Climate groups file suit against Diablo Canyon

March 11, 2024, 7:00AMNuclear News
In this 2013 photo, workers test switches and gauges in Diablo Canyon’s Unit 2 control room and review the results while the reactor is shut down for refueling and routine maintenance. (Photo: PG&E)

Three climate groups filed a motion for the immediate closure of Diablo Canyon nuclear power plant in California, saying the nuclear plant poses an “unacceptable safety risk.”

San Luis Obispo Mothers for Peace, Environmental Working Group, and Friends of the Earth also requested a hearing with the Nuclear Regulatory Commission to force the agency to consider the groups' safety concerns regarding the 2,200-MW power plant. They argue that plant owner Pacific Gas & Electric has not acquired the proper environmental permits to continue operating the facility.

The groups believe that the location of Diablo Canyon—near Avila Beach in San Luis Obispo County—makes it susceptible to an earthquake that could cause a catastrophic nuclear meltdown. Their court filing also says keeping Diablo Canyon on line “hurts the state’s shift to safe, renewable energy and prolongs the risk of disaster at the plant.”

"The aging Diablo Canyon nuclear plant, which sits atop a web of fault lines, is not only unnecessary for California's electricity supply, but unsafe,” said Caroline Leary, general counsel and chief operating officer for Environmental Working Group, in a prepared statement. “Federal regulators with the [NRC] must not ignore its risks to the public and the environment.”

PG&E has long contested claims of danger due to seismic activity, saying that Diablo Canyon was built and retrofitted to withstand powerful earthquakes.

Short-term reprieve: The California Public Utilities Commission granted a five-year license extension to Diablo Canyon this past December, which allows PG&E to operate Unit 1 until October 31, 2029, and Unit 2 until October 31, 2030. Meanwhile, the NRC is considering a 20-year license extension for the plant.

The state commission's vote was compelled by Senate Bill 846, which was signed by Gov. Gavin Newsom in September 2022, to address concerns over the availability of enough clean energy to replace the plant. But critics say the decision should not have been made without knowing the costs of continued operations at Diablo Canyon.

Carbon-free asset: Diablo Canyon, the state’s only remaining nuclear plant, generates roughly 17 percent of California’s zero-carbon energy and 9 percent of the state’s total generation.

A 2022 study from the Brattle Group found that extending Diablo Canyon’s lifespan could help California decarbonize “more quickly, more reliably, and at a lower cost”—approximately $5 billion less—than if the plant shut down in 2025 as previously planned. According to the report, keeping Diablo Canyon on line would displace gas-fired generation and provide more time for the state to more than quadruple its current footprint of solar and wind units.

From the filing: The three climate groups cite an analysis by Peter Bird, professor emeritus of geophysics and geology at UCLA. He maintains that over the course of a 20-year extension—if approved by the NRC—the site would have a 2.8 percent higher chance of a severe accident.

“The NRC is responsible to ensure that operation of the Diablo Canyon reactors does not pose a significant risk to public health and safety or the environment,” said Diane Curran, attorney for San Luis Obispo Mothers for Peace, in a prepared statement. “The public will be looking to these federal regulators to address their serious concerns about whether it is safe to continue running this aging reactor in a significant earthquake zone for years past their expiration dates.”

In addition to the earthquake safety concerns, the groups allege that PG&E has not received the proper environmental permits from the California Coastal Commission to continue operating the plant.

Without the state commission's evaluation of the impacts potentially associated with the power plant's continued operations, the NRC cannot approve PG&E's license renewal application because it is incomplete, the groups said in their filing.

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