NRC Grants Diablo Canyon 20-Year License Extensions, Its 100th Renewal

The NRC's 99th and 100th commercial reactor license renewals both belong to one California address: Pacific Gas and Electric's Diablo Canyon Power Plant in San Luis Obispo County, where on April 2, 2026, the agency formally extended the operating lives of the two-unit, 2.3-gigawatt station through the mid-2040s.

Facility Operating License Nos. DPR-80 and DPR-82, covering the plant's twin Westinghouse pressurized water reactors, now expire November 2, 2044, and August 26, 2045, respectively. The 20-year extensions cap a three-year process requiring PG&E to navigate NRC scrutiny alongside a parallel track of state and regional approvals: the California Public Utilities Commission, the State Lands Commission, the California Coastal Commission, and the Central Coast Regional Water Quality Control Board, whose February 26, 2026, sign-off on state water permits cleared the final regulatory obstacle before NRC could act.

For California's grid, the stakes are concrete. Diablo Canyon supplies roughly 9% of the state's total electricity and approximately 20% of its emissions-free power, serving about 4 million customers from a coastal site roughly 12 miles southwest of San Luis Obispo. "Diablo Canyon is the state's largest source of clean energy and a cornerstone of reliability," PG&E CEO Sumeet Singh said, noting that meeting growing demand in a changing climate demands an unwavering operational focus. PG&E Senior Vice President and Chief Nuclear Officer Paula Gerfen underscored the technical side: "Throughout the license renewal process and our more than 40-year history, we've demonstrated our constant commitment to operating Diablo Canyon with safety at the forefront."

Jeremy Groom, acting director of the NRC's Office of Nuclear Reactor Regulation, called Diablo Canyon "a stabilizing force for California's electric grid" at the signing ceremony and grounded the milestone in what a license renewal actually certifies: not a rubber stamp, but a conclusion reached through "rigorous review, continuous inspection and technical refinement" that the plant's aging management programs remain adequate.

That is the technical core of any renewal decision. The NRC evaluates whether operators can manage time-limited aging analyses, monitor and mitigate reactor pressure vessel embrittlement, track cable insulation degradation, and maintain passive safety systems through an extended operating period far beyond original design intent. The agency's final supplemental environmental impact statement concluded that continued operation into the mid-2040s would carry a small environmental impact.

There is, however, a statutory ceiling built into California law that the NRC's certificate cannot lift on its own. Senate Bill 846, signed by Gov. Gavin Newsom in 2022, currently authorizes Diablo Canyon to operate only through 2030, irrespective of what the federal license now permits. Any operation between 2030 and the NRC's newly issued expiration dates requires affirmative action from the California Legislature, meaning the plant's practical lifespan still hinges on a future policy vote in Sacramento.

For anyone working through the administrative record, the primary documents are the NRC's record of decision, the final supplemental environmental impact statement, and PG&E's original application, all accessible through the NRC's Agencywide Documents Access and Management System. In a renewal of this complexity, the technical factors that most often determine the outcome are reactor pressure vessel embrittlement projections, the scope of aging management programs for passive components, and the treatment of environmentally assisted fatigue. Diablo Canyon's complete file is now the capstone of the NRC's 100-renewal public record.