Southern California Edison on Wednesday announced plans to eliminate 600 non-union jobs this summer as it winds down operations at the San Onofre nuclear power plant.

The unit of Rosemead’s Edison International said the facility’s workforce eventually will be cut from 1,500 to 400 by next year. SoCal Edison announced early this month that it would permanently shut San Onofre’s Unit 2 and Unit 3.

The plant, which once provided electricity to about 1.4 million Southern California households and businesses, has not been working since January 2012, when a tube in a replacement steam generator system leaked radioactive steam. Edison laid off about 730 San Onofre employees last August.

SoCal Edison announced the layoffs as part of its obligations under the state’s Worker Adjustment and Retraining Notification Act. Non-union employees affected by the workforce reduction will be laid off within 60 days. The company plans to negotiate with unions on transition plans for additional affected union members.