Units 2 and 3 of the plant, which is also known by the abbreviation SONGS, have been shut down since January 2012. Unit 1 was retired in 1992.
Unit 2 was taken out of service January 9, 2012, for a planned routine outage. Unit 3 was taken offline January 31, 2012, after station operators detected a small leak in a tube inside a steam generator manufactured by Mitsubishi Heavy Industries. Two steam generators manufactured by MHI were installed in Unit 2 in 2009 and two more were installed in Unit 3 in 2010, one of which developed the leak, according to parent company Edison International.
After months of analysis and tests, Southern California Edison submitted a restart plan to the Nuclear Regulatory Commission in October 2012. SCE proposed to restart Unit 2 at 70 percent of it power capacity for an initial period of approximately five months. That plan was based on work done by engineering groups from three independent firms with expertise in steam generator design and manufacturing, Edison says.
The NRC has been reviewing SCE’s plans for restart of Unit 2 for the last eight months, during which several public meetings have been held. A recent ruling by an adjudicatory arm of the NRC, the Atomic Safety and Licensing Board, creates further uncertainty regarding when a final decision might be made on restarting Unit 2, Edison says.
According to Edison, additional administrative processes and appeals could result in delay of more than a year. During this period, the costs of maintaining SONGS in a state of readiness to restart and the costs to replace the power SONGS previously provided would continue. Moreover, it is uneconomic for SCE and its customers to bear the long-term repair costs for returning SONGS to full power operation without restart of Unit 2, Edison Says. The extended unit closures created a disparity in wholesale power prices between the northern and southern portions of the state. SCE has concluded that efforts are better focused on planning for the replacement generation and transmission resources which will be required for grid reliability.
The California Independent System Operator, the grid operator for most of the state, noted in its Summer Loads and Resources Assessment that 2,502 MW of capacity (capacity adjusted for planning purposes) have been added since June 2012, with an additional 891 MW slated to come online by June 1, 2013. The two off-line San Onofre units, in comparison, total 2,246 MW.