Central Argentina de Elementos Modulares, Nuclear reactor prototype in Zárate, Buenos Aires Province, Argentina

The CAREM is a nuclear reactor with an integral design where the entire cooling system sits within the reactor vessel and operates at uniform pressure. The facility sits next to the Atucha Nuclear Power Plant and relies on regular supplies of enriched uranium oxide for operation.

Construction of the CAREM-25 reactor started in 2014 as Argentina's first domestically designed nuclear power plant. This project marked an important turning point in the country's energy policy.

The name CAREM stands for Central Argentina de Elementos Modulares, a modular plant meant to be built from repeated units. In 2005 a US Department of Energy panel picked it among about a dozen small-reactor projects of greatest interest worldwide. In March 2024 CNEA and INVAP signed a memorandum at Bariloche to explore exporting the reactor and associated services.

The CAREM-25 site is a fenced construction zone beside the Atucha I plant, about 8 km from Zárate, and is not open to visitors; access is limited to CNEA and contractor personnel. Work stopped in September 2024 after 153 workers were laid off, and union representatives put the concrete structures at roughly 85% complete. The reactor vessel and internal components are the parts to watch for progress.

The reactor uses natural circulation for its cooling system, which eliminates the need for pumps and lowers accident risk. This passive safety feature is a particularly important part of its design.