Event Notification Report for March 24, 2024

VALID SPECIFIED SYSTEM ACTUATIONS OF UNIT 2 TRAIN B EMERGENCY DIESEL GENERATOR AND TRAIN B AUXILIARY FEEDWATER

The following information was provided by the licensee via email:

"At 1634 MST on March 24, 2024, an engineered safety features (ESF) service transformer deenergized resulting in a loss of power to the Unit 2 Train B 4.16 kV Class 1E Bus. The Unit 2 Train B emergency diesel generator (EDG) automatically started and energized the Unit 2 Train B 4.16 kV Class 1E Bus.

"As a result of the loss of power on the Unit 2 Train B 4.16 kV Class 1E Bus and subsequent load sequencing after the Unit 2 Train B EDG started, the Unit 2 Train B auxiliary feedwater (AFW) pump automatically started as designed. The Train B AFW pump was not needed for steam generator level control and no auxiliary feedwater valves repositioned. The Train B AFW Pump did not supply feedwater to the steam generators.

"All systems operated as designed. Per the emergency plan, no classification was required due to the event. Units 1, 2, and 3 remain in Mode 1 at 100 percent power. The 4.16 kV Class 1E Buses in Units 1 and 3 were not affected by the deenergization of the ESF service transformer.

"The cause of the ESF service transformer being deenergized is under investigation.

"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of emergency AC electrical power systems and auxiliary feedwater system.

"The NRC Resident Inspectors have been informed."

AGREEMENT STATE REPORT - Y-90 THERAPY MISADMINISTRATION

The following information was received from the California Department of Public Health, Radiological Health Branch (RHB) via email:

"On 3/24/24, the alternate radiation safety officer phoned the RHB to report a medical event associated with a yttrium-90 (Y-90) therapy. A patient receiving Y-90 therapy was underdosed by more than 20 percent from the planned dose.

"RHB will investigate."

California Report Number: 032424

A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.

INVALID ACTUATION OF AUTOMATIC TURBINE DRIVEN AUXILIARY FEEDWATER PUMP

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), under the provision of 10 CFR 50.73(a)(1), detailing the event in which an unplanned actuation of the turbine driven auxiliary feedwater pump (TDAFP) at the Callaway plant occurred in response to an invalid actuation signal.

"The actuation occurred at 2056 [CDT] on 3/21/2024 during restoration from maintenance on the NN12 inverter. The actuation signal was received while closing breaker NK0211 (for connecting the inverter to its associated 125-VDC bus). In response to the TDAFP actuation, operators closed the flow control valves and reduced turbine load by approximately 10 MW electrical. Initial investigation showed that a spurious manual actuation signal had been received and cleared 5 seconds later.

"The direct cause of the event was due to a voltage transient generated on the NK02 125-VDC bus during closure of the NK0211 breaker. The actuation occurred due to degradation of a 48-VDC power supply (PS1) within engineered safety features actuation system (ESFAS) logic cabinet SA036C. The power supply exhibited elevated ripple during testing as part of troubleshooting efforts, which was indicative of degradation of the regulation circuitry within the supply. This degradation prevented the power supply from sufficiently filtering the transient that occurred on the 125-VDC bus associated with the NN12 inverter. The power supply was replaced."

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
The licensee originally submitted this event under 10 CFR 50.72(b)(3)(iv)(A) in EN 57043. The licensee has retracted EN 57043.

ELUATE EXCEEDING PERMISSIBLE CONCENTRATION

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

On March 24, 2024, a generator experienced a breakthrough event. The elution from a Curium technetium-99m (Tc-99m) generator did not meet the concentration requirements of 0.15 microcuries molybdenum-99 (Mo-99)/millicurie Tc-99m per 10 CFR 35.204. The generator is from lot number 914024034. The elution contained 1251.3 millicuries of Tc-99m and 203.1 microcuries of Mo-99, resulting in a ratio of 0.16 microcurie Mo-99/millicurie Tc-99m.

The elution was not used to prepare a radiopharmaceutical kit or for dispensing of patient doses. The elution was set aside immediately for decay and disposal. The generator was eluted multiple times following the breakthrough and none of those elutions exceeded the regulatory limit. Curium, the manufacturer, was notified on 3/29/2024. The generator is being quarantined pending disposal.

AGREEMENT STATE REPORT - BROKEN LOCK ON RADIOGRAPHY CAMERA

The following information was received from the Colorado Department of Public Health and Environment via email:

"This letter is serving as notification of an equipment failure under [Colorado Regulation] Section 4.52.2.3 and 5.38.1.3. A QSA Global 880 Delta camera was received from Source Production and Equipment Company, Inc. (SPEC), after being resourced. During the check-in procedure and mechanism check, it was discovered that the lock that controls access to the pigtail attachment was broken in the locked position. The camera was tagged out until it could be sent to Industrial Nuclear Company (INC), for repairs on 04/04/2024. The lock was repaired at INC, and the camera was returned to the licensee on 04/10/2024 with no issues."

Colorado Event Report ID: CO240011