Diablo Canyon safe to run for 60 years, report said. Should it be reviewed?
A recent test conducted by PG&E and its contractor shows that materials in Unit 1 at the Diablo Canyon nuclear power plant are unlikely to deteriorate and break during the next 60 years, PG&E said.
As of July 1, the U.S. Nuclear Regulatory Commission had not yet certified the report.
The power plant, nestled into seaside hills near Avila Beach, has two nuclear rectors that generate about 18,000 gigawatt-hours of energy per year — enough to serve 4 million Californians, according to PG&E.
In April, the U.S. Nuclear Regulatory Commission granted PG&E a 20-year license to operate the power plant until 2045. However, PG&E only has state permission to run the plant until 2030. The state Legislature would need to pass a law to extend operations beyond 2030 in order for PG&E to use the entirety of its license.
On April 21, 2025, PG&E withdrew Capsule B from the Unit 1 reactor pressure vessel, which holds the reactor’s radioactive core and the water that cools it.
According to PG&E’s operating license for Unit 1, the company is supposed to periodically remove and test capsules from the reactor — which monitor the reactor for embrittlement. Embrittlement happens when radiation from operating the nuclear reactor causes its materials to become more likely to break.
Because the capsules are closer to the fuel than the reactor is, and they are made of materials already most susceptible to embrittlement, they deteriorate more quickly than the reactor itself. Inspection of these can help indicate how much time it will take for the reactor to reach unsafe levels of embrittlement.
After Capsule B was withdrawn, PG&E sent it to Westinghouse for testing.
Those tests revealed that Unit 1 is safe to operate without embrittlement for another 60 years, PG&E said.
“These comprehensive findings affirm Diablo Canyon’s continued ability to deliver safe, reliable and carbon-free electricity to nearly 4 million Californians, underscoring its essential role in the state’s clean energy future,” the power plant’s chief nuclear officer and senior vice president Paula Gerfen said.
PG&E submitted a report on the test results to the U.S. Nuclear Regulatory Commission on Monday.
The commission plans to publish findings on the report by Oct. 1, agency spokesperson Tressa Smith said.
“Our response will depend on our staff’s assessment of the significance and impact to the plant,” she said in an email to The Tribune.
San Luis Obispo County Supervisor Bruce Gibson urged the Diablo Canyon Independent Safety Committee to have the report independently peer-reviewed, according to an email sent to the committee’s legal counsel Robert Rathie on Tuesday morning.
“Peer review would be an important assurance to the public regarding the safety implications of the report’s findings,” Gibson said in the email.
This story was originally published July 7, 2026 at 9:00 AM.
