Diablo Canyon Power Plant

Anthony Brown
March 17, 2015

Submitted as coursework for PH241, Stanford University, Winter 2015


Fig. 1: Diablo Canyon Power Plant located in San Luis Obispo. (Source: Wikimedia Commons)

The Diablo Canyon Power Plant, as pictured in Fig. 1, is an electricity-generating nuclear power plant in San Luis Obispo County, California that is the only nuclear plant operational in the state due to the shutdown of the San Onofre Nuclear Generating Station in 2013. This power plant operated by Pacific Gas & Electric occupies fewer than 545 acres of the 12,820 acre-property owned by Pacific Gas and Electric Company and produces about 7% of the electricity California uses, supplying the needs of more than 3 million people. Diablo Canyon Power Plant has operated at a steadily increasing percentage of capacity over its lifetime due to a practice of constant upgrading and updating of the equipment. This facility also boasts one of the best safety records in the industry according to the Institute of Nuclear Power Operations. [1]

Diablo Canyon Power Plant began commercial operation in 1985 and is powered by two Westinghouse-designed 4-loop pressurized water reactors -Unit 1 and Unit 2. These two reactors have a generation capacity of 2,300 megawatts and produce about 18,000 gigawatt hours of electricity annually. The two pressurized water reactors with steam generators are housed in two massive steel-reinforced concrete containment structures centered between a turbine building, spent-fuel handling bulding and security facilities. Other plant components include water intake system, water discharge system structure and the independent spent fuel storage installation known as dry cask storage. The company delivers power to 15 million customers, or one in every 20 Americans and DCPP expects to spend a total of $50 million over the next three years to meet internal goals and all of the NRC's post-Fukushima requirements. [1]

Power Plant Safety

According to documents submitted by the owner of the Diablo Canyon plant to the federal Nuclear Regulatory Commission, Diablo Canyon Power Plant can safely withstand earthquakes, tsunamis and flooding. PG&E officials submitted new documentation ordered that is now required due to the 2011 disaster at the Fukushima nuclear plant in Japan. [2] Diablo Canyon is unique among U.S. nuclear plants, sitting amid a web of earthquake faults in a seismically active state, one just 650 yards from the reactors. The plant's equipment has a robust safety margin above the design, meaning it can withstand greater vibrations. Also, there is no equipment in the plant that would be at risk from the type of shaking found to slightly exceed the design. The conclusion is at the heart of a report that re-evaluates seismic and flooding risks at the coastal plant, located midway between Los Angeles and San Francisco. [3] Diablo Canyon's critics have long questioned PG&E's assurances that the plant is safe. When construction began, in 1968, none of the four closest faults had even been discovered. The Hosgri was found in 1971, and the Shoreline in 2008 but after much research and analysis we now know the DCPP can withstand a major earthquake striking on multiple nearby faults at once. [4]

© Anthony Brown. 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] P. Mayeda and K. Riener, "Economic Benefits of Diablo Canyon Power Plant," Pacific Gas and Electric Company, June 2013.

[2] A. Covarrubias, "Diablo Canyon Nuclear Plant Safe in Earthquakes, PG&E Says in Report," Los Angeles Times, 13 Mar 15.

[3] "Diablo Canyon Nuclear Plant Design Can Withstand Powerful Earthquakes," NBC Southern California, 13 Mar 15.

[4] D. Baker, "PG&E: Diablo Canyon Nuclear Plant Can Withstand 10,000-year Quake," San Francisco Chronicle, 12 Mar 15.