Event Notification Report for January 08, 2026

AGREEMENT STATE REPORT - STUCK-OPEN GAUGE SHUTTER

The following information was provided by the South Carolina Department of Environmental Services (the Department) via phone and email:

"The licensee informed the Department on December 31, 2025, that a fixed gauging device was disabled or failed to function as designed. The licensee reported that a Berthold model LB 7400-series fixed gauging device (serial number KW507), containing a 20 mCi Cs-137 sealed source, had a shutter stuck in the open position and that the shutter handle had broken off. The licensee reported that the device is attached to a process vessel and indicated that access has been restricted. The licensee also reported that dose rate survey results of the gauging device were at background.

"The licensee did not report any overexposures or ongoing health/safety concerns.

"A Department inspector will be dispatched to the facility. This event is still under investigation by the Department."

INVALID SPECIFIED SYSTEM ACTUATION

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

"This report is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A), using the telephone option in 10 CFR 50.73(a)(1) in lieu of a written licensee event report, concerning an event in which Callaway experienced an automatic actuation of the auxiliary feedwater (AFW) system in response to invalid AFW actuation signals. The reactor protection system was not involved. A low suction pressure signal was also received which aligned the AFW pumps to essential service water. An unknown amount of water from the ultimate heat sink entered the steam generators, necessitating a plant shutdown after secondary water chemistry program action levels were exceeded. This AFW actuation was complete and the AFW system started and functioned successfully in accordance with the initiating actuation signals. This actuation occurred at 0748 CST on November 12, 2025, and was reported (and later retracted) as event notification 58035.

"The most probable cause of the actuations was the intermittent failure of a 15V DC logic power supply within engineered safety features actuation system logic cabinet SA036D. The power supply was replaced."