Current Event Notification Report for April 26, 2024

EN Revision Imported Date: 4/26/2024

EN Revision Text: AUTOMATIC TURBINE DRIVEN AUXILIARY FEEDWATER PUMP ACTUATION

The following information was provided by the licensee via email:

"At 2056 on 3/21/24, Callaway Plant was in Mode 1 at approximately 100 percent power when an automatic start of the turbine driven auxiliary feedwater pump occurred. The event occurred while restoring inverter NN12 from maintenance. NN12 is the normal in-service inverter for the group 2 120-VAC instrument bus (NN02). The actuation occurred while swapping from the swing inverter (NN18) to the normal in-service inverter (NN12).

"All safety systems responded as expected. At 2334, the turbine driven auxiliary feedwater pump was secured.

"The plant is being maintained in a stable condition, in mode 1.

"The NRC Resident Inspector was notified"

The licensee is investigating the cause of the automatic start.


* * * RETRACTION ON 4/25/2024 AT 1432 EDT FROM GREG CIZIN TO ERNEST WEST * * *

"Event Notification (EN) 57043, made on 03/21/2024 pursuant to 10 CFR 50.72(b)(3)(iv)(A), is being retracted based upon further investigation into the cause of the turbine driven auxiliary feedwater pump (TDAFP) actuation. The TDAFP received an invalid manual initiation signal caused by a voltage transient that was generated on the NK02 125-VDC bus upon closure of downstream breaker NK0211 (while restoring inverter NN12 from maintenance). This actuation signal was due to degradation of a 48-VDC power supply (PS1) within engineered safety features actuation system (ESFAS) logic cabinet SA036C. This degradation likely prevented the power supply from sufficiently filtering the transient that occurred on the 125-VDC bus associated with the NN12 inverter."

Notified R4DO (Warnick)

EN Revision Imported Date: 4/26/2024

EN Revision Text: AGREEMENT STATE REPORT - Y-90 MICROSPHERE MISADMINISTRATION

The following information was provided by the Arkansas Department of Health, Radiation Control Radioactive Material Program (the Agency) via email:

"The radiation safety officer for Central Arkansas Radiation Therapy Institute (CARTI) contacted the Agency on March 21, 2024, to advise of a yttrium-90 (Y-90) microsphere therapy administration in which the patient received 20 percent greater than the prescribed dose. The administration occurred on February 7, 2024. Treatment was only to one side of the liver. The amount was localized to the liver. The physician felt the delivered dose was clinically effective, and no further treatment is planned. No adverse patient impacts are expected.

"The discovery was made during a quarterly review of their written directive on March 20, 2024.

"The Agency is awaiting further information from the licensee."

* * * UPDATE ON 4/25/24 AT 1045 EDT FROM SUSAN ELLIOTT TO BILL GOTT * * *

The following information was provided by the Arkansas Department of Health, Radiation Control Radioactive Material Program (the Agency) via email:

"The discovery was made during a quarterly review of their written directive on March 12, 2024 (Corrected date).

"The authorized user prescribed an activity of 2.6 GBq (70 mCi) on February 7, 2024. The technologist drew up 3.17 GBq (85.8 mCi) which was 122 percent of the prescribed activity and delivered the syringe to the authorized user. The authorized user performed the administration within 30 minutes of the dose being drawn. The administered activity was estimated to be 84.5 mCi, 120 percent of the prescribed activity.

"The authorized user contacted the patient's referring physician and both were satisfied with the activity delivered as the goal was to ablate the entire segment of diseased liver. The absorbed doses to all other tissues were below the targets for treatment with Y90.

"Personnel interviews were conducted by the department on April 2, 2024, aimed at gaining insight into the incident and engaging in discussions regarding the procedures involved.

"The event is considered closed."

Notified R4DO (Warnick) and NMSS Events Notification (email)

Arkansas Event #: AR-2024-2

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.

AGREEMENT STATE REPORT - MEDICAL UNDERDOSE

The following information was provided by the Pennsylvania Department of Environmental Protection Bureau of Radiation Protection (the Department) email:

"On April 18, 2024, the licensee informed the Department of a medical event. It is reportable per 10 CFR 35.3045.

"On April 17, 2024, a patient was receiving an iodine-131 [sodium iodine solution] treatment. The patient was prescribed 100 mCi of I-131. However, the patient received only 5 mCi of I-131. At this time no other information is available. The Department will update this event as soon as more information is provided.

"The Department will perform a reactive inspection. More information will be provided upon receipt."

PA Event Number: PA240006

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.

AGREEMENT STATE REPORT - STUCK SHUTTER

The following was received from the Texas Department of State Health Services (the Department) via email:

"On April 18, 2024, the Department was notified by the licensee that the shutter on a Vega model SH-F1 nuclear gauge failed to close. The gauge contains a 20 millicurie (original activity) cesium - 137 source. Open is the normal position for the gauge shutter. The licensee reported there is no risk of additional radiation exposure to members of the general public or radiation workers, due to this failure. The manufacturer has been contacted to repair the gauge shutter. Additional information will be provided as it is received in accordance with SA-300."

Texas Incident Number: 10100

Texas NMED Number: TX240013

AUTOMATIC REACTOR SCRAM WITH ECCS ACTUATION

The following information was provided by the licensee via email:

"On 4/24/2024 at 2215 CDT, Browns Ferry Unit 1 experienced an automatic reactor scram. The cause of the scram is currently under investigation. The main steam isolation valves (MSIVs) remain open with the main turbine bypass valves controlling reactor pressure. The reactor feedwater pumps are in service to control reactor water level.

"Primary containment isolation systems (PCIS) Groups 2, 3, 6, and 8 isolation signals were received. Upon receipt of these signals, all components actuated as required. Following the reactor scram, due to reactor water level reaching minus 45 inches, both high pressure coolant injection (HPCI) and reactor core isolation cooling (RCIC) initiation signals were received, and both initiated as designed. All safety systems operated as expected.

"This event requires a 4-hour report per 10 CFR 50.72(b)(2)(iv)(A), `Any event that results or should have resulted in emergency core cooling system (ECCS) discharge into the reactor coolant system as a result of a valid signal except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.'

"This event requires a 4-hour report per 10 CFR 50.72(b)(2)(iv)(B), `Any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.'

"This event requires an 8-hour report per 10 CFR 50.72(b)(3)(iv)(A), `Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B): 1) Reactor protection system (RPS) including: reactor scram or reactor trip. 2) General containment isolation signals affecting containment isolation valves in more than one system or multiple main steam isolation valves (MSIVs). 4) ECCS for boiling water reactors (BWRs) - high-pressure coolant injection (HPCI). 5) BWR reactor core isolation cooling system (RCIC).'

"All safety systems operated as expected. At no time was public health and safety at risk. The NRC resident inspector has been notified."

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:

Units 2 and 3 were not affected.

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.

CONFIGURATION OF 'B' AND 'C' RESIDUAL HEAT REMOVAL LOOPS IN AN UNANALYZED CONDITION

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

"On April 25, 2024, it was determined that between March 25, 2024, 2015 [EDT] and March 30, 2024, 2024 [EDT], the condensate transfer and storage system was employed as a method of alternate keepfill in place of the installed residual heat removal (RHR) system's waterleg pump for RHR system loops `B' and `C'. This condition is not bounded by existing design and licensing documents.

"Therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(ii)(B).

"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."