Westinghouse pressurized water reactor that operated for 25 years, closed permanently in 1992; it has been dismantled and is used as a storage site for spent fuel. It had a spherical containment of concrete and steel; the smallest wall was thick. It generated 456 MWe gross, and 436 MWe net, when operating at 100% capacity. Units 2 and 3, Combustion Engineering two-loop pressurized water reactors, generated 1,127 MWe gross, and 1,070 MWe and 1,080 MWe net respectively, when operating at 100% capacity. In a ten-year project completed in 2011 and costing $671 million, Edison replaced the steam generators in both reactors with Mitsubishi steam generators of modified design. Because of the reactors' two-loop design, uncommon for such large reactors of that era, the steam generators were among the largest in the industry. A common shortcoming of these large steam generators was tube wear, requiring replacement earlier than their 40-year design life. The steam generators being the largest components in the reactor required a temporary hole through the concrete containment shell. The Unit 2 replacement was completed in 2009 and Unit 3 in 2011. Edison estimated that the modernization would save customers $1 billion during the plant's license period, which at the time ran until 2022. During its operation until 2012, SONGS provided about 20% of the power to large portions of Southern California. Site status summary The San Onofre Nuclear Generating Station (SONGS), operated by Southern California Edison (SCE) is approximately 100 km (60 mi) south of Los Angeles, 6.5 km (4 mi) south of San Clemente, CA. It is located between I-5 and the Pacific Ocean, within the boundary of the Camp Pendleton military reserve. The site originally comprised three nuclear power plants. Unit 1 commenced operation in 1968, and shut down in 1992. Units 2 and 3 permanently ceased operations in June 2013. Dismantlement of Unit 1 is essentially complete. The turbine building was removed and the licensee completed reactor pressure vessel internal segmentation and cutup; however, the licensee was unable to make arrangements for shipping the reactor pressure vessel to a disposal facility because of the size and weight of the vessel and shipping package. The licensee is making plans to ship the vessel offsite during the decommissioning activities for Units 2 and 3 because the radioactivity has decayed to a level that allows it to be treated as low level waste. SONGS-1 was a Westinghouse 3-loop