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Nuclear Event – Automatic Reactor Trip: (Unusual Event) Waterford Unit 3, Killona, LA

2017/07/20

North America – USA | State of Louisiana, Killona, Waterford Unit 3 Nuclear Power Station
Location: 29°59’43.0″N 90°28’16.0″W
Present Operational Age: ~32 years
Emergency Class: UNUSUAL EVENT
10 CFR Section:
50.72(a) (1) (i) – EMERGENCY DECLARED
50.72(b)(2)(iv)(B) – RPS ACTUATION – CRITICAL
50.72(b)(3)(iv)(A) – VALID SPECIF SYS ACTUATION
50.72(b)(3)(v)(A) – POT UNABLE TO SAFE SD

Nuclear Event in USA on Monday, 17 July 2017, 16:17 [CDT].

UNUSUAL EVENT DECLARED DUE TO LOSS OF OFFSITE POWER

During a rain and lightning storm, plant operators observed arcing from the main transformer bus duct and notified the control room. The decision was made to trip the main generator which resulted in an automatic reactor trip. The plant entered EAL SU.1 as a result of the loss of offsite power for greater than fifteen minutes. Plant safety busses are being supplied by both emergency diesel generators while the licensee inspects the electrical system to determine any damage prior to bringing offsite power back into the facility. Offsite power is available to the facility. No offsite assistance was requested by the licensee.

During the trip, all rods inserted into the core. Decay heat is being removed via the atmospheric dump valves with emergency feedwater supplying the steam generators. The main steam isolation valves were manually closed to protect the main condenser. There were no safeties or relief valves that actuated during the plant transient. There is no known primary-to-secondary leakage. Reactor cooling is via natural circulation. All safety equipment is available for the safe shutdown of the plant.

The licensee has notified the NRC Resident Inspector, Louisiana Department of Environmental Quality and the local Parish emergency management agencies.

Notified DHS SWO, FEMA, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email).

* * * UPDATE ON 7/17/17 AT 2007 EDT FROM MARIA ZAMBER TO DONG PARK * * *

This notification is also made under 10 CFR 50.72(b)(3)(v)(D).

“This is a non-emergency notification from Waterford 3.

“On July 17, 2017 at 1606 CDT, the reactor automatically tripped due to a loss of Forced Circulation, which was the result of Loss of Offsite Power (LOOP) to the electrical (safety and non-safety) buses. Both ‘A’ and ‘B’ trains of Emergency Diesel Generators (EDGs) started as designed to reenergize the ‘A’ and ‘B’ safety buses. The LOOP caused a loss of feedwater pumps, resulting in an automatic actuation of the Emergency Feedwater (EFW) system.

“Prior to the reactor trip, at 1600 CDT, personnel noticed the isophase bus duct to main transformer ‘B’ glowing orange due to an unknown reason. Due to this, the main turbine was manually tripped at 1606 CDT. Following the turbine trip, the electrical (safety and non-safety) buses did not transfer to the startup transformers as expected due to an unknown reason.

“The plant entered the Emergency Operating Procedure for LOOP/Loss of Forced Circulation Recovery.

“At 1617 CDT, an Unusual Event was declared due to Initiating Condition (IC) SU1 – Loss of all offsite AC power to safety buses [greater than] 15 minutes.

“All safety systems responded as expected.

“The plant is currently in mode 3 and stable with the EDGs supplying both safety buses and with EFW feeding and maintaining both steam generators. Offsite power is in the process of being restored.”

The licensee has notified the NRC Resident Inspector, Louisiana Department of Environmental Quality and the local Parish emergency management agencies.

* * * UPDATE FROM ADAM TAMPLAIN TO HOWIE CROUCH AT 2203 EDT ON 7/17/17 * * *

The licensee terminated the Notification of Unusual Event at 2056 CDT. The basis for terminating was that offsite power was restored to the safety busses.

The licensee has notified Louisiana Department of Environmental Quality, St. John and St. Charles Parishes, Louisiana Homeland Security Emergency Preparedness, and will be notifying the NRC Resident Inspector.

Notified IRD (Stapleton), NRR (King), R4DO (Hipschman), DHS SWO, FEMA, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email).

* * * UPDATE FROM SCOTT MEIKLEJOHN TO HOWIE CROUCH AT 1724 EDT ON 7/19/17 * * *

This update is being reported under 10 CFR 50.72(b)(3)(v)(B).

“During the event discussed in EN# 52863, at 1642 CDT [on July 17, 2017], Condensate Storage Pool (CSP) level lowered to less than 92% resulting in entry to Technical Specification (TS) 3.7.1.3. Level in the CSP was lowered due to feeding from both Steam Generators with EFW. Normal makeup to the CSP was temporarily unavailable due to the LOOP. Filling the CSP commenced at 1815 CDT [on July 17, 2017], and TS 3.7.1.3 was exited on July 18, 2017 at 0039 CDT.”

The licensee notified the NRC Resident Inspector. Notified R4DO (Hipschman).

Source: NRC  Event Number:  52863

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