United States Nuclear Regulatory Commission - Protecting People and the Environment

LICENSEE: SOUTH CAROLINA ELECTRIC & GAS CO.
SITE: SUMMER 1 EN NUMBER: 36218
DOCKET: EVENT DATE: 08-06-99
RX TYPE: PWR EVENT TIME: 10:00
VENDORS: W-3-LP NOTIFY DATE: 09-23-99
EMERGENCY CLASS: N/A REGION: 2 STATE: SC TIME: 17:08
OPS OFFICER: FANGIE JONES
10 CFR SECTION: CCCC UNSPECIFIED PARAGRAPH
UNIT SCRAM CODE RX CRIT INIT PWR INITIAL MODE CURR PWR CURRENT MODE
1 N Y 100 Power Operation 100 Power Operation

10 CFR PART 21 REPORT - ABB K-LINE BREAKER DEFECT AFTER REPAIR

"This report is being made pursuant to 10CFR21.21 to identify a Substantial Safety Hazard with an ABB K-line Breaker.

"On August 6,1999, Virgil C. Summer Nuclear Station (VCSNS) determined that a Substantial Safety Hazard could exist with ABB K-line breakers failing to trip, Improper routing/support of the shunt trip wires during refurbishment caused interference with the red, trip shaft paddle on the left side of the breaker. This condition was found on a breaker installed in safety-related switchgear at VCSNS. This breaker condition-was compared to several other ABB K-line breakers at the plant site. The other breakers were found to have the wires routed in a different direction, precluding interference with the red, trip shaft paddle.

"VCSNS utilizes these breakers in many applications, including the 480 VAC, safety related electrical buses. The shunt trip wiring problem is considered a defect in repair. This condition represents a potential for a common mode failure for safety-related K-line breakers.

"The vendor has been notified of the shunt trip wiring problem and has agreed to modify the procedure for the refurbishment of these breakers. VCSNS Engineering has determined that vendor procedure changes should prevent recurrence of this problem."

The licensee notified the NRC Resident Inspector.

Page Last Reviewed/Updated Thursday, March 29, 2012