Event Notification Report for April 21, 2025

AGREEMENT STATE REPORT - MEDICAL EVENT

"The licensee initially reported an underdose event that involved a CyberKnife (linear accelerator), and the event was referred to our X-ray inspection unit. On 4/11/25, our X-ray unit informed us that the underdose event involved an Elekta Gamma Knife Perfexion (Co-60) that experienced an electrical sensor failure that caused the patient's treatment to be interrupted.

"The original planned treatment using stereotactic radiosurgery to the right trigeminal nerve using a single 4 mm collimator open shot to deliver a maximum of 80 Gy (76 Gy at the 95 percent isodose line). The treatment time was to take 49.24 minutes. However, after 12.47 minutes of treatment, a system error on the GK unit triggered a stop in treatment. All radiation sources (Co-60) were retracted to home positions and the patient was automatically removed from the treatment bore by the robotic couch with the shielding doors automatically closing. The patient only received 25 percent of the dose on 3/26/25, or about 20 Gy.

"On 3/27/25, the machine was successfully repaired by an Elekta engineer and the patient came back to the facility to complete treatment. The authorized user physicians modified their written directive and treatment plan to give an additional maximum dose of 70 Gy (66.5 Gy at the 95 percent isodose line) to the same treatment area. The patient successfully completed the treatment."

California 5010 Number: 032625

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.

MEDICAL TRANSPORT WITH CONTAMINATION

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

"At approximately 0215 EDT, on April 13, 2025, a uranium recovery and recycle services (URRS) operator was performing a pressure check of a dissolver system filter housing following change out of the filter cartridges. Uranyl nitrate solution discharged from the housing lid/housing body interface onto the operator's coveralls in the upper left arm area. In accordance with the operating procedure, the operator was wearing a full-face shield, safety glasses, chemical gloves, and a chemical apron that covers the torso area. The chemical apron does not cover the arm area.

"The operator reported the exposure to a URRS chief operator and the skin area on the upper left arm was rinsed for approximately fifteen minutes. The incident commander, a medical first responder from the Columbia Fuel Fabrication Facility (CFFF) emergency brigade and a health physics (HP) technician were contacted to respond to the URRS area. After decontamination efforts on the affected area of the arm, HP direct [on contact] survey results were 500 disintegrations per minute (dpm) per 100 cm squared of alpha [radiation] for the left bicep area.

"The filter housing lid was secured properly and passed the pressure check required by the operating procedure. This event did not impact safety equipment. A causal analysis and corrective actions will be documented in the Corrective Action Program (CAP).

"All smear survey results of the exposed skin area were below clean area limits (less than 200 dpm per 100 cm squared). As a precaution to ensure comprehensive evaluation and treatment for uranyl nitrate/nitric acid exposure to the skin, the operator was transported by ambulance to an offsite medical facility. The affected portion of the employee's arm was bandaged and wrapped in gauze and tape, and the employee was accompanied by a CFFF HP technician for evaluation. Contamination surveys were performed for the ambulance and the gurney used to transport the employee, and all results were below clean area limits, indicating no spread of contamination during care for the employee. All potentially contaminated materials associated with the transport were collected and returned to the CFFF for disposal. The employee was provided with an over-the-counter topical ointment and released from the offsite medical facility at 0735 on April 13, 2025.

"The CFFF is a licensed Part 70 facility subject to 10 CFR 70 Subpart H, and the event did not challenge the performance requirements of 10 CFR 70.61 as analyzed in the Integrated Safety Analysis."

EMERGENCY CORE COOLING SYSTEM (ECCS) ACCUMULATORS INOPERABLE

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

"At 0028 EDT on 4/20/2025, it was discovered that all trains of the ECCS accumulators were simultaneously inoperable. Therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). The safety function was restored at 0028 on 04/20/2025 and all required trains have been declared operable. There was no impact to the other unit.

"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 sample lines for each accumulator cold leg were open for inspection, which crossties the cold leg accumulator gas spaces. Upon discovery of this condition, the sample lines were subsequently closed, and the accumulators were declared operable.