The NEMO 3 detector, devoted to search for the neutrinoless double-beta dec
ay, will be able to reach the sensitivity to [m(v)] of the order of 0.1 eV.
The expected performance of the detector for signal detection and both int
ernal and external background rejection is presented. A specific study of t
he neutron-induced background is given. The NEMO Collaboration is now mount
ing the detector in the Frejus underground laboratory. (C) 2000 MAIK "Nauka
/Interperiodica".