The plant has been offline for more than three months due to the tubing deterioration. The figures released Tuesday come just days after SCE said it hopes to restart at least one of the plant's twin reactors next month.
The chairman of the Nuclear Regulatory Commission insists there is no timetable for restarting the plant.
Costs related to the long-running shutdown could climb over $100 million, company officials say, and state officials have warned about possible rotating blackouts in Southern California while the reactors are offline.
About 7.4 million Californians live within 50 miles of San Onofre, which can power 1.4 million homes.
The Associated Press contributed to this report.