{"id":572274,"date":"2026-01-20T10:51:58","date_gmt":"2026-01-20T13:51:58","guid":{"rendered":"https:\/\/revistapesquisa.fapesp.br\/?p=572274"},"modified":"2026-01-20T10:51:58","modified_gmt":"2026-01-20T13:51:58","slug":"brazil-takes-another-step-towards-building-a-nuclear-powered-submarine","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/brazil-takes-another-step-towards-building-a-nuclear-powered-submarine\/","title":{"rendered":"Brazil takes another step towards building a nuclear-powered submarine"},"content":{"rendered":"

The Brazilian Navy is taking another step towards achieving its goal of adding a nuclear-powered submarine to its fleet. A crucial phase of the Brazilian project\u2014the electromechanical assembly of the section called block 40, which will house the prototype reactor responsible for generating the thermal energy for propulsion\u2014is at an advanced stage, according to the Naval Force. To test this equipment, a full-scale model of the submarine’s mid and rear sections, blocks 10 to 40, is nearing completion at one of the laboratories of the Aramar Nuclear Industrial Center (CINA). This military complex, dedicated to nuclear research and commonly referred to simply as Aramar, is located in Iper\u00f3, 115 kilometers from the city of S\u00e3o Paulo.<\/p>\n

A research unit called the Nuclear Power Generation Laboratory (Labgene) was set up exclusively to test the nuclear reactor. Its main building, a large hangar, about 30 meters (m) high, is where the submarine prototype is being assembled. According to the Navy, the propulsion plant will initially be tested with steam from a conventional fossil-fuel boiler. Only afterwards will it be powered by nuclear fuel, also produced at Aramar.<\/p>\n

The purpose of Labgene is to validate the operation of the naval propulsion reactor and its integrated electromechanical and control systems. The vessel will be built approximately 550 kilometers away, at the Itagua\u00ed Naval Complex in Rio de Janeiro.<\/p>\n

\u201cThe construction of an onboard nuclear plant is unprecedented in Brazil. We have never done it before. We will need to test it extensively before installing it on the submarine,\u201d said Vice Admiral Celso Mizutani Koga, director of the Navy Technological Center in S\u00e3o Paulo (CTMSP), during a visit by FAPESP Research<\/em> reporters to CINA in May this year. \u201cWe will have to ensure that all safety and performance requirements are met. We estimate that it will take three years for Labgene to begin producing energy through nuclear fission.\u201d<\/p>\n

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L\u00e9o Ramos Chaves \/ Pesquisa FAPESP <\/span>A building in Aramar where uranium concentrate is converted into uranium hexafluoride gas, part of the nuclear fuel production processL\u00e9o Ramos Chaves \/ Pesquisa FAPESP <\/span><\/p><\/div>\n

The reactor designed by the Navy is a pressurized water reactor (PWR), the most commonly used model in nuclear power plants worldwide, including Brazil\u2019s Angra 1 and 2 plants on the coast of Rio de Janeiro. The state-owned company Nuclebr\u00e1s Equipamentos Pesados (NUCLEP), created in 1975 to serve the Brazilian Nuclear Program (PNB), is handling the development of the block 40 components.<\/p>\n

“We are doing a lot from scratch because the countries with nuclear submarine manufacturing technology do not share it, which creates numerous challenges due to its novelty and the need for domestic development,” says Koga.<\/p>\n

Despite the complexity and challenges involved in building a nuclear plant\u2014whether on board a submarine or at a power station\u2014it operates similarly to a thermoelectric generator: heat from burning fuel produces steam, which drives a turbine connected to a power generator.<\/p>\n

In a nuclear generator, the steam is created not by the combustion of diesel oil or natural gas, but by the thermal energy released during the fission (splitting) of uranium atoms, the base mineral for nuclear energy. Heat conduction circuits containing heated water and steam drive the turbine that powers the electrical system’s generators, producing electricity. The advantage of nuclear energy over fossil fuels is its high energy density: one pellet of enriched uranium weighing just a few grams releases the same thermal energy as one ton of coal.<\/p>\n

Secret military program<\/strong>
\nThe construction of a conventionally armed nuclear submarine (the SNCA) using Brazilian technology is one of two objectives of the Navy\u2019s Nuclear Program (PNM), one of the arms of the PNB. Now under the responsibility of the CTMSP, the program began in secrecy under the codename Chalana in 1979, during the military dictatorship (1964\u20131985). It was only made public after democracy was reestablished in the country.<\/p>\n

Since then, the program has faced numerous challenges and budget constraints that have nearly resulted in it being shuttered and have forced its timeline to be repeatedly revised. Experts interviewed by Pesquisa FAPESP<\/em> estimate that the vessel will only be ready by the middle or end of next decade.<\/p>\n

Construction of the SNCA, named \u00c1lvaro Alberto (1889\u20131976) in honor of the scientist and Navy officer who helped create Brazil\u2019s nuclear program, is also part of the Submarine Development Program (Prosub), a partnership between Brazil and France. The agreement includes the development of four conventional diesel-electric powered submarines (see<\/em> Pesquisa FAPESP issue n\u00b0<\/em>\u00a0274<\/em><\/a>).<\/p>\n

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L\u00e9o Ramos Chaves \/ Pesquisa FAPESP <\/span>A model of the submarine reactorL\u00e9o Ramos Chaves \/ Pesquisa FAPESP <\/span><\/p><\/div>\n

\u201cToday, only six nations are capable of manufacturing nuclear submarines: the US, Russia, China, the UK, France, and India,\u201d says Rear Admiral S\u00e9rgio Lu\u00eds de Carvalho Miranda, the Navy\u2019s director of nuclear development. \u201cBrazil is the first country without nuclear weapons to build this type of submarine.\u201d The main advantages of nuclear submarines over conventional models, the officer explains, are higher speeds, greater ability to remain undetected, and the capacity to stay at sea for longer periods of time. \u201cIt can remain submerged on surveillance, defense, and reconnaissance missions for long periods without needing to surface or return to base to refuel,\u201d he says.<\/p>\n

Physicist Claudio Geraldo Sch\u00f6n, head of the nuclear engineering course at the Polytechnic School of the University of S\u00e3o Paulo (POLI-USP), believes nuclear submarines are an important deterrent. \u201cBecause they are so fast and quiet, they can approach other vessels without being noticed,\u201d he says. “For Brazil, with its vast maritime territory, it is important to have a vessel like this to protect our national resources and guarantee our sovereignty at sea,” he explains.<\/p>\n

Another goal set by the PNM was to master the technology for producing nuclear fuel. Through collaborations with the Institute for Energy and Nuclear Research (IPEN), the program achieved early results on this front in the 1980s, when Brazil created its own ultracentrifugation technology, the stage of the process when the uranium undergoes isotope enrichment.<\/p>\n

\u201cOnly 13 countries know how to enrich uranium. That is the bottleneck of the nuclear fuel cycle,\u201d says nuclear engineer Renato Cotta, a consultant for the PNM and researcher at the Alberto Luiz Coimbra Institute for Graduate Studies and Research in Engineering at the Federal University of Rio de Janeiro (COPPE-UFRJ) (see interview<\/a><\/em>). \u201cThose that master this technology do not share it with others.\u201d That, he explains, is because anyone able to enrich uranium for power generation is also capable of producing the raw material needed to build atomic bombs.<\/p>\n

To understand how uranium is enriched and transformed into nuclear fuel, it is important to know that in nature, the mineral contains only about 0.7% of the isotope U-235 (the ideal isotope for nuclear fission). Isotopes are atoms of the same chemical element but with different atomic masses. The predominant isotope in natural uranium is U-238, accounting for more than 99% of the total. To generate electricity at nuclear power plants, uranium must be composed of at least 5% U-235; for submarine fuel, it must be enriched to 19%.<\/p>\n

To achieve the desired level, uranium ore is converted into a gas, which then goes through a cascade of ultracentrifuges operating in series and parallel to concentrate the U-235. The enriched gas is then converted back into a powder, producing the raw material for the pellets used in nuclear fuel. The entire process takes place at various structures at CINA, which employs more than 1,200 people.<\/p>\n

\u201cThe nuclear fuel cycle is not a secret. You can look up how the process works, the materials required, and the necessary chemical reactions in any book. The difficult part is having the technology to actually do it,\u201d says USP\u2019s Sch\u00f5n. During Pesquisa FAPESP<\/em>\u2019s visit to Aramar, reporters were allowed to see the Isotopic Enrichment Laboratory (LEI), where the uranium is enriched, but not the ultracentrifuges.<\/p>\n<\/div>

\n \n \n \n <\/picture>Alexandre Affonso \/ Pesquisa FAPESP<\/span><\/div>
\n

\u201cIt is an industrial secret. Not even IAEA [International Atomic Energy Agency] inspectors, who regularly conduct safety checks at Aramar, have visual access to them,\u201d Miranda explained. Unrestricted access to the centrifuges is forbidden to prevent reverse engineering\u2014visual analysis of the equipment could reveal its technological principles and how it functions.<\/p>\n

The purpose of the IAEA inspection is to ensure that Brazil is not enriching uranium to greater levels than the country has stated in international agreements. As a signatory of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), Brazil\u2019s nuclear fuel production and submarine reactor development are subject to IAEA oversight.<\/p>\n

The nuclear fuel used in the Angra 1 and 2 plants is produced locally by Ind\u00fastrias Nucleares do Brasil (INB), a state-owned company located in Resende, Rio de Janeiro. The ultracentrifuges in operation at INB were manufactured by the Navy. \u201cWe have already supplied equipment for the assembly of 10 cascades,\u201d says Koga, from CTMSP. \u201cWe cannot disclose how many devices are used in each cascade. Like many aspects of nuclear fuel production, that is classified information.\u201d<\/p>\n

The story above was published with the title “A distant dream<\/strong>” in issue 354 of August\/2025.<\/p>\n","protected":false},"excerpt":{"rendered":"Assembly of the prototype reactor that will propel the vessel is underway; project is set to be completed in the next decade","protected":false},"author":23,"featured_media":572291,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[169],"tags":[228,243,2413],"coauthors":[116],"class_list":["post-572274","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-technology","tag-engineering","tag-innovation","tag-technology"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/572274","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/23"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=572274"}],"version-history":[{"count":1,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/572274\/revisions"}],"predecessor-version":[{"id":572307,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/572274\/revisions\/572307"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media\/572291"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=572274"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=572274"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=572274"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=572274"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}