Diablo Canyon: What next?

July 8, 2022, 7:00AMNuclear NewsBy George Apostolakis, James Ellis, and Steven Nesbit
The Diablo Canyon nuclear power plant.

The state of California recently and quite sensibly cracked the door back open for continued operation of the Diablo Canyon nuclear power plant past the current operating license expiration dates in 2024 (Unit 1) and 2025 (Unit 2). The nonprofit North American Electric Reliability Corporation’s recently released 2022 Summer Reliability Assessment highlights the risk of electricity shortages in California. Given that concern, as well as the benefits of continued Diablo Canyon operation—including much needed clean, reliable energy; good jobs; and potential for large-scale production of fresh water—another look at the shutdown decision made several years ago is clearly warranted. Sen. Dianne Feinstein (D., Calif.) reinforced this point when she added her voice to the growing chorus of policymakers advocating extended operation for Diablo Canyon.

So, what next? Expressing a willingness to take a second look is the necessary first step, but it must be followed by concrete actions to carry out that reconsideration and enable continued operation of the power plant. It is not necessary to make a final decision today, but action is needed now to preserve the option of continued operation in the future.

First and foremost, the state of California should encourage Diablo Canyon’s owner, Pacific Gas and Electric (PG&E), to take immediate steps to resubmit to the Nuclear Regulatory Commission the application for renewal of the plant’s operating licenses—this is critical. License renewal was well underway in March 2018 when PG&E officially withdrew the application pursuant to a state-brokered agreement to take the reactors out of service in 2024 and 2025. Time will be required to restart and complete the license renewal process. If it proves impossible to finish in the available time, there are regulatory measures that could allow interim operation, provided the application is resubmitted in a timely manner.

Being willing to reconsider past decisions in light of new information is a hallmark of good governance; so too are gathering as much information as possible before making extremely consequential decisions and keeping options open. Restarting the license renewal process is consistent with these principles. The NRC is a competent and impartial regulatory authority, and so a favorable decision regarding license renewal would provide objective assurance that the plant can continue to operate safely in the future, as it already has for many years. Restarting license renewal now is a prudent action that will serve Californians’ best interests and would not prejudice the final decision on whether to keep the units running past their expiration dates. The monetary investment in license renewal over the next few years is small, compared with the investments necessary to ensure a clean and secure future energy supply for California.

In addition to the state of California, PG&E, and other stakeholders working cooperatively and promptly to resubmit the renewal application, these parties must carry out all other necessary actions to preserve the option of future Diablo Canyon operation. It is important to not foreclose by inaction the opportunity to continue generating clean, secure, and affordable electricity at Diablo Canyon.


George Apostolakis was a professor at the Massachusetts Institute of Technology who served as a commissioner of the Nuclear Regulatory Commission. He lives in California and directs the Nuclear Risk Research Center in Japan.

Admiral James Ellis, Jr. retired as president and chief executive officer of the Institute of Nuclear Power Operations after a career in the U.S. Navy. He is an Annenberg Distinguished Fellow at the Hoover Institution in Stanford, Calif.

Steven Nesbit retired from Duke Energy, the nation’s second largest nuclear utility, and is the Immediate Past President of the American Nuclear Society.


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