  Nuclear processes in solid environment are investigated. It is shown that if
a slow, quasi-free heavy particle of positive charge interacts with a "free"
electron of a metallic host, it can obtain such a great magnitude of momentum
in its intermediate state that the probability of its nuclear reaction with an
other positively charged, slow, heavy particle can significantly increase. It
is also shown that if a quasi-free heavy particle of positive charge of
intermediately low energy interacts with a heavy particle of positive charge of
the solid host, it can obtain much greater momentum relative to the former case
in the intermediate state and consequently, the probability of a nuclear
reaction with a positively charged, heavy particle can even more increase. This
mechanism opens the door to a great variety of nuclear processes which up till
know are thought to have negligible rate at low energies. Low energy nuclear
reactions allowed by the Coulomb assistance of heavy charged particles is
partly overviewed. Nuclear $pd$ and $dd$ reactions are investigated
numerically. It was found that the leading channel in all the discussed charged
particle assisted $dd$ reactions is the electron assisted $d+d\rightarrow $
$^{4}He$ process.
