Event Notification Report for August 25, 2025

CONCURRENT REPORT FOR OFFSITE NOTIFICATION

The following is a summary of the information provided by the licensee via phone and email:

Centrus American Centrifuge Operating (ACO) received notification from a Fluor-BWXT Portsmouth (FBP) environmental technician supervisor that the chlorine level at outfall '013/X-2230N' was at 0.159 mg/L. This exceeds the National Pollutant Discharge Elimination System (NPDES) permit limit on total chlorine at outfall '013' of 0.05 mg/L. Centrus ACO notified the Ohio Environmental Protection Agency at 1539 EDT.

Centrus ACO asked FBP to resample on the morning of 8/19/2025 to further confirm the exceedance. Centrus ACO is currently investigating to determine the cause of the exceedance. This report is in accordance with condition notification #12803.

The NRC regional office was notified.

MAJOR LOSS OF EMERGENCY ASSESMENT CAPABILITY

The following information was provided by the licensee via phone and email:

"On 08/20/2025 at 2308 EDT, the Fermi 2 active seismic monitoring system provided indication of a potential seismic activity event. Plant abnormal procedures were entered, and compensatory measures were met and remain in place. Neither the United States Geological Survey (USGS) nor the next closest nuclear power plant could confirm/validate the readings obtained at Fermi. The seismic monitoring system was declared inoperable to validate the calibration of the system. Fermi 2 has two active seismic monitors: one on the reactor pressure vessel pedestal and one in the high pressure core injection (HPCI) room. Only the HPCI room seismic monitor was declared inoperable. The HPCI room accelerometer is the sole trigger for the seismic recording system (which outputs peak accelerations experienced during a seismic event) and the associated control room alarm. This is used in assessment of the magnitude of an earthquake for emergency action level HU 2.1.

The loss of the active seismic monitoring system is reportable within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii).

No seismic activity has been felt on-site, and the USGS recorded no seismic activity in the area.

The NRC Resident Inspector has been notified.

An alternative means of monitoring seismic event entry is still available per the emergency plan via USGS.

CONCURRENT REPORT - FIRE IMPAIRMENT

The following information was provided by the licensee via phone and email:

"At approximately 1035 (EDT) on August 22nd, 2025, the New Hanover County Deputy Fire Marshal was notified per North Carolina Fire Code requirements that a fire suppression system riser, which provides sprinkler protection to a portion of the fuel manufacturing operation (FMO), was impaired due to missing ceiling tiles. A fire watch for the affected area has been initiated. Because the New Hanover County Deputy Fire Marshal was notified, a concurrent notification to the NRC Operations Center is being made per 10 CFR 70, Appendix A(c)."

The NRC regional inspectors were notified.