Are Advanced Nuclear Reactors As Good As They’re Promoted To Be?

Originally published on Forbes.com on May 4, 2026

New concepts for advanced reactors are thriving, and boosted by new government funding, but there are serious detriments to commercial success.

President Trump has ordered some aging coal power plants to stay on after their decommission date. The goal is to keep electricity prices down. But aging plants are generally decommissioned when their infrastructure needs to be repaired or replaced, which can be a costly affair. One analysis was based on 90 coal power plants that are due to close. If these were kept open by DOE orders, it could cost consumers $30 – $60 million every year for each plant. 

A new alternative source of electricity is to promote what are called advanced nuclear reactors, which were funded by President Biden, and this has been continued by President Trump. The current DOE looked at over 2,000 Biden-era funding awards. While billions of dollars in renewable and carbon capture loans were cut, many survived, but with a caveat that DOE preferred a focus on baseload power and nuclear expansion, including small modular reactors (SMRs).

Advanced Nuclear Reactors

What are advanced nuclear reactors? The next-generation reactors, up to 300 MW (Mega Watts), are smaller than traditional reactors, easier to construct, safer, and more efficient. They can use coolants other than water, such as molten salt or gas. These allow a reactor to operate at higher temperatures and lower pressures, which boosts efficiency and safety.

Their goal is to produce clean electricity or heat for industry.  Examples are to decarbonize systems run by fossil energy, desalinate salt water for drinking, or boost electricity for renewable grids that are less reliable.

An obvious advantage of advanced nuclear reactors is that they can operate in remote areas, such as oil drilling sites away from an electric grid, or in systems that require dedicated power, such as data centers.

Small Modular Reactors (SMRs) will produce from tens of MW to hundreds of MW. Modular reactors are designed to be built in a factory, which should lower costs. But in one commercial deployment in Utah, expenses blew up, and the community canceled the order. The initial project was for 12 SMR’s from NuScale to generate 600 MW by 2023 for an estimated cost of $3 billion. The price ballooned to $9.3 billion in 2023. And scaled down to 462 MW. The project was terminated in November 2023.

Two examples from the spectrum of advanced nuclear reactors are summarized here.

Natrium Reactor By TerraPower

Last month, Bill Gates’ company, TerraPower, got federal approval to build the advanced nuclear reactor called Natrium in Kemmerer, Wyoming.  Natrium, which will produce 345 MW, is intermediate in size between an SMR and a traditional nuclear reactor—the facilities in the figure occupy 44 acres. A sodium test facility will ensure the sodium coolant controls pressure more safely than the water coolant it replaces, and that a separate molten salt system can store energy up to 5.5 hours. The reactor is scheduled to open in 2030.

TerraPower’s investors and partners include Bechtel, GE Hitachi, PacifiCorp, and Berkshire Hathaway. DOE is supporting the project, and it’s the greatest single contribution ever committed to a private project.

Oklo, Volatile Star of SMRs.     

Oklo is developing its Aurora Powerhouse line of SMRs, which will be safer by using molten sodium coolant, but also able to run on fresh or recycled nuclear fuel. The latest version will produce 15-50 MW of power, but is planned to expand to 100 MW. Oklo also promises to produce special radioisotopes for medical and industrial end users.

Oklo is an advanced nuclear power startup out of Santa Clara, founded in 2013 by Jacob DeWitte. The original proposal was denied a license by the NRC in 2022. But things changed in 2025. Oklo had financial backing from Sam Altman, CEO of OpenAI, who served as Oklo board chair until April. The concept for the next Aurora powerhouse, called Aurora-INL, broke ground at Idaho National Laboratory in September 2025. But it won’t be built until 2030.

Oklo won big when DOE funds were handed out in their new Reactor Pilot Program, initiated by Trump in May of 2025. Oklo was selected for three out of eleven total projects. Also, Aurora-INL won’t need to be approved by the NRC, as it can be licensed by DOE under the Reactor Pilot Program.

But as summarized in September 2025, there has been strong criticism about the cost. Several professionals said reactor costs were greatly undervalued: a construction cost of $86 million would more likely be $300 – $500 million.  

Despite this, the company was flying high, and Oklo’s valuation hit $20 billion near the end of 2025. Since its SMR design is not certified, the company has no revenue, and cost estimates are dubious, its market cap came down quickly—by the end of 2025, it was $11.5 billion. The market cap is ~$12.4 billion as of 27 April.

The latest twist in this tale is a new collaboration, just announced, between Oklo, NVIDIA, and Los Alamos National Laboratory. The goal is to leverage AI at NVIDIA and nuclear materials science at Los Alamos to improve Aurora-INL by making it more efficient and reducing waste. This makes sense since DOE has a formal Genesis Mission that aims to unite industry with government labs to explore AI breakthroughs in scientific discovery, energy dominance, and national security.

Nuclear Waste From Small Modular Reactors

Nuclear waste has, and always will be, the supreme detriment of nuclear reactors. This embodies two things: fear of leakage of radioactive material from a live reactor, and refusal to store radioactive waste “in my backyard, or anywhere else in my state”.

Advanced nuclear reactors, including SMRs, have been spotlighted by the Secretary of Energy to help solve the electrical power surge needed for data centers and AI. Despite early assurances, research has shown that SMRs create 2 to 30 times greater volumes of nuclear waste. 

This was research in 2022 by Stanford and the University of British Columbia. A study lead author, Lindsay Krall, said, “Our results show that most small modular reactor designs will actually increase the volume of nuclear waste in need of management and disposal, by factors of 2 to 30 for the reactors in our case study. These findings stand in sharp contrast to the cost and waste reduction benefits that advocates have claimed for advanced nuclear technologies.”

Problem of cost

A slew of data illustrates the grave uncertainty in the estimated costs of advanced nuclear. First, the cost of new nuclear reactors, whether traditional reactors or SMRs, is substantially higher than that of renewable energies. A robust study by CSIRO in Australia concluded the LCOE cost range for wind and solar with storage and transmission is the lowest of all new-build power technologies in 2023 and 2030.

In Utah, smaller projects like NuScale’s community project have seen estimates surge from $3 billion to more than $9 billion for roughly 460-600 MW of power.

A single 300 MW Westinghouse AP300, planned for 2027, aims for around $1 billion in 2027. This is about the production from a coal-fired power plant. It’s an SMR version of the flagship AP1000 that generates 1200 MW. Several AP1000s are being built in Ukraine, for example. But the cost of an AP1000 is about $7 billion. This means electricity from the AP300 SMR will be a bit more expensive than from an AP1000.  

Last, a report from May 2025 argues that SMRs are the most expensive source of electricity per kW. Costs sometimes exceeding $20,000/kW.