Event Notification Report for October 16, 2026

EN Revision Imported Date: 10/16/2026

EN Revision Text: PART 21 - EMERGENCY DIESEL GENERATOR STARTING AIR COMPRESSOR FAILURES

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

Paragon Energy Solutions has determined a defect exists in Ingersoll Rand/Paragon compressors supplied to the DC Cook plant, part numbers H7100X10-MOD and H7100X15. DC Cook reported failures in four compressors used during emergency diesel generator startup. Paragon's initial analysis found that the second-stage valve plate gasket had failed, allowing gasket material to enter the valve seat. This created excessive back-pressure, lifting the first-stage relief valve, and reducing compressor discharge pressure below required performance. All compressors exhibiting this failure mode were manufactured in 2022 or later using an updated valve plate design.

Because this condition, if left uncorrected, could create a safety hazard, Paragon is submitting this initial notification in accordance with 10 CFR Part 21. The issue has been entered into Paragon's nonconformance reporting system, and replacement compressors equipped with the original valve plate design are being provided to DC Cook. Paragon is working with Ingersoll Rand to complete the root-cause evaluation. Paragon has recommended that DC Cook monitor in-service compressors for signs of degradation while the final Part 21 evaluation is completed.

Affected plant: DC Cook

Point of Contact:
Kenny Morrison
Vice President, Quality Assurance
Paragon Energy Solutions, LLC
KMorrison@paragones.com
817-284-0077

* * * UPDATE ON 10/15/2026 AT 1332 EDT FROM KENNY MORRISON TO CHRISTOPHER PRESCOTT * * *

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

Paragon's final evaluation confirms the previously described compressor failure mechanism and concludes that a 2022 design change to the high-pressure valve plate gasket configuration is a potential contributing cause. Paragon determined that all affected compressors were manufactured in 2022 or later and identified no similar failures in operating experience prior to that design change.

Paragon is replacing the affected valve plate and gasket configuration with the original qualified design, revising supporting testing and dedication documents, and supplying retrofitted replacement compressors to the customer.

Notified R3 Reactor Events (email), Part 21 and 50.55 Reactors (email).

AGREEMENT STATE REPORT - MEDICAL EVENT

The following is a summary of information provided by the Florida Bureau of Radiation Control (BRC) via email:

On October 8, 2026, BRC received a report from the medical physicist at a hospital cancer center regarding an error that occurred during a stereotactic body radiation therapy treatment. The patient was scheduled to receive eight total fractions. It was later determined that the first three fractions, administered on September 26, September 29, and October 1, 2026, had been delivered to the wrong anatomical site.

According to the report, the physician had correctly identified the intended treatment location, but the site marking placed on the patient did not match the intended area. As a result, the treatment team delivered the initial three doses to the patient's left cheek rather than to the correct target location. The error was discovered on October 7 at approximately 1000 EDT during a review of the treatment setup.

Once the mistake was identified, the patient was informed of the event and provided with an updated treatment plan. The facility is preparing a detailed written report outlining the circumstances and contributing factors. Determination of the maximum dose received to the incorrect location is still pending.

The incident was referred to the BRC materials and licensing division for further review. An environmental consultant from BRC began the investigation on October 8. Additional documentation and analysis will continue as part of the follow up process.

Florida incident number: FL26-087

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.

EN Revision Imported Date: 10/16/2026

EN Revision Text: AGREEMENT STATE REPORT - LOST AND RECOVERED DENSITY GAUGE

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

"Bruin Geotechnical Services Inc. reported the loss of a Troxler moisture density gauge and transit case around 0600 PDT. The operator failed to close and secure the metal overpack box and close the tailgate of the truck prior to departure. The radiation safety officer (RSO) reports that the transit case was locked, but there was no source handle lock on the gauge.

"The gauge is a Troxler model 3411B (S/N 38996) and contains 8 mCi Cs-137 and 40 mCi Am-241/Be sources.

"Lancaster police and the California Highway Patrol were notified of the loss. Company staff began searching local roadways.

"Around 1100 PDT, Lancaster police notified the RSO that a member of the public had dropped off the gauge and case at their office.

"The gauge was recovered and returned to the licensee. Leak testing is being performed, and the gauge will not be used until negative results are confirmed by the vendor. RHB will continue to investigate this incident."

California 5010 number: 100826

AGREEMENT STATE REPORT - STUCK SHUTTER

The following information was provided by the Texas Department of State Health Services (the Agency) via phone and email:

"On October 8, 2026, the licensee notified the Agency regarding a nuclear gauge whose source shutter mechanism had failed to function as intended. The gauge, an Industrial Dynamics model FT-100, contains a 300 mCi Am-241 sealed source. The licensee reported that the gauge was discovered with the source shutter stuck in the open position. Open is the normal operating position. The discovery was made on October 8, 2026, during routine maintenance. The licensee stated that there is no risk of additional radiation exposure to the public or workers due to this source shutter mechanism failure. The licensee has contacted Industrial Dynamics to have the gauge repaired."

"Additional Information will be made available in accordance with SA 300 reporting requirements"

Texas incident number: 10335
Texas NMED number: TX260043

AGREEMENT STATE REPORT - LOST EXIT SIGN

The following is a summary of information provided by the Colorado Department of Public Health and Environment via email:

Two exit signs, each containing 7.5 curies of tritium (15 curies total), were determined to be lost by the licensee.

Manufacturer: Isolite Corporation
Model Number: SLX60

Colorado Event Report ID Number: CO260024

THIS MATERIAL EVENT CONTAINS A 'Less than Cat 3' LEVEL OF RADIOACTIVE MATERIAL

Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf

RCS PRESSURE BOUNDARY DEGRADED

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

"At 1305 EDT on October 15, 2026, it was determined that the reactor coolant system (RCS) pressure boundary did not meet the acceptance criteria under ASME, Section XI IWB-3514, 'Standards for Examination Category B-F, Pressure-Retaining Dissimilar Metal Welds in Vessel Nozzles, and Examination Category B-J, Pressure-Retaining Welds in Piping.' The condition will be resolved prior to plant startup. This event is being reported as an eight-hour non-emergency notification per 10 CFR 50.72(b)(3)(ii)(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:

The condition was discovered during ultrasonic testing (UT). The flaw is located between the pressurizer and the "A" pressurizer safety valve at a pipe elbow.