Event Notification Report for November 25, 2017

EN Revision Imported Date : 01/17/18

EN Revision Text: MANUAL REACTOR SCRAM DURING STARTUP

"At 0238 [CST] a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 [CST], with reactor power just above the point of adding heat, IRM [Intermediate Range Monitor] channels A, C, and D received a spurious upscale trip signal which immediately cleared. Upon investigation, operability of RPS [Reactor Protection System] scram function for Intermediate Range Detectors was placed in question. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical."

The licensee notified the NRC Resident Inspector.

* * * UPDATE ON NOVEMBER 26, 2017, AT 1850 FROM GRAND GULF TO MICHAEL BLOODGOOD * * *

"At 0238 [CST] a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 [CST], with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event is being reported under 10CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical.

"This Revised Statement to Event Notification # 53090 is being made to make it clear that only four IRM channels (A, C, D, G) were Inoperable and that the IRM RPS SCRAM function was still available from the four remaining Operable IRM channels (B, E, F, and H)."

The licensee notified the NRC Resident Inspector.

Notified R4DO (O'Keefe)

* * * RETRACTION ON 01/16/2018 AT 1629 EST FROM JASON COMFORT TO DAVID AIRD * * *

"On 11/25/17, at 0149 [CST], with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. At 0238 [CST] a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event was initially being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical.

"After the trip alarms were received, the Operators spent approximately twenty minutes investigating possible causes and implications, and consulted with Reactor Engineering and the Shift Technical Advisor. The investigation showed that the plant was stable and the upscale IRM alarms were spurious. A review of plant technical specifications by the operators determined that a plant shutdown was not required. After further discussions, Operations concluded that a shutdown to allow further investigation of the issue was the prudent course of action. Prior to shutting down, Operations spent approximately twenty minutes reviewing procedures, notifying personnel to exit containment, and conducting a brief. The shutdown was then conducted by inserting a manual reactor scram by placing the reactor mode switch in SHUTDOWN.

"This was initially reported under 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the RPS. Based on the sequence of events, and Operator actions in conducting the shutdown, the event is considered 'part of a pre-planned sequence during testing or reactor operation' as specified in 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.73(a)(2)(iv)(A). In accordance with NUREG-1022, Section 3.2.6, the event is not reportable as an actuation of RPS."

The licensee notified the NRC Resident Inspector.

Notified R4DO (Taylor).

Original EN Text: MANUAL REACTOR SCRAM DURING STARTUP

"At 0238 [CST] a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 [CST], with reactor power just above the point of adding heat, IRM [Intermediate Range Monitor] channels A, C, and D received a spurious upscale trip signal which immediately cleared. Upon investigation, operability of RPS [Reactor Protection System] scram function for Intermediate Range Detectors was placed in question. This event is being reported under 10CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical."

The licensee notified the NRC Resident Inspector.

* * * UPDATE ON NOVEMBER 26, 2017, AT 1850 FROM GRAND GULF TO MICHAEL BLOODGOOD * * *

"At 0238 [CST] a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 [CST], with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event is being reported under 10CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical.

"This Revised Statement to Event Notification # 53090 is being made to make it clear that only four IRM channels (A, C, D, G) were Inoperable and that the IRM RPS SCRAM function was still available from the four remaining Operable IRM channels (B, E, F, and H)."

The licensee notified the NRC Resident Inspector.

Notified R4DO (O'Keefe)

MANUAL REACTOR TRIP DUE TO LOSS OF MAIN FEED WATER

"At time 2025 [CST] on 11/25/17, Unit 2 reactor was manually tripped due to a loss of all Main Feedwater. Operators observed both Main Feed Pumps tripped and SG [Steam Generator] levels decreasing, resulting in the direction for a manual reactor trip. The reactor trip actuated a turbine trip, both Motor Driven Auxiliary Feedwater Pumps started on the loss of both Main Feed Pumps, and Steam Generator Lo Lo levels started the Turbine Driven Auxiliary Feedwater Pump. All systems responded as expected. There was no work in progress at the time of the incident.

"Currently Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IP0-0078 and the Emergency Response Guideline Procedure Network has been exited. Decay Heat is being rejected to the Main Condenser via Steam Dump Valves."

The licensee has notified the NRC Resident Inspector.