Diablo Canyon Power Plant

Diablo Canyon Power Plant is an electricity-generating nuclear power plant at Avila Beach in San Luis Obispo County, California. The plant has two Westinghouse-designed 4-loop pressurized-water nuclear reactors operated by Pacific Gas & Electric. The facility is located on about 750 acres (300 ha) in Avila Beach, California. Together, the twin 1,100 MWe reactors produce about 18,000 GW·h of electricity annually, supplying the electrical needs of more than 2.2 million people, sent along the Path 15 500-kV lines that connect to this plant. It was built directly over a geological fault line, and is located near a second fault.

The plant is located in Nuclear Regulatory Commission Region IV. In November 2009, PG&E applied to the Nuclear Regulatory Commission (NRC) for 20-year license renewals for both reactors.

Units
Unit One

Unit One is a 1,122 MWe pressurized water reactor supplied by Westinghouse. It went online on May 7, 1985 and is licensed to operate through November 2, 2024. In 2006, Unit One generated 9,944,983 MW·h of electricity, at a nominal capacity factor of 101.2 percent.

Unit Two

Unit Two is a 1,118 MWe pressurized water reactor supplied by Westinghouse. It went online on March 3, 1986 and is licensed to operate through August 20, 2025. In 2006, Unit Two generated 8,520,000 MW·h of electricity, at a capacity factor of 88.2 percent. The plant draws cooling water from the Pacific Ocean, and during heavy storms both units are throttled back by 80 percent to prevent kelp from entering the cooling water intake. The cooling water is used once and is not recirculated but rather returned to the Pacific Ocean at higher temperature.

Earthquake hazard

Diablo Canyon was originally designed to withstand a 6.75 magnitude earthquake from four faults, including the nearby San Andreas and Hosgri faults, but was later upgraded to withstand a 7.5 magnitude quake. It has redundant seismic monitoring and a safety system designed to shut it down promptly in the event of significant ground motion.

History

Pacific Gas & Electric Company went through six years of hearings, referenda and litigation to have the Diablo Canyon plant approved. A principal concern about the plant is whether it can be sufficiently earthquake-proof. The site was deemed safe when construction started in 1968.

However, by the time of the plant's completion in 1973, a seismic fault, the Hosgri fault, had been discovered several miles offshore. This fault had a 7.1 magnitude quake 10 miles offshore on November 4, 1927, and thus was capable of generating forces equivalent to approximately 1/16 of those felt in the 1906 San Francisco earthquake.

The company updated its plans and added structural supports designed to reinforce stability in case of earthquake. In September 1981, PG&E discovered that a single set of blueprints was used for these structural supports; workers were supposed to have reversed the plans when switching to the second reactor, but did not. According to Charles Perrow, the result of the error was that "many parts were needlessly reinforced, while others, which should have been strengthened, were left untouched." Nonetheless, on March 19, 1982 the Nuclear Regulatory Commission decided not to review its 1978 decision approving the plant's safety, despite these and other design errors.

In response to concern that ground acceleration, or shaking, could cause spillage of submerged fuel rod assemblies which, upon exposure to air, could ignite, PG&E and NRC regulators insist that the foregoing scenario is anticipated and controlled for, and that there is no basis to anticipate spillage. Additional seismic studies are in process, however completion of those studies is not a condition precedent to re-issuance of the operating licenses for the two onsite units.

Starting October 22, 2008, Unit 2 was taken offline for approximately two days due to a rapid influx of jellyfish at the intake.

The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Diablo Canyon was 1 in 23,810, according to an NRC study published in August 2010. In April 2011, in the wake of the Fukushima nuclear incident in Japan, PG&E asked the NRC not to issue license renewals until PG&E can complete new seismic studies, which are expected to take at least three years.

Labor

Overall, there are approximately 1200 employees of Pacific Gas and Electric and 200 employees of subcontractors. Several unions represent the workforce at Diablo, among them the International Brotherhood of Electrical Workers and the International Association of Machinists. Control Technicians and electricians who work for Crane Nuclear, one of many subcontractors, are represented by the IBEW Local 1245. 1245 also represents PG&E meter readers, clerical workers, etc. Local 639,which is involved with Diablo but is under "spring outage", also supports solar energy development as part of the overall energy industry portfolio. This outage has been retracted as of June 10, 2011 The outages are routine for maintenance and the complex process of refueling, and created 1,000 temporary jobs, according to PG&E. Other workers are represented by the Plumbers and Pipefitters.

According to a SLO Tribune interview with PG&E's Chris Johns, "tragedy in Japan has prompted more concerns from Diablo Canyon’s 1,800 employees than any other issue, Becker said. Plant managers are holding brown-bag lunch meetings with employees to address those concerns".

DCISC

The Diablo Canyon Independent Safety Committee (DCISC) was established as a part of a settlement agreement entered into in June 1988 between the Division of Ratepayer Advocates of the California Public Utilities Commission (PUC), the Attorney General for the State of California, and Pacific Gas and Electric Company(“PG&E”).

The DCISC consists of three members, one each appointed by the Governor, the Attorney General and the Chairperson of the California Energy Commission. They serve staggered three-year terms. The committee has no authority to direct PG&E personnel.

Emergency planning

The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.

The 2010 U.S. population within 10 miles (16 km) of Diablo Canyon was 26,123, an increase of 50.2 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within 50 miles (80 km) was 465,521, an increase of 22.4 percent since 2000. Cities within 50 miles include San Luis Obispo (12 miles to city center) and Paso Robles (31 miles to city center).

Public participation and protest

Diablo Canyon was built and entered service despite legal challenges and civil disobedience from the anti-nuclear protesters of the Abalone Alliance. Over a two-week period in 1981, 1,900 activists were arrested at Diablo Canyon Power Plant. It was the largest arrest total in the history of the U.S. anti-nuclear movement.

In spring of 2011, State Senator Sam Blakeslee and US Representative Lois Capps both expressed concern for a renewed safety review. Speaking before the Senate Committee on Environment and Public Works, the congresswoman stated that she believed the "Nuclear Regulatory Commission should stay the license renewal process until the completion of independent, peer reviewed, advanced seismic studies of all faults in the area." The Alliance for Nuclear Responsibility began circulating a petition to similar effect, going further and calling for an outright halt to relicensing. An array of San Luis Obispo-based anti-nuclear groups including Mothers for Peace also called for the closure of Diablo Canyon nuclear power plant.

The Alliance for Nuclear Responsibility also works at the level of the California Public Utilities Commission and initiated a letter writing campaign to Governor Jerry Brown, which requests he "instruct the CPUC to rescind the Certificate of Public Convenience and Necessity for ... Diablo Canyon ... and allow them to operate conditionally only under the agreement by the utilities to immediately begin to fully comply with completion of the state-directed AB 1632 studies."

Post-Fukushima developments

According to Victor Dricks, senior public affairs officer for NRC Region IV, the Commission conducted a nationwide review of nuclear power plants for their capacity to respond to earthquakes, power outages and other catastrophic events, and Diablo was found to have "a high level of preparedness and strong capability in terms of equipment and procedures to respond to severe events."

On June 2, 2011, the NRC announced that it would delay the environmental part of the relicensing application but that it had completed the safety portion. A few days later, the Atomic Safety Licensing Board indicated that it would defer adjustment of the adjudicatory schedule of the four contentions brought by SLOMFP, a community based organization, accordingly. The ASLB made no findings regarding the merits of the contentions. Both parties to the dispute claim these developments as victories: Pacific Gas and Electric as well as San Luis Obispo Mothers for Peace.

Building Activity

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