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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56810 | 23 October 2023 00:48:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | Average Power Range Monitors Declared Inoperable | The following information was provided by the licensee via phone and email: On October 21, 2023, at 2048 EDT, reactor recirculation pump (RRP) 12 tripped. The cause for the trip is under investigation. Following the RRP trip, the average power range monitors (APRMs) flow bias trips were inoperable due to reverse flow through RRP 12. The APRMs were restored to operable on October 21, 2023, at 2058 EDT, when the RRP 12 discharge blocking valve was closed. This 8-hour non-emergency report is being made based upon requirements of 10CFR50.72(b)(3)(v)(A) which states: "Licensee shall notify the NRC of any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (A) Shut down the reactor and maintain it in a safe shutdown condition." The NRC Resident Inspector has been notified. | Reactor Recirculation Pump | |
| ENS 55137 | 13 March 2021 02:02:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | Reactor Recirculation Pump Trip | On March 12, 2021, at 2102 (EST), Reactor Recirculation Pump (RRP) 13 tripped. The cause for the trip is under investigation. Following the RRP trip, the Average Power Ranger Monitors (APRMs) flow bias trips are inoperable due to reverse flow through RRP 13. The APRMs were restored to operable on March 12, 2021, at 2110 (EST) when the RRP 13 Discharge Blocking Valve was closed. This 8-hour non-emergency report is being made based upon requirements of 10 CFR 50.72(b)(3)(v)(A) which states: 'Licensee shall notify the NRC of any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (A) Shut down the reactor and maintain it in a safe shutdown condition.' The licensee has notified the NRC Resident Inspector. | Reactor Recirculation Pump | |
| ENS 54199 | 4 August 2019 21:45:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | Average Power Range Monitors Declared Inoperable | On August 4, 2019 at 1745 (EDT), Reactor Recirculation Pump (RRP) 11 tripped. The cause for the trip is under investigation. Following the RRP trip, the Average Power Range Monitors (APRMs) flow bias trips are inoperable due to reverse flow through RRP 11. The APRMs were restored to operable on August 4, 2019 at 1807, when the RRP 11 Discharge Blocking Valve was closed. This 8-hour non-emergency report is being made based upon requirements of 10CFR50.72(b)(3)(v)(A) which states: 'Licensee shall notify the NRC of any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (A) Shut down the reactor and maintain it in a safe shutdown condition.' The licensee has notified the NRC Resident Inspector. | Reactor Recirculation Pump | |
| ENS 48696 | 23 January 2013 20:16:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Concurrent Loss of High Pressure Reactor Makeup Systems Capability | On 1/23/2013 at 1516 (EST), Nine Mile Point 2 (NMP2) had a failure of a Reactor Building General Area temperature trip unit occur resulting in the closure of an isolation valve on the Reactor Core Isolation Cooling (RCIC) system steam supply line. Concurrent with this failure, the High Pressure Core Spray (HPCS) system was inoperable for planned surveillance testing. With both the RCIC and HPCS systems inoperable, NMP2 entered a Technical Specification Required Action to be in Mode 3 within 12 hours. At 1550, the HPCS system was restored to OPERABLE. Based on the concurrent loss of the high pressure reactor makeup capability of these two systems, it was determined that the condition is reportable under section 50.72(b)(3)(v) as the following safety functions were impacted: (A) Shutdown the reactor and maintain it in a safe shutdown condition; and (D) Mitigate the consequences of an accident. NMP2 remains in a stable condition at rated power. The offsite grid is stable with no restrictions or warnings in effect. The licensee notified the NRC Resident Inspector. | Reactor Core Isolation Cooling High Pressure Core Spray | |
| ENS 40217 | 3 October 2003 01:00:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | Loss of Safe Shutdown Capability Due to All Oprm Channels Being Declared Inoperable. | According to information provided by Nuclear Fuels, Reactor Engineering and G. E. Nuclear Energy, a condition exists in the Oscillation Power Range Monitors (OPRM's) that could contribute to exceeding a Safety Limit. This condition involves excessive confirmation count resets attributed to both the conditioning filter cutoff frequency and period tolerance values. G.E. Nuclear Energy can not confirm that performance of the OPRM's with the conditioning filter cutoff frequency and period tolerance settings currently in use would prevent a condition whereby a Safety Limit MCPR could be violated during an anticipated instability event. The OPRM conditioning filter cutoff frequency and period tolerance are currently set as allowed by licensing documentation, and are calculated as specified in NEDO-32465-A, Reactor Stability Detect and Suppress Solutions Licensing Basis Methodology for Reload Applications. As a result, all OPRM's at Nine-Mile Point Unit 2 are considered inoperable. This INOPERABILITY determination is based on information received from G.E. Nuclear Energy which evaluated the Nine Mile Point OPRM performance on July 24, 2003. The licensee has taken action to address this condition in accordance with Technical Specification 3.3.1.1, Reactor Protection System Instrumentation. The licensee has a procedure providing guidance for alternate methods to detect and suppress thermal hydraulic instability. The licensee has notified the NRC Resident Inspector. | Reactor Protection System |