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| Entered date | Event description | |
|---|---|---|
| ENS 56171 | 20 October 2022 11:31:00 | The following information was provided by the licensee via email: At 0427 CDT on October 20, 2022, Grand Gulf Nuclear Station (GGNS) was in Mode 1 at 100 percent power when a failure of a draw down surveillance resulted in the loss of secondary containment. During the performance of the surveillance GGNS was unable to maintain secondary containment pressure, as required by Technical Specification Surveillance Requirement 3.6.4.1.4, greater than or equal to 0.266 inches of water vacuum for 1 hour at a flow rate of less than or equal to 4000cfm. The test was secured. Secondary containment was declared inoperable and Technical Specification 3.6.4.1 A.1 was entered at 0427 CDT. Secondary containment was restored to operable status at 0520 CDT by restoring the configuration to a previously known operable condition. This event is being reported as an event or condition that could have prevented the fulfillment of a safety function. The NRC Resident Inspector was notified. |
| ENS 54244 | 28 August 2019 19:10:00 | On Wednesday, August 28, 2019, at 1316 CDT, Grand Gulf Nuclear Station experienced a power loss to the Control Room High Pressure Core Spray (HPCS) Instrumentation Panel due to an internal inverter failure. The power loss caused the loss of the HPCS System (a single train system). The minimum flow valve (a Primary Containment Isolation Valve) for HPCS opened due to this power loss as well. This valve was manually closed in response to this, and the outboard isolation requirement for the associated penetration (which) is closed (for the) system remained intact throughout this event. No other accident mitigation systems were affected by this event. The cause of this event is under investigation at this time. The NRC Resident Inspectors were notified. This Condition is an 8-hour reportable condition as an event or condition that could have prevented the fulfillment of a safety function, in accordance with 10 CFR 50.72(b)(3)(v)(D). |
| ENS 54201 | 5 August 2019 17:06:00 | On August 5, 2019, at 0936 CDT, Grand Gulf entered Technical Specification (TS) 3.6.4.1 due to a Secondary Containment personnel door, 1A401B, not being able to meet its design function. Door 1A401B was unable to be closed and latched. This condition is being reported as a loss of safety function. The station also entered 05-S-01-EP-4, Auxiliary Building Control (Secondary Containment) to address Auxiliary Building differential pressure due to the opened Secondary Containment penetration. Actions were taken to close and latch Door 1A401B. Secondary Containment has been declared operable. TS 3.6.4.1 and 05-S-01-EP-4 were exited. The NRC Resident Inspector was notified of the condition. |