[en] Argentina has two nuclear power plants (PHWR) and currently it is in its final stage the construction of a third reactor of the same type: Atucha-2. Over the years the designs of their fuel assemblies have been improved product of operational experience, fabrication evolution and technical-economic needs. The changes have been evolving in some cases, such as increasing the uranium mass in the fuel rods. Other changes have represented a total conversion of the nuclear reactor operation; like the use of slightly enriched uranium (0,85%). At the present the initial design of the Atucha-2 fuel assembly is completed and the first core is currently under construction. Future evolution of this fuel might be based on the previous experience and also will consider the information from the operation. To study the changes that could be implemented on the Atucha-2 fuel rod the effects of some design parameters have been calculated. Aspects like pellet density, pellet porosity, pellet geometry, dishing volume, pellet-cladding gap size and initial pressurization were considered and their effects on the thermo-mechanical behavior of the entire fuel rod in terms of safety and performance were analyzed. In this paper are presented the studies of the evolutionary design changes proposed for Atucha-2 fuel rod and the analysis for their eventual implementation. Safety limits that might be affected are identified and safety margins evaluated. (author)

[en] The National Atomic Energy Commission of Argentina (CNEA) has performed the engineering activities for the first core of CNA-2 (745 MWe, natural uranium - pressurized heavy water reactor), the 3rd Nuclear Power Plant in Argentina, whose construction was resumed in 2006. The objective of these activities is to have at CNA-2 a reliable fuel, manufactured corresponding to a verified design. CNEA adapted the KWU/Siemens original design for the fabrication in Argentina, taking into account information obtained from experience of design, fabrication and operation of CNA-1 fuel, for which shares many design features with CNA-2 fuel

[en] Full text: Argentina has two nuclear power plants, Embalse (CANDU 6,600 MWe) and Atucha 1 (PHWR, 357 MWe). Both reactors operate with natural uranium fuel (UO₂) and are moderated and cooled with pressurized heavy water. Currently it is in its final stage the construction of a third reactor of the same type (Atucha 2, 745 MWe) and is planned to build new plants in accordance with a growing demand and the need to diversify the national energy matrix. Fuel assemblies for these power plant are manufactured in Argentina and over the years their designs have been improved product of operational experience, fabrication evolution and technical - economic needs. The changes in both fuel designs have been evolving in some cases, such as increasing the mass of the fuel pellets. Other changes have represented a total conversion of the nuclear reactor operation; this is the case of the use of slightly enriched uranium (0.85 %) in Atucha 1, since 2001, allowing a higher burnup and therefore an important reduction on fuel consumption. At the present the initial design of the Atucha-2 fuel assembly is completed and the first core is currently under construction. Future evolution of this fuel might be based on the previous experience and also will consider the information from the operation. To study the changes that could be implemented on the Atucha-2 fuel rod the effects of some design parameters have been studied. Aspects like pellet density, pellet porosity, pellet geometry, dishing volume, plenum volume, pellet-cladding gap size and initial pressurization were considered and their effects on the thermo-mechanical behavior of the entire fuel rod in terms of safety and performance were analyzed. Fuel fabrication constrains and potential improvements were also considered. In this paper are presented the studies of the evolutionary design changes proposed for Atucha-2 fuel rod and the analysis for their implementation. Safety limits that might be affected are identified and safety margins evaluated. (author)

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