Meeting Challenges & Moving Forward
In the nuclear industry, safety comes first. It's in our industry's DNA to learn safety lessons and apply them at nuclear facilities across America. The San Onofre Nuclear Generating Station is unique among nuclear operators around the world in the extent to which we have planned for extreme events such as the earthquake and tsunami at Fukushima Daiichi in March 2011.
San Onofre's reactors were originally designed with added engineering and safety measures, but Southern California Edison (SCE), like its industry colleagues, is making even more improvements and responding to the lessons learned from the events at Fukushima Daiichi and preparing to meet whatever Mother Nature may have in store.
Safety is Our No. 1 Priority
In January 2012, SCE safely shut down Units 2 and 3. Unit 2 was due for planned maintenance and Unit 3 was safely taken offline when the station operators detected a small leak in one of that unit's almost 20,000 steam generator tubes. Both units at the plant remain safely shut down. SCE's engineers, leading experts and the independent Nuclear Regulatory Commission are working to determine a safe operating solution for the facility's steam generators.
Over the past several months, we have assembled leading nuclear experts from around the world and have conducted more than 170,000 inspections. Inspections and testing showed wear in the steam generating tubing in both units. Some wear was expected, but the inspections and testing also showed significant amounts of unexpected wear, predominantly found in Unit 3.
Engineers determined that the unexpected wear was associated with excessive vibration of the tubes in certain areas of the steam generators. It is not clear whether Unit 3 will be able to restart without excessive additional repairs. The Unit 2 steam generator tubes have performed very differently from the Unit 3 tubes indicating that the tube supports in Unit 2 are in much better condition and remain effective.
Adhering to Industry Standards
A team of internal and external steam generator experts has prepared corrective action, and repair and operations plans, to ensure SCE meets the high safety standards required by the Nuclear Regulatory Commission. SCE has provided the NRC with the materials needed to request restart of Unit 2. California-based utilities adhere to some of the strictest local and state regulatory requirements in the United States. The NRC will take the necessary time to review all plans and materials before making a decision about restart. Safety is our No. 1 priority and there are no deadlines for restarting either unit.
Myth vs. Fact
It is a myth that San Onofre isn't built for a Southern California big earthquake. Every U.S. nuclear power plant – including San Onofre – is designed to withstand the maximum potential earthquake for its location without releasing radioactive materials.
Understanding the Difference
There are a number of differences between San Onofre and Fukushima Daiichi Nuclear Power Station in Japan, including facility design, seismic risk, back-up and safety features and emergency response.