The San Onofre Nuclear Generating Station

Kyra Carusa
March 23, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: Highway view of the San Onofre Nuclear Generating Station located in Southern California. (Source: Wikimedia Commons)

The San Onofre nuclear generating station, pictured in Fig. 1, is a nuclear power plant located in the San Diego county of California. The plant first began operating in 1968 with only Unit 1 open. In 1983 Unit 2 opened and in 1984 Unit 3. Upgrades to the plant were also made in 2009 and 2010. When the plant wass up and running at its full capacity it had over 2,200 workers. As of today, the ownership of the facility is 78.2% Edison International, 20% San Diego Gas and Electric Company, and 1.8% the City of Riverside Utilities Department. Unit 1 is a first-generation Westinghouse pressurized water reactor. Units 2 and 3 use Combustion Engineering two-loop pressurized water reactors. In 2012, the San Onofre nuclear generating station provided 20% of Southern California's power. Over the years, though, the nuclear plant has had some technical problems. Over time, this cut down the plant's ability to produce safe power for Southern California. [1]

Initial Shutdown

In January of 2012, Unit 2 was shut down for basic maintenance and clean-up reasons. These changes were completely routine and necessary for replacement of reactor heads. [1] Within the same month, Unit 3 had a radioactive leak. Even though this was below the allowable environmental limit, the reactor was shut down. An investigation was made on the entire plant to ensure safety before it would open again. Both unit 2 and 3 were found to have massive premature wear on the steam generators that had been replaced the year before. [2] The plant was not allowed to open again until the cause of the leaks and the premature tube degradation were found and understood. Since this incident neither Unit has reopened. A decommissioning of them both was completed in June 2013. [2]

Safety Issues

SONG has faced many safety issues over the years. There are concern over nuclear waste being stored at the plant, health hazards from radioactive material, and inadequate evacuation plans. Complaints were submitted to the NRC in 2012 regarding the plant's safety. In July 2012, the NRC's final report identified ten issues that needed followup, stating "the plant will not be permitted to restart until the licensee has developed a plan to prevent further steam generator tube degradation and the NRC independently verifies that it can be operated safely." [3] These issues could not be resolved. This led to the decommissioning of the entire plant. Even though the decommissioning started in June 2013, SCE announced in August 2014 that decommissioning would take 20 years, cost $4.4 billion, and result in spent fuel being held on-site in dry casks indefinitely. [1,2]

© Kyra Carusa. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] M. Wald, "Nuclear Power Plant in Limbo Decides to Close," New York Times, 7 Jun 13.

[2] M. Lee, "A Year off the Grind," San Diego Union Tribune, Jan 13.

[3] "Memorandum and Order (Resolving Issues Referred by the Commission in CLI-12-20)", U.S. Nuclear Regulatory Commission, LBP-13-07, 13 May 13.