HOUSTON (Reuters) - An independent nuclear regulatory panel on Monday called for a full public hearing on the proposed restart of one of the two damaged San Onofre nuclear reactors, a move that will delay Southern California Edison's plan to run the plant this summer.
The Atomic Safety and Licensing Board ruling favored petitioner Friends of the Earth, an anti-nuclear group that sought more public input of the Nuclear Regulatory Commission's (NRC) review of steam generator problems at the San Onofre nuclear power plant.
Both reactors at the 2,150-megawatt San Onofre nuclear station, halfway between Los Angeles and San Diego, have been shut since January 2012 following discovery of a serious problem with accelerated degradation of tubes in the units' new steam generators.
Loss of the plant's output has strained Southern California's power grid and state agencies are prepared for a second summer without San Onofre.
SCE, a unit of Edison International, is seeking approval from the NRC to restart San Onofre 2 this summer and to run the unit at a reduced rate for five months, then shut it to inspect for further tube damage.
Damon Moglen of Friends of the Earth called the ruling "a complete rejection of Edison's plan to restart its damaged nuclear reactors without public review or input."
An SCE spokeswoman said the utility was still reviewing the ruling and declined to comment.
Late last month, Edison's Chief Executive Ted Craver said the utility may decide by year end to retire one or both San Onofre reactors if its restart request is denied, citing uncertainty over NRC timing and SCE's ability to recover costs related to the extended outage.
The reactor can only restart if the NRC concludes it can operate safely.
Pressure has been growing on the NRC and the utility to agree to a full review of safety issues at San Onofre from elected officials and anti-nuclear groups.
The board concluded that SCE's restart plan, known as the Confirmatory Action Letter process, is effectively a license amendment proceeding that gives the public the right to a hearing with testimony and cross-examination of witnesses.
In an effort to speed up the NRC review, SCE submitted a limited license amendment request in April seeking approval to operate San Onofre 2 at no more than 70 percent capacity for the remainder of the unit's 18- to 24-month fuel cycle. That license amendment allows public comment, but not a full public hearing in advance of the unit's restart.
In Monday's order, however, the ASLB ruling cited three reasons that the proposed restart plan involves changes that necessitate a comprehensive safety review.
The ASLB order also disagreed with one of SCE's primary contentions, saying the design of San Onofre's replacement steam generators "differ in significant respects" from the original generators.
SCE wants to restart Unit 2 where tube damage was less severe than in Unit 3, but the ASLB said the design of the new generators was identical. The generators were manufactured by Mitsubishi Heavy Industries.
"The unprecedented extent of tube wear and failures that SCE experienced in (Unit 3's) replacement steam generators reveal that these steam generators have serious design and operational issues," the ruling said.
The three-member board of administrative judges, independent of the NRC staff, conducts adjudicatory hearings on major agency licensing actions.
SCE operates San Onofre and owns a 78 percent stake in the plant. Sempra Energy's San Diego Gas & Electric owns 20 percent and the city of Riverside holds a small stake.
(Reporting by Eileen O'Grady in Houston; Editing by David Gregorio, Bernard Orr)