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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 53699 | 28 October 2018 04:00:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Non Essential Service Water Inoperable | During the performance of Service Water Essential header swap, SWN-6 (Supply to Turbine Building Oil Coolers) valve stem became disconnected from its gear box at 85% open and could not be operated. Therefore, the non-essential service water system was inoperable. LCO 3.0.3 was entered at 0930 (EDT) with required actions to be in Mode 3 in 7 hours, Mode 4 in 13 hours and Mode 5 in 37 hours. Repair efforts were successful at shutting SWN-6, and LCO 3.0.3 was exited at 1305 (EDT) before adding any negative reactivity in support of shutdown. ('TS Required S/D' box not checked.) This condition constituted a loss of safety function which requires an 8 hour report (in accordance with) IAW 50.72(b)(3)(v)(B): Without the ability to close SWN-6, the non-seismic portion of the conventional Service Water System could not be isolated as required in the event of either a seismic event or as required in the EOPs. The nonessential service water system is required to support the recirculation phase post (Design Basis Accident) DBA for accident mitigation. The licensee notified the NRC Resident Inspector and the State of New York. | Service water | |
| ENS 52836 | 30 June 2017 05:30:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | Condensate Storage Tank Declared Inoperable | On June 30, 2017 at time 0130 (EDT), the Condensate Storage Tank (CST) was declared inoperable per Technical Specification 3.7.6. A pin hole sized through wall leak was discovered on the downstream side of CD-123, 32 Auxiliary Boiler Feed Pump Bearing Cooling Relief Valve, which is unisolable to the CST. No type of Non-Destructive Examination (NDE) can be used to effectively characterize the defect. Based on the inability to characterize the defect and the fact that the degradation mechanism is not readily apparent, the valve is considered inoperable because the valve has lost its ability to maintain a pressure boundary. As a result, the CST is inoperable. Currently, the CST has 580,000 gallons of water contained in the tank, which is well above the minimum required amount of 360,000 gallons. City water is the backup means to supply water to the Auxiliary Feedwater System, and this has been verified to be operable in accordance with the Actions of the Technical Specification. The CST must be restored to operable status within 7 days. The CST provides cooling water to remove decay heat and the minimum amount of water in the Condensate Storage Tank is the amount needed to maintain the plant for 24 hours at hot shutdown following a trip from full power. The CST satisfies Criteria 2 and 3 of 10 CFR 50.36. This event was determined to be reportable as a Loss of Safety Function pursuant to 10 CFR 50.72(b)(3)(v)(B). The licensee will notify the NRC Resident Inspector and the State of New York. | Auxiliary Feedwater | |
| ENS 51329 | 18 August 2015 17:31:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Residual Heat Removal Heat Exchanger Outlet Valves Unanalyzed Condition | At 1331 hours (EDT) on August 18, 2015 with the plant in mode 1, IP2 entered TS (Technical Specification) 3.0.3 upon determination by the Shift Manager that MOV-746 and 747 at the outlet of the Residual Heat Removal (RHR) Heat Exchangers may not (fully) open on an Sl (Safety Injection) signal if there was a degraded grid voltage (where the voltage at the 480V Safeguards Buses is below the minimum drop-out value of 415V and above the loss-of-voltage value of 206.6V). The MOV 746 and 747 valves are normally closed so the Sl signal with degraded voltage present could cause the fuses to fail. The time when the fuses would fail and the extent to which the MOVs open has not yet been analyzed. Immediate corrective actions was taken to replace the fuses with fuses that would not fail. The RHR trains were restored to an operable condition at 1419 and 1431 hours. This event is potentially reportable under 10 CFR 50. 72(b)(3)(ii) and 10 CFR 50.72(b)(3)(v) since the condition has not yet been fully analyzed but has been corrected. The plant remained at 100% power during the time of this event. All technical specification requirements were followed. The licensee will notify the NRC Resident Inspector and the State. | Residual Heat Removal | |
| ENS 45765 | 13 March 2010 23:25:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | Emergency Diesel Generators (Edgs) Declared Inoperable Due to Service Water Tagout | At 1825 EST service water to '22' and '23' EDGs was isolated while applying a protective tagout to the service water '1-2-3' header. Previously, the supply from the other service water header '4-5-6' was also isolated. '21' EDG was out of service on a tagout. This resulted in a condition where no service water flow to the Emergency Diesel Generators was available for approximately three minutes. Service water flow was restored by opening the supply from the '1-2-3' service water header. During this condition, LCO 3.8.2 was not met. All required actions for LCO 3.8.2 were performed. LCO 3.8.2 was met when service water flow was restored to the Emergency Diesel Generators. The Emergency Diesel Generators were required to support residual heat removal in the event of a loss of offsite power. At no time was residual heat removal lost. The licensee will inform the NRC Resident Inspector. | Service water Emergency Diesel Generator Residual Heat Removal | 05000247/LER-2010-003 |
| ENS 42524 | 25 April 2006 09:00:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | Service Water Piping Flooding Concern Impacts Rhr | At 0500 hours on April 25, 2006 with the plant in mode 5 and RCS loops filled, Operations declared the 21 and 22 Residual Heat Removal (RHR) pumps inoperable (see IP2-CR-2006-2133). This is reportable under 10 CFR 50.72(b)(3)(v)(B) as an event that at the time of discovery could have prevented the RHR pumps from removing residual heat. Residual heat removal is still available through the steam generators. The pumps were declared inoperable, but remained in operation, after a degraded horizontal section of Service Water (SW) line 405 was identified. SW line 405 is a non-ASME Section XI, non-Class A, seismically supported 24 inch return line routed through the Steam Generator Blowdown (SGBD) Tank room in the Plant Auxiliary Building (PAB) about 15 feet above the floor elevation of 51 feet. The ability of the pipe to withstand a seismic event has not currently been demonstrated. The consequence of a failure of this pipe is the flooding of the SGBD Tank room, cascading water down to the pipe case and then to the 15 foot PAB elevation. Water can drain to the transformer yard through a door at that elevation but the bottom of the RHR pump motors is lower than the door sill. Compensating actions have been implemented. These include provisions to open the door to the transformer yard with a security guard to monitor the open door, install sand bags at the entrance to the RHR pump room to prevent water entry, and install blocking devices to prevent backflow through the RHR pump room floor drains. A 24 hour watch is being provided for implementation of these compensatory measures. The watch will have a sump pump should it be necessary for leaks. The RHR pumps were declared operable at 1200 hours. Corrective action for SWS pipe 405 is being planned. The licensee notified the NRC Resident Inspector.
Indian Point 2 is withdrawing the 8-hour non-emergency notification made on April 25, 2006, at 1231 hours. (Log No. 42524). The notification on April 25, 2006, reported an event or condition that could have prevented the Residual Heat Removal pumps from removing residual heat (10CFR54.72(b)(3)(v)(B)). On April 25, 2006, at approximately 0500 hours, Operations declared the 21 and 22 Residual Heat Removal (RHR) pumps inoperable after a degraded horizontal section of Service Water (SW) line 405 was identified. SW line 405 is a non-ASME Section XI, non-Class A, seismically supported 24 inch return line routed through the Steam Generator Slowdown (SGBD) Tank room in the Plant Auxiliary Building (PAS) about 15 feet above the floor elevation of 51 feet. The ability of the degraded pipe to withstand a seismic event had not been demonstrated. The consequence of a failure of this pipe is the flooding of the SGBD Tank room, cascading water down to the 15 foot PAB elevation where the RHR pumps are located potentially flooding the RHR pump motors. Compensating actions were implemented and the RHR pumps declared operable at 1200 hours. Subsequently, a detailed engineering calculation was performed that included development of a finite element model of the piping using the SAP 2000 software package. The calculational methodology was based on ASME Section XI, Appendix H, Code Case N-513-1 and was augmented with stress intensity factor solutions from API-579. Stresses resulting from pressure, deadweight, and seismic loads were evaluated and found acceptable demonstrating that the overall structural integrity of the piping is maintained for all loading conditions. Based upon the observed pipe leak rate of approximately 15 gallons per hour (gph), an evaluation of the potential flaw size corresponding to this leak for the lower bound internal pressure was performed. It was concluded that the small stress contribution that would result from seismic loading would cause the flaw to have negligible propagation during a seismic event. Since it was determined that the pipe could support stable flaws much larger than the small flaw that corresponded to the observed leak rate, engineering concluded that the through wall flaws that produced the leakage did not threaten the structural integrity of the pipe. The estimated leakage that could have occurred from the pipe during a seismic event is bounded at 26 gph. Because the 26 gph leakage rate is well within the capacity of the two PAB sump pumps (50 gallons per minute each), there was never any threat to flooding the PAB or a challenge to the operability of the RHR pumps. The licensee notified the NRC Resident Inspector and will be notifying the New York Public Service Commission. Notified R1DO (M. Sykes). | Steam Generator Service water Residual Heat Removal |