05000361/LER-2004-003, Regarding Momentary Loss of Operability of the Offsite Power Grid
| ML042020401 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/16/2004 |
| From: | Waldo R Southern California Edison Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 04-003-00 | |
| Download: ML042020401 (2) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3612004003R00 - NRC Website | |
text
SOUTHERN CALIFORNIA 3J EDISONs An EDISON INTERNATIONAL* Company Dr. Raymond W. Waldo Station Manager San Onofre July 16, 2004 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001
Subject:
Docket Nos. 50-361, 50-362 Licensee Event Report No. 2004-003 San Onofre Nuclear Generating Station, Units 2 and 3 Gentlemen:
This submittal provides Licensee Event Report (LER) 2004-003. The LER describes a momentary loss of operability of the offsite power grid at San Onofre Units 2 and 3 due to a 230 kV transmission line fault in Arizona.
Any actions listed are intended to ensure continued compliance with existing commitments as discussed in applicable licensing documents; this LER contains no new
commitments
If you require any additional information, please so advise.
Sincerely, LER No. Units 2 and 3 2004-003 cc:
B. S. Mallett, NRC Regional Administrator, Region IV C. C. Osterholtz, NRC Senior Resident Inspector, San Onofre Units 2 & 3 P.O. Box 128 San Clemente, CA 92672-0128 949-368-8725/PAX 88725 Fax 949-368-6183 waldorw@songs.sce.com f10z2
i
Abstract
On 06/14/2004 at 0741 PDT, with both units near full power, the offsite power grid [FK] connected to San Onofre experienced a system disturbance. Alarms [ALM] alerted control room Operators (utility, licensed) thai grid frequency dipped below 59.7 Hz. The lowest frequency was a momentary dip to about 59.5 Hz. The grid returned to normal frequency bands within three minutes, remaining stable thereafter. Units 2 and 3 were otherwise unaffected by the grid disturbance.
Southern Califomia Edison (SCE) declared offsite power inoperable per its operating procedures. NUREG 1022, Revision 2 indicates offsite power unavailability is reportable regardless of whether other electrical power systems are available. SCE reported this event to the NRC Operations Center (Log No. 40818) in accordance with 10 CFR 50.72(b)(3)(v)(D). This report is provided in accordance with 10 CFR 50.73(a)(2)(v)(D).
The grid disturbance was initiated by a failed insulator [INS] on a 230 kV transmission line outside Phoenix, AZ. The failed insulator caused a 230 kV transmission line to fall into a transmission tower and short circuit.
No corrective actions are required. As the diesel generators [DG] for both units were operable during this event, there was little safety significance to this event. SONGS Units 2 and 3 have not previously experienced loss of offsite power due to offsite grid disturbances.