AZ SB1418

Exempts small modular reactors colocated with large industrial energy users from the standard certificate of environmental compatibility process in Arizona counties with populations under 500,000, requiring only 30 days' written notice to the Corporation Commission before construction.

Allows utilities to replace existing thermal electric generating units with small modular reactors or construct new ones on or adjacent to previously approved plant sites without seeking new environmental certificates or hearings.

Expands the definition of "plant" to include nonthermal electric generating units and small modular reactors with nameplate ratings of 200 megawatts or more (increased from the previous 100 megawatt threshold).

Directs the Corporation Commission to adopt rules defining key terms including "colocated with," "large industrial energy user" (based on energy demand in megawatts), and "small modular reactor" (with maximum eligible nameplate rating of at least 200 megawatts).

Prohibits county zoning ordinances from restricting small modular reactor construction when colocated with a large industrial energy user that has received zoning entitlements, in counties with populations under 500,000.