Event Notification Report for April 18, 2019

AGREEMENT STATE REPORT - STOLEN MOISTURE DENSITY GAUGE

The following was received via email:

"On 4/18/2019, [California Department of Public Health-Radiologic Health Branch (CDPH-RHB)] received a notification from [the California Governor's Office of Emergency Services] regarding a stolen moisture density gauge. The gauge involved is a Troxler Model 3430, S/N 31163, containing 9 mCi of cesium-137 and 44 mCi of americium-241. The gauge was stolen from an authorized user's truck parked near his residence at 1830 PDT on 4/17/2019. At the time of the incident, the device was secured in a Type A package, chained to the bed of the truck. On 4/18/2019, around 1000 PDT, the user discovered that the gauge was stolen from his vehicle. Immediately after the incident a report was filed with the Sacramento County Sherriff Office. RHB will be following up on this investigation."

CA 5010 Number: 041819

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

INVALID ACTUATION OF A UNIT 2 CONTAINMENT ISOLATION LOGIC DUE TO A BLOWN FUSE

"This 60-Day telephone notification is being made per the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of Limerick Generating Station Unit 2 containment isolation logic.

"On April 18, 2019, while performing a relay replacement on the Division 2/4 Main Steam Line logic, a partial containment isolation occurred due to a blown fuse.

"The following systems had components that actuated due to the partial isolation:
Reactor Water Clean-Up System
Primary Containment Instrument Gas System
Drywell Chilled Water System
Reactor Enclosure Cooling Water System
Core Spray System

"The Residual Heat Removal System received an isolation signal; however, the system remained in service because the isolation was defeated in accordance with plant procedures.

"This event resulted in partial Group 2A, 3, 7A, 8A, and 8B isolations. The systems successfully functioned per the plant design and plant configuration."

The licensee notified the NRC Resident Inspector.

60-DAY OPTIONAL TELEPHONIC NOTIFICATION DUE TO INVALID SPECIFIED SYSTEM ACTUATION

"This 60-day telephone notification is being made in accordance with the reporting requirements specified by 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a general containment isolation signal affecting multiple Main Steam Isolation Valves (MSIVs).

"On April 18, 2019 at approximately 0110 EDT, during performance of an ASME reactor vessel leak check, all four inboard MSIVs closed as a result of actuation of the Main Steam Line (MSL) high flow instrumentation. The high flow signal was spurious on the 'D' channel with no flow in the MSLs. Since an actual high flow condition did not exist at the time of the actuation, the actuation was considered invalid. The MSIVs functioned as designed on actuation of the MSL high flow instrumentation. All outboard MSIVs were closed at the time of the actuation in accordance with the vessel leak check procedure.

"The NRC Resident Inspector has been notified."