NRC Approved Safety Report for Diablo Canyon Plant

The U.S. Nuclear Regulatory Commission cleared material testing results for the plant's Unit 1 reactor.

Updated on Sept. 25, 2026 in Nuclear

Isometric editorial illustration of a cylindrical metal reactor component resting on a concrete block, representing nuclear safety testing. — The U.S. Nuclear Regulatory Commission has officially approved safety findings confirming the structural integrity of the Unit 1 reactor at the Diablo Canyon power plant. AI Illustration. Upload story photo >

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The U.S. Nuclear Regulatory Commission officially approved a safety report detailing material deterioration tests at the Diablo Canyon nuclear power plant. The findings from these tests confirm that the Unit 1 reactor vessel remains safe for operation.

Why it matters

The report evaluates the integrity of reactor materials against radiation-induced embrittlement to ensure long-term structural safety. This assessment is a critical component for maintaining the facility's viability as a major energy provider for California.

The analysis, conducted by Westinghouse, evaluated material samples to determine the plant's structural longevity. Current testing indicates the Unit 1 pressure vessel can maintain safety for another 60 years.

The players

U.S. Nuclear Regulatory Commission

This federal agency is responsible for overseeing the safety of civilian nuclear energy in the United States.

PG&E

This utility company operates the Diablo Canyon power plant and provides electricity to millions of Californians.

Westinghouse

This major energy company specializes in nuclear power technology and performed the material testing on the capsule.

The details

PG&E submitted the comprehensive material evaluation on June 29, 2026, following the April 2025 removal of a test capsule from the Unit 1 reactor. While the federal commission has granted a license extension through 2045, the plant currently holds state permission to operate only until 2030.

April 21, 2025: PG&E withdrew Capsule B from the Unit 1 reactor.
April 2026: The NRC granted a license extension until 2045.
June 29, 2026: PG&E submitted the test report to the NRC.
September 24, 2026: The NRC announced approval of the safety report.
2030: PG&E's current state permission to operate expires.

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The Big Picture

The approval of this safety report follows the rigorous regulatory protocols required by the Nuclear Regulatory Commission license renewal framework. This milestone confirms that material standards align with federal safety expectations for the extended life of the reactor.

The plant generates 18,000 gigawatt-hours of energy per year, supporting the power needs of 4 million Californians. Continued operation depends on reconciling the current 2030 state expiration date with federal license approvals.

The takeaway

While federal safety benchmarks have been met for extended operation, the facility faces a 2030 deadline for state-level authorization. Achieving long-term energy stability at the site requires legislative action to align state permission with the 2045 federal license extension.