Nadanian played in the Soviet Union Junior Chess Championships of 1987, 1988 and 1989, in the Armenian Chess Championships of 1997, 1998 and 1999 (7th–8th places), in the 32nd Chess Olympiad in Yerevan 1996, in the 13th European Chess Club Cup 1997, in the Zonal tournament in 1998, where he shared 7th–11th places out of 72 participants, in the European Individual Chess Championships of 2000 and 2014 and in the FIDE World Rapid and Blitz Championships 2013 in Khanty-Mansiysk. In 2014, playing board 4, he helped his team BKMA Yerevan to a silver medal in the Armenian Team Chess Championship.