Event Notification Report for May 13, 2020

AUTOMATIC REACTOR TRIP

"At 0208 EDT on 05/13/2020, Sequoyah Unit 1 was at 100% power when an automatic reactor trip signal was received concurrent with a low steam line pressure safety injection signal.

"The low steam line pressure safety injection signal was actuated from the steam pressure rate of decrease feature. Main steam isolation valves (MSIVs) automatically closed as designed and steam generator pressures stabilized following the isolation. All other safety-related equipment operated as designed, with the exception of 1-FCV-61-122 Glycol inboard containment isolation valve which failed to automatically isolate on a Phase A containment isolation signal. The corresponding outboard containment isolation valve, 1-FCV-61-110, automatically isolated as designed which isolated penetration X-114.

"Safety injection was terminated at 0221 EDT 5/13/20, and Unit 1 is currently being maintained in Mode 3 at normal operating temperature and pressure with auxiliary feedwater supplying the steam generators and decay heat removal via steam generator atmospheric relief valves.

"There is no indication of any primary to secondary leakage. The electrical alignment is normal with shutdown power supplied from off-site power. There is no current operational impact to Unit 2.

"There is no impact on public health or safety. Post safety injection actuation investigation is in progress.

"The NRC Resident Inspector has been notified."

LOSS OF EMERGENCY RESPONSE FACILITY

"At 1000 CDT on May 13, 2020, the Byron Station Technical Support Center (TSC) emergency ventilation system inlet isolation damper would not open as required to support system operation. This failure affected the ability of the TSC ventilation system to maintain adequate radiological habitability in the event of an emergency with an airborne radiological release. All other capabilities of the TSC were unaffected by this condition. If an emergency was declared requiring TSC activation during this period, the TSC would be staffed and activated using existing emergency planning procedures. If the TSC became uninhabitable, the Station Emergency Director would relocate the TSC staff to an alternate TSC location in accordance with applicable procedures. The TSC emergency ventilation system inlet isolation damper has been repaired and is now functional. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii) because the discovered condition affected the functionality of an emergency response facility.

"The NRC Resident Inspector has been notified."

FIRE INVOLVING LOSS OF INTEGRITY OF LICENSED CONTAINER

"At approximately 0800 EST on May 13, 2020, a thermal reaction occurred inside a production hot cell during a rubidium dissolution process. The pressure created by the reaction caused the back door of the hot cell to open approximately six inches for a few seconds. Curium employees performing the dissolution process immediately activated the hot cell fire suppression system to put out the fire, closed the hot cell door and placed the production area in a secured state. The open hot cell door released airborne radioactive material to a localized area inside the controlled and posted production area. Six employees that were in the vicinity of the production hot cell presented contamination. Contamination was also found on the floor immediately around the production hot cell.

"Curium's RSO isolated the affected area and used the data collected from personal surveys to preliminarily estimate the potential dose to the six employees and the total activity released from the hot cell. The initial dose estimates indicated that the employee with the highest exposure potentially received approximately 6.5 mrem DDE and <1 mrem CEDE. Urinalysis was performed to confirm the internal exposure and intake. At the time of this report, the urinalysis results are still pending. Analysis of air samples taken in the immediate affected area indicated the presence of Sr-82, Sr-85, Rb-83, Rb-84, and Rb-86. After the performance of contamination surveys, decontamination of affected employees and analysis of samples, Curium employees decontaminated the affected area. After decontamination procedures were completed, the affected area was released for normal operations within the same business day without the need for imposing additional radiological controls or restrictions. Radiological surveys confirmed that there was no detectable release of radioactive material to uncontrolled areas adjacent to the hot cell production area.

"Curium performed a preliminary root cause analysis on May 13, 2020. After completing a preliminary assessment of the dose and release of radioactive materials, Curium reviewed the notification requirements prescribed in 10 CFR 20.2203, 20.2204 and 30.50 and made a determination that neither the immediate nor 24-hour notification requirements were warranted. Curium performed a formal root cause analysis on May 14, 2020. Despite a belief that notification was not required, Curium communicated the incident in good faith to Mr. Jason Draper (NRC Region III) on May 14, 2020 at 1100 EST. After further discussions with Mr. Draper throughout May 14, 2020 and further review of the incident and conditions, Curium personnel made a decision to self-report the incident to the NRC Operations Center as specified under 10 CFR 30.50(b)(4).

"Curium is in the process of finalizing the root cause analysis, finalizing the dose estimates, completing confirmatory actions."