Headquarters Daily Report JUNE 26, 1996 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS û REGION I û REGION II û REGION III û REGION IV û PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION II JUNE 26, 1996 Licensee/Facility: Notification: Tennessee Valley Authority MR Number: 2-96-0058 Sequoyah 1 2 Date: 06/26/96 Soddy-Daisy,Tennessee Dockets: 50-327,50-328 PWR/W-4-LP,PWR/W-4-LP Subject: REACTOR TRIP AND UNUSUAL EVENT DUE TO COUPLING CAPACITOR EXPLOSION IN SWITCHYARD Reportable Event Number: 30667 Discussion: On June 23, 1996, a coupling capacitor potential device failed in the Sequoyah 500kV switchyard, resulting in the explosion of the device and a small localized fire. The event occurred at 5:14 p.m., EDT, and caused a ground condition of the 500 kV Bus 1. The ground was properly cleared; however, the licensee believes the resultant vapors from the explosion caused a conductive medium (ionized gas) resulting in a second temporary ground on Bus 2. This ground was cleared by a main transformer differential relay which opened the main generator output breakers and subsequently caused a main turbine and reactor trip of Unit 1. The plant responded as expected. All safety systems functioned normally and offsite power to the unit was not affected. Unit 2 was not affected by the incident. A Notice of Unusual Event was declared at 5:37 p.m., based upon an explosion within the protected area which caused damage to permanent structures. The fire was extinguished at 5:40 p.m., and the NOUE was terminated at 6:07 p.m. At Sequoyah, the switchyard is within the protected area. The device which failed is used to measure phase angle difference for generator synchronization to the grid and is described as a type KG-WT 525 MICAFIL hermetically sealed coupling capacitor with a carrier ground switch, grounding choke coil, and lightning arrestor. The licensee's preliminary investigation indicates that the device has been inservice for approximately 25 years. The licensee also indicates that the TVA system has approximately 40 similar devices on the grid with no previous failures of this nature. The cause of the failure has not yet been determined. Subsequent walkdowns and inspection of shrapnel or fire damage identified broken turbine building windows, main transformer C phase conductor arcing damage, and some scarring (cosmetic) damage to the main transformer. The licensee inspected the other coupling capacitor in the 500 kV switchyard and completed testing and checkout of various electrical equipment prior to restart. The licensee is continuing repair work on Bus 1. Regional Action: The senior resident inspector responded to the site and verified plant conditions. The resident inspectors conducted independent walkdowns of the affected area and are continuing to follow the licensee's root cause evaluation. REGION II MORNING REPORT PAGE 2 JUNE 26, 1996 MR Number: 2-96-0058 (cont.) Contact: Mark S. Lesser (404)331-0342 _ REGION II MORNING REPORT PAGE 2 JUNE 26, 1996 Licensee/Facility: Notification: MR Number: 2-96-0059 General Electric Company Date: 06/26/96 Wilmington,North Carolina Dockets: 07001113 License No: SNM-1097 Subject: INADVERTENT ALARMING OF NUCLEAR CRITICALITY ALARM SYSTEM Discussion: At approximately 2:00 p.m. on June 25, 1996, during a thunderstorm, the criticality alarm system at GE Wilmington inadvertently alarmed due to lightning associated with the storm. Plant workers immediately evacuated the affected site area in response to the alarm, and the Emergency Organization manned the Command Center to evaluate the situation. Subsequent surveys showed no elevated radiation levels, confirming the alarm as false. Workers returned to their work area following the Emergency Organization's declaration of the false alarm. The detector which gave the false alarm is located out-of-doors, and some distance from the fuel manufacturing building. A second criticality alarm system detector, which provides redundant coverage of this same area, did not alarm or otherwise indicate elevated radiation levels. Also, with the redundant coverage provided by this second detector, no portion of criticality alarm system's operability was lost during this event. The detector which alarmed was reset and put back into operation at approximately 4:00 p.m. Regional Action: Region II discussed the event with GE Wilmington representatives and determined that no further followup action is necessary. Contact: D. Kasnicki (404)331-5903 _ REGION III MORNING REPORT PAGE 3 JUNE 26, 1996 Licensee/Facility: Notification: Cleveland Electric Illuminating Co. MR Number: 3-96-0068 Perry 1 Date: 06/25/96 Perry,Ohio SRI VIA PC Dockets: 50-440 BWR/GE-6 Subject: PLANT MANAGEMENT CHANGES Discussion: On June 25, 1996, Region III was notified by the licensee that effective June 24, 1996, four managers had been reassigned. Mr. Robert Schrauder, who was Nuclear Support Director, entered the senior licensed operator training program, and was replaced by Mr. Lonnie Worley. Mr. Worley, who was the Nuclear Assurance Director, was replaced by Mr. William Kanda. Mr. Kanda, who was the Training Manager, was temporarily replaced by Mr. Christopher Persson from within the training section. Mr. Persson will be the acting Training Manager until the licensee selects a permanent replacement. Regional Action: None Contact: R. D. LANKSBURY (708)829-9631 _