Event Notification Report for May 17, 2016

SPECIFIED SYSTEM ACTUATION - LOSS OF 1 B-B ELECTRICAL BUSS

"On May 17, 2016, at 1630 hours while restoring from a plant modification related to new 'loss of phase' circuitry, the 1 B-B 6.9kV buss de-energized resulting in a loss of voltage on the buss. The loss of voltage was caused by the loss of voltage relays that separated offsite power from the 1 B-B 6.9kV buss. At the time, the 1 B-B emergency diesel generator was removed from service for planned maintenance.

"In response to the loss of power on the 1 B-B 6.9kV buss, the operators entered abnormal operating instruction, AOI 43.02, Loss of Unit 1 Train B Shutdown Boards, and started emergency diesel generators 1 A-A, 2 A-A, and 2 B-B. All equipment operated properly. The emergency diesel generators were not required to be paralleled to the boards.

"Offsite power was restored to the 1 B-B 6.9kV buss at 1802 hours on May 17, 2016. This condition did not result in any adverse impact on the health and safety of the public. This event is reportable under 10 CFR 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section, except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.'"

The NRC Resident Inspector has been notified.

FITNESS-FOR-DUTY CONFIRMED POSITIVE

A contract supervisor had a confirmed positive for illegal drugs during a for-cause fitness-for-duty test. The employee's access to the plant has been terminated.

The licensee notified the NRC Construction Resident Inspector.

MISSISSIPPI AGREEMENT STATE REPORT - STUCK SHUTTER ON LEVEL GAUGE

The following information was obtained from the state of Mississippi via email:

"Licensee reported a stuck shutter on an Ohmart/VEGA Model SH-F1 level gauge, during semi-annual checks of shutter operation. The failure was identified on 05/17/2016 by the licensee and was immediately reported to RSO. The RSO supposes stuck shutter failure was caused by age and oxidation. Licensee has contacted the manufacturer, Ohmart, for repair of shutter mechanism. Gauge remains in its normal operating position.

"Isotope(s): Cs-137
Activity: 10 mCi
Source Serial No. 0441GK
Source Model No. A-2102"

Mississippi Report Number: MS-16003

* * * UPDATE AT 1655 EDT ON 07/29/16 FROM H. BENJAMIN CULPEPPER TO S. SANDIN VIA EMAIL * * *

"The stuck shutter has been closed and equipment involved removed and placed into a secure storage facility, on site, by an Ohmart Vega representative. There are no plans to put the unit back into service."

Mississippi closed this case as of July 29, 2016.

Notified R4DO (Pick) and NMSS Events Notification via email.

PART 21 REPORT - DEFECT IN A SIGNAL CONVERTER TRANSFORMER

The following report was received from the manufacturer via fax:

Nutherm International, Inc. reported on a defect found in "Moore Industries SCT Signal Converter (Part Number SCT/4-20MA/10-50MA/117VAC/UB) based upon the failure analysis of a failed component. The conclusion was that the wire insulation in T2 transformer was damaged by the transformer manufacturing facility during assembly. This damage reduced the insulation resistance and dielectric breakdown between the windings of the transformer. These damaged transformers were subsequently installed by Moore Industries into the signal converters. The failure of the transformer resulted in early, catastrophic failure of the signal converter.

"Moore Industries tested the transformers remaining in stock and found one (1) of the remaining two-hundred nineteen (219) transformers exhibited this condition. In all documented cases involving failure of this transformer, the impacted units had passed pre-installation functional testing but failed within four months after installation."

Affected nuclear power stations include: Peach Bottom Atomic Power Station and the Sequoyah Nuclear Station.

REACTOR COOLANT LEAKAGE WITH THE REACTOR IN COLD SHUTDOWN

"On May 17, 2016 with the plant in Mode 4 [Cold Shutdown] during a refueling outage, personnel entered the drywell to perform a walkdown. At 0945 CDT, water was identified leaking from flexible hoses located at the inner elbow of MSL [Main Steam Line] B and MSL C. It was concluded that the leakage was from an elbow tap welded to the flexible hoses associated with flow instrumentation on MSL C and MSL B. Due to the refueling outage, the plant subsequently entered Mode 5 at 0955 and is currently in Mode 5 [Refueling] and 0 percent rated thermal power. The degraded component on MSL B was previously replaced in 2008 and on MSL C in 2007. The station has determined that this event is reportable under the provisions of 10 CFR 50.72 (b)(3)(ii)(A) as an event or condition that resulted in the condition of the nuclear power plant, including its principal safety barriers being seriously degraded, as an 8-hour notification.

"The NRC Resident Inspector has been notified."