On February 3, 2006, at about 1646 PST the Devers-Palo Verde line relayed. This required an evaluation of grid nomograms for San Onofre. At about 1815 PST, the Grid Control Center (GCC) notified San Onofre that the grid nomograms predicted offsite power would not be within limits if San Onofre Unit 3 were to trip (San Onofre Unit 2 is currently shutdown in a refueling outage and Unit 3 is operating at about 100 percent power). Plant Operators declared offsite power
inoperable at about 1815 PST.
At about 1843 PST, the GCC notified San Onofre that the grid operator added generation to the grid and that offsite power was within nomogram limits. Plant Operators declared offsite power operable at that time. Consistent with the guidance provided in NUREG-1022, Rev. 2, Southern California Edison is reporting this event in accordance with 10CFR50.72(b)(3)(v)(D).
All four San Onofre diesel generators (two per Unit) remained
operable during this event. The San Onofre Senior Resident Inspector has been notified of this event and will be provided with a copy of this report.
