Event Notification Report for March 01, 2024

EN Revision Imported Date: 3/1/2024

EN Revision Text: OFFSITE NOTIFICATION - WORKPLACE INJURY

The following information was provided by the licensee via email:

"On February 1, 2024, a contract worker was transported offsite for medical treatment due to a work-related injury that required the individual to be admitted to the hospital. The individual was free-released from the site prior to transport.

"The injury and hospitalization were reported by the contract worker's employer to OSHA per 29 CFR 1904.39(a)(2). Based upon that notification to another government agency, Tennessee Valley Authority is reporting this per 10 CFR 50.72(b)(2)(xi).

"The NRC Senior Resident Inspector has been notified of this event."

* * * RETRACTION ON 2/29/24 AT 12:29 EST FROM MATTHEW SLOUKA TO KAREN COTTON * * *

The following information was provided by the licensee via email:

The purpose of this notification is to retract a previous Event Notification, EN 56941, reported on 02/01/2024.

"On 02/01/2024, at 15:32 EST, Browns Ferry Nuclear Plant (BFN) made an Event Notification 56941 notifying the NRC of a notification to another government agency. During further review of NRC reporting guidance, BFN has concluded that the contract worker's employer report to OSHA was below the reporting threshold outlined in NUREG 1022, Revision 3.

"The NRC Resident Inspector has been notified."

AUTOMATIC REACTOR SCRAM

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

"At approximately 0839 [CST] with Unit 1 in Mode 1 at 100 percent power, the reactor automatically scrammed due to the depressurization of the SCRAM air header caused by an invalid signal that [occurred] during system testing. The SCRAM was uncomplicated with all systems responding as expected. The cause and details of the event are under investigation. Containment isolation valves actuated and closed on a valid Group 2 signal.

"Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B), and an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) for the Group 2 isolation signal.

"Operations responded using the emergency operating procedure and stabilized the plant in Mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves.

"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. State as well as Wright and Sherburne Counties will be notified."

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

The Anticipated Transient Without Scram (ATWS) circuit was being tested when an invalid signal was sent to depressurize the SCRAM air header.

SPECIFIED SYSTEM ACTUATION - AUTOMATIC START OF EMERGENCY DIESEL GENERATORS

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

"At 1350 EST on 2/28/2024, with Calvert Cliffs Unit 1 in Mode 5 at 0 percent power and Unit 2 in Mode 1 at 65 percent power, an actuation of the '1A' and '2A' emergency diesel generators' auto-start occurred due to an undervoltage condition on the number 11 and number 21 4kV buses which are fed from the number 11 13kV bus. The '1A' and '2A' emergency diesel generators automatically started as designed when the 4kV buses' undervoltage signals were received.

"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the '1A' and '2A' emergency diesel generators.

"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 undervoltage condition was caused by the feeder breaker to the number 11 13 kV bus opening during electrical maintenance.