California Regulators Approve $722.6 Million for Diablo Canyon Extension

California's sole operational nuclear power facility, the Diablo Canyon Power Plant in San Luis Obispo County, is advancing towards extended operations, with the California Public Utilities Commission (CPPUC) recently approving $722.6 million in ratepayer costs to cover its continued function through December 31, 2025. This decision marks a critical step in the plant's bid to remain online beyond its previously scheduled shutdown dates of 2024 and 2025 for its two units. The plant's rigorous operational standards are exemplified by its advanced training facilities, including a full-scale control room simulator.

An "incredible photo of the nuclear ☢️ reactor control room sim in Diablo Canyon, California," shared by user JJ on social media, underscores the plant's commitment to operational excellence and safety. Simulation engineer Brian Sawyer noted that the plant maintains an exact replica of its control room where operators undergo intensive training, including drills for scenarios like earthquakes and terrorist attacks. This crucial training ensures operators are prepared for any eventuality, spending approximately 20% of their careers in these simulations.

The push to extend Diablo Canyon's lifespan stems from California's evolving energy needs, particularly the growing demand from artificial intelligence and data centers, alongside the state's ambitious clean energy targets. Originally slated for decommissioning, the plant received a lifeline through Senate Bill 846 in 2022, which authorized its continued operation for up to an additional five years, until 2029 for Unit 1 and 2030 for Unit 2. This extension aims to bolster grid reliability and prevent reliance on fossil fuels.

Pacific Gas and Electric (PG&E), the plant's operator, submitted an application to the Nuclear Regulatory Commission (NRC) in November 2023 for a 20-year license renewal. The NRC recently finalized its safety and environmental reports in June 2025, with a final decision expected in August 2025. While federal funding, including $1.1 billion from the Department of Energy, and projected electricity sales are expected to offset some costs, consumer advocacy groups have voiced concerns over the financial burden on ratepayers.

Diablo Canyon contributes nearly 10% of California's total electricity and 20% of its carbon-free power, serving over 3 million Californians. Despite significant progress in regulatory approvals and financial backing, the plant still requires approvals from the California Coastal Commission and the state water board. These agencies are reviewing the plant's long-term environmental impact, particularly concerning its once-through cooling system, as the state balances energy reliability with environmental protection.