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| Entered date | Event description | |
|---|---|---|
| ENS 49884 | 8 March 2014 10:25:00 | On March 8, 2014 at 0325 (EST), Secondary Containment Zone 2 (Unit 2 Reactor Building) differential pressure went to 0.0 inches WG (water gauge) following a routine transfer of Unit 2 Reactor Protection System (RPS) Power supplies. Upon restoration from the RPS power supply transfer, one of the Reactor Building Exhaust Fans tripped due to a malfunction of its discharge damper. Zone 2 HVAC was restored at 0335 by placing the other train of fans in service. Zone I (Unit 1 Reactor Building) and III (Common Refuel Floor Area) ventilation remained in service and stable. Zone 2 differential pressure recovered to SR 3.6.4.1.1 requirements of 0.25 inches WG within a few minutes and was verified to be stable. LCO 3.6.4.1 was entered at 0325 and exited at 0354. Tech Spec for Secondary Containment Operability requires a negative pressure of at least 0.25 inches water gauge for all three Reactor Building Ventilation Zones. There have been no further perturbations in differential pressure and secondary containment remains operable. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a safety function. There is no redundant Susquehanna Secondary Containment System. The licensee notified the NRC Resident Inspector. |
| ENS 49867 | 4 March 2014 01:50:00 | On March 4, 2014 at 0025 EST, Secondary Containment drawdown testing surveillance failed to meet acceptance criteria of SR 3.6.4.1.5 due to maximum flow rate exceeding the allowable value. Secondary Containment drawdown testing was being performed on Reactor Building Zone 1 and Zone 3 with Zone 2 HVAC shutdown. Upon failure of the surveillance, Secondary Containment ventilation was realigned to a previous successfully tested and known operable alignment for Zones 1, 2 and 3. This alignment consists of all Reactor Building Zones in service and Zone 3 aligned to the Railroad Bay. Upon restoration of Secondary Containment ventilation to a known operable alignment, operability was restored and Secondary Containment LCO 3.6.4.1 was cleared at 0128 EST on March 4, 2014. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG-1022, Rev. 3, Section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee informed the NRC Resident Inspector. |
| ENS 49492 | 1 November 2013 09:51:00 | On November 1, 2013 at 0309 EDT, Secondary Containment Zone I (Unit 1 Reactor Building) differential pressure was lost following a routine transfer of Reactor Protection System Power supplies. Upon restoration from the power supply transfer, one of the Reactor Building Exhaust Fans tripped. There were no obvious malfunctions associated with the equipment and fan was able to be restarted. Zone II (Unit 2 Reactor Building) and III (Common Refuel Floor Area) ventilation remained in service and stable. Zone I differential pressure recovered within a few minutes and was verified to be stable. LCO 3.6.4.1 was entered for both units at 0309 EDT and exited at 0315 EDT. Tech Spec Secondary Containment Operability requires a negative pressure of at least 0.25 inches water gauge. There have been no further perturbations in differential pressure and secondary containment remains operable. This event is being reported under 10 CFR 50.72(b)(3)(v) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee notified the NRC Resident Inspector. See similar event number #49489. |