We study nondissipative fission dynamics in a wide range of mass asymm
etry, covering three groups of nuclear decay modes: cluster radioactiv
ities; alpha-decay and cold fission. The WKB action integral is calcul
ated by using the Werner-Wheeler inertia tensor and the deformation en
ergy within Yukawa-plus-exponential model extended to binary systems w
ith different charge densities. The optimum dynamical trajectory in a
threedimensional deformation space (elongation, necking-in and mass-as
ymmetry) is determined by solving a nonlinear system of differential e
quations. This new method is illustrated for three decay modes of U-23
4: alpha-decay, Mg-radioactivity and cold fission with 100Zr as a ligh
t fragment.