How Sustainable Is Nuclear Energy?

How sustainable is nuclear energy?

Nuclear energy is a form of energy generated from the process of nuclear fission, where atoms are split to produce heat and electricity. Sustainability refers to meeting the needs of the present generation without compromising the ability of future generations to meet their own needs. When discussing whether nuclear energy is sustainable, we examine its entire lifecycle impact on the environment, society, and economy. Factors like safety, reliability, emissions, waste management, land and water use, and fuel supply determine how sustainable nuclear energy is compared to other energy sources.

Nuclear Waste

Nuclear waste is produced from the burning of uranium fuel in nuclear reactors. There are two main categories of nuclear waste: high-level waste and low-level waste.

High-level waste contains the fission products and transuranic elements generated in the reactor core. It is highly radioactive and requires careful management. High-level waste is typically processed into a stable glass form using a process called vitrification and stored for many years while its radioactivity decreases. After 40-50 years, the radioactivity of high-level waste decreases substantially. Long-term disposal options for high-level waste include deep geological disposal in underground facilities like the proposed Yucca Mountain repository in the United States.

Low-level waste encompasses materials with low levels of radioactivity, like paper, tools, and protective clothing exposed to radiation. Low-level waste does not require shielding and is often stored on-site until its radioactivity decreases naturally through decay. Some low-level waste can be safely disposed of in landfill sites (Source 1).

Proper radioactive waste management is an important consideration for the sustainability of nuclear power. While methods exist to safely handle nuclear waste, long-term disposal solutions must be implemented to isolate waste over long time periods until radioactivity decreases to safe levels (Source 2).


The safety record of nuclear reactors has been excellent overall. According to the U.S. Nuclear Regulatory Commission blog, the U.S. Navy’s nuclear training program emphasized a safety-first approach which contributed to a strong nuclear reactor safety record despite incidents like Three Mile Island and Chernobyl.

As R.M. Heinz wrote in an article for the journal Fossils, Nuclei, Parsimony, and Sunlight, “Despite Three Mile Island and Chernobyl, the nuclear reactor safety record is excellent.” Heinz noted further that we actually get more radiation exposure from generating electricity via fossil fuels than we do from nuclear power.



The construction costs of nuclear power plants are significantly higher compared to other electricity generation sources. According to a 2008 study by Synapse Energy Economics, the construction costs of nuclear plants in the mid-2000s were much higher than earlier estimates, with costs escalating rapidly since 2000 ( The study found that the overnight capital cost (construction cost if built overnight) for nuclear power plants built in the mid-2000s ranged from $2,300 to $4,000 per kilowatt, much higher than earlier estimates. Operating costs are also significant, with nuclear power having among the highest operating and maintenance costs per unit of electricity generated compared to other sources.

More recent estimates put the overnight construction costs of new nuclear reactors between $5,500-$8,100 per kilowatt, with levelized costs ranging from $112-$189 per megawatt hour ( This makes nuclear power one of the most expensive options for new electricity generation capacity.


Nuclear energy has by far the highest capacity factor of any energy source, meaning nuclear plants are reliably generating electricity over 90% of the time (1). The average capacity factor for nuclear plants in the U.S. is over 93%, compared to around 56% for coal plants and 35% for wind and solar plants (2). This makes nuclear the most reliable energy source available.

The high capacity factors of nuclear contribute greatly to overall grid reliability. Nuclear plants operate continuously at full power, meaning they can always be counted on to meet electricity demand. Other sources like wind and solar produce intermittently based on weather conditions. The consistent power from nuclear balances out fluctuations from renewables (3).

With capacity factors consistently around 90% or higher, nuclear generates large amounts of low-carbon electricity with exceptional reliability. This makes nuclear a critical component of America’s electricity grid.

Land Use

Nuclear power plants require a large amount of land, primarily due to security and safety reasons. They typically need approximately 1.5 acres per megawatt of installed capacity. For example, a 1,000 megawatt plant would require around 1,500 acres of land, excluding access roads and any buffer areas. The land is used not only for the plant itself but also buffer areas for security, exclusion zones in case of accidents, access roads and facilities for storing spent fuel or radioactive waste.

According to the 2021 land use survey conducted by Comanche Peak Nuclear Power Plant, the total acreage of the plant site is approximately 4,000 acres. This includes the reactor and turbine building footprint as well as space for access roads, parking, equipment laydown, transmission switchyards and extensive buffer areas for security and safety [1]. In comparison, a natural gas power plant typically requires only around 10 acres for a 1,000 megawatt facility.

Thus nuclear power requires significantly more land than other electricity generation sources for the amount of power produced. This large footprint can be a constraint, especially in densely populated areas where available land is limited. However, the actual plant facilities themselves take up a small portion of the required space. The majority is buffer zones and access roads located in remote areas.

Water Use

Nuclear power plants require significant amounts of water for cooling and steam generation. According to the Nuclear Energy Institute, nuclear power plants withdraw nearly 8 times more freshwater than natural gas plants per unit of electricity generated. However, nuclear plants consume similar amounts of water as fossil fuel power plants overall.

A 2011 report by the Union of Concerned Scientists found that nuclear plants in the U.S. withdraw approximately 860 billion gallons of fresh water per year, with consumption around 60-65 billion gallons per year via evaporation. This is comparable to coal and natural gas plants. For example, the West County Energy Center, a natural gas plant in Florida, evaporates around 43 billion gallons per year.

Most nuclear plants utilize once-through cooling systems which return water to the original source. Though large quantities of water are withdrawn, impacts on water resources are location dependent. Overall consumption through evaporation is similar between nuclear and fossil fuel plants. Advanced reactor designs may reduce water needs in the future through use of air cooling.


Fuel Supply

Uranium is mined commercially in over 20 countries around the world. Proven reserves of uranium are sufficient for producing nuclear power for about 80-100 years at current usage rates, according to the World Nuclear Association. Additional undiscovered reserves, lower-grade ores that may become economical with higher uranium prices, and the prospect of breeding fissile plutonium-239 from fertile uranium-238 all extend these reserve estimates.

With seawater containing trace amounts of uranium, the oceans hold an estimated 4 billion tonnes of uranium. Advances in extraction technology could make this vast uranium source economically viable in the future. For now, conventional uranium reserves and mining are sufficient to fuel the world’s nuclear reactors.


The lifecycle greenhouse gas emissions of nuclear power are an important consideration when evaluating its sustainability. According to a report by Stanford University, the lifecycle carbon footprint of nuclear power ranges from 98-180 gCO2/kWh. This is higher than wind, solar, geothermal and some forms of hydro power, which typically range from 10-40 gCO2/kWh. However, nuclear’s lifecycle emissions are still lower than those from natural gas (500-600 gCO2/kWh) and coal (800-1000 gCO2/kWh). Proponents argue that nuclear power is an important low-carbon energy source that can help mitigate climate change when replacing fossil fuel generation. Critics counter that the emissions are still too high and that investment should focus on truly renewable sources. Overall, the lifecycle emissions data shows nuclear as a lower carbon option than fossil fuels, but higher than some other low-carbon alternatives.


When considering the most important factors related to sustainability, nuclear energy has both advantages and disadvantages compared to other energy sources. On the positive side, nuclear produces very low emissions and air pollution compared to fossil fuels, requires less land use than renewables like solar or wind, and provides highly reliable baseload power. However, nuclear energy faces challenges with radioactive waste management, water consumption for cooling, and concerns around plant safety and accidents. While the fuel supply from uranium is abundant, it’s a finite resource. Overall, nuclear energy can play an important role in a clean energy future, but needs continued innovation and vigilance around its unique risks.

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