  A new type of decay corresponding to the neutronless $^{10}$Be-accompanied
fragmentation of $^{252}$Cf is studied. We employ a cluster model similar to
the model used for the description of cluster radioactivity.
  No preformation factors were considered.
  The ternary relative isotopic yields were calculated as the ratio of the
penetrability of a given ternary fragmentation over the sum of penetrabilities
of all possible ternary neutronless fragmentations. The corresponding barriers
between the light and heavy fragment and between the $^{10}$Be cluster and the
two heavier fragments were computed with the help of a double folding potential
generated by M3Y-$NN$ effective interaction and realistic fragment ground state
deformations.
  Also, we studied the influence of the fragment excitation energies on the
yields, by including the level densities and the
  $\beta$-stretching of the fragments.
  The new phenomenon could be experimentally observed by the triple gamma
coincidence technique between the fragments and $^{10}$Be.
