  We consider the motion of a quasi one dimensional beam of Bose-Einstein
condensed particles in a disordered region of finite extent. Interaction
effects lead to the appearance of two distinct regions of stationary flow. One
is subsonic and corresponds to superfluid motion. The other one is supersonic,
dissipative and shows Anderson localization. We compute analytically the
interaction-dependent localization length. We also explain the disappearance of
the supersonic stationary flow for large disordered samples.
