ENS 42245

From kanterella

Jump to navigation Jump to search

v t e ENS Event
09:55 Jan 9, 2006
Title	Loss of Charging System Impact on Safe Shutdown Capability
Event Description	At 0455 EST, the control room received a Plant Process computer alarm for the 'C' Charging pump and entered TS 3.0.3. TS 3.0.3 was entered due to both ECCS trains becoming inoperable due to the loss of the charging subsystem safety function. The 'A' charging pump (backup) was started at 0458 and had sufficient flow for only several minutes. The control room then attempted to start the 'B' charging pump (standby) at 0459 with no success. At 0500 Charging and Letdown was secured and at 0501, operators identified a potential 'B' charging pump pulse dampener bladder failure and entered AOP 2568 for RCS leakage. The 'B' Charging pump suction and discharge were isolated at 0510 and at 0544 the 'C' charging pump was vented and restored to service. The licensee exited TS 3.0.3 at 0554 and entered TS 3.5.2 A since 'B' train of ECCS was restored to operability. The licensee suspects that the nitrogen from the bladder on the discharge of the pump leaked through the 'B' charging pump to the common charging pump suction header and caused gas intrusion to the running 'C" charging pump and to the common suction header for the standby charging pumps. TS 3.5.2 Bases does not credit the charging system for Design Basis Accident (DBA) mitigation, however the charging system is credited for two beyond DBA events - ATWS and Complete Loss of Secondary Heat Sink. At 1343 EST, the control room received a Charging low flow alarm with the 'C' charging pump in service. Charging and Letdown were secured and the licensee entered TS 3.0.3 at 1344. At 1459 the licensee completed the fill and vent of the 'C' charging pump and started the pump at 1514 and placed Charging and Letdown into service. The licensee is performing an engineering evaluation to keep the 'C' charging pump running and an Operability Determination must be completed prior to declaring the 'C' charging pump operable. The licensee continues to troubleshoot the 'A' charging pump to restore to operability. Once the 'C' charging pump is declared operable, the licensee will exit TS 3.0.3 The licensee notified the NRC Resident Inspector, and both state and local emergency response organizations.

ENS 42245 +/-
Where
Millstone Connecticut (NRC Region 1)
Reporting

10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
Time - Person (Reporting Time:+7.23 h0.301 days <br />0.043 weeks <br />0.0099 months <br />)
Opened:	Robert Maloney 17:09 Jan 9, 2006
NRC Officer:	Jeff Rotton
Last Updated:	Jan 9, 2006
42245 - NRC Website
v • d • e

v t e Emergency Notification System
Millstone with 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
WEEKMONTHYEAR2020-08-04T21:45:00 [Table view]
[ENS list for Millstone]

Retrieved from "https://kanterella.com/w/index.php?title=ENS_42245&oldid=427580"