SALEM - MANUAL REACTOR TRIP DUE TO LOSS OF CIRCULATORS AFTER UPTAKE OF RIVER ICE - NRC Event Reports

"A manual trip of Salem Unit 2 was initiated due to a loss of 4 circulators due to an excessive uptake of river ice. Strong northwest winds, freezing temperatures and abnormally low tide levels contributed to the ice formation on the river. The operating crew entered EOP-TRIP-A, appropriately transitioned to EOP-TRIP-2 and stabilized the plant at no load conditions (MODE 3 Hot Stand-by).

"All rods fully inserted on the trip and all systems responded as designed with decay heat being removed via the Steam Dump system, with condenser vacuum maintained. All three AFW Pumps auto started due to low Steam Generator level due to closure of 21-23CN27, low pressure feed water heater inlet isolation valves. There were no other significant equipment challenges associated with the reactor trip.

"Salem Unit-2 is currently in mode 3. The Reactor Coolant System temperature is 547 [degrees] F with pressure at 2235 psig [NOT and NOP]. All ECCS and ESF Systems are available and no ECCS systems actuated during the event. No personnel injuries occurred as a result of the trip. [The Unit 2 reactor trip recovery is uncomplicated.]."

Unit 1 power was also reduced to 80%. Although the combination of strong northwest winds, freezing temperatures and an abnormally low tide contributed to the ice formation on the river, operators foresee no further complication due to the ice conditions.

DUANE ARNOLD - DIESEL GENERATOR AUTO START DUE TO FAILED LINE ARRESTOR IN SWITCHYARD

"This report is being made under 10CFR50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in Paragraph (b)(3)(iv)(B) of this section' due to an auto start of the 'A' Standby Diesel Generator.

"The auto start of the 'A' Standby Diesel Generator occurred on a valid bus undervoltage condition caused by a momentary fault on the 161 kV Vinton line. Switchyard inspection revealed a failed 161 kV line arrestor [on] one of the phases of the Vinton line. The 'A' Standby Diesel Generator supply breaker was not required to close onto its respective essential bus as it remained powered from its normal power supply, 1X003 Start-up Transformer, during and after the event. Offsite power remained fully operable during and following the event. The 'A' Standby Diesel Generator has been returned to the standby/readiness condition.

"As designed, the 'A' Emergency Service Water systems auto started when the 'A' Standby Diesel Generator started. The Emergency Service Water systems have been returned to the standby/readiness condition.

"The 'B' Well Water Pump tripped as a result of the electrical transient. The 'A' Well Water pump and 'B' Emergency Service Water pump were manually started by operators in accordance with Abnormal Operating Procedure 408, Well Water System Abnormal Operation.

"The in-service Reactor Water Cleanup pump tripped which removed RWCU from service. The RWCU system has been returned to service.

"The in-service Spent Fuel Pool Cooling pump tripped as a result of the electrical transient. Spent Fuel Pool Cooling has been returned to service. Spent fuel pool temperature rose 0.7 [degrees] F while the pump was out of service.

"All ECCS systems were available before the event and have remained available following the event."

The licensee is not in any Technical Specification LCO's as a result of this event. The in-service Spent Fuel Pool Cooling pump was OOS for approximately 58 minutes.