Diablo Canyon Plant

Sydney Shaw
April 23, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017

About the Facility

Fig. 1: The Diablo canyon nuclear plant. (Source: Wikimedia Commons)

The Diablo Canyon Power Plant sits 1,000 acres west of Avilla Beach in San Luis Obispo County, California (see Fig. 1). [1] About 12 acres of the beach actually covers the power-portion of the electricity- generating nuclear power plant. Diablo Canyon has been operating safely since 1985 and remains the only operational power plant in the state of California. The plant has two Westinghouse Pressurized Water Reactors (four loop nuclear reactors) that are operated by Pacific Gas & Electric and are licensed to run sufficiently until 2025. A this time when the plant closes California will be free of all commercial power plants. Consequently the state will also lose 2240MW of carbon- free power. [1] The Nuclear Regulatory Commission inspectors assess the Diablo Canyon facility daily to ensure the system is being operated safely and efficiently (which in turn, prevents uncalled disasters). The plant produces reliable energy that is free of greenhouse gases. Unlike conventional generation resources, Diablo saves 7 million tons of greenhouse gases per year with its production of clean energy. [1] Per year, both units of Diablo Canyon produce 28,000 gigawatt-hours of electricity, which comprises about 8.6% of the electricity that the state of California uses. This means that the plant supplies electrical needs to around 3 million people on the Pacific Coast. [1]


As previously stated, the plant is made up of two pressurized water reactor units, both supplied by Westinghouse. Unit One is a 1,122 MWe pressurized water reactor that went online in 1985 and is schedule to run until November 2, 2024. [1] This unit generates about 9,944,983 MW-h of electricity per year at a capacity factor of 101.2 percent. Unit two is bigger is a 1,118 MWe pressurized water reactor that went online a year after unit two and is set to operate until August 20, 2025. [1] This unit is less powerful than unit two. It generates about 8.53 million MW-h electricity at a capacity factor of 88.2 percent. [1] For the process of cooling, the plant is able to draw water from the Pacific Ocean (thanks to its convenient location). For the condenser, the plant uses a once-through cooling system as it returns unused water back to the Pacific Ocean at regulated temperatures. Diablo Canyon is designed to withstand a 6.75 magnitude earthquake, proving to be a steady and sturdy plant. [1]


The Diablo Canyon Power Plant is an electricity-generating nuclear power plant located on the Pacific Coast near Avilla Beach. It began operating in 1985 and will be shutting down in 2025. The plant is the last operational power plant in California and provides Northern and Central Californians with a sufficient amount of clean electricity and energy. The plant runs with two Westinghouse pressurized water reactors, which are inspected regularly.

© Sydney Shaw. 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, June 2013.