Monte Carlo simulations of self-avoiding tethered cl-lain conformations in small spherical cavities were performed at relatively high segment densities. Tethered drain systems were studied as models of swollen cores of multimolecular block copolymer micelles in selective solvents. Simulations were performed on a tetrahedral lattice using (i) a mutually independent simultaneous self-avoiding walk of all chains and (ii) a modified equilibration algorithm similar to that proposed by Siepmann and Frenkel [Siepmann, J. I.; Frenkel, D. Mel. Phys. 1992, 75, 59] for dense polymer melts. Distribution of lengths of tethered end-to-free end vectors, r(TF), of individual chains, and their angular orientations, phi, with respect to the radial direction was calculated during computer simulations. Processes of nonradiative energy transfer between end-attached donors and traps and processes of excitation energy migration among identical fluorophores in systems of constrained self-avoiding tethered chains with fluorescently tagged free ends were also studied by computer-based, simulations.