The United States nuclear fleet generated approximately 775 terawatt-hours of electricity in 2023, representing roughly 19.5% of total US electricity generation. The fleet consists of 93 operating reactors at 54 plants across 28 states, making the US the world's largest nuclear electricity producer by absolute output.

Nuclear energy is the largest source of carbon-free electricity generation in the United States, producing more zero-carbon electricity annually than all US wind and solar capacity combined. This attribute has made nuclear generation increasingly relevant to state and federal clean energy goals that require dispatchable, around-the-clock power sources.

The average US reactor is more than 40 years old, reflecting the generation build-out of the 1970s and 1980s and the two-decade pause in new construction that followed Three Mile Island and the restructuring of US electricity markets. License renewal applications have extended operating licenses for most of the current fleet to 60 years, with some plants seeking 80-year licenses from the Nuclear Regulatory Commission.

Capacity factors for the US nuclear fleet have improved significantly over the past three decades, rising from below 65% in the early 1990s to above 92% in recent years. This improvement reflects better maintenance practices, longer fuel cycles, and the elimination of unplanned outages through advanced diagnostics.

The Nuclear Energy Institute tracks US and global nuclear data and publishes the annual report from which these figures are drawn. The institute also monitors the pipeline of advanced reactor projects, including small modular reactors and Generation IV designs, that represent the next phase of US nuclear development.

Source: Nuclear Energy Institute -- https://www.nei.org/resources/statistics