05000443/LER-2005-005
| Seabrook Station | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4432005005R00 - NRC Website | |
I. Description of Event
On April 13, 2005 at 0350 with the plant in Mode 6 and core reload in progress, an actuation of the reactor protection system (RPS) [JC] resulted from a low water level in steam generator (SG)-B [AB, SG]. While SG-B was in wet lay-up recirculation, an incorrect valve alignment resulted in an inadvertent transfer of water from SG-B to SG-D. This transfer of water decreased the level in SG-B to the low water level reactor trip setpoint, resulting in an actuation of the RPS. This valid actuation of the RPS did not actuate any other components because the reactor trip breakers were already open and the emergency feedwater system [BA] was removed from service.
SG-B was in wet lay-up recirculation on April 12, 2005, and this configuration required that manually operated feedwater system valve FW-V87 [BA, V], emergency feedwater isolation to SG-D, remain closed. On April 13, 2005, SG-D was filled with demineralized water. The procedure for restoring from this evolution placed FW-V87 in its normal position of open, contrary to the position specified by the procedure for wet lay-up recirculation of SG-B. Opening of FW-V87 established a flow path from SG-B, which was on recirculation, to SG-D. The operators were alerted to the lowering level in SG-B upon receipt of alarms associated with a SG low level reactor trip and emergency feedwater system actuation. The flow path between the two SGs was then isolated.
Ill. Cause of Event The cause of this event was a procedure inadequacy. A lack of coordination in controlling the position of FW-V87 between the procedures for placing SGs in wet lay-up recirculation and for filling SGs resulted in FW-V87 being placed in an incorrect position. As a result of this procedure deficiency, an inadvertent transfer of water occurred between SG-B and SG-D.
Ill. Analysis of Event This event resulted in a valid actuation of the RPS and met the reporting criterion of 10CFR50.72(b)(3)(iv)(A). An eight-hour report (event #41593) was made to the NRC at 1019 on April 13, 2005. This event is of regulatory significance because it resulted in the actuation of a system provided to mitigate the consequences of an accident.
This event had no adverse impact on the plant or on the health and safety of the public. No equipment was actuated following actuation of the RPS and no consequences resulted from the event. No inoperable structures, systems, or components contributed to this event. This condition did not involve a Safety System Functional Failure.
IV. Corrective Action The procedures utilized to drain, fill, and recirculate the steam generators will be revised to provide the appropriate coordination between the processes.
V. Additional Information
The Energy Industry Identification System (EIIS) codes are included in this LER in the following format: [EIIS system identifier, EIIS component identifier].
Similar Events A review of LERs submitted in the last five years found no similar events involving a valid system actuation as a consequence of an inadequate procedure.