05000244/LER-2003-006

LER-2003-006,

R. E. Ginna Nuclear Power Plant
Event date:
Report date:
2442003006R00 - NRC Website

I. � PRE-EVENT PLANT CONDITIONS:

On November 13, 2003 the plant was in Mode I at approximately 100% reactor power. The on-site electrical system was in the 50/50 lineup configuration, meaning that each off-site circuit was providing power to two (2) of the four (4) 480 Volt Safeguards Busses. The control room had entered procedure ER-SC.1, Adverse Weather Plan, at 0817 hours0.00946 days <br />0.227 hours <br />0.00135 weeks <br />3.108685e-4 months <br /> due to high winds (sustained greater than 55 mph) in the area.

B. � DESCRIPTION OF EVENT:

A. EVENT:

At approximately 0954, off-site power Circuit 751 was lost due to the high winds being experienced in the area (peak winds of approximately 60 to 70 mph). This resulted in the temporary loss of safeguards Bus 16 and Bus 17. However, the B EDG automatically started and supplied power to these busses as designed.

Off-site power Circuit 767 remained operable during this event. The off-site power configuration was later switched to 100/0, with Circuit 767 supplying all off site power requirements. The plant remained at approximately 100% power throughout the event.

TO THE EVENT:

None

C. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:

• November 13, 2003, 0954 EST: Event Date and Time, Loss of off-site power Circuit 751 and B EDG start.

• November 13, 2003, 1009 EST: Electrical system placed in the 100/0 off-site power alignment on Circuit 767

• November 13, 2003, 1016 EST: Bus 16 and Bus 17 returned to off-site power (Circuit 767), B EDG Shutdown

• November 13, 2003, 1237 EST: Notification of B EDG start, event #40319, under 10CFR50.72(b)(3XivXA).

NRC FORM 3644 (1-2001)

• November 15, 2003, 0026 EST: Electrical system returned to the 50/50 alignment.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None, since there were no failures of any components with multiple functions.

E. METHOD OF DISCOVERY:

The condition was immediately apparent from plant indications and response in the Control Room.

F. SAFETY SYSTEM RESPONSES:

All safety systems functioned as designed.

III. CAUSE OF EVENT:

The cause of the event was high wind conditions which caused the overhead lines of off-site power Circuit 751 to make contact with a tree branch, resulting in electrical arcing and the subsequent loss of Circuit 751. The branch apparently dislodged from a tree that is outside the distance requiring normal tree trimming, landing across the phases of the circuit.

This event is NUREG-1022 Cause Code (C), "External Cause"

IV. ASSESSMENT OF THE SAFETY CONSEQUENCES OF THE EVENT:

This event is reportable in accordance with 10 CH( 50.73, Licensee Event Report System, item (a)(2)(iv)(A), which requires a report ot Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)03) of this section, except when:

(1) The actuation resulted from and was part of a pre-planned sequence during testing or reactor operation; or (2) The actuation was invalid and; (1) Occurred while the system was properly removed from service; or (ii) Occurred after the safety function had been already completed.

The Ginna UFSAR section 8.1.4.4 states in part, "Although severe weather increases the probability of a loss of offsite power, it has only a slight effect on the risk of a station blackout. � The emergency power systems at Ginna Station were thoroughly reviewed for operability in the instances of severe and extreme natural phenomena such as floods, tornadoes, and snowstorms as . MC FORM 366A 0-2001) _ .

part of the Systematic Evaluation Program (SEP). The Ginna Station design basis, therefore, already includes the system design features and procedures to ensure that no unacceptable loss of emergency onsite power will occur during severe weather events.

The B EDG operated as designed throughout the event, ensuring a reliable source of power to the AC emergency busses at all times. The A EDG was operable, but was not challenged.

One off-site power circuit (767) was not affected by the weather conditions and remained in service.

It was subsequently aligned to carry all off-site loads until Circuit 751 could be restored. This is consistent with Ginna Technical Specifications Section 3.8.

Therefore, it was determined that the plant responded within it's design and licensing basis, that there were no unreviewed safety questions, and that the public's health and safety was assured at all times.

V. � CORRECTIVE ACTIONS:

A. � ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL

STATUS:

• Off-site power was restored to Bus 16 and Bus 17.

• Circuit 751 restored to service.

B. � ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Circuit 751 was subsequently patrolled by electrical engineering and RG&E line personnel.

No threatening hanging branches or growth into the lines was identified. However, several trees which may have impacted the performance of the circuit are being scheduled for removal.

RG&E has initiated a self assessment and risk analysis of Circuit 751 reliability which will provide recommendations to station management regarding the following:

• Procedure changes to provide better direction on off-site power alignments during various plant modes and weather conditions.

• Possible modifications to the off-site power system.

NRC FORM 3130A (I-2001) A

A. FAILED COMPONENTS:

None

B. PREVIOUS LERs ON SIMILAR EVENTS:

An historical search of LERs was conducted with the following results:

The following LERs were the result of the loss of Circuit 751. Although these events resulted in the auto start of an Emergency Diesel Generator, only one (2003-005) resulted in a plant trip because of the operating mode and electrical configuration at the time of the event.

• 2003-005

• 1998-005

• 1997-002

• 1995-006

• 1995-007

• 1994-012

• 1994-005

• 1992-007

• 1991-002 C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (MS) COMPONENT

SYSTEM REFERRED TO IN THIS LER:

COMPONENT IEEE 803 IEEE 805

FUNCTION IDENTIFIER SYSTEM IDENTIFICATION

Off-Site Power Circuit 751 ix EB Emergency Diesel Generators DG EK

D. SPECIAL COMMENTS:

None NRC FORM MA (14001)