California Regulators Vote to Keep Diablo Canyon Nuclear Plant Open Another Five Years

California’s Diablo Canyon nuclear plant can continue operating at least through much of 2030 after state energy regulators on Dec. 14 voted to keep the facility open an additional five years.

The state’s Public Utilities Commission (PUC) on Thursday agreed to extend the closure date for Diablo Canyon, which originally was scheduled to shut down in 2025. The next step is for the U.S. Nuclear Regulatory Commission (NRC) to consider whether to extend the plant’s operating licenses. The NRC earlier this year said the plant could continue operating while PG&E, the plant’s operator, seeks a license renewal.

Diablo Canyon is home to two pressurized water reactors designed by Westinghouse. The 2,250-MW plant has been in service since the mid 1980s. The plant is located near Avila Beach in San Luis Obispo County, on the Pacific Coast between San Francisco and Los Angeles. The plant currently supplies about 10% of the state’s electricity.

It has been California’s only operating nuclear power plant after the closure of the San Onofre facility in 2013. The PUC, while voting to keep the plant in operation, also noted the cost to maintain the plant an additional five years could reach $6 billion.

Karen Douglas, the PUC commissioner assigned to the case, said Thursday’s 3-0 vote “is an important measure towards supporting the reliability of the California electricity grid as we move forward in our energy transition. California’s path forward in the energy transition hasn’t always been easy and won’t always be easy.”

Safety Concerns

The PUC’s vote comes after years of debate about the plant’s continued operations, in part due to safety concerns because of Diablo Canyon’s location in an earthquake zone. A state judge in August of this year tossed a lawsuit filed by the Friends of the Earth environmental group. The group wanted to block PG&E from extending the plant’s lifecycle.

The NRC in October then rejected a request for environmental groups that wanted officials to immediately take at least one of Diablo Canyon’s two reactors offline.

“The American Nuclear Society applauds the decision by the California Public Utilities Commission to extend the operations of Diablo Canyon nuclear power plant through 2030,” said Kenneth Petersen, president of the American Nuclear Society, in an email to POWER. “The California PUC commissioners made the right choice in preserving California’s largest and most reliable clean energy source, Diablo Canyon nuclear power plant. Keeping California’s lights on requires keeping Diablo Canyon online.

“Extending plant operations of Diablo Canyon beyond 2025 will safeguard California’s clean energy transition by shoring up California’s power grid with an always-on and affordable source of dispatchable clean baseload electricity, generated by nuclear energy,” said Petersen.

PG&E in 2016 had said it would close the plant by 2025, shutting Unit 1 in 2024 and Unit 2 the following year. That plan changed, though, when the state was faced with power shortages due to the retirement of other baseload power facilities, and higher demand for electricity during extreme heat waves that taxed the state’s power grid. State officials, including Gov. Gavin Newsom, while continuing to push for more renewable energy resources also said Diablo Canyon could help the state combat climate change because nuclear power does not produce greenhouse gases. Newsom originally was among those pushing for the plant to be closed.

Thursday’s decision calls for keeping Unit 1 open through Oct. 31, 2029, with Unit 2 operating at least until Oct. 31, 2030. A public comment period prior to Thursday’s vote included statements from groups in favor of keeping the plant open, as well as from those opposed to extending its operation.

PG&E in November 2022 said it had received a conditional award of about $1.1 billion from the U.S. Dept. of Energy to help pay the costs of keeping both reactors operating. The utility had applied for funding through the DOE’s Civil Nuclear Credit Program.

Darrell Proctor is a senior associate editor for POWER (@POWERmagazine).

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