A federal panel on nuclear safety has called for a full public hearing on a proposal to restart a damaged reactor at the San Onofre nuclear plant, siding in large part with the environmental group Friends of the Earth in an order published Monday.

The Atomic Licensing and Safety Board found that the destructive vibrations among steam generator tubes that have sidelined San Onofre are not accounted for in the plant’s official safety blueprint, known as the updated Final Safety Analysis Report.

An evaluation by Nuclear Regulatory Commission staff of plans to restart the plant at partial power amounts to an amendment of the operating rules – creating the opportunity for public hearings on the proposal, the board found.

The decision by a three-member panel of administrative judges, independent of nuclear commission staff, complicates plant operator Southern California Edison’s efforts build a secure regulatory footing to restart the Unit 2 reactor as costs mount for repairs and replacement power. Unit 3 has more severe problems that Edison says could take years to resolve.

The plant, once capable of powering 1.4 million homes at time, has been sidelined since Jan. 31, 2012, when a small radiation leak helped uncover rapid wear on steam generator tubes […]