The U.S. Nuclear Regulatory Commission and an environmental group came to vastly different interpretations Monday of a federal review panel's decision Monday on the troubled San Onofre nuclear plant.
The plant's owner, Southern California Edison, meanwhile, said it is still trying to figure out what the ruling means.
San Onofre has been in the midst of multiple regulatory reviews since a tube in the plant's newly replaced steam generators sprung a leak and released a small amount of radioactive steam in January 2012.
The incident led to the plant's ongoing shutdown and to a discovery that the tubes were wearing out much more quickly than expected.
The NRC ordered Edison in March 2012 to keep the plant closed until it could determine the cause and how to fix it.
Edison in October proposed to restart one of the plant's two units at 70% power, saying that the reduced power would alleviate conditions that caused the tubes to vibrate excessively and knock against support structures and adjacent tubes. NRC staff are still reviewing the proposal.
The environmental group Friends of the Earth argued that Edison misled the NRC about the extent of design changes in the new steam generators and that it should be required to go through a formal license amendment process with trial-like public hearings before being allowed to restart the plant.
A panel of judges with the NRC's Atomic Safety and Licensing Board — which is independent of NRC staff — was asked to decide whether the commission's order last March constituted a de facto license amendment proceeding that would require an opporunity for public hearings.
The board ruled Monday that the proceedings intiated by the NRC order did constitute a de facto license amendment process "subject to a hearing opportunity."
The panel also said in its decision and that restarting the plant would constitute an "experiment," which would require a license amendment.
The board found that the environmental group's contention that San Onofre "cannot be allowed to restart without a license amendment and attendant adjudicatory public hearing," was moot and declined to rule on it.
Friends of the Earth claimed victory, saying that the panel's decision means the NRC may not allow restart of the plant before conducting hearings on a broad range of issues, and called it a "devastating" blow to Edison's hopes of restarting the plant.
But NRC spokesman Scott Burnell said the board's decision is separate from staff's review of the restart plan and does not necessarily require a hearing before restarting the plant.
To make matters more complicated, Edison last month also put in a request for a narrow license amendment to allow it to run the plant at less than its full licensed power.
The company asked the NRC to make a decision under an expedited process that would potentially allow the plant to restart before holding public hearings.
Burnell said that process is also separate from the board's ruling.
"It is possible that the staff could reach a restart decision before a hearing on the license amendment request is completed," he said. "...We have yet to see if anyone requests a hearing on the license amendment application, and the staff's reviews continue as before."
Friends of the Earth's Energy and Climate Director Damon Moglen said the NRC's contention that the panel ruling does not require hearings before a restart was "kind of like saying that the chairs moving on the deck of the Titanic don't mean that the boat is going down."
He also suggested that a move by the NRC to allow a restart before a hearing could lead to litigation.
Edison spokeswoman Jennifer Manfre said only that the company is still reviewing the board's decision.
Meanwhile, in a separate proceeding in San Francisco, state regulators held a first day of hearings in a process that could eventually lead to customers' rates being lowered due to the plant's extended outage.