One of the two reactors at the San Onofre Nuclear Generating Station could safely restart and work at full power, but only for 11 months, a consultant for Southern California Edison (SCE) said.
The utility, operator and majority owner of the San Onofre plant, said a technical evaluation by Intertek APTECH of Sunnyvale — which came in response to Nuclear Regulatory Commission (NRC) questions — found 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 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 in the other reactor, Unit 3. No one was hurt, and officials shut down the reactor.
Unit 2 was undergoing scheduled maintenance at the time and a subsequent investigation found that steam generator tubes were degrading faster than expected, and many of them ended up plugged. Unit 2 never restarted.
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.”