Event Notification Report for March 12, 2024

EN Revision Imported Date: 3/12/2024

EN Revision Text: INVALID ACTUATION OF CONTAINMENT ISOLATION VALVES

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

"This 60-day optional telephone notification is being made in lieu of a Licensee Event Report (LER) submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B).

"At approximately 2333 EST on January 1, 2024, an invalid actuation of group 6 primary containment isolation valves (PCIVs) (i.e., containment atmospheric control/monitoring (CAC/CAM) and post-accident sampling system (PASS) isolation valves) occurred. Reactor building ventilation isolated and standby gas treatment started per design. No manipulations associated with the isolation or reset logic were ongoing at the time.

"Troubleshooting determined that the group 6 isolation signal resulted from spurious relay contact actuation in the main stack radiation high-high isolation logic due to relay contact oxidation. The main stack radiation monitor is a shared component that sends isolation signals to Unit 1 and Unit 2. There were no Unit 1 actuations. Only the relay contacts associated with Unit 2 actuated. The relay has been replaced.

"The actuation was not initiated in response to actual plant conditions. It was not an intentional manual initiation and there were no parameters satisfying the requirements for initiation of the system. Therefore, this event has been determined to be an invalid actuation.

"During this event the PCIVs functioned successfully, and the actuations were complete. This event did not result in any adverse impact to the health and safety of the public."

The NRC Resident Inspector had been notified.

AGREEMENT STATE REPORT - LOST SOURCE FOUND

The following is a summary of the information provided by the Louisiana Department of Environmental Quality (LDEQ) via email:

At 2152 CST on March 3, 2024, a lost source was found along Corporate Blvd., Baton Rouge, LA. The device is a Model IC-51 Calibrator with 1000 mCi of Cs-137 as of August 25, 1980. The label on the device indicates the manufacturer was Gulf Nuclear, Inc., of Webster, Texas. LDEQ took possession of the device on March 4, 2024, and has it at the time of this report.

Event Report ID No.: LA20240003


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

STUCK IRRADIATOR SOURCE

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

At 1000 MST on 3/5/24, a 10,000 Ci Co-60 source (Model 7810) became stuck in the unshielded position during operator training. The irradiator is a J.L. Shepherd, Model SDF-34-M1, panoramic dry-source storage type. Upon determining that the source was stuck, the operator attempted to manipulate the source back into the shielded position using the emergency cable, but it came loose. Site staff have secured the irradiator facility.

No personnel exposure occurred, and there are no elevated dose rates outside of the irradiator enclosure. The site has requested manufacturer support to resolve the issue.

The NRC Project Manager (O'Keefe) has been notified.

AGREEMENT STATE REPORT - STUCK SHUTTER

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

"On March 5, 2024, the Department was notified by the licensee that during routine shutter testing, the shutter on a Vega SH-F2C failed to close. Open is the normal operating position for the gauge shutter. The gauge contains a 500 millicurie (original activity) cesium-137 source. The gauge is in an area that is accessed only to test the shutter as it is located 230 feet off the ground. The gauge does not present an exposure risk to any individual. The licensee has contacted a service company to repair the gauge. Additional information will be provided as it is received in accordance with SA-300."

Texas Incident Number: 10093

NMED Number: TX240008

AGREEMENT STATE REPORT - LOST EXIT SIGNS

The following information was provided by the California Department of Public Health, Radiologic Health Branch via email:

"Isolite Corporation notified the California State Warning Center of the loss of a container containing eight tritium exit signs with a total activity of 60.8 curies of tritium (H-3). Fifty-one containers of tritium signs were to be delivered by [common carrier]. Only 50 containers of tritium exit signs were delivered, leaving one container containing the eight exit signs missing. [The common carrier] is currently conducting a search to determine the status of the missing container of exit signs. Since this exceeds the amount of H-3 by greater than 1000 times the value in Appendix C of Part 20, it constitutes a less than or equal to 24-hour reportable event."

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

EN Revision Imported Date: 3/11/2024

EN Revision Text: FITNESS FOR DUTY

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

A non-licensed supervisor had a confirmed positive fitness for duty test. Unescorted access for the individual has been denied at all Dominion Energy sites. The NRC Senior Resident Inspector has been notified.

ESSENTIAL CHILLED WATER TRAINS DECLARED INOPERABLE

The following information was provided by the licensee via email:

"On 3/9/2024 at 2126 CST, train C essential cooling water was declared inoperable due to a through-wall leak on the discharge vent line. This would also cascade and cause train C essential chilled water to be inoperable.

"On 3/10/2024 at 0353 CDT, train B essential chilled water was declared inoperable due to chilled water outlet temperature greater than 52 degrees F following startup of essential chiller 12B. Chilled water outlet temperature was adjusted to less than 52 degrees F at 0440 CDT, and train B essential chilled water was declared operable.

"This condition resulted in the inoperability of two of the three safety trains required for the accident mitigating functions including: high head safety injection, low head safety injection, containment spray, electrical auxiliary building HVAC, control room envelope HVAC, and essential chilled water.

"This is an 8 hour reportable condition per 10CFR50.72(b)(3)(v)(D) because it could affect the ability to mitigate the consequences of an accident."

The licensee notified the NRC Resident Inspector.

MANUAL REACTOR TRIP

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

"On March 11, 2024, at 1337 EDT, with Unit 1 in Mode 1 at 35 percent power performing power ascension activities, the reactor was manually tripped due to the 'A' reactor feed pump (RFP) tripping on low suction pressure. Due to the power level at the time, the 'B' RFP had not been placed in service. Closure of containment isolation valves (CIVs) in multiple systems and actuation of high-pressure coolant injection (HPCI) and reactor core isolation cooling (RCIC) occurred as a result of reaching the actuation setpoint on reactor water level as designed. The trip was not complex, with all safety systems responding normally post-trip. Operations responded and stabilized the plant. The 'B' RFP was placed in service and is controlling reactor water level. Decay heat is being removed by discharging steam to the main condenser using turbine bypass valves. Unit 2 is not affected.

"Due to the emergency core cooling system (ECCS) discharging into the reactor, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(A). Also, the Reactor Protection System actuation while critical is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Additionally, it is reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of CIVs, RCIC and HPCI.

"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 cause of the 'A' RFP is under investigation. The reactor electric plant remains in a normal lineup with both emergency diesel generators available. There were no temperature or pressure technical specification limits approached.