The Bugey 3 experiment, designed to measure oscillations of reactor neutrinos, has used 3 identical detection modules, each of 600 liters, filled with a new 6Li-loaded liquid scintillator. These modules were located in two shielding bunkers, respectively 15 and 40 m away from the reactor core. We describe here the mechanical characteristics of these modules, their shielding, the associated electronics, the trigger, the acquisition systems, the calibration and monitoring of these detectors, and the Monte Carlo simulations of their response to particles. We conclude on the overall performance of this new detection technique which has allowed the recording of 120000 neutrino interactions with good neutron efficiency (49%), low background (2.5 evts/hr) and good energy resolution (4% at 4.4 MeV).