Pinnacle West Capital Corporation Nuclear Decommissioning Trust

The trust exists solely to fund the decommissioning of the Palo Verde Nuclear Generating Station's three units after their operating licenses expire. It operates under Nuclear Regulatory Commission (NRC) financial assurance rules and IRS Section 468A, which allows tax-deferred compounding on contributions collected from ratepayers. Withdrawals can only occur for eligible decommissioning expenses, and any surplus after site restoration reverts to ratepayers.

APS treasury personnel manage day-to-day portfolio operations under the direction of an internal investment committee. The Pinnacle West Capital board holds ultimate fiduciary responsibility. Allocation decisions must comply with state utility commission orders and NRC guidelines that prioritize safety and liquidity over excess returns. External managers are used for specialized fixed-income and equity sleeves.

Pinnacle West reported total plan assets of roughly $1.4 billion as of year-end 2023. APS's 29.1% share of Palo Verde decommissioning costs is estimated at more than $500 million. The trust has been consistently overfunded relative to minimum NRC requirements, though cost estimates are revised periodically based on updated engineering studies and inflation assumptions.

APS owns 29.1% of Palo Verde through a co-ownership agreement with six other entities: Salt River Project, Southern California Edison, El Paso Electric, Public Service Company of New Mexico, Southern California Public Power Authority, and Los Angeles Department of Water and Power. Each co-owner maintains its own decommissioning trust, and each is severally liable for its proportional share of site-wide cleanup costs.

The primary risks are long-duration interest-rate sensitivity, nuclear-specific inflation for dismantlement services, and regulatory changes that could alter collection mechanisms. Pinnacle West disclosed in its 2024 filings that cost-escalation rates for specialized labor and waste disposal exceeded earlier forecasts, prompting upward revisions to target trust balances over the remaining license life.