Event Notification Report for May 23, 2024

EN Revision Imported Date: 5/23/2024

EN Revision Text: AUTOMATIC REACTOR TRIP

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

"At 1641 CDT on May 12, 2024, with Unit 2 in Mode 1 at 15 percent power, the reactor automatically tripped due to a unit auxiliary transformer lockout. During the trip, all control rods fully inserted. The cause of the transformer lockout is currently unknown. Emergency diesel generator (EDG) 21 and 23 actuated and all three engineered safety feature (ESF) busses were energized.

"All equipment responded as expected except for steam generator power operated relief valve (PORV) 2C which failed to open when required in automatic, and the load center (LC) E2A output breaker which failed to close automatically but was closed manually. Steam generator PORV 2C did open when placed in manual, although it subsequently failed to full open and was then closed. Primary system temperature and pressure are currently being maintained at 567 degrees/2235 psig following start of reactor coolant pumps 2A and 2D.

"Due to the reactor protection system actuation (RPS) while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). This event is also being reported per 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the emergency diesel generators. There was no impact to 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:

South Texas Project Unit 2 was in Mode 1 at 15 percent power due to performance of testing and analysis on the main turbine prior to the RPS actuation.

* * * UPDATE FROM ROBERT DEWOODY TO BRIAN P. SMITH ON MAY 22, 2024 AT 1805 EDT * * *

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

"South Texas Project is submitting the following correction to the event notification:

"The steam generator (SG) power operated relief valve (PORV) '2C' did not fail to open automatically. System pressure during this event did not reach the automatic setpoint for the PORV (1225 psi), and there was no demand for it to open automatically. During the event, SG PORV '2C' was taken to manual and it went full open when the 'up' button was pushed slightly. It went closed when the 'down' button was pressed to close it manually. In addition, the load center 'E2A' output breaker initially failed to close automatically, however, after operations placed it in 'pull-to-lock' and returned the hand switch to automatic, it closed automatically."

Notified R4DO (Dixon).

EN Revision Imported Date: 5/23/2024

EN Revision Text: AGREEMENT STATE REPORT - LOST BRACHYTHERAPY SEED

The following was provided by the Illinois Emergency Management Agency (the Agency) via email:

"The Agency was contacted on 5/13/24 concerning one lost iodine-125 brachytherapy seed with an activity of approximately 0.267 millicuries. On 5/13/24, Bard Brachytherapy received a package from Northside Hospital - Gwinnett (Lawrenceville, GA), and initially identified a total of seven of the nineteen iodine-125 brachytherapy seeds were missing. Five seeds were found shortly thereafter in the packing material. The common carrier was called to return to the Bard facility and an additional seed was located within the delivery vehicle. Additional searches of the local Schaumburg, IL [common carrier] hub and O'Hare airport facility were unsuccessful in locating the final seed. The Agency was notified that the final seed was considered lost. The package is reported as having left Lawrenceville, GA and then Norcross, GA before arriving at the Schaumburg, IL facility. Reportedly, the package had no indication of damage from transit. The cause of the loss seed appears to be inadequate packaging when shipped."

Illinois event number: IL240013.

* * * UPDATE ON 5/22/2024 AT 1058 EDT FROM GARY FORSEE TO SAMUEL COLVARD * * *

"The licensee's written report was received 5/22/23 and provided no additional information. Exposures to the carrier and other members of the public are not expected to exceed reportable limits. Due to the small size and the proximity required to accumulate a reportable exposure, this incident is not expected to result in public exposures exceeding regulatory limits. The Illinois licensee followed reporting timelines and package receipt procedures. Provided no new information becomes available that would allow identification of the seed, reasonable search efforts have been undertaken and this matter is considered closed."

Notified R3DO (Ziolkowski), R1DO (Carfang), NMSS Events Notification (email), ILTAB (email).

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