05000362/LER-2004-003

LER-2004-003, Invalid Actuation of Emergency Diesel Generator due to an Invalid Signal

Docket Number
Event date:	12-2-2004
Report date:	01-13-2005
3622004003R00 - NRC Website

On 12/2/2004 at about 0247 PST, with Unit 3 defueled, Emergency Diesel Generator (EDG) (EK) 3G002 actuated.

This report is being made under 50.73(a)(2)(iv)(A) for an invalid actuation of an EDG due to an invalid signal.

A Test Technician performing planned work in an Engineered Safety Features (ESF) Actuation System (JE) relay cabinet attempted to "jumper out" sections of the ESF actuation circuits to prevent actuation of certain ESF components.

Instead, the jumper caused a momentary transient on the circuit power supplies and the resulting voltage dip was sufficient to actuate the EDG from the SIAS relay. The EDG functioned as designed.

This event was caused by personnel error. As an immediate corrective action, SCE now requires the use of jumpers to be preplanned. SCE is completing a review of maintenance work processes to determine if alternate or additional program enhancements are needed.

Since actual plant conditions did not require actuation of the EDG, this is an invalid actuation resulting from an invalid signal. At the time of this event, Unit 2 was operating at about 100 percent power and Unit 3 was in a refueling outage.

There was no safety significance to this event. In the past 3 years, SCE has not reported any events of invalid EDG actuations due to an invalid signal.