One of the best ways California would be able to endure another summer without power from Southern California Edison’s (SCE’s) San Onofre Nuclear Generating Station would be to convert the Huntington Beach Units 3 and 4 into synchronous condensers, allowing them to act somewhat like spinning flywheels to adjust grid conditions, experts from the California Independent System Operator Corp. (CAISO) told its Board of Governors at a meeting last week.

The operator of the state’s wholesale transmission grid last year requested that AES Corp.’s two Huntington Beach gas-fired units be brought back to fill the void left by the two-reactor plant’s indefinite shutdown. However, the air emission credits for the two units expire at the end of October.

"As synchronous condensers, the Huntington Beach units do not produce electricity and, therefore, no air emissions credits are required," CAISO said. They would also not need to comply with new once-through cooling restrictions. Instead, like spinning flywheels, they would provide voltage support normally supplied by the nuclear plant to the local 230-kV switchyard. "Megavars, instead of megawatts, would be produced and used to push megawatts through the grid, much like water pressure helps push water through a hose," it said.

San Onofre Unit 2 was taken offline in January for maintenance and Unit 3 was shut down later that month after a leak was discovered in a steam generator tube. Further investigation showed unusual tube wear in both units, likely caused by faulty computer modeling and manufacturing issues, federal inspectors concluded in July. The plant’s shutdown has caused SCE more than $165 million in inspection, repair, and replacement power costs.

The Nuclear Regulatory Commission (NRC) ordered the plant to remain offline until the cause of the unusual wear was determined and corrected. But operators of the beleaguered nuclear plant could file a plan to restart Unit 2 with the NRC as soon as October, NRC Chair Allison Macfarlane told lawmakers at a U.S. Senate Committee on Environment and Public Works hearing last week. Unit 3, which had more tube damage, may continue to be shut for a longer time.

Sources: POWERnews, CAISO, SCE, NRC

—Sonal Patel, Senior Writer (@POWERmagazine)