  The background, basis, feasibility, structure, evidence, and geophysical
implications of a naturally occurring Terracentric nuclear fission georeactor
are reviewed. For a nuclear fission reactor to exist at the center of the
Earth, all of the following conditions must be met: (1) There must originally
have been a substantial quantity of uranium within Earth's core; (2) There must
be a natural mechanism for concentrating the uranium; (3) The isotopic
composition of the uranium at the onset of fission must be appropriate to
sustain a nuclear fission chain reaction; (4) The reactor must be able to breed
a sufficient quantity of fissile nuclides to permit operation over the lifetime
of Earth to the present; (5) There must be a natural mechanism for the removal
of fission products; (6) There must be a natural mechanism for removing heat
from the reactor; (7) There must be a natural mechanism to regulate reactor
power level, and; (8) The location of the reactor or must be such as to provide
containment and prevent meltdown. Herndon's georeactor alone is shown to meet
those conditions. Georeactor existence evidence based upon helium measurements
and upon antineutrino measurements is described. Geophysical implications
discussed include georeactor origin of the geomagnetic field, geomagnetic
reversals from intense solar outbursts and severe Earth trauma, as well as
georeactor heat contributions to global dynamics.
