[en] A systematic study of numerical stability of the emission of fast low-density nucleonic jets in one-dimensional nuclear slab collisions is performed. Spurious jets are shown to be connected with either a to large grid-point space or with a too small space range of integration. From a systematics of obtained results and comparison with fast-particle predictions in more realistic, but some-what contradictorily time-dependent Hartree-Fock method (TDHF) studies it is concluded that the coupling of the intrinsic motion to the relative motion in a TDHF evolution is very weak so that the Fermi-jet mechanism cannot be responsible for most of the energetic nucleons observed in experiment