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| Entered date | Event description | |
|---|---|---|
| ENS 42635 | 12 June 2006 18:00:00 | On 6/12/06 at 07:54 am CDT, the Wolf Creek Generating Station removed the Nuclear Plant Information System (NPIS) computer from service for planned maintenance. Following this maintenance, one of the NPIS multiplexers (MTJX 'D') failed to re-establish communications with the computer, and efforts to restore the computer to service have been unsuccessful. The failure to restore the NPIS computer has resulted in a loss of functionality of the Safety Parameters Display System (SPDS). Efforts continue to restore the NPIS computer to service, which will restore SPDS functionality. Due to SPDS being lost for longer than a short period of time, Wolf Creek Nuclear Operating Corporation is making this ENS notification pursuant to the criteria of 10 CFR 50.72(b)(3)(xiii). There is no other loss of emergency assessment capability concurrent with the ongoing loss of SPDS. Plant personnel have entered the appropriate Off-Normal procedure and are obtaining local readings for the equipment that is normally monitored by SPDS and NPIS. It is unknown at this time when NPIS/SPDS will be restored. The licensee notified the NRC Resident Inspector. * * * UPDATE FROM T. DAMASHEK TO P. SNYDER AT 1735 ON 6/13/06 * * * SPDS has been restored as of 1605 CDT. The licensee will notify the NRC Resident Inspector. Notified R4DO (Bywater). |
| ENS 41786 | 21 June 2005 16:35:00 | During integrated ESFAS System Testing coming out of RF 14, it was noted (on 5/10/05) that 4 dampers receiving an SI signal did not reposition full closed as required. The dampers serve to isolate the Condenser Air Removal Ductwork in the Turbine Building from the Filtration train in the Auxiliary Building. Failure of these dampers to close was determined on 05/27/2005 to constitute an unanalyzed condition in that this path is assumed isolated in the accident analysis. The dampers receive a signal to close but are powered from an AC source requiring a Diesel Generator to supply power from a safety related motor control center. The problem occurs when a signal for loss of offsite power is inserted coincident with an SI signal. The dampers start to close, but there was no seal in circuit so that motion to the closed condition would continue once the affected Diesel Generator reenergized the safety related bus and power supply. The plant was in Mode 5 at time of discovery, but has operated at power with this configuration since the initial startup of the unit. The dampers could have been closed as evidenced by troubleshooting at the time relying on operator action once the Diesel Generator had reenergized the bus. There is no requirement for Sl and Auxiliary Building isolation in Mode 5. A modification was completed to the circuitry prior to entering Mode 4 where automatic isolation is required. The Reportability Evaluation was completed on 5/27/2005 but was not reported within the required 8 hours. The reportability of 8 hours was discovered during review on 06/21/2005 of the completed evaluation. Licensing personnel were immediately contacted. The licensee notified the NRC Resident Inspector. |
| ENS 40517 | 13 February 2004 11:00:00 | At 0810 CST on 2-13-2004, all four Steam Generators alarmed with Steam Flow/Feed Flow Mismatch alarms, followed by indication of decreasing level in "D" Steam Generator. The reactor tripped approximately 20 seconds later on Lo-Lo level at 23.5% in "D" Steam Generator, as required. The cause of the loss of feedwater flow to "D" Steam Generator is under investigation. All plant safety related systems operated as required. The Steam Dumps, which function to remove excess heat as the secondary systems shutdown, exhibited control problems resulting in operation of the Steam Generator Atmospheric Relief Valves (ARVs) until the steam dump controller setpoint was adjusted and the steam dumps began to operate normally. The steam dumps are currently operating in automatic. The Steam Generator ARVs closed when the steam dumps began to operate. The auxiliary feedwater system actuated as designed, and a Feedwater Isolation signal was generated as designed on Lo-Lo Steam Generator Level. The plant is currently stable in Mode 3 at NOP and NOT while plant personnel investigate the causes of the trip and formulate the repair/restart plan. Decay heat is currently being removed via the steam dumps. The plant electrical system responded normally and all emergency diesel generators remain in standby. There are no primary to secondary leaks. The licensee notified the NRC Resident Inspector. |