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| Entered date | Event description | |
|---|---|---|
| ENS 53647 | 5 October 2018 09:59:00 | EN Revision Text: UNPLANNED LOSS OF THE ASSESSMENT CAPABILITY DUE TO TECHNICAL SUPPORT DIESEL At 05:52 CDT on 10/5/2018, the (Wolf Creek Nuclear Operating Corporation) (WCNOC) Technical Support Center (TSC) Diesel fuel oil transfer pump would not run. There was ongoing modification to the facility Halon system at the time. The modification process had included a jumper to the fuel oil transfer pump to allow it to continue to be available. This issue was discovered during testing as the modification was progressing. The pump was verified to function on 10/4/2018 by normal operations rounds. If an emergency is declared requiring the TSC activation during the time the TSC diesel is non-functional, the TSC will be staffed and activated using existing emergency planning procedure. If offsite power is lost, the TSC will relocate to the Alternate TSC using existing emergency planning procedures. There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
Event Notification (EN) 53647, made on October 8, 2018, is being retracted because during the time that the TSC Diesel fuel oil transfer pump was not available, normal power was continuously available. The Alternative TSC was also available. Consequently, the condition did not meet the criteria for a 8-hour notification per 10 CFR 50.72(b)(3)(xiii) for any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability (e.g., significant portion of control room indication, Emergency Notification System, or offsite notification system). The NRC Resident Inspector has been notified of the Event Notification retraction. Notified R4DO (Pick). |
| ENS 49339 | 11 September 2013 20:37:00 | Wolf Creek has commenced a plant shutdown in accordance with Technical Specifications. The A Train Class 1E Electrical Equipment Air Conditioning unit was declared non-functional due to a possible failed compressor cylinder, as indicated by increased vibration. This failure could prevent the unit from performing its required function over its required mission time, as required by Technical Specifications 3.8.4, 3.8.7, and 3.8.9. The following safety related electrical equipment was declared inoperable: 4.16KV Bus NB01; 480 Volt AC buses NG01 and NG03; 120 Volt Instrument AC inverters and buses NN11, NN13, NN01 and NN03; 125 VDC chargers and buses NK11, NK13, NN01 and NN03. Technical Specification 3.0.3 was entered at 1645 CDT on 9/11/2013 from Technical Specification 3.8.7 due to two out of four 120 VAC inverters (NN11 and NN13) being inoperable. Plant shutdown to Mode 5 commenced at 1731 CDT. The unit is currently at approximately 50% power. All electrical systems listed above remain available but are declared inoperable due to inadequate room cooling capability. No major equipment is out of service. The NRC Resident Inspector has been notified. No switchgear room temperature limits were challenged. See EN #49008 (May 6, 2013) and EN #49126 (June 17, 2013) for similar events.
At 00:36 CDT 9/12/13, Wolf Creek had an Auxiliary Feedwater Actuation during a plant shutdown in accordance with Technical Specifications. The plant was in Mode 3, all control rods inserted, with reactor trip breakers closed when low steam generator levels prompted a manual reactor trip. A Valid Auxiliary Feed Actuation signal was received due to low steam generator levels. All Auxiliary Feedwater pumps started and operated as expected. The licensee has informed the NRC Resident Inspector. R4DO (Hay) notified. |
| ENS 46990 | 26 June 2011 18:00:00 | 6/26/11 at 1609 CDT, the reactor was manually tripped due to the trip of the 'B' Main Feed Pump while operating in Mode 1 at approximately 82% reactor power. The unit was increasing power to 95% after the current refuel outage. The cause of the trip of the 'B' Main Feed Pump is not known at this time. All equipment functioned normally as expected. The investigation into the cause of the 'B' Main Feed Pump trip is ongoing at this time. Current plant status is Mode 3. The NRC Senior Resident has been contacted. All rods fully inserted upon reactor trip. The unit is stable with Auxiliary Feedwater supplying the Steam Generators. Decay heat is being removed to the Main Condenser via steam dumps. The electrical system is in a normal post-trip alignment. The licensee characterized the reactor trip as uncomplicated.
A valid Auxiliary Feed(water) actuation signal (occurred) due to trip of both of the Main Feed pumps from a turbine trip and low steam generator levels. This is reportable under 10CFR50.72 (b)(3)(iv)(A), 8-hour report. All auxiliary feed pumps started and operated as expected. The licensee will notify the NRC Resident Inspector. Notified R4DO (Deese). |
| ENS 46685 | 19 March 2011 06:54:00 | Following a scheduled plant shutdown for refueling the operators were forced to close the Main Steam Isolation Valves (MSIV's) to limit plant cooldown. While opening MSIV's to restore steam to the secondary, a Reactor Trip and Safety Injection (SI) occurred. The MSIV bypass valves were opened to equalize pressure across the MSIV's. Steam header pressure dipped when the MSIV for 'C' Steam Generator (S/G) was opened. The low steamline pressure bistables are rate sensitive and actuated to cause the SI when steam pressure dipped. Lowest steamline pressure was 1040 psig, the low steam line pressure SI actuates at 615 psig. During the SI the PZR (Pressurizer) PORV's cycled approximately 10 times to limit RCS pressure. When the PORV's opened the 'B' PZR Code Safety Main Control Board (MCB) and plant computer alarm actuated but the actual MCB indication did not change nor does plant response indicate that a PZR Code Safety opened. This appears to be an indication problem related to the PORV's cycling. All equipment functioned as required. The station electric buses are aligned to normal offsite power. Decay heat removal is being discharged to the atmospheric relief valves with no indication of primary to secondary leakage. The licensee notified the NRC Resident Inspector.
1. The expected system actuations that occurred when the plant experienced a Safety Injection (SI) 03/19/11 at 04:04 CDT, previously reported on EN 46685 for 10CFR50.72(b)(2)(iv)(A), is also reportable under 10CFR50.72(b)(3)(iv)(A) for Specified System Actuation. 2. During the recovery of the Safety Injection (SI) actuation that occurred 03/19/11 at 04:04 CDT and previously reported on EN 46685, the Safety Injection Signal was reset which blocked any further automatic actuation. This was directed per the appropriate procedure step. There is no Technical Specifications allowed condition for both trains of ECCS to be inoperable, therefore the unit entered Tech. Spec. 3.0.3 due to the Auto SI feature being blocked. LCO 3.5.2 action C.1. directs immediate entry into LCO 3.0.3. The entry into TS 3.0.3 was made at 0411 CDT and exited at 0639 CDT when the Reactor Trip Breakers were reclosed which re-enabled the automatic SI signal. This is reportable under 10CFR50.72(b)(3)(v)(D) for Accident Mitigation. NRC Resident was notified of the update. Notified R4DO(Cain). |