Nuclear energy startup Last Energy raises $100 million for its small steel-encased reactor

After years of being wasted, it’s time to be a nuclear startup.

“For the first half decade that I was telling people I was in nuclear, I had to convince them, ‘This is why nuclear is important,’” Brett Kugelmas, founder and CEO of Last Energy, told TechCrunch. “Now everyone comes to us and says, ‘Oh yeah, of course, nuclear is a key part of the solution.’ I’m like, OK, great, I’m glad everyone has caught on to it now.

Last Energy builds small modular reactors – compact nuclear power plants that can be manufactured in large quantities to reduce costs. The company’s reactors are designed to produce 20 megawatts of electricity, enough to power nearly 15,000 homes.

It has momentum. Last Energy just closed a $100 million Series C led by Astera Institute with participation from AE Ventures, Galaxy Fund, Gigafund, JAM Fund, The Haskell Company, Ultranative, Woori Technology and others.

The company joins a slew of nuclear startups that have raised funding in recent months, fueled by data centers’ insatiable energy demands. Google-backed X-Energy raised $700 million last month, while Antares raised $96 million two weeks ago. In August, Aalo Atomics raised $100 million to build its reactor prototype.

What sets Last Energy apart from competitors is its approach: The company uses an old reactor design developed by the government decades ago. The initial pressurized water reactor design was built for the NS Savannah, the world’s first nuclear-powered commercial ship. That ship’s power plant was about one-tenth the size of Last Energy’s planned commercial reactor. Kugelmas said the company’s updated design should produce 20 megawatts of electricity.

However, the company started smaller. First, Last Energy is building a 5-megawatt pilot reactor at a site it leases from Texas A&M. Kugelmas said the new funding will fully fund the pilot project and help the company begin offering its first commercial products. Last Energy hopes to have the pilot reactor operational next year, with its 20MW commercial-scale unit entering production in 2028.

Last Energy’s starter reactor is not designed to be maintained during its lifetime. Instead, Last Energy permanently encases each core in 1,000 tons of steel. Kugelmas estimates the metal will cost about $1 million. “Most people think concrete is cheaper,” he said. “But not when the concrete is nuclear grade.”

The reactors will arrive at the site equipped with enough uranium to last six years. Aside from the electrical and control connections, there are no other penetrations that break the steel wall. Heat from fission reactions heats the steel, and water flowing through pipes outside harvests the heat needed to spin a steam turbine.

When the reactor’s operating time is up, Last Energy will leave it on site, where the steel chamber will serve as a waste barrel, eliminating the need for separate disposal.

The hope is that this approach, combined with advances in manufacturing, will bring down the price of nuclear power. Kugelmass did not commit to a price, instead pointing to other industries that cut prices in half for every tenfold increase in production.

“I don’t think it’s going to be as good in nuclear because there are some additional fixed costs you have in nuclear in terms of some of the special regulations, but that’s the kind of trend you can see,” he said. “We’re not thinking about one or two, we’re thinking about tens of thousands.”