  Ternary fission of actinides probes the state of the nucleus at scission.
Light clusters are produced in space and time very close to the scission point.
Within the nonequilibrium statistical operator method, a generalized Gibbs
distribution is constructed from the information given by the observed yields
of isotopes. Using this relevant statistical operator, yields are calculated
taking excited states and continuum correlations into account, in accordance
with the virial expansion of the equation of state. Clusters with mass number
$A \le 10$ are well described using the nonequilibrium generalizations of
temperature and chemical potentials. Improving the virial expansion, in-medium
effects may become of importance in determining the contribution of weakly
bound states and continuum correlations to the intrinsic partition function.
Yields of larger clusters, which fail to reach this quasi-equilibrium form of
the relevant distribution, are described by nucleation kinetics, and a
saddle-to-scission relaxation time of about 7000 fm/c is inferred. Light
charged particle emission, described by reaction kinetics and virial
expansions, may therefore be regarded as a very important tool to probe the
nonequilibrium time evolution of actinide nuclei during fission.
