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| Entered date | Event description | |
|---|---|---|
| ENS 41417 | 17 February 2005 22:05:00 | The following information was provided by the licensee via facsimile: During testing of the Division 2 Diesel Generator Testable Rupture Disc (TRD), it was discovered that excessive force was needed to open its damper. The function of the TRD is to open to relieve exhaust pressure should the diesel generator's non-safety exhaust silencer become blocked. Upon inspection of the TRD, some deformation was noted on the TRD damper. Since the possibility that the condition might exist on the other two divisional diesel generators could not be ruled out, they were also declared inoperable and LCO 3.0.3 entered. An unanalyzed condition potentially exists because a change in engineering design potentially affected multiple trains. Since all three diesel generators are inoperable, a loss of off-site power would challenge safe shutdown capability, the ability to remove decay heat and accident mitigation. A plant shutdown required by Technical Specifications (LCO 3.0.3) was required due to declaring all 3 divisional diesel generators inoperable. LCO 3.0.3 was entered at 1730 hrs on 2/17/05. No power reduction was required as the Division 2 Diesel Generator was declared operable at 2011 after unlatching its Testable Rupture Disc (TRD) (and LCO 3.0.3 was exited). The resident NRC inspector was informed of the LCO 3.0.3 entry and exit (and this event notification). No other notifications of governmental agencies or the press are planned. At the time of the notification to NRC Headquarters, the Division 1 EDG TRD had been unlatched and declared operable. The Division 3 EDG TRD was expected to be unlatched within the next hour. |
| ENS 41344 | 19 January 2005 05:54:00 | The environmental temperature of the tornado missile enclosure for the Emergency Diesel Generators during an accident condition when all three testable rupture disks open is expected to exceed the limiting temperature for the structural concrete. A detailed analysis of the capability of the tornado missile enclosure concrete to meet that standard cited in the USAR section 3.8.3.3.7 has not been located. At 0237 on 19 January 2005, Division 1,2 & 3 Diesel Generators were declared inoperable. Actions of Technical Specification 3.8.2 were directed and compliance verified. NRC Resident Inspector was notified of this event by the licensee.
The following information was provided by the licensee by fax: An 8-hour notification was made on January 19, 2005, in accordance with 10CFR50.72(b)(3)(ii)(B), for an unanalyzed condition and 10CFR50.72(b)(3)(v)(D), for the loss of the accident mitigation safety function. This report was made after declaring division 1, 2, and 3 diesel generators inoperable because the tornado missile enclosure concrete analysis demonstrating compliance with USAR section 3.8.3.3.7 could not be located. Compensatory measures were taken to protect the concrete and vent lines in the area while an analysis was performed. The required analysis was performed by a contract engineering firm. On March 23, 2005, the analysis was owner accepted with comments for incorporation into the final report. None of the comments affected the conclusion of the analysis. This analysis confirmed that the concrete enclosure, as originally designed, supported operability of the diesel generators and their support subsystems. Modifications are being implemented to improve the design margin of the safety related enclosure under accident conditions with the testable rupture disks open. These design modifications are improvements and were not required for past diesel generator operability. Since the operability of the diesel generators and their support subsystems were not affected, there was no unanalyzed condition that significantly degraded plant safety, nor was there a loss of safety function. Since there was no reportable condition, ENF 41344 is retracted. The NRC Resident Inspector was notified. Notified RDO (Kozak) |
| ENS 41310 | 6 January 2005 04:01:00 | At approximately 0106 on 1-6-05, Reactor Recirculation Pumps A and B down-shifted from fast to slow speed which resulted in reactor power decreasing from 100% to approximately 46%. As operators started to reduce power using control rod insertion, Reactor Recirculation Pump A tripped to 'off.' At 0112 on 1-6-05, a manual reactor scram was inserted due to operating under undesirable power to flow conditions. At approximately 0119, the operators were unable to start the Motor Feedwater Pump, Reactor Core Isolation Cooling system was manually started. Level control was established using a Reactor Feed Pump Turbine and Reactor Core Isolation Cooling. The Main Steam Isolation Valves were closed to limit cooldown. Reactor level is being controlled with the Reactor Core Isolation Cooling System and safety relief valves are available for reactor pressure control. The cause of the Reactor Recirculation Pumps down-shifting and the subsequent trip of Reactor Recirculation Pump A is still under investigation. The cause of the Motor Feedwater Pump failure to start is likewise under investigation. All control rods fully inserted. The lowest reactor level reached was 154 inches above TAF. The electrical grid is stable and ESF systems remain available. Reactor pressure and level are being maintained by the Reactor Core Isolation Cooling system. The licensee notified the NRC Resident Inspector. |