The seaside plant between Los Angeles and San Diego has been shut down since January 2012, after a small radiation leak led to the discovery of unusual damage to hundreds of tubes that carry radioactive water.
Southern California Edison wants to change the plant’s federal operating rules to permit the Unit 2 reactor to run at no more than 70 percent power, which company engineers and consultants believe will limit unusual tube wear.
Edison submitted a tentative request to the Nuclear Regulatory Commission, technically known as a license amendment, that if approved would cap Unit 2’s capacity at 70 percent, down from the now-required 100 percent.
“We are considering the proposed voluntary amendment as the best path to get Unit 2 safely up and running before the hottest months of the year hit our region,” SCE President Ron Litzinger said in a statement.
Critics of the nuclear power industry say the plant is unsafe to operate at any power level and should be shut down permanently and dismantled.
Kendra Ulrich, a spokeswoman for Friends of the Earth, said in a statement the company was attempting to sidestep more thorough safety reviews that would require public hearings.
According to Edison documents, members of the public can request a hearing on the license amendment, but if NRC staff finds there is no significant hazard, the hearing can be held after the amendment is approved.
“This is not a footnote in a license as Edison claims, but a severely damaged reactor that is unsafe to operate,” Ulrich said.
The problems at San Onofre focus on its steam generators, which were installed in a $670 million overhaul in 2009 and 2010.
Last year, federal regulators blamed heavy tube wear in the generators on a botched computer analysis that they said badly misjudged how water and steam would flow in the reactors, along with manufacturing problems.
Edison has been trying since October to convince the Nuclear Regulatory Commission that it’s safe to run Unit 2 at no more than 70 percent power.
In earlier filings, Edison argued that its 70 percent target for Unit 2 was, in effect, full power. It later submitted another analysis showing the reactor could run at 100 percent power, but the research found the risk of a tube break could reach unacceptable levels after 11 months.
Edison said a final proposal could be submitted as soon as Wednesday, after company officials meet with the NRC staff in Maryland.
If approved, the license change could essentially eliminate the debate over the full power threshold.
Before a restart could take place, the company would also have to meet a series of steps the NRC outlined last year.
The future of the heavily damaged Unit 3 reactor, where the radiation leak occurred after a tube break last year, is not clear. Edison has said that because of manufacturing differences, Unit 2’s generators did not suffer the extent of deep tube wear witnessed in its sister plant.
Decaying generator tubes helped push San Onofre’s Unit 1 reactor into retirement in 1992, even though it was designed to run until 2004.
San Onofre is owned by SCE, San Diego Gas & Electric and the city of Riverside.