Nuclear generation accounted for 17 percent of US electricity output in 2025, according to Energy Information Administration data, with May 2026 figures released on July 23. The agency projects that share falling to between 12 and 15 percent by 2050 across every case it modeled.

The decline is a share effect rather than an output collapse. Nuclear capacity projections stay close to flat through the near term outlook, meaning the fleet generates roughly what it generates today while total electricity demand rises around it. Data center load growth is the largest single contributor to that denominator expansion.

The agency tracks four measures that describe fleet performance: operable unit count, net generation, share of total net generation, and capacity factor. Capacity factor is the metric where the US fleet leads globally, running above 90 percent, which means the reactors produce close to their theoretical maximum output over a year.

Holding a flat share would require capacity additions roughly matching demand growth. Every large reactor now under construction or in licensing, combined with the small modular designs moving through NRC review, falls short of that pace on current schedules.

The gap between flat capacity and rising demand explains why utility resource plans increasingly pair nuclear license renewals with gas and solar additions rather than treating them as alternatives.

Source: US Energy Information Administration - https://www.eia.gov/nuclear/generation/