Why New Large and Small Nuclear Reactors are Not Green
By Mark Z. Jacobson, The National Interest
Published on August 20, 2025
Despite their considerable allure in the eyes of many, and despite being put forth as the cure to the energy crisis, nuclear reactors are not green.
Air pollution, global warming, and energy security are three of the biggest problems facing the world. Many have suggested that new nuclear reactors can help solve these problems. However, due to the long time from planning to operation alone, new reactors are useless for solving any of these problems. This is just one of seven issues with nuclear electricity that illustrate why it can’t be classified as “green.” Developing more clean, renewable energy is a viable solution.
Long Planning-to-Operation Time
The planning-to-operation (PTO) time of a nuclear reactor includes the time to identify a site, obtain a site permit, purchase or lease the land, obtain a construction permit, finance and insure the construction, install transmission, negotiate a power purchase agreement, obtain permits, build the plant, connect it to transmission, and obtain an operating license.
Long Planning-to-Operation Time
The planning-to-operation (PTO) time of a nuclear reactor includes the time to identify a site, obtain a site permit, purchase or lease the land, obtain a construction permit, finance and insure the construction, install transmission, negotiate a power purchase agreement, obtain permits, build the plant, connect it to transmission, and obtain an operating license.
Cost
The 2025 cost of electricity for the new Vogtle nuclear reactors is $199 (169 to 228) per megawatt-hour. This compares with $61.5 (thirty-seven to eighty-six) for onshore wind and $58 (thirty-eight to seventy-eight) for utility-scale solar PV. Thus, new nuclear costs three (two to 6.2) times as much as new solar and wind. But nuclear’s cost does not include the cost to clean up the three Fukushima Dai-ichi reactor meltdowns, estimated at $460 to $640 billion, or ten to 18.5 percent of the capital cost of every reactor worldwide. Also, the cost of storing nuclear waste for 200,000 years is ignored. About $500 million is spent yearly in the United States to safeguard waste.
Air Pollution and Global Warming From Nuclear
There is no such thing as a close-to-zero-emission nuclear power plant. Carbon-equivalent emissions per unit of electricity from new nuclear power plants are nine to thirty-seven times those of onshore wind. Higher nuclear emissions are due to emissions from the background electric grid during the long PTO time of nuclear as compared with that of wind, emissions from mining and refining uranium, emissions from constructing and decommissioning a reactor, and heat and water-vapor emissions during reactor operations.
Weapons Proliferation Risk
The growth of nuclear electricity has historically increased the ability of several nations, most recently Iran, to enrich uranium or harvest plutonium to build or attempt to build nuclear weapons. The Intergovernmental Panel on Climate Change (IPCC) states, with “robust evidence and high agreement,” that “barriers to and risks associated with an increasing use of nuclear energy include…nuclear weapons proliferation concerns…” Building a reactor allows a country to import and secretly enrich uranium and harvest plutonium from uranium fuel rods to help develop nuclear weapons. This does not mean every country will, but some have. Small modular reactors (SMRs) increase this risk, because SMRs can be sold more readily to and transported to countries without nuclear power.
Meltdown Risk
To date, 1.5 percent of all nuclear power plants built have melted down to some degree. Meltdowns have been either catastrophic (Chernobyl, Ukraine, in 1986; three reactors at Fukushima Dai-ichi, Japan, in 2011) or damaging (Three Mile Island, Pennsylvania, in 1979; Saint-Laurent, France, in 1980). The nuclear industry claims that new reactor designs are safe. But new designs are generally untested, and there is no guarantee that a new reactor will survive a disaster.
Waste Risk
Consumed fuel rods from nuclear reactors are radioactive waste. Most rods are stored near the reactor that used them. This has given rise to hundreds of radioactive waste sites that must be maintained for at least 200,000 years. The more nuclear waste that accumulates, the greater the risk of a leak that damages water supply, crops, animals, and/or humans.
Mining Lung Cancer Risk
Underground uranium mining, which is about half of all uranium mining, causes lung cancer in miners because uranium mines contain radon gas, some of whose decay products are carcinogenic. Wind and solar do not have this risk because they do not require continuous fuel mining, only one-time mining to produce the infrastructure, and such mining does not involve radon.
In sum, new nuclear takes seven to twenty-one years longer, costs two to 6.2 times as much, and emits nine to thirty-seven times the pollution per unit of electricity as new wind or solar. Beyond simply not being “green,” nuclear energy also has weapons proliferation risks, meltdown risks, waste risks, and mining lung cancer risks, which clean renewables avoid. SMRs will continue most of these problems and increase the risk of proliferation. In 2024, China added 378 gigawatts of wind, solar, and hydropower, ninety-five times the nuclear power it finished. Thus, even where nuclear is growing fastest, renewables are beating it by two orders of magnitude.
Finally, many existing reactors are so costly, their owners are demanding subsidies to stay open. But subsidizing existing nuclear may increase carbon emissions and costs versus replacing the plants with wind or solar.