Southern California Edison, the majority owner and operator of the San Onofre Nuclear Generating Station, said it submitted plans to the Nuclear Regulatory Commission to repair and restart the plant’s Unit 2 reactor.

Unit 2 and Unit 3 have been shut down since January when operators discovered a leak in a generator tube in Unit 3. The company also shut down Unit 2 that month for planned maintenance.

Unit 1 has been shut down since 1992.

In its plan that must be approved by the NRC before any operations resume, the company proposes to operate Unit 2 at 70 percent power for five months, and then shut the unit down for inspection before restarting it again. The company provided no timetable on when NRC would complete its review and when it would resume operations at Unit 2.

Edison said it plugged six tubes in Unit 2 that had wear of better than 35 percent and plugged more than 500 other tubes preventively. The company said steam generators are built with additional tubes so they can be taken out of service, and that only 2.6 percent of the total tubes in Unit 2 were plugged.

Edison said three independent experts in steam generators conducted analyses that validate the safety of the restart and operations plans.

Southern California Edison has a 78 percent ownership of the San Onofre plant, with San Diego Gas & Electric owning 20 percent, and the city of Riverside the remaining amount.