California ISO drafts backup plan in case of long San Onofre outage

The California Independent System Operator (Cal ISO), the grid operator for most of the state’s electric transmission, warns portions the Los Angeles Basin might face reliability challenges if both units of Southern California Edison’s San Onofre nuclear plant remain offline this summer.

The backup plan that the Cal-ISO unveiled March 22 involves temporary revival of certain regional generating units that were scheduled to be mothballed. The plan also calls for speeding completion of some key transmission projects, included the Sunrise Powerlink, and increased conservation and demand side management.

The 2,200 MW pressurized water reactor complex has not been producing power since January due to tube leaks being detected in steam generators. SCE is an Edison International (NYSE: EIX) subsidiary that is the operator and majority owner of San Onofre.

Unit 3 has been shut down since Jan. 31 after station operators detected a leak in one of the unit’s steam generator tubes. Unit 2 was taken out of service for a planned outage on Jan. 9. Both units are now offline. In mid-March the Nuclear Regulatory Commission (NRC) sent an Augmented Inspection Team to the plant to perform equipment inspections.

An SCE spokesperson stressed neither unit will be returned to service until the utility is sure they can be operated safely. The leaks were evidently detected in connection with a small radiation leak in January, the spokesperson confirmed March 23.

After a root cause is determined for the problem, SCE will be able to draft a repair plan and timetable, the spokesperson said.

The steam generators are fairly new given that both were installed within the past four years. The price of the steam generator replacement project was $180m, the spokesperson said.

Cal ISO could tap natural gas backup generation

“Fortunately, there are resource options available to help mitigate reliability risks,” said ISO President and CEO Steve Berberich. “We are actively working with San Diego Gas & Electric, Southern California Edison and others because prudent mitigation planning takes adequate lead time and summer heat is only a couple months away.

Sempra Energy (NYSE: SRE) subsidiary San Diego Gas & Electric and the city of Riverside, Calif., are also co-owners in the San Onofre nuclear station.

Without the plant’s nuclear units, the Los Angeles area is short about 240 MW. The Huntington Beach power plant units 3 and 4 would add 450 MW, mitigating the shortage, the Cal-ISO said. The units were slated for retirement this summer, an ISO spokesperson said March 23.

Energy Central records indicate AES (NYSE: AES) recently sold Huntington Beach units 3 and 4 to an Edison International subsidiary, Edison Mission Group, although AES appears to remain the operator.

Technical studies presented at ISO’s March 22 board meeting show very tight reserve margins for San Diego and the Los Angeles Basin, especially during summer heat waves.

Industry contingency planning potentially includes returning to service the Huntington Beach units previously slated for retirement. This not only adds 452 MW of capacity in the LA Basin, but it also enables 350 MW of additional imported power to transfer into San Diego.

It also calls for speeding up a couple of transmission projects. Completion of the Barre-Ellis & Sunrise Powerlink transmission projects would be accelerated.

Also certain demand reduction programs would be re-activated. The ISO would also help coordinate military and public agency conservation.

About Wayne Barber 4201 Articles
Wayne Barber, Chief Analyst for the GenerationHub, has been covering power generation, energy and natural resources issues at national publications for more than 20 years. Prior to joining PennWell he was editor of Generation Markets Week at SNL Financial for nine years. He has also worked as a business journalist at both McGraw-Hill and Financial Times Energy. Wayne also worked as a newspaper reporter for several years. During his career has visited nuclear reactors and coal mines as well as coal and natural gas power plants. Wayne can be reached at