05000361/LER-2008-003

LER-2008-003, Disturbance on the Pacific DC Intertie cause offsite power frequency to dip below operability limits

Docket Number
Event date:	5-29-2008
Report date:	6-06-2008
Reporting criterion:	10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
3612008003R00 - NRC Website

4. TITLE

Disturbance on the Pacific DC Intertie cause offsite power frequency to dip below operability limits 5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED

MO DAY YEAR YEAR SEQUENTIAL NUMBER

NO MO DAY YEAR SONGS Unit 3 50-362

FACILITY NAME DOCKET NUMBER

5 20 2008 2008-002-00 6 06 2008 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 10 CFR : (Check all that apply) MODE 20.2201(b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)

9. OPERATING

20.2201(d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)10. POWER 99LEVEL 20.2203(a)(1) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 73.71(04) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(5) 1:- 20.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B) OTHER Specify in Abstract below or in NRC Form1. ? .,,. 20.2203(a)(2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 366A 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A) X 50.73(a)(2)(v)(D) 20.2203(a)(2)(v) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) -

• 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B) 12 LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code) Thomas R. Yackle, Director Operations 949-368-4440

13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT

MANU- REPORTABLE MANU- REPORTABLE TOCAUSE SYSTEM COMPONENT CAUSE SYSTEM COMPONENTFACTURER TO EPIX FACTURER EPIX N 15. EXPECTED14. SUPPLEMENTAL REPORT EXPECTED MONTH DAY I YEARSUBM SSION X NOYES (If yes, complete EXPECTED SUBMISSION DATE) DATE 16. ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 sing e-spaced typewritten lines) On May 20, 2008, at about 1310 PDT, the offsite power grid connected to San Onofre Nuclear Generating Station (SONGS) experienced a momentary disturbance. Control Room indicators alerted Operators that grid frequency dipped below 59.7 Hz, to about 59.69 Hz. Southern California Edison (SCE) reported this event in accordance with 10CFR50.72(b)(3)(v)(D) (NRC Log No. 44227). The frequency dip at SONGS lasted approximately 10 seconds and was caused by a disturbance on the Pacific DC Intertie line in Oregon.

SCE is submitting this follow-up written report in accordance with 10CFR50.73(a)(2)(v)(D).

During this occurrence, Unit 2 was operating at about 99 percent power; Unit 3 was operating at about 80 percent power.

During the event, both trains of onsite AC sources [EK] on Unit 3 and one train on Unit 2 were available. The size and duration of the frequency dip were small. Consequently, there was little to no safety significance to the event.

There are no corrective actions required at SONGS due to this event.

events.