OK, here's the list of the 15 member
republics of the USSR proper.
Where
Pseudo_Intellectual has it slightly wrong is with
Chechnya,
Dagestan, and
Nagorno-Karabakh. The first two are members of the
Russian Federation, which itself is a collection of member
republics.
Nagorno-Karabakh is a territory under dispute between
Armenia and
Azerbaijan.
All fifteen of these republics became independent countries once the USSR collapsed. The troubles in Chechnya are a case of a member republic of Russia wishing to become independent itself.