[en] We introduce a percolation model to account for secondary interactions in ultrarelativistic nuclear collisions: Overlapping hadrons, after string fragmentation, are regarded as quark matter droplets rather than individual particles. An analysis of droplet sizes for S+S scattering at 200 GeV reveals: There are large fluctuations concerning the droplet volume, i.e., although it is most likely to produce hadrons or small droplets, there is a sizable probability to form big droplets with masses above 100 GeV. (orig.)