Event Notification Report for May 02, 2025

EN Revision Imported Date: 5/20/2025

EN Revision Text: AGREEMENT STATE REPORT - MEDICAL EVENT

The following information was provided by the Washington State Department of Health (the Department) via email:

"On 5/5/2025, at 1320 PDT, the Department was notified of a medical event. This event occurred on the afternoon of Friday, 5/2/2025. This event was discovered by the licensee's radiation safety officer on 5/5/2025. The incident may require reporting under WAC 246-240-651(1)(i)(A). A detailed report will be delivered within 15 days of 5/5/2025."

Medical Isotope: Y-90
Administered Dose: 32 percent of the intended dose.

Washington Incident Number: WA-25-006

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.

* * * UPDATE ON 5/19/2025 AT 1536 EDT FROM DANE BLAKINGER TO KAREN COTTON * * *
The root cause appears to be mechanical failure; the administration set will be inspected by Boston Scientific. The Department will review the information provided by Boston Scientific, which may result in corrective actions for the University of Washington and other licensees that use the same equipment.
Notified: R4DO (Josey) and NMSS Events

PART 21 - THERMAL SLEEVE DEFECT

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

The affected component is the thermal sleeve in the control rod drive mechanism (CRDM) penetration tube in the replacement Reactor Vessel Closure Head (RVCH) provided to the Callaway plant in 2014. The reportable defect is the unanticipated wear rate of the CRDM thermal sleeve flanges supplied to Callaway as part of the replacement RVCH that was installed in the fall of 2014.

During the Callaway refueling outage in the spring of 2025, the thermal sleeve at location H08 was found resting on the upper internals. A ring shaped remnant of the thermal sleeve flange had become separated and was present in the CRDM adapter.

Measurements were performed on the remaining CRDM thermal sleeves to determine the amount of thermal sleeve descent from the nominal design configuration. Descent distances ranged from 0.03 to 1.7 inches, with four thermal sleeves having descent of 0.9 inches or more.

The failure of a thermal sleeve resulting in a detached flange segment can impact the performance of the corresponding CRDM with the potential to impede or prevent control rod insertion. This issue was first reported under 10 CFR 21 by Westinghouse.

Since the identification of the thermal sleeve flange wear issue by Electricite de France (EdF) in 2018, Framatome is unaware of any instances of a control rod failing to insert due to CRDM thermal sleeve events, even at plants which have experienced multiple locations with complete thermal sleeve flange separation.

Framatome is conservatively making this notification because the undetected simultaneous failure of multiple thermal sleeves could potentially create a safety hazard if multiple control rods fail to fully insert.

Although the causal analysis in still in process, Framatome has reviewed the other replacement RVCHs supplied by Framatome to the US fleet and have not identified any other plants which contain an equivalent combination of conditions that would indicate the potential for accelerated thermal sleeve flange wear.

For the other US plants with Framatome supplied replacement RVCHs with thermal sleeves, Framatome will provide a notification to continue using the current and future inspection guidance published by industry bodies.

Affected plants: Callaway Energy Center

Framatome Contact Information:

Gayle Elliott
Director, Licensing Regulatory Affairs
Framatome Inc.
gayle.elliott@framatome.com