  We study the impact of fission on the production and destruction of translead
nuclei during the r-process nucleosynthesis occurring in neutron-star mergers.
Abundance patterns and rates of nuclear energy production are obtained for
different ejecta conditions using three sets of stellar reaction rates, one of
which is based on microscopic and consistent calculations of nuclear masses,
fission barriers, and collective inertias. We show that the accumulation of
fissioning material during the r process can strongly affect the free neutron
abundance after the r-process freeze-out. This leads to a significant impact on
the abundances of heavy nuclei that undergo $\alpha$ decay or spontaneous
fission, affecting the radioactive energy production by the ejecta at
timescales relevant for kilonova emission.
