Groups file new petition to close Diablo Canyon nuclear power plant

In a new motion filed Tuesday, three groups say keeping Diablo Canyon nuclear power plant operating in San Luis Obispo County poses an “unacceptable safety risk.”

Mothers for Peace, Environmental Working Group and Friends of the Earth filed request for a hearing with the U.S. Nuclear Regulatory Commission to force the NRC to consider the groups’ safety concerns about the 2,200-megawatt power plant and their contention that plant owner PG&E has not acquired the proper environmental permits to continue operating the facility.

The groups’ request for a hearing was accompanied by a petition requesting the NRC order the immediate closure of Diablo Canyon “due to the unacceptable risk of a seismically induced severe accident.”

In other words, the groups are concerned a large earthquake in the area of the plant — located just north of Avila Beach — could cause a catastrophic nuclear meltdown.

The request for a hearing and petition to shut down the power plant come about three months after the NRC granted review of PG&E’s application to renew the operating license for the plant. The decision allowed PG&E to continue running the power plant past its originally scheduled closure dates in 2024 and 2025 while the NRC reviews the application to keep the reactors running another 20 years.

“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.”

The allegations raised by the groups have long been denied by PG&E, which maintains that the power plant is safe.

“Updated assessments continue to confirm that the plant is seismically safe,” wrote PG&E spokesperson Suzanne Hosn in an email to The Tribune. “Built to withstand extreme natural disasters, including earthquakes, the plant’s design features state-of-the-art seismic supports.”

NRC reviewing PG&E’s application for license renewal

In December, the California Public Utilities Commission, the agency that regulates privately owned public utilities in the state, authorized PG&E to continue operating Diablo Canyon’s reactors until 2029 and 2030. Diablo Canyon is California’s last remaining nuclear power plant.

The commission’s vote was compelled by Senate Bill 846, signed by Gov. Gavin Newsom in September 2022. It was done without the body fully knowing the costs of continued operations and on the premise that Diablo Canyon was needed because not enough clean energy is available to replace the plant by the end of 2023.

SB 846 says that the state’s failure to procure enough clean energy to fully replace Diablo Canyon has left it no other option but to keep the nuclear power plant operational.

Diablo Canyon provides about 9% of the state’s electricity and has since become what California officials say is the best solution to ensure the state has a reliable energy grid as electricity demand rises in the face of climate change, electrification and other factors.

Since the NRC accepted PG&E’s license renewal application for review in December, the agency has embarked on a review process that includes “detailed safety and environmental reviews,” according to an NRC news release at the time. The review process could take up to five years, but typically takes between 22 and 30 months, according to the NRC.

Groups say Diablo Canyon’s license shouldn’t be renewed because of safety, environmental concerns

By requesting a hearing, Mothers for Peace, Environmental Working Group and Friends of the Earth aim to force the NRC to conduct a public hearing to air their concerns about Diablo Canyon’s continued operations.

“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 Nuclear Regulatory Commission must not ignore its risks to the public and the environment.”

The groups’ safety concerns are not new — they have filed several petitions over the past year to request the NRC close the plant.

In their request for a hearing, the groups claim PG&E has underestimated the risks of an earthquake to the power plant.

Should Diablo Canyon continue to operate another 20 years, there’s a 2.8% probability of a “severe accident,” according to an analysis conducted by Peter Bird, a professor emeritus of geophysics and geology at UCLA, included in the groups’ request for a hearing.

“Under NRC guidance, such a high core damage frequency calls for ‘immediate regulatory action’ to ‘maintain the plant in a safe condition,’” the groups request for a hearing said. “In this context, it requires the denial of PG&E’s license renewal application.”

In her email to The Tribune, Hosn noted that PG&E recently reassessed Diablo Canyon nuclear power plant’s ability to withstand powerful earthquakes.

“The updated SB 846 seismic assessment — whose process and results were independently reviewed by geosciences and risk experts, including the UCLA Garrick Institute for the Risk Sciences — found no significant increase in seismic risk to Diablo Canyon Power Plant that would change previous conclusions by the U.S. Nuclear Regulatory Commission that the site is seismically safe,” Hosn wrote.

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

Impacts the Coastal Commission still needs to evaluate “include PG&E’s failure to address effects on coastal uses and resources for the full 20-year period covered by PG&E’s license renewal application instead of only five years; effects on fragile coastline areas and recreational activities of a proposed reduction in the size of the security area around (Diablo Canyon); the substantial loss of marine life productivity from continued reliance on (Diablo Canyon’s) once-through cooling system; effects of proposed dredging activities at (Diablo Canyon); effects of continued operation on Environmentally Sensitive Habitat Areas, and effects of continued operation on traffic and circulation,” the request for a hearing said.

Without the Coastal 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.

“PG&E agreed in 2016 to shut down this dangerous nuclear power plant by 2024 and 2025, but now it is joining public officials to push for another extension,” said Hallie Templeton, legal director for Friends of the Earth, in a prepared statement. “We will keep prioritizing people and the planet by ensuring that the risks associated with Diablo Canyon’s extension are closely analyzed before any decisions are made.”