Global Status of SMRs and Microreactors 2026: From Design to Actual Construction
For years, small modular reactors (SMRs) and microreactors were more of a catalog of designs than an industry. In 2026, that picture changed. There are still dozens of concepts on paper —the OECD Nuclear Energy Agency tracks over 100 designs—, but the useful debate is no longer “how many are there.” It is which ones are licensed, concrete on site, or have a first paying customer.
Definitions and Promises
An SMR, in the most commonly used definition, is a reactor of up to about 300 MWe, with components manufactured off-site and assembled on-site. A microreactor is even smaller: the U.S. EIA generally places them at 20 MW or less, designed for military bases, mining, islands, data centers, or microgrids.
The promise is the same: less civil work, more standardization, and uses that a large plant does not cover. The risk is also the same: the first of its kind almost always arrives late and more expensive.
The Most Advanced Western SMR: BWRX-300 in Canada
The most concrete project in the West is the BWRX-300 from GE Vernova Hitachi in Darlington, Ontario. It is a BWR of about 300 MWe, with conventional LEU fuel (less than 5% enrichment) and natural circulation. Ontario Power Generation obtained construction licensing in 2025. In March 2026, the hold point for foundation was surpassed, and the unit is already classified as under construction. The goal for first electricity is around 2028-2030. More units are planned at the same site.
That data matters for LATAM. It is not a render. It is civil work, Canadian regulator, and a light water design, the technology family that Mexico, Argentina, and Brazil already know. In the United States, TVA is advancing a BWRX-300 at Clinch River. In 2026, the NRC staff recommended the construction permit, and the file was ready for the commissioners' decision. Japan and the U.S. also announced a package to deploy several BWRX-300s in Tennessee and Alabama.
NuScale: Certified, still without the first plant in the U.S.
NuScale remains the only SMR with full NRC certification. The original 50 MWe module was certified in 2023; the uprated US460 design of 77 MWe received Standard Design Approval in May 2025. A VOYGR-6 plant adds 462 MWe; a VOYGR-12, 924 MWe.
The first U.S. project (UAMPS, Idaho) was canceled in 2023 due to costs. The most tangible progress is in Doicești, Romania: in February 2026, the shareholders of Nuclearelectrica approved advancing the RoPower project of six modules. NuScale reports components in manufacturing, but the first physical module is still not complete, and commercial operation is estimated for the early 2030s. Certification is not the same as the first grid connection.
Rolls-Royce, Holtec, and Westinghouse: The light water race
The Rolls-Royce SMR, a PWR of about 470 MWe and high manufacturing content, was selected in 2025 as the preferred technology of the British program. The first targeted site is Wylfa, in Wales. Czechia, via ČEZ, also chose it. The design is in the final phase of the Generic Design Assessment of the United Kingdom; there is still no nuclear concrete. The operation is expected to begin in the early 2030s.
Holtec SMR-300 (~300 MWe) is progressing with support from the DOE for a first deployment alongside the restart of Palisades, in Michigan. The Westinghouse AP300 (~300-330 MWe) is part of the AP1000 already operating in Vogtle, Georgia: less technological novelty, more operational legacy. Its certification is anticipated around 2027.
Natrium and advanced technology SMRs
The other milestone of 2026 is Natrium, from TerraPower: a sodium-cooled fast reactor of 345 MWe, with thermal storage of molten salts to follow demand. In March 2026, the NRC issued the construction permit for Kemmerer, Wyoming —the first for an advanced non-light commercial reactor in decades— and in April, construction began with Bechtel. The goal is to develop up to eight Natrium plants. The operational target is around 2030. The bottleneck here is not just the construction: it is the HALEU fuel.
Kairos Power is building the Hermes demonstrator in Oak Ridge (fluoride salts and TRISO fuel). X-energy is advancing the Xe-100, a ~80 MWe per module HTGR, with an environmental permit from the NRC in process. These are designs distinct from the BWRX or NuScale: more flexible in process heat, more dependent on new fuel and supply chain.
China and Russia: Leadership in operation and grid
Outside of the West, the board is different. China is building the ACP100 (Linglong One) in Changjiang, Hainan, of about 125 MWe. The connection target had been set for 2026; databases like PRIS from the IAEA, updated in mid-2026, still listed it as under construction with no firm criticality date. If it connects to the grid, it would be the first commercial land-based SMR in China.
Russia operates the Akademik Lomonosov, floating plant, and advances RITM-type land units. They are the only ones with SMR connected to the grid continuously.
In Latin America, Argentina designed CAREM-25, a conceptual pioneer of national SMR. Construction, which began in 2014, has faced repeated stoppages and in 2026 several sources report it as suspended or being redefined, while the government explores SMR with private capital. The regional fact is not that LATAM “does not exist” in SMR. It is that the continuity of work weighs as much as the design.
Microreactors: From prototypes to military budget
The segment of less than 20 MW accelerated in 2025-2026 due to two key clients: defense and data centers. In August 2026, the U.S. Army announced up to $2.2 billion for five companies —Antares, BWXT, General Atomics, Radiant, and Westinghouse— with the goal of having at least one microreactor on a base by fall 2028. Radiant, for example, targets ~1 MWe transportable units. Westinghouse is developing eVinci (~5 MWe). Oklo is advancing Aurora (15-75 MWe) with initial work in Idaho and a pilot with the Air Force in Alaska. Last Energy proposes a PWR of ~20 MWe. Nano Nuclear presented KRONOS MMR to the NRC.
The DOE also launched a pilot program for advanced reactors. Several startups reached criticality in environments authorized by the DOE, not necessarily with commercial licensing from the NRC. That distinction is critical: a test reactor is not a plant that sells electricity.
For LATAM, the most realistic use case is not to copy the U.S. Army's budget. It is remote mining, desalination, industrial heat, and islands or weak grid systems: just the niche that microreactors claim to occupy.
What to read behind the headline?
Three filters allow avoiding marketing:
- Is there a building permit and is there construction? Darlington and Kemmerer pass that filter. Most of the 100 designs do not.
- Does the fuel exist at scale? LWRs with LEU have an advantage. Natrium, Kairos, Oklo, and several micros depend on HALEU or TRISO.
- Who pays for the first unit? Canada has OPG. Romania bet on NuScale. The U.S. mixes DOE, Army, and hyperscalers. Without a buyer, the SMR remains a PDF.
The conclusion for 2026 is sober: SMRs are no longer science fiction, but they are also not a fleet. For Latin America, the conversation should focus on technologies that already have a regulator, factory, and defined customer.
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Sources
- OECD-NEA, SMR Digital Dashboard (Updates 2025-2026).
- U.S. EIA, Small modular reactors and microreactors under development in the United States, April 2026.
- U.S. NRC trackers: NuScale US460 and Natrium Construction Permit (March 2026).
- Ontario Power Generation / CNSC: BWRX-300 Darlington, construction progress 2026.
- World Nuclear Association, SMR Design Database, July 2026.
- World Nuclear News and industry reports on RoPower, Rolls-Royce SMR, and Linglong One.
- The New York Times, August 2026: U.S. Army contract for microreactors.
- IAEA, SMR catalog and PRIS database.
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