Nuclear Plants in California

Operating nuclear power plants in California are Diablo Canyon, near San Luis Obispo, [pictured in a PG&E photo to the right] and San Onofre, about midway between Los Angeles and San Diego. Nuclear units at both plants use ocean water for cooling.

Pacific Gas and Electric Company (PG&E) owns the Diablo Canyon Nuclear Power Plant, which consists of two units. Unit 1 is a 1,073 megawatt (MW) PWR which began commercial operation in May 1985, while Unit 2 is a 1,087 MW PWR which began commercial operation in March 1986.

Southern California Edison Co. and San Diego Gas & Electric own the two operating units at the San Onofre Nuclear Generating Station. Unit 2 is a 1,070 MW PWR that began commercial operation in August 1983, while Unit 3 is a 1,080 MW PWR that began commercial operation in April 1984.

California also has four commercial nuclear power plants and an experimental plant that are no longer in operation. These include:

• The Santa Susana Sodium Reactor Experimental (SRE) was a small sodium-cooled experimental reactor built by Southern California Edison and Atomics International at Santa Susana, near Moorpark in Ventura County. It came on line in April 1957, began feeding electricity to the grid on July 12, 1957, and closed February 1964. This reactor used sodium rather than water as a coolant and produced a maximum of about 7.5 megawatts (electric). It was considered as the country's first civilian nuclear plant. On July 26, 1959, the SRE suffered a partial core meltdown. Ten of 43 fuel assemblies were damaged due to lack of heat transfer and radioactive contamination was released. The plant has subsequently been dismantled.


• The Vallecitos Nuclear Power Plant near Pleasanton, Calif., was jointly built by PG&E and General Electric Company and operated from 1957 to 1967. This was a small, 30 megawatt power plant. On October 19, 1957, Vallecitos connected to the electrical grid and became the first privately funded plant to supply power in megawatt amounts to the electric utility grid. The plant was shut down in December 1967. The plant is in SAFSTOR and there are no plans for any significant dismantlement in the foreseeable future. All nuclear fuel has been removed from the site.


• The 63 MW Boiling Water Reactor at the Humboldt Bay Nuclear Power Plant in Eureka was in operation by PG&E from August 1963 to July 1976. It was the seventh licensed nuclear plant in the United States. It was closed because the economics of a required seismic retrofit could not be justified following a moderate earthquake from a previously unknown fault just off the coast. It was permanently shut down July 2, 1976, and retired in 1985. The plant was then placed in SAFSTOR (with spent nuclear fuel rods stored in water pools on site) until anticipated full decommissioning in 2015. See more on SAFSTOR below.


• The 913 MW Pressurized Water Reactor at the Rancho Seco Nuclear Power Plant, located about 25 miles south of Sacramento, is owned by the Sacramento Municipal Utility District in and was operation from April 1975 to June 7, 1989. It was closed by public referendum.


• The 436 MW San Onofre Unit 1 Pressurized Water Reactor was in operation from January 1968 to November 30, 1992. It was closed by its owners rather than incur $125 million in required modifications.

Except for Vallecitos and Santa Susana, these facilities have not been decommissioned (which involves have a plan for dismantling the reactor and transporting all radioactive materials to a site for disposal.) However, the U.S. Nuclear Regulatory Commission (NRC) staff in 1996 approved the decommissioning plan for the Rancho Seco Nuclear Power Plant.

The dismantling process will occur in stages, with "final teardown" scheduled to begin in 2008. The nuclear spent fuel produced during 14 years of operation at Rancho Seco was kept cool in a water pool on site and is now in protective dry storage.

The Vallecitos facility, a General Electric nuclear plant, was the first reactor in the country to be decommissioned. The plant is in SAFSTOR and there are no plans for any significant dismantlement in the foreseeable future.

Under SAFSTOR, often considered "delayed DECON," a nuclear facility is maintained and monitored in a condition that allows the radioactivity to decay; afterwards, it is dismantled. Under DECON (immediate dismantlement), soon after the nuclear facility closes, equipment, structures, and portions of the facility containing radioactive contaminants are removed or decontaminated to a level that permits release of the property and termination of the NRC license.

Spent fuel can either be reprocessed to recover usable uranium and plutonium, or it can be managed as a waste for long-term ultimate disposal. Since fuel re-processing is not commercially available in the United States and has not been shown to be commercially viable n this country, spent fuel is typically being held in temporary storage at reactor sites until a permanent long-term waste disposal option becomes available.

The Future of Nuclear Power in California

California law prohibits the construction of any new nuclear power plants in California until the Energy Commission finds that the federal government has approved and there exists a demonstrated technology for the permanent disposal of spent fuel from these facilities. California's existing nuclear power plants provide a significant amount of California's non-fossil fuel based energy and power but produce significant amounts of spent nuclear fuel. Continued operation of these plants will require substantial investments in replacement steam generators, turbines and other major pieces of equipment, ongoing recruitment and training to maintain an experienced nuclear work force, and accommodation of evolving federal policy regarding nuclear technology, in addition to other requirements.

In June 1976, California enacted legislation directing the California Energy Commission to perform an independent investigation of the nuclear fuel cycle. This investigation was to assess whether the technology to reprocess nuclear fuel rods or to dispose of permanently high-level nuclear waste had been demonstrated, approved and was operational. (See Public Resources Code 25524.1 (a) (1), 25524.1 (b), and 25524.2 (a) for a precise description of the specific findings and conclusions). After extensive public hearings, the Energy Commission determined that it could not make the requisite affirmative findings concerning either reprocessing of nuclear fuel or disposal of high-level waste. This information was published in a report: Status of Nuclear Fuel Reprocessing, Spent Fuel Storage and High-level Waste Disposal, Energy Commission publication P102-78-001, January 1978.) As a result, the development of new nuclear energy facilities in California was prohibited by law.

The U.S. Nuclear Regulatory Commission has exclusive jurisdiction over radiological aspects of nuclear facilities, and, therefore, California is preempted from imposing upon operators of nuclear facilities any regulatory requirements concerning radiation hazards and nuclear safety. California may, however, impose requirements related to other issues. The U.S. Supreme Court, in Pacific Gas and Electric Company v. State Energy Commission, 461 U.S. 190, 103 S. Ct. 1713 (1983), held that the federal government has preempted the entire field of "radiological safety aspects involved in the construction and operation of a nuclear plant, but that the states retain their traditional responsibility in the field of regulating electrical utilities for determining questions of need, reliability, costs, and other related state concerns."

It has been more than 25 years since the last comprehensive Energy Commission assessment of nuclear power issues. As part of the development of its 2005 Integrated Energy Policy Report, the Commission began a comprehensive assessment of the status of currently operating plants in California, the status of federal spent fuel storage/disposal programs and reprocessing, and the potential role of nuclear power in California's energy future. A consultant report from that proceeding is available on the main nuclear page.