town in Buenos Aires provincia (province), eastern Argentina, northwest of Buenos Aires city, on a main railway line. It is the site of a nuclear power plant, Atucha I, a pressurized reactor that has supplied power to the national grid, Argentine Interconnection System (Sistema Argentino de Interconexión; SADI), since 1974. The construction of an Atucha II began in 1981 but has been repeatedly delayed by funding shortfalls. Pop. (latest est.) 152.