Reactor Core Isolation Cooling (RCIC) is a system which injects cooling water at high pressure. Not as much water as HPCI
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| | Site | Start date | Title | Description |
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| ENS 57418 | Grand Gulf | 10 November 2024 09:37:00 | Manual Reactor Scram | The following information was provided by the licensee via phone and email:
On November 10, 2024, at 0337 CST, Grand Gulf Nuclear Station (GGNS) was operating in mode 1 at 100 percent power when a manual scram was initiated due to degrading main condenser vacuum. The cause of the degrading main condenser vacuum is not known at this time and is being investigated. All control rods fully inserted and there were no complications. Reactor pressure was initially maintained with main turbine bypass valves. Reactor water level was initially maintained with main feedwater and condensate.
At 0457, operators transitioned pressure control to safety relief valves and began using reactor core isolation cooling (RCIC) to maintain reactor water level. This was performed using plant procedures due to degrading vacuum. GGNS is currently in mode 3. Reactor level is being maintained with RCIC and pressure is being maintained using the safety relief valves.
The manual reactor protection system (RPS) actuation is being reported in accordance with 10 CFR 50.72(b)(2)(iv)(B) and the RCIC actuation is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A).
The NRC Senior Resident Inspector was notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
At the time of the notification, main steam isolation valves had shut on low vacuum.
- * * UPDATE ON 11/10/24 AT 1236 CST FROM MELISSA LIMBECK TO KERBY SCALES * * *
The following update was provided by the licensee via phone and email:
This update is being made to report the following occurrences which took place after the scram reported in event number 57418.
On November 10, 2024, at 0545 CST, a group 1 containment isolation signal resulted in the closure of all MSIVs. The signal was due to continued degradation of condenser vacuum post-trip. At 0620, an automatic RPS actuation occurred when reactor water level lowered to level 3. This RPS actuation occurred with all control rods fully inserted. Reactor water level lowered following closure of an open safety relief valve and was recovered to within the established band.
The events are being reported as specified system actuations in accordance with 10 CFR 50.72(b)(3)(iv)(A).
The NRC Senior Resident Inspector has been informed of the update.
Notified R4DO (Dixon) | | IR 05000298/2024003 | Cooper | 5 November 2024 | Integrated Inspection Report 05000298/2024003 | | | IR 05000259/2024003 | Browns Ferry | 4 November 2024 | Integrated Inspection Report 05000259/2024003 and 05000260/2024003 and 05000296/2024003 | | | IR 05000277/2024003 | Peach Bottom | 4 November 2024 | Integrated Inspection Report 05000277/2024003 and 05000278/2024003 | | | IR 05000458/2024003 | River Bend | 31 October 2024 | Integrated Inspection Report 05000458/2024003 | | | IR 05000321/2024003 | Hatch | 30 October 2024 | Edwin I Hatch, Units 1 and 2 - Integrated Inspection Report 05000321/2024003 and 05000366/2024003 | | | IR 05000254/2024010 | Quad Cities | 28 October 2024 | Age Related Degradation Inspection Report 05000254/2024010 and 05000265/2024010 and Notice of Violation | | | ML24299A263 | Browns Ferry | 25 October 2024 | Response to Apparent Violation in NRC Inspection Report 05000260/2024090, EA-24-075 | | | ML23335A013 | | 25 October 2024 | IMC 0308 Attachment 3 Appendix K, Technical Basis for Maintenance Risk Assessment and Risk Management Significance Determination Process | | | ML24283A166 | Clinton | 23 October 2024 | Enclosure 2 Clinton Audit Summary RCI and RAIs | |
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