Diablo Canyon provides nearly 9% of California’s electricity and 17% of its zero-carbon energy. Ten years ago, Pacific Gas & Electric (PG&E) reached an agreement with environmental and labour groups to retire unit 1 in November 2024 and unit 2 in August 2025. In September 2022 – as California’s energy grid saw its highest-ever peak demand during a record-breaking heatwave – the state passed a law allowing the two units to continue operation until 2030.
US nuclear power plants are initially licensed by the US Nuclear Regulatory Commission (NRC) to operate for up to 40 years. Operators can request a 20-year initial licence renewal, which covers an operating life of up to 60 years. Second – or subsequent – licence renewals can allow operation up to 80 years.
The Diablo Canyon units’ licences were due to expire in 2024 and 2025, respectively. Applications for licence renewals have to be submitted at least five years before a licence is due to expire: PG&E had submitted licence renewal applications for the Diablo Canyon units in 2009, but withdrew those applications in 2018 with the expectation that the plants would close before the licences expired. The company requested for the NRC to resume the relicensing in 2022.
The NRC’s approval comes after a three-year review process that addressed safety and environmental matters, including a safety evaluation and a final supplemental environmental impact statement which were issued in June 2025. The process has also included approvals from state and regional agencies including the California Public Utilities Commission, the State Lands Commission, the California Coastal Commission and the Central Coast Regional Water Quality Control Board.
“The NRC’s approval of Diablo Canyon’s licence renewal application marks an important milestone for California’s energy future,” PG&E CEO Sumeet Singh said. “Diablo Canyon is the state’s largest source of clean energy and a cornerstone of reliability.”
Although the NRC has determined that Diablo Canyon is safe and environmentally sound to operate for another 20 years, extending operations past 2030 would require action from California’s legislature.
With the completion of the Diablo Canyon licence renewal, there are no initial licence renewals currently under consideration by the NRC, although Tennessee Valley Authority has notified the regulator it intends to submit an application to renew Watts Bar unit 1’s initial licence later this year.
