any unusual characteristics of the work location.
E. ANALYSIS OF EVENT
The AFW actuation occurred as required following receipt of the SGFP trip. After the AFW actuation initiated, control room personnel acted appropriately to throttle flow to the SGs. Had the SGFPs tripped and the AFW system actuated while the reactor was at power, there would have been no additional consequences or implications because the systems operated as designed. Based on these considerations, there was no adverse effect on plant safety or on the health and safety of the public as a result of this event.
The event does not represent a safety system functional failure.
F. CORRECTIVE ACTIONS
1) By June 23, 2004, procedure 13620-1/2, "Condenser Air Ejection System," will be revised to change a Caution note to a procedure step. This caution advises personnel to ensure that the AFW actuation signal received upon trip of SGFPs is disabled prior to breaking condenser vacuum.
2) By September 17, 2004, the Operations Dept. Manager will hold training session briefings with control room operators, discussing this event and reinforcing expectations for managing and executing simultaneous activities.
3) The standard outage schedule will be reviewed by September 17, 2004, to ensure that the appropriate sequence and level of work is planned for the control room staff during times of peak refueling outage activity.
G. ADDITIONAL INFORMATION
1) Previous Similar Events:
There have been no previous similar events in the last three years.
2) Failed Components:
None FACILITY NAME (1) 05000-425 . .s� YEAR� NUMBER DOCKET� LER NUMBER (6 3) Energy Industry Identification System Code:
Auxiliary Feedwater System — BA Main Feedwater System — SJ Reactor Coolant System - AB