The CAREM Project has reached a new milestone in the development of the 12 steam generators for the prototype CAREM-25 in Argentina. More than 700 tubes, each 35 meters long, have been delivered to the site, Combustibles Nucleares Argentinos (CONUAR), announced on 4 May.

CAREM - the name is taken from Central ARgentina de Elementos Modulares - is Argentina's first domestically-designed and developed 25 MWe nuclear power unit. The prototype of the small pressurised water reactor design is being built at a site adjacent to the Atucha nuclear power plant in Lima, 110 km northwest of Buenos Aires. First concrete was poured for the reactor in February 2014, marking the official start of its construction. At least 70% of the components and related services for CAREM-25 are to be sourced from Argentine companies.

A steam generator for the CAREM-25  

CONUAR said it had developed the tubes jointly with the National Atomic Energy Commission (CNEA), mainly through the Department of Mechanical Engineering, Materials and Non Destructive Testing of the CAREM Area Management, and Fábrica de Aleaciones Especiales (FAE), which was in charge of the equipment's production. Manufacturing of the pipes required the construction and commissioning of the world's longest vacuum furnace for stress relief thermal treatment, CONUAR said.

The Alloy 690 tubes were manufactured according to EPRI (Electric Power Research Institute) guidelines and a series of additional requirements established by the CNEA.

"As these pipes must be straight and seamless, FAE had to build a special furnace over 37m long, specially designed for the treatment of this kind of pipes at temperatures between 500 and 850 degrees Celsius," CONUAR said.

The stainless-steel chamber has a diameter of 1.27m and it is surrounded by a set of heating resistors divided into 18 zones, each with an independent control system that guarantees uniformity of temperature, it said. The entire set is managed through a complex computer system that monitors all variables and feeds a database with all records, it added.

Each of the CAREM-25 steam generators consists of 52 helical tubes grouped in six layers. CONUAR will oversee the qualification and development of the turns and welds for the manufacture of the first mock-up, the production of which will start this year.

The 32 MWe prototype will be capable of supplying electricity to, for example, a city with a population of 120,000 inhabitants. More powerful units of this design will have a capacity of about 120 MWe.

The CAREM Project aims to enable Argentina to compete in the global market for small modular reactors. It will not only be the first nuclear power plant designed and built by a Latin American country, but in the whole Southern Hemisphere, CONUAR said.