Event Notification Report for September 28, 2011

PENNSYLVANIA AGREEMENT STATE REPORT - INDUSTRIAL GAUGE SHUTTER FAILURE

The following information was obtained from the Commonwealth of Pennsylvania via fax:

"Event type: Shutter Failure

"Notifications: On September 28, 2011, the Department's [Pennsylvania Department of Environmental Protection] Southwest Regional Office received notification via phone from the licensee at approximately 1530 hrs. of a reportable event listed under 10CFR 30(b)(2). (Note, this is similar but a different event from PA 110022 [EN#47226]).

"Event Description: The shutter failure was identified while performing a routine preventative maintenance and standardization. The shutter became stuck in the closed position and could not be opened. No radiation exposure to personnel ensued during this event. The device is identified as: Manufacturer (IRMS), Model (TG-2), Serial# (00M0397-I5), Isotope (Americium- 241), and Activity (3 Ci).

"Cause of the Event: Spring Default Piston

"Actions: Service provider repairs were completed the same day by replacing the source holder which was then surveyed, wipe tested, and put back into operation."

PA Report No.: PA110026

AUTOMATIC REACTOR SCRAM DUE TO A TURBINE TRIP

"At 0414 [CDT] on 9/28/2011, the Unit 3 reactor automatically scrammed due to actuation of the Reactor Protection System [RPS] from a turbine trip. Preliminary indications show the turbine tripped on a generator trip with generator neutral overvoltage (359GN) relay actuation. Cause of relay actuation is under investigation. Seven Safely Relief Valves (SRVs) cycled due to the reactor pressure transient with reactor pressure automatically controlled by the Main Turbine Bypass Valves. All systems responded as expected to the turbine trip. No Emergency Core Cooling System (ECCS) or Reactor Core Isolation Cooling (RCIC) reactor water level initiation set points were reached. Primary containment isolation and initiation signals for groups 2, 3, 6 & 8 were received as expected. Reactor water level is being automatically controlled by the feedwater system.

"This event is reportable within 4 hours per 10 CFR 50.72(b)(2)(iv)(B) 'any event or condition that results in actuation of the RPS when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.' It is also reportable within 8 hours per 10 CFR 50.72(b)(3)(iv)(A) and requires an LER within 60 days per 10 CFR 50.73(a)(2)(iv)(A).

"The NRC Resident Inspector has been notified."

All control rods fully inserted. The plant is being supplied from offsite power and is in a normal shutdown configuration. The MSIVs are open with decay heat being removed via steam to the main condenser using the bypass valves. There was no impact on Units 1 or 2.

TECHNICAL SUPPORT CENTER VENTILATION OUT OF SERVICE

"Due to unsatisfactory performance of TSC HVAC operation per Condition Report 355263, the TSC HVAC is considered non-functional until performance of the corrective work activity is performed. If an emergency condition occurs during the time these work activities are being performed, which requires activation of the TSC, the contingency plan calls for utilization of the TSC, as long as radiological conditions allow for habitability of the facility. Procedure 73EP-EIP-063-0, Technical Support Center Activation, provides instructions to direct TSC management to the Control Room and TSC support personnel to the Simulator Building to continue TSC activities if it is necessary to relocate from the primary TSC so that TSC functions can be continued.

"This event is reportable per 10CFR50.72 (b)(3)(xiii) as described in NUREG-1022, Rev. 1 since this activity affects the functionality of the TSC emergency response facility for the duration of the evolution."

The licensee corrected an issue with the electrical power fuse block and returned the unit to service at 1210. The licensee cleared the associated action statement for this issue at 1350.

The NRC Resident Inspector has been notified.

PART 21 REPORT - DIODE FAILURES DUE TO DETERIORATION

The following was received via fax:

"Component Description: International Rectifier (IR) and Vishay 150 amp clamp diodes with either forward or reverse bias These are Ametek Solid-state Controls part numbers 07-600150-00 and 07-600151-00. Diodes can be either installed in Ametek Solid-state Controls UPS equipment or provided as a spare part.

"The diode failures due to this suspected defect have occurred generally at around the third or fourth year of operating life of the device. There are no warning signs that a failure is imminent, or detection method for predicting an approaching failure.

"The investigation has revealed that the diode failures were due to voltage transients or punch through. A failure analysis by Southwest Research concluded that the device having an 'alloy junction' can deteriorate after three to four years of operation resulting in a 'punch through' condition within the device causing the diode to short.

"The actual cause has not been determined; however it is suspected that the alloy junction type device may have sensitivity to age or voltages causing the device to more rapidly degrade.

"The failures described above, could result in loss of output voltage and transfer of the static switch to the bypass source which could result in a potential damage to the load.

"We have only two known failures in systems at this voltage level. We feel the failure rate has been extremely low and the risk is minimal. Each operating facility will need to evaluate the potential risk to their operation."

The licensee did not indicate which NRC licensees, if any, are affected by this notice.