SAN CLEMENTE (CBS) — Southern California Edison has announced that the troubled San Onofre nuclear power plant will remain shut down through August.

The plant has been partially offline since January, when the agency determined tubes that carry radioactive steam were leaking, while others were wearing out much more quickly than expected.

Edison says it will now have to obtain back-up power for nearly 1.5 million customers and that outages are possible this summer if there is a prolonged heat wave.

Federal officials have scheduled a public hearing on June 18 in San Juan Capistrano.