A consultant concluded that one of the two reactors at the San Onofre Nuclear Generating Station could be safely restarted and put to use at full power, Southern California Edison announced today, but only for 11 months.
The utility, operator and majority owner of SONGS, said a technical evaluation by Intertek APTECH of Sunnyvale -- which came in response to Nuclear Regulatory Commission questions -- found that Unit 2 could operate at 100 percent with full integrity of steam generator tubes. Intertek used simulations and models to predict the time line of how long the reactor could operate without risking more tubes rupturing. Under one model the unit could be run for a little under a year, under the other model, a little more than a year.
The nuclear plant on the northern San Diego County coastline has been idle since January 2012, when a small leak was found in the other reactor, Unit 3. No one was hurt, and the reactor was shut down.
Unit 2 was undergoing scheduled maintenance at the time and hasn't been restarted.
A subsequent investigation found that steam generator tubes were degrading faster than expected, and many of them were plugged.
SCE, which owns nearly 80 percent of the plant, has filed a plan with the NRC to restart Unit 2 at 70 percent power. The company has not fixed the problem, but has determined the cause, and believes operating at lower power will remove the steam conditions that caused the tubes to rattle, rub against each other, and wear out prematurely.
"While we have no intent to restart Unit 2 at full power, this demonstrates the amount of safety margin we have built into our analyses,'' said Pete Dietrich, SCE's senior vice president and chief nuclear officer. "We welcome this additional safety analysis but remain steadfast in our commitment to restart Unit 2 at only 70 percent power.''
Anti-nuclear activists have challenged the restart plans. They contend the steam generators, installed in 2010 and 2011, were of such a different design from their predecessors that the utility should have had to go through an extensive license amendment process.
John Large, a London-based nuclear engineer for a group called Friends of the Earth, said the report actually shows that SONGS will progressively destroy itself.
"If the Intertek analysis is correct, the plant only has a remaining total service life of one year at full power, or 16 months at 70 percent power,'' Large said. "After this I doubt if any option will exist for Edison to repair the plant's steam generators because the problem lies deep within the tube bundle, being essentially inaccessible by human or machine.''
He said there are " enormous uncertainties'' with predicting degradation of the tubes.
An NRC timeline shows that a decision on the restart plan could come in late April or May.
San Diego Gas & Electric owns 20 percent of the plant and receives one-fifth of SONGS' power when it's operational.
