Argentina’s Economy Minister Luis Caputo has announced a $1.2bn private investment by US-based Meitner Energy to construct a 300 MWe small modular reactor (SMR) at the Atucha nuclear complex. This project marks a historic turning point for the country’s energy sector. This is the largest single private investment in the history of Argentina’s nuclear development. Caputo said Meitner Energy Latam CEO Teófilo Lacroze and Pablo Franzetti, the company’s head of external affairs and new business in Argentina, had formally presented the proposal to build the reactor at Atucha using private US capital.
The plant will feature the ACR-300 (Advanced Compact Reactor), a Generation III+ pressurised water SMR. The reactor design, funded by US capital, was developed by Argentina’s state-owned private technology company INVAP (INVestigación APlicada – applied research). INVAP patented the ACR-300 in the US in 2024.
While Meitner Energy holds the commercial deployment licence, the underlying technology relies on a hybrid framework that bridges Argentina’s experience in heavy-water reactors with modern global utility standards. Its core physics adapt traditional Candu heavy-water moderation principles but replaces heavy-water cooling with standard light-water cooling. A single unit generates 300 MWe per single modular unit. Argentina’s ultimate national plan seeks to cluster these, aiming to scale up to four units at the Atucha site for a combined 1.2 GWe capacity.
The reactor can use slightly enriched uranium (SEU), natural uranium, or mixed oxide (mox) fuels. This diverse fuel compatibility reduces reliance on specialised external supply chains. The design leverages extensive factory fabrication. Major components are completely manufactured off-site and transported to the site for final assembly. This is expected to reduce construction to five years.
Beyond standard civilian electrical grid baseloads, the ACR-300 is specifically tailored to power industrial projects such as the Vaca Muerta oil fields as well as localised, remote infrastructure including artificial intelligence data centres. Despite its patents, nuclear industry experts note the design is still in an early phase. Adriana Serquis, former National Atomic Energy Commission (CNEA – Comisión Nacional de Energía Atómica) head has warned that the reactor still lacks deep, granular engineering details.
Meitner Energy is a joint venture. The US-based Ansari Group (led by businessman Hamid Ansari) holds a 60% controlling stake, while the remaining 40% belongs to Black River Technology, a US firm controlled directly by INVAP.
The company is named after Lise Meitner, the pioneering physicist who co-discovered nuclear fission. Meitner Energy’s Argentine subsidiary quietly established its local footprint in mid-2024, putting a team of over 120 professionals to work validating the engineering and conceptual design viability of the ACR-300. Former Shell Latin America President Teófilo Lacroze assumed office as the global CEO in April. The following month, Meitner Energy made its official public debut, launching its corporate identity and establishing ownership over the ACR-300 reactor patents.
The $1.2bn investment is expected to qualify for Argentina’s proposed “Super RIGI” (Régimen de Incentivo para Grandes Inversiones en Nuevas Industrias – Incentive Regime for Large Investments in New Industries), currently before parliament. This framework offers 30 years of tax stability and foreign exchange benefits for mega-projects exceeding $1bn.
“Super RIGI” is a legislative upgrade to Argentina’s original investment framework. It specifically targets multi-billion-dollar investments in nascent or emerging technological industries. The draft bill (No. 5-PE-2026 was signed by President Javier Milei and sent to Congress in late May. The Chamber of Deputies (Lower House) approved the bill, and it is now awaiting a final vote of approval in the Senate. To qualify for the package, projects must inject a minimum of $1bn in assets, with at least $200m committed within the first two years.
Eligible projects will enjoy reduced corporate income tax (down to 15%) and a low 7% tax on dividends, which automatically drops further to 3.5% after four years. Once a project is approved, the law secures 30 years of total regulatory stability. Any local regulations that conflict with national Super RIGI benefits will be legally rendered void.
The project is projected to generate roughly 2,000 direct jobs across its development, construction, commissioning, and operational phases. Construction is slated to take five years, pending formal environmental and technical licensing from Argentina’s Nuclear Regulatory Authority (ARN – Autoridad Regulatoria Nuclear).
This deal represents a radical shift toward economic deregulation under President Javier Milei’s administration. Historically, Argentina’s nuclear plants (Atucha I, Atucha II, and Embalse) were entirely state-led and state-funded initiatives. Caputo highlighted that this model allows the state to establish predictable market conditions while the private sector assumes the capital risk.
However, the announcement has sparked domestic debate. The shift to private funding coincides with deep austerity budget cuts and layoffs at CNEA. Critics and scientific union leaders point out the paradox of using state-developed INVAP tech while simultaneously defunding and halting CAREM-25, Argentina’s own long-standing, 85%-complete state SMR project. The Meitner Energy announcement came just days after the government dismissed 61 CNEA employees, including highly specialised professionals and technicians, many of whom had been working on the CAREM, which was on track to be the world’s first operating SMR before the construction was halted.
Presidential spokesman Adrián Ravier highlighted in an X post that “for the first time, a private company will expand Argentina’s energy infrastructure” and push the country’s technological boundaries. “The changes spearheaded by President Javier Milei have built the confidence needed for an international company to choose our country to build a 100% privately owned nuclear reactor,” Ravier noted.
Secretary of Nuclear Affairs Federico Ramos Napoli, also writing on X, said: “Argentina has more than 70 years of nuclear track record, top-level institutions, and talent recognised worldwide. That a private company chooses our country to build its first reactor confirms that this technical capital, with the right conditions, turns into investment, jobs, and baseload clean energy.”
