The document discusses ways that nuclear power plant operational efficiencies have improved in the US over the last 40 years. It states that while the number of plants has remained constant, the percentage of nuclear power in the energy mix has increased due to a substantial rise in capacity factor from 60% in 1980 to over 90% today. This was achieved primarily by reducing outage times, extending fuel cycles, using higher-burnup fuel, and decreasing unplanned outages and fuel failures. The improvements allowed nuclear plants to generate more electricity without building new reactors.