For more than a decade, Stanford University professor Mark Jacobson has demonstrated how the U.S. and 139 other countries can transition to renewable energy for all purposes by 2050, without nuclear energy. Yet the debate on the necessity of nuclear power to abate climate chaos lingers on. Jacobson testified before the Minnesota House of Representatives, alongside Nukewatch, in February 2025 to oppose the repeal of the state’s longstanding moratorium on new nuclear reactor construction.

By Mark Z. Jacobson

Some advocate that nuclear power is a “clean” carbon-free electricity source, but they don’t look at the full scope of its impacts. New nuclear electricity costs about 3-14 times that of onshore wind per unit electricity generated. Nuclear also takes 7 to 21 years longer between planning and operation than wind, and produces 9 to 37 times the emissions per unit electricity generated as wind. In addition, nuclear creates risk and cost associated with weapons proliferation, core meltdown, uranium mining, radioactive waste, and carbon-equivalent emissions.

Nuclear advocates claim it is still needed because wind and solar are intermittent and need natural gas for backup. However, nuclear itself never matches power demand so it needs backup. Even in France, which has the world’s highest-penetrating nuclear energy programs, the maximum ramp rate is 1 to 5 % per minute, which means they need natural gas, hydropower, or batteries, which ramp up 5 to 100 times faster, to meet peaks in demand. Today, in fact, batteries are beating natural gas for wind and solar backup needs throughout much of the world.

Dozens of independent scientific groups have further found that it is possible to match intermittent power demand with clean, renewable supply and storage, without nuclear or fossil fuels, at low cost.

Finally, many existing nuclear reactors are so costly that their owners are demanding subsidies to stay open. In 2016, three upstate New York reactor operators requested and received subsidies to stay open using the argument that the reactors were needed to keep emissions low. However, subsidizing such reactors may increase carbon emissions and costs compared to replacing them with wind or solar.

As we wait for even a single new reactor to be built, climate change will accelerate. Utility-scale wind and solar farms, on the other hand, take an average of only one to five years from planning to operation. Rooftop solar PV projects are down to only a six-month timeline. So, transitioning to 100% clean, renewable energy for all purposes as soon as possible would result in tens of millions fewer deaths than a nuclear scenario. Here are seven major problems with nuclear energy:

1. Long Time Lag
The time lag between planning and operation of a nuclear reactor includes the time to identify a site, obtain a site permit, purchase or lease the land, obtain a construction permit, obtain financing and insurance for construction, install transmission, negotiate a power purchase agreement, obtain operating permits, build the reactor, connect it to transmission, and obtain a final operating license.

The planning-to-operation (PTO) times of all nuclear reactors ever built have been 10-22 years. For example: the Olkiluoto 3 reactor in Finland – PTO time of 22 years; the Hinkley Point C nuclear reactor – PTO time of 20 years; the Vogtle 3 and 4 reactors in the U.S. state of Georgia – PTO times of 17 and 18 years, respectively; the Flamanville, France, Unit 3 reactor – PTO time of 20 years; the Haiyang 1 and 2 reactors in China – PTO times of 13 and 14 years, respectively; the Taishan 1 and 2 reactors in China – PTO times of 12 and 13 years, respectively.

Planning and procurement for four reactors in Ringhals, Sweden started in 1965. One took 10 years, the second took 11 years, the third took 16 years, and the fourth took 18 years to complete. Many claim that France’s 1974 Messmer plan resulted in the building of its 58 reactors in 15 years. This is not true. The planning for several of these nuclear reactors began long before. In addition, 10 of the reactors were completed between 1991-2000. As such, the whole planning-to-operation time for these reactors was at least 32 years, not 15; that of any individual reactor was 10 to 19 years.

There is no evidence that small modular reactors (SMRs) will reduce PTO times compared with large units. Indeed, no commercialized SMR exists worldwide. In the United States, the only company building an SMR with its design approved by the Nuclear Regulatory Commission lost its main purchaser, lost 84% of the value of its stock from its peak, was sued by its shareholders for securities fraud, and laid off 28% of its full-time staff, all near the end of 2023. Their test reactor, if it will be built at all, is not anticipated to be available until after 2030, far too late for it to be an effective solution to air pollution or climate change.

2. Cost
Lazard [the world’s largest independent investment bank] found in a 2023 study that the levelized cost of energy (LCOE) for a new U.S. nuclear reactor is more than three times that for onshore wind or utility-scale solar PV. The cost of nuclear is an underestimate for several reasons. First, Lazard assumes a construction time for nuclear of 5.75 years. However, the Vogtle 3 and 4 reactors, the only ones built in the U.S. in the past 20 years, took 9 and 10 years, respectively for construction. Lazard also assumed a mean capital cost at only 70% of the actual cost of the Vogtle reactors ($35 billion for 2.23 GW). These changes alone suggest an LCOE of nuclear that is 3 to 14 times that of onshore wind.

Lazard’s cost estimate for nuclear energy does not include the cost of the major nuclear meltdowns in history. For example, the estimated cost to clean up the damage from three Fukushima Daiichi nuclear reactor core meltdowns, is $460 to $640 billion. This is $1.2 billion, or 10 to 18.5 percent of the capital cost, of every nuclear reactor worldwide. In addition, Lazard’s cost estimate does not include the cost of storing radioactive waste for hundreds of thousands of years. In the U.S. alone, about $500 million is spent yearly to safeguard high-level waste from about 92 civilian nuclear reactors. This amount will increase as more waste accumulates. After the nuclear reactors retire, the spending must continue for hundreds of thousands of years with no revenue stream from electricity sales to pay for the storage. There is no reason to think SMRs will be less expensive than large reactors.

3. Weapons Proliferation Risk
The growth of nuclear reactors for electricity generation and research has historically increased the ability of nations to harvest plutonium or enrich uranium to be used in nuclear weapons. The Intergovernmental Panel on Climate Change (IPCC) recognizes this fact. They concluded in the Executive Summary of their 2014 report on energy, with “robust evidence and high agreement” that nuclear weapons proliferation concern is a barrier and risk to the increasing development of nuclear energy:

“Barriers to and risks associated with an increasing use of nuclear energy include operational risks and the associated safety concerns, uranium mining risks, financial and regulatory risks, unresolved waste management issues, nuclear weapons proliferation concerns, and adverse public opinion.”

The building of a nuclear reactor for energy in a country that does not currently have a reactor forces the country to import uranium for nuclear energy production. If the country so chooses, it can also secretly enrich the uranium to create weapons-grade uranium and harvest plutonium from uranium fuel rods for use in nuclear weapons. The link between nuclear energy and weapons was clarified further as follows: “For example, uranium enrichment and plutonium reprocessing facilities are dual-use in nature because they can be used to produce fuel for power reactors or fissile material for nuclear weapons.”

4. Meltdown Risk
To date, about 1.5 percent of all nuclear power reactors ever built have melted down to some degree. Meltdowns have been either catastrophic (Chernobyl, Russia in 1986; three reactors at Fukushima Dai-ichi, Japan in 2011) or damaging (Three-Mile Island, Pennsylvania in 1979; Saint-Laurent France in 1980). Nuclear energy developers, including developers of SMRs, have proposed new reactor designs that they suggest are safer. However, these designs are generally untested, and there is no guarantee that the reactors will be designed, built, and operated correctly or that a natural disaster or act of terrorism, such as an airplane flown into a reactor, will not cause the reactor to fail, resulting in a major disaster.

5. Mining Cancer Risk
Underground uranium mining (which comprises over one-third of all uranium mining) causes cancer in many miners because uranium mines contain radon gas, which is a radioactive decay product of uranium. Some of radon’s decay products, such as polonium, are carcinogenic. The risk of radon-related cancers (including lung cancer, leukemia, and extra-thoracic cancer) from underground uranium mining is high. Because SMRs require uranium just as large reactors do, cancer risk from underground uranium mining extends to SMRs as well.

6. Carbon-Equivalent Emissions & Air Pollution
There is no such thing as a zero- or close-to-zero emission nuclear reactor. Even existing reactors emit carbon or carbon-equivalent emissions due to the continuous mining and refining of uranium needed for the reactor. This includes emissions from the background grid while consumers wait 10 to 22 years for nuclear to come online or be refurbished, relative to 1 to 5 years for wind or solar.

In addition, all nuclear reactors contribute carbon-dioxide-equivalent (CO2e) emissions from the water vapor and heat they release. This contrasts with solar panels and wind turbines, which reduce heat or water vapor fluxes to the air. The rest of the emissions associated with nuclear are due to the CO2e emitted during the construction and decommissioning of the reactor and due to producing the energy needed to mine and refine uranium. A nuclear reactor may take decades after it starts running to offset the emissions it allowed from the grid during its PTO phase.

China’s investment in nuclear reactors that take so long between planning and operation, instead of wind or solar, resulted in China’s CO2 emissions increasing by 1.3 percent from 2016 to 2017 rather than declining by about 3 percent. The resulting difference in air pollution emissions may have caused 69,000 excess deaths in China in 2016 alone, with additional deaths in years prior and since. SMRs face similar carbon-equivalent emissions and air pollution mortality.

7. Waste Risk
Last but not least, irradiated fuel rods from nuclear reactors are radioactive waste. Most fuel rods are stored at the same location as the reactor that irradiated them. This has given rise to hundreds of radioactive waste sites in many countries that must be maintained and funded for at least 200,000 years — far beyond the lifetime of any nuclear reactor. The more of this waste that accumulates, the greater the risk of radioactive leaks, which can damage water supplies, crops, animals, and humans. Small modular reactor designs only exacerbate the waste dilemma.

— Mark Jacobson, submitted this testimony on Jan. 17, 2024 to a U.S. House of Representatives Subcommittee. here reprinted and edited for space.

A.Zoom recording of Prof. Jacobson’s March 4 presentation and his slides.

B. MN Plan for 100% Wind, Water & Solar by 2050: Zero Air Pollution and Zero Carbon From All Energy Without Blackouts at Low Cost in Minnesota (Research/Data)

https://web.stanford.edu/group/efmh/jacobson/Articles/I/21-USStates-PDFs/21-WWS-Minnesota.pdf

C. 100% Wind, Water, and Solar (WWS) All-Sector Energy Roadmaps for the United States

https://web.stanford.edu/group/efmh/jacobson/Articles/I/WWS-USA.html

D. Infographic Roadmaps to Transition Cities, States, and Countries to 100% Wind-Water-Solar (WWS) for all Energy Purposes

https://sites.google.com/stanford.edu/wws-roadmaps/home

Global Plan for 100% Wind, Water & Solar by 2050: A Solution to Global Warming, Air Pollution, and Energy Insecurity for 149 Countries (Research/Data)

https://drive.google.com/file/d/1L-cKZ8ev-GLmcjd4lYqLH7l1xZRhX6IN/view