US NRC allows Diablo Canyon nuclear units to keep operating while new license renewal request reviewed

The US Nuclear Regulatory Commission has granted an exemption Pacific Gas and Electric needs to avoid the risk that one or both units at its Diablo Canyon nuclear plant in California would have to shut at the end of their operating licenses starting in 2024, the agency said in a March 2 letter.

NRC said that if PG&E submits a license renewal application no later than Dec. 31 for the two units and the agency finds the application acceptable, the existing operating licenses for the reactors will be considered to remain in place even after their upcoming expiration dates while the agency completes its review.

The NRC decision avoids the potential, which was seen as more than likely by analysts, that Diablo Canyon would have had to shut at least one unit in November 2024 while the agency review was underway.

On Jan. 24, the agency rejected PG&E's request to resume the review of a previously withdrawn license renewal application for the reactors but said it was evaluating whether to grant the exemption to its rules on timely renewal. The application had been withdrawn when the operator planned to permanently shut the units.

PG&E said in a March 2 statement that it intended to submit an application "by the end of 2023."

Senior Vice President and Chief Nuclear Officer Paula Gerfen said in the company's statement that 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."

The California Energy Commission adopted a staff report Feb. 28 that recommended pursuing extending the operation of the Diablo Canyon plant through 2030 to ensure electricity reliability amid increasing load, and more extreme and frequent weather events.

The state of California enacted a law in September directing PG&E to extend the operation of the reactors to 2030, five years beyond the expiration of the current licenses for Diablo Canyon-1 and Diablo Canyon-2, in 2024 and 2025, respectively. They have a combined capacity of 2.4 GW.

In issuing the exemption, NRC said the exemption "is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security." The agency also determined the continued operation of the plant is in the public interest because of serious challenges to the reliability of California's electricity grid.

NRC said its review of a license renewal application typically takes 22 months, and some analysts had predicted that without the exemption a temporary shutdown was likely.

Diablo Canyon had been scheduled to shut as part of an agreement among owner PG&E Corp., subsidiary PG&E, and environmental, labor, and nuclear safety groups. But concerns over the state's ability to meet its clean energy targets, as well as the formation of a federal credit program, prompted California officials and PG&E to rethink the closures and led to the passage of the state law as well as the request to resume the review.

One of California's US senators, Democrat Dianne Feinstein, said in a statement that she was "pleased" by the NRC action. "The next few years are going to be critical for California's energy transition," Feinstein said. "This decision will allow Diablo Canyon to serve as a bridge to a clean-energy future, maintaining a reliable source of carbon-free power as we continue to invest in renewable energy."

The anti-nuclear group Friends of the Earth said NRC was "contorting its rules and procedures" by permitting the plant to operate while the agency reviewed the future license renewal application. Normally, NRC requires that plants submit renewal applications at least five years ahead of time for plants to be allowed to operate past the expiration date of an initial license should the agency review be ongoing at the time.