A mechanism of ternary nuclear fission is described, using a statistic
al approach to the final stage of nuclear fission before the fragment
separation, and also a surface potential well for the interaction of a
n alpha particle or other light nuclei with the fragments. After its p
roduction in the equatorial region of the touching fragments, the thir
d light nucleus, as the fragments separate, first moves into the gap b
etween the fragments. Then, once it is in the gap, it climbs up the ou
ter slopes of the potential wells of the two fragments, reaching the w
ell edges. After this, the light fragment leaves the potential well of
one of the fragments and descends into the potential well of the othe
r. After undergoing reflection from the inner wall of the potential we
ll of this fragment, it surmounts the outer barrier and travels toward
the neighboring fragment. It is then accelerated in the Coulomb field
of the two fragments. Some light nuclei fall into the potential gutte
r surrounding the fragment and leave the fragment in the direction of
its motion. The mechanism makes it possible to find the momentum distr
ibution of light nuclei before acceleration in the Coulomb field of th
e fragments. The mechanism predicts the presence, in ternary fission,
of two components of light nuclei with different properties, which ari
se in their reflection from different fragments. Experiments to verify
this mechanism are proposed.