Regulatory progress for continued operation of Diablo Canyon

Diablo Canyon unit 1's current licence expires in November 2024 and unit 2's in August 2025. Normally, NRC regulations allow a reactor's operating licence to remain in effect beyond its expiry date provided that the licensee has already applied for a renewal at least five years prior to expiration, which the NRC calls "timely renewal".

PG&E applied to renew the licences in November 2009, but withdrew the application in 2018 after agreeing to close the plant at the end of its current licences. At that time, it was thought that the plant's output would no longer be required as California focused on an energy policy centred on efficiency, renewables and storage. However, 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 units to continue to operate until 2030 to ensure a reliable energy system.

PG&E asked the NRC to resume its review of the licence renewal application, but in January the regulator ruled that a new application would need to be submitted. This meant that PG&E could not meet the timely renewal requirement, and therefore it needed to seek the exemption.

"After evaluating the company's exemption request, the NRC staff determined that the exemption is authorised by law, will not present undue risk to the public health and safety, and is consistent with the common defence and security," the regulator said. "In addition, the staff determined Diablo Canyon's continued operation is in the public interest because of serious challenges to the reliability of California's electricity grid."

The exemption means that Diablo Canyon's licences will remain in effect provided PG&E submits a sufficient licence renewal application by 31 December. If granted, the licence renewal would authorise continued operation for up to 20 years, the NRC said.

PG&E confirmed it intends to submit a new licence renewal application by year-end. "PG&E will continue on the path to extend our operations beyond 2025 to improve statewide electric system reliability and reduce greenhouse gas emissions as additional renewable energy and carbon-free resources come online," Senior Vice President and Chief Nuclear Officer Paula Gerfen said.

Continued operation 'prudent'

Earlier this week the California Energy Commission (CEC) also approved a recommendation that Diablo Canyon should continue operating until 2030 to ensure grid reliability. The commission voted unanimously in favour of an analysis developed in consultation with the California Independent System Operator and the California Public Utilities Commission that found continued operation of the plant "until at least 2030" was "prudent".

"As California confronts a rapidly changing climate, extraordinary heat events and record energy demand are becoming increasingly ordinary. The state needs to keep all options on the table to protect public health and safety," said CEC Vice Chair Siva Gunda. "This includes maintaining Diablo Canyon's operations to support reliability statewide in the near-term. An extension would allow more time for additional clean energy projects to come on-line as we work on the long-term transition away from fossil fuels."