This rocket works by
exploding a fission device behind a spacecraft, with the radiation and
and various particle pressure pushing the craft forward. Since
this, by definition, involves exploding radioactive materials, it is
probably a bad idea to do this around an inhabited world if you react
poorly to radiation (as humans do).
Fission explosive rocketry somewhat efficiently
converts matter to energy (up to a small fraction of one percent), so
it is possible to create interstellar drives based on this
technology.
The other form of fission rocketry involves the use
of an
controlled fission
explosive behind the spacecraft. It is called
Fission Rocketry.