Nuclear energy companies are trying to shrink reactors to the size of shipping containers in a bid to compete with electric batteries as a source of zero-carbon energy.
Led by Westinghouse, the race to develop “microreactors” is based on the notion they can replace diesel and gas generators used by everything from data centres to remote off-grid communities to offshore oil and gas platforms.
“Initially, the idea was there are parts of the economy that are very difficult to decarbonise, especially remote communities that depend on transportable diesel, which is very expensive,” said Jon Ball, head of Westinghouse’s eVinci microreactor programme. “But the level of interest has really expanded and we believe this is going to be a significant growth area.”
The nuclear industry is enjoying a renaissance as governments and big tech companies search for clean sources of power to meet their climate commitments. Dozens of projects are already under way to develop small modular reactors, which have capacities of up to about 300 megawatts.
Microreactors have a much smaller output of up to 20MW, enough to power roughly 20,000 homes, and are likely to operate like large batteries, with no control room or workers on site. The reactors would be transported to a site, plugged in and left to run for several years before being taken back to their manufacturer for refuelling.
Westinghouse in December won approval from US nuclear regulators for a control system that will eventually allow the 8MW eVinci to be operated remotely. The reactor, which has minimal moving parts, uses pipes filled with liquid sodium to draw heat from its nuclear fuel and transfer it to the surrounding air, which can then run a turbine to produce electricity or be pumped into heating systems.
“Our goal is to be able to operate autonomously from a central location where we can just simply monitor a fleet of reactors that are deployed around the world,” said Ball.
The reactor uses small quantities of ceramic-coated Triso fuel, which is designed to withstand extreme temperatures without melting down.
The eVinci is the first microreactor to complete engineering studies for a test programme — expected to start in 2027 — at the Idaho National Laboratory in the US, and Westinghouse recently signed a deal with Core Power, a UK start-up looking to develop nuclear power plants at sea.
“It is on track for an operating licence at the US Nuclear Regulatory Commission . . . We think 2029 is the time it comes, which is as early as anything will come on to the market,” said Mikal Bøe, chief executive of Core Power. He added that he hoped the two companies could start building an order book in 2027 and 2028.
Ball said two of the target markets for eVinci reactors were data centres and the oil and gas industry, both on and offshore. He said the ability to run several microreactors side by side would make data centres more resilient than with a single source of energy.
Microreactors are also likely to be used by the mining industry, particularly to excavate cobalt, manganese and other critical minerals that are often located in remote locations, said Ian Farnan, a Cambridge professor of earth and nuclear materials.
He said the problem was “you have to cut 1,000 tonnes of rock for one tonne of product”.
“This will change how you run a mine. Currently, we use diesel. Aside from its cost and carbon intensity, the logistics of getting diesel to remote sites make a lot of these mines unviable. If you could install a reactor that lasts 10 to 20 years, you’ve got a power source sorted.”
Nasdaq-listed Nano Nuclear Energy has hired Farnan to help design a low-pressure-coolant microreactor that it hopes to bring to market by 2031.
Other companies that have established leading positions in the new microreactor industry include New York-listed BWX Technologies, which already builds nuclear reactors for US navy submarines and aircraft carriers, and X-energy, which raised $500mn in September from investors including Amazon and Ken Griffin, founder of the Citadel hedge fund.
Both companies were selected for Project Pele, a US defence department commission for a portable nuclear reactor that could be deployed to any site on an aeroplane and run for several years before being moved on.
But J Clay Sell, chief executive of X-energy, said the market for microreactors was “still emerging”.
“We’ve probably invested as much as anyone in the sector,” he said. “But when you go down in size, the economics become much more challenged. You have to get to a greater level of scale for microreactors to become economic.”
Bøe said microreactors would be price-competitive once production lines were scaled up. “If you have an order book of 60 to 120 reactors, you see an economy of numbers,” he added, saying the aim was to produce electricity for somewhere between $100 and $150 per megawatt hour.
“That’s not grid-scale competitive, but it is very competitive for ports, terminals, petrochemical facilities, island locations, remote locations,” he said. “The cost of bringing diesel and gas into these places is prohibitively high.”
But there are questions over how to build, transport and run microreactors safely, said Ronan Tanguy, programme lead for safety and licensing at the World Nuclear Association.
Regulators still have to draw up rules around whether microreactors can be operated remotely and how to make them safe from cyber attacks. Rules are also needed around transporting them, especially across national borders, and whether they should be fuelled in a factory or on site. Given their smaller size, they may also pose an easier target for nuclear fuel theft.
Westinghouse said the eVinci would pass the same aircraft impact assessment test that applies to larger reactors but Tanguy noted that many existing rules for reactors were either “disproportionate or not applicable for microreactors”. It would be very difficult to deliberately hit such a small target with an aircraft, he noted.
“The International Atomic Energy Agency is likely to issue high-level safety standards and those are usually taken into national regulation,” he said. “It is not going to be quick. If people want it to get done, yes it can be, but there’s lots of work involved.
