05000318/LER-2024-003, Automatic Reactor Trip Due to Main Turbine Loss of Load
| ML24344A197 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 12/09/2024 |
| From: | Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24344A195 | List: |
| References | |
| LER 2024-003-00 | |
| Download: ML24344A197 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 3182024003R00 - NRC Website | |
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Abstract
On October 10, 2024, at 0557, Calvert Cliffs Nuclear Power Plant Unit 2 incurred an uncomplicated automatic reactor trip from 100 percent power due to a Main Turbine Loss of Load trip initiated by the Reactor Protection System (RPS). The Loss of Load trip was the result of an internal Main Generator Exciter failure that led to a loss of field on the Main Generator that in turn led to a load reject trip from the Main Turbine. The direct cause of the Exciter failure was a failed stationary field pole electrical connection. Impacted Exciter components were replaced and an extent of condition inspection on the other field pole electrical connections was performed prior to returning the Exciter to service. The root cause evaluation for this event is still in progress at this time. A monitoring plan has been initiated for exciter performance until the root cause is identified and corrected.
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(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/) Page 4 of 4
G. PREVIOUS OCCURRENCES
A review of Calvert Cliffs events was performed. A reactor trip due to a failure of a Main Generator Exciter occurred on July 18, 2024, and was reported under LER-2024-002-00. A discussion of why previous corrective actions did not prevent recurrence will be addressed in the supplement once the root cause evaluation is completed. There were no other previous occurrences identified.
H. COMPONENT FAILURE DATA
Component IEEE 803 IEEE805 FUNCTION ID SYSTEM ID Exciter EXC TL