Effectively addressing global warming requires a rapid transformation of the ways in which we produce and consume energy. The scope and impacts of climate change—including rising seas, more damaging extreme weather events, and severe ecological disruption—demand that we consider all possible options for limiting heat-trapping gas emissions.  

Electricity is the largest source of U.S. carbon emissions. Renewable energy technologies and energy efficiency measures can help dramatically cut the sector’s emissions, and are safe, cost-effective, and available today. Yet limiting the worst effects of climate change may also require deploying other low- or no-carbon energy solutions, including nuclear power, which today supplies approximately 20 percent of U.S. electricity.

Like renewables, nuclear power has very low lifecycle carbon emissions. It also faces substantial economic challenges, and carries significant human health and environmental risks. The Union of Concerned Scientists strongly supports policies and measures to strengthen the safety and security of nuclear power. We also favor a price on carbon, which would make nuclear power more cost-competitive with fossil fuels.

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Nuclear power and natural gas

Nuclear power is the third largest electricity source in the United States, though its share of total electricity production has recently declined. Low natural gas prices and costly age- and safety-related repairs have led to some nuclear reactors retiring early, replaced in large part by natural gas.

Though cleaner than coal, natural gas is still a fossil fuel that generates large amounts of carbon pollution. In the long-term, replacing aging nuclear reactors with natural gas is not a climate solution; instead, the cost and safety risks of continuing to operate the reactors should be weighed against replacing them with the most cost-effective low or no-carbon alternatives.

The role of nuclear power in the United States is currently limited by its high cost. A strong economy-wide price or limit on carbon would make all low-carbon energy sources, including nuclear, more cost-competitive with natural gas and coal.

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Nuclear power risks and impacts

Nuclear power entails substantial safety and security risks, waste disposal challenges, and water requirements. These risks also make nuclear power vulnerable to public rejection (as seen in Japan and Germany following the Fukushima disaster of 2011).

Many of nuclear power’s risks can and should be substantially reduced, regardless of whether new nuclear power plants are built. Since its founding, UCS has served as a nuclear safety watchdog, working to ensure that U.S. nuclear power is adequately safe and secure. Our recommendations include better enforcement of existing regulations, expedited transfer of nuclear waste into dry casks, strengthened reactor security requirements, and higher safety standards for new plants. We advocate the continued prohibition of reprocessing and a ban on the use of plutonium-based fuels. In addition, we support continued research and development of nuclear power technologies that are safer, more secure, and lower cost.

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