Event Notification Report for August 27, 2022

TURBINE TRIP DUE TO MAIN TRANSFORMER FIRE

The following information was provided by the licensee via email:

"At 0810 EDT on August 27, 2022, with Unit 2 at 27% power, the operating crew received an annunciator for a Turbine Trip Without Reactor Trip. At 0812 EDT, a report came in from the field of a fire in the north yard due to an "A" Main Transformer upper bushing failure. The station fire brigade was dispatched and offsite assistance was requested. However, at 0842 EDT the fire was put out, prior to needing the offsite assistance. No Emergency Action Level threshold was exceeded for this event. The switchyard is in a normal alignment for providing offsite power to Unit 2. At 1015 EDT, the Virginia Department of Emergency Management (VDEM) was notified of the event. Additionally, a notification to the Virginia Department of Environmental Quality will be made due to approximately 100 gallons of oil reaching the ground. As such, this issue is being reported per 10 CFR 50.72(b)(2)(xi) for "'Any event or situation for which a news release is planned or notification to other government agencies has been or will be made.'"

The NRC Resident Inspector was notified.

AGREEMENT STATE REPORT - STOLEN MOISTURE DENSITY GAUGE

The following information was provided by the state of Florida via email:

"[The licensee's Radiation Safety Officer] (RSO) called at 1946 EDT to report a stolen Troxler Soil Moisture Density Gauge. The Pacifica technician found the chain and padlock were cut. The initial discovery was at approximately 0830 EDT, but was not reported to the RSO until later in the day. When asked why the incident was reported nearly 12 hours later, [the RSO] stated that the technician had a morning exam, and that he was afraid of losing his job. Additionally, since [the RSO] had not notified Law Enforcement at the time of his report, he was instructed to do so. Finally, [the RSO] was instructed to email this [Florida Bureau of Radiation Control] Duty Officer with the report number, along with his description of the event."

Incident number: FL22-099

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

PART 21 - SERVICE WATER BOOSTER PUMP BEARING HOUSING COVER OIL LEAK

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

"On August 27, 2022, while in Mode 1 at 100 percent power, Nebraska Public Power District (NPPD) Cooper Nuclear Station (CNS) identified a 3 drops per minute (dpm) oil leak from the radial (inboard) bearing housing cover on one of four residual heat removal (RHR) service water booster pumps (SWBP); specifically, SWBP-D.

"Subsequent analysis determined that the leak was a result of a deviation with the configuration of the labyrinth seal drain path. This deviation was due to an error introduced in a manufacturing drawing used by the vendor for the fabrication of four new replacement pumps. The bearing housing cover is a unique design to CNS for the RHR SWBPs.

"On March 1, 2024, NPPD completed a substantial safety hazard evaluation and determined that the manufacturing drawing error could cause a substantial safety hazard. The NRC Resident Senior Resident has been notified. This is a non-emergency notification required by 10 CFR 21.21(d)(3)(i). A written notification will be provided within 30 days."

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

All four SWBPs had a similar housing design. Three of the four pump housings have been replaced. No other nuclear plant is affected due to the housing design being unique to CNS.