Event Notification Report for November 20, 2025

HPCI INOPERABLE

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

"At 1613 CST on November 17, 2025, it was discovered that the single train of high pressure coolant injection (HPCI) was inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). The isolation condenser was operable during this time period.

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

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

A fuse in the turbine stop valve circuit blew during initial system testing for unit startup.

FITNESS FOR DUTY VIOLATION

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

"On November 18, 2025, [non-licensed] supervisor violated the station's fitness for duty (FFD) policy. The employee's unescorted access to Palisades Nuclear Plant has been terminated. The event was determined to be reportable under 10CFR26.719(b)(2)(ii).

"The NRC Resident Inspector has been notified."

LOSS OF REACTOR ENCLOSURE RECIRCULATION

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

On November 18, 2025, at 0328 CST, as the licensee was initiating the standby gas treatment system in support of planned maintenance on normal reactor building ventilation, the '2A' reactor enclosure recirculation system (RERS) fan failed to establish flow upon the system initiation signal. The '2B' RERS fan was previously inoperable due to a planned maintenance window. Technical specification action statement 3.6.5.4.B was entered with both Unit 2 RERS fans inoperable. The '2B' RERS fan was restored to operable at 0523 EST. The licensee returned normal reactor building ventilation to service to restore secondary containment differential pressure.

Due to inoperability of both RERS trains, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72.(b)(3)(v)(C).

The licensee reported there was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector was notified.

EN Revision Imported Date: 11/21/2025

EN Revision Text: PART 21 INTERIM REPORT OF DEVIATION

The following is a synopsis of information provided by Curtiss-Wright (CW) via email:

On 5/21/2025, Xcel Energy notified Curtiss-Wright about the failure of two NAMCO limit switches provided under CW project CJ21087 (tag number CJ2108701, serial numbers 01 and 04). The limit switches were dedicated by CW and shipped on 2/28/2025 to Xcel Energy. The switches failed a bench test performed by Xcel Energy, which aimed to verify that the contacts properly revert to their original state during spring return. Xcel Energy found that the contacts reverted to their original state prior to the audible click/snap, which is supposed to indicate contact changeover.

The two units were returned to Curtiss-Wright on 5/29/2025. The test result was fully duplicated on one of the switches. For the other switch (serial number 04), the switch contacts intermittently failed to return to the original state at all, requiring manual assistance to do so.

On 6/26/2025, CW sent the parts to NAMCO for repair. CW retested the parts after the repair. Part 04 still had the same issue with failing to reset as noted earlier. That limit switch was returned to NAMCO for a full evaluation.

CW anticipates an update to this notification with final results on 9/23/2025.

Potentially affected U.S. nuclear power plants: unknown at the time of the notification.

Contact Information:
Mark Papke
Quality Assurance Manager
Curtiss-Wright
4600 East Tech Drive
Cincinnati, OH 45245
mpapke@curtisswright.com

* * * UPDATE ON 9/23/25 AT 0850 EDT FROM MARGIE HOVER TO KAREN COTTON * * *

The following information was provided by Curtiss-Wright (CW) via email:

On 6/26/2025 CW sent the relays to NAMCO for repair and the parts were returned to CW on June 26. CW retested the limit switches and one failed for the same issue as noted earlier, the failed limit switch was returned to NAMCO for a full evaluation.
The failure is still under investigation and CW has been in communication with NAMCO, the manufacturer.

Once the evaluation is complete this report will be updated. CW anticipates an update to this notification with final results on 11/24/2025.

Notified R3DO (Szwarc) and the Part 21/50.55 Reactors group

* * * UPDATE ON 11/21/25 AT 1635 EDT FROM MARGIE HOVER TO JORDAN WINGATE * * *

The following information was provided by Curtiss-Wright (CW) via email:

The NAMCO evaluation/report issued to CW on September 4, 2025, concluded that the failure was caused by improper sizing of the hub on the top of the shuttle/slide assembly. The hub was too small which prevented proper fit with the latch and, therefore, the switch could not open or close as intended.

NAMCO confirmed that this failure was only reported on PN: EA700-80926, Date Code: 0425 and also confirmed that the design of PN: EA700-80926 nor supplier of the shuttle/slide assembly has not changed in many years. NAMCO has changed their supplier for the shuttle/slide assembly since the manufacture of PN: EA700-80926, Date Code: 0425. It should also be noted that NAMCO now performs the slow latch test as stated above on all limit switches, not just the E700 series.

To address this issue, CW will be revising all affected NAMCO limit switches' dedication plans to incorporate the slow latch test. CW recommends that end users should perform slow latch testing as a part of their bench or field test procedures upon receiving any Namco limit switches. These actions should preclude a possible recurrence of this failure mechanism.

Please note that CW has not supplied P/N: EA700-80926 of the impacted date code 0425 to any other end users.

Notified R3DO (Orlikowski) and the Part 21/50.55 Reactors group

EN Revision Imported Date: 11/21/2025

EN Revision Text: ACTUATION OF AUXILIARY FEEDWATER SYSTEM

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

"At 0748 CST, on November 12, 2025, Callaway Plant experienced an automatic actuation of the auxiliary feedwater (AFW) system in response to auxiliary feedwater actuation signals (AFAS). A low suction pressure signal was also received which aligned the AFW pumps to essential service water (ESW). An unknown amount of water from the ultimate heat sink (UHS) entered the steam generators, necessitating a plant shutdown due to exceeding secondary water chemistry program action levels. During the shutdown, with the plant at approximately 28 percent power, high vibration was received on the main turbine, requiring a manual turbine trip. The cause of the AFAS is not yet known. The plant is currently stable in mode 3.

"This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A).

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

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

Decay heat is being removed via steam dump valves to the main condenser.

* * * RETRACTION ON NOVEMBER 20, 2025, AT 1409 EST FROM ZACH MILLIGAN TO JORDAN WINGATE * * *

The following is a summary of the retraction provided by the licensee via phone and email.

Event Notification 58035, made on November 12, 2025, pursuant to 10 CFR 50.72(b)(3)(iv)(A), is being retracted following a review of the cause of the auxiliary feedwater system's automatic actuation. The AFW system actuation was traced to a power supply malfunction, which also caused the auxiliary feedwater pumps to align with essential service water. Because the actuation resulted from a spurious power supply failure, rather than signals triggered by plant conditions or parameters meeting system initiation criteria, it is considered invalid and not reportable under 10 CFR 50.72(b)(3)(iv)(A).

The NRC Resident Inspector has been informed.

Notified R4DO (Drake)

AGREEMENT STATE REPORT - GAUGE SHUTTER FAILURE

The following information was provided by the Radiation Health Branch of the Kentucky Department for Public Health and Safety (The Department) via email:

"The Department was notified on 11/12/2025, by the radiation safety officer (RSO) from Big Rivers Electric Corporation, that during a routine six-month inventory/shutter checks, two sources were identified to have problems with the shutters closing.

"Both [gauges] measure density in the scrubber material and are mounted on piping. No exposure is possible unless the piping or gauge is removed. Primary action is to notify personnel and modify the red tag system to indicate that until this is resolved, no maintenance can be allowed on the piping because the shutters on the gauges cannot be safely closed.

"Until further notice, the piping where these gauges are mounted cannot have any maintenance activities performed on them. Red tag authorities should make note that the gauges cannot be red tagged because the shutters do not close.

"Maintenance will be performed on the gauges by an authorized contractor."

Gauge 1 information:
Manufacturer: Kay Ray
Model number: 20493
Serial number: 7062BP
Activity: 10 mCi Cs-137

Gauge 2 information:
Manufacturer: Ronan
Model number: SA8-C5
Serial number: 2104CP
Activity: 20 mCi Cs-137

AGREEMENT STATE REPORT - MEDICAL EVENT

The following information was provided by the California Department of Public Health, Radiologic Health Branch via email:

"The University of California Los Angeles (UCLA) health [center] reported that a patient being treated for liver cancer underwent a Y-90 Sirtex SirSpheres brachytherapy treatment on November 12, 2025. This is a preliminary report of a medical event, per 10 CFR 35.3045.

"The authorized user's (AU) written directive called for two vials of Y-90 activity to treat two different segments of the right lobe via two different arterial branches of the lobe. The first prescription was for 108.11 mCi and 114 mCi (105.73 percent) was successfully delivered.
"The second prescription was for the right lobe, segment 4A using 13.51 mCi but only 10.04 mCi (74.32 percent) was able to be delivered.
"The authorized user believes his patient reached stasis, so he halted the procedure per the Sirtex IFU (instructions for use). Arterial flow is intermittently checked throughout the infusion process.
"The undelivered activity was determined by measuring the exposure rate at a known distance from the post-treatment waste after the administration. UCLA health [center] will submit a 15-day report to the Department."

California 5010 Number: 111225

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.