Giant Nuclear Reactor May
Run Earth's
Magnetic Field
By Phil Berardelli
UPI Deputy Science and Technology
Editor
6-11-2
Thousands of miles beneath our feet,
a giant nuclear reactor seems to be at
work deep within Earth's core, and
preliminary research suggests it may be
the mysterious power source behind
the planet's magnetic field and thermal
energy, upon which all life on the
planet depends for its survival,
scientists told United Press
International.
New data analyzed by J. Marvin
Herndon, geoscientist and president of
Transdyne Corporation, of San Diego,
Calif., and Daniel F. Hollenback, a
nuclear engineer and criticality
expert at Oak Ridge National Laboratory,
in Oak Ridge, Tenn., show the reactor
-- a ball of uranium about five miles
in diameter and located at the center
of the core -- may have been
operating nearly since the formation
of the planet.
Herndon told UPI he has been
searching for evidence of the deep-Earth
reactor for more than a decade. In
1992, he published a series of papers on
planet-sized nuclear reactors based
on the discovery, 20 years earlier, of
the remnants of a large, natural
reactor located at the Oklo uranium mine
in the Republic of Gabon in western
Africa.
French scientists had discovered the
Oklo reactor and determined it had
operated for tens of thousands of
years some two billion years ago, Herndon
said, "but at the time of its
discovery there were too many pieces missing
to know what that really
meant."
Nuclear reactors operating inside
planetary cores might explain some
mysteries that have puzzled
scientists for years, Herndon said. For
example, since the 1960s, astronomers
have known Jupiter radiates nearly
twice the energy it receives
from the Sun. But up to now, they have not
been able to explain the phenomenon
in a way that makes sense, he said.
Earth's magnetic field is an even
bigger mystery. Some mechanism obviously
generates the field, and many
scientists think the field is formed from
fluid iron in Earth's main outer core
acting like a giant electric dynamo,
or motor. The geomagnetic field, as
it is called, shuts down periodically
and sometimes reverses its polarity
-- with the North and South poles
exchanging their magnetic
charges.
The energy sources previously thought
to power the dynamo are unable to
decrease and then increase again,
Herndon explained, so scientists have had
to resort to assuming the
dynamo mechanism is inherently unstable. But
a
nuclear reactor can decrease power
output -- and even shut itself down --
and come back to life
again, increasing to its full operating power, he
said.
Current knowledge of the structure of
Earth's interior is derived mainly
from seismic data and chemical
analyses of common meteorites, Herndon
continued. Based on that data,
scientists estimate about 30 percent of
Earth's mass comprises an outer core,
he said, which is thought to consist
of iron and maybe one or more lighter
elements such as sulfur.
The solid inner core is
much smaller -- less than 2 percent of Earth's
mass.
Still, current popular geophysical
models cannot explain, from an energy
standpoint, a planet-sized magnetic
field that operates like Earth's --
with its varying power levels and
periodic shutdowns, Herndon said.
Herndon said he received a major
insight when he studied a different type
of meteorite. Enstatite chondrite
meteorites, as they are called, have
chemical compositions similar to
Earth's interior. Unlike more common
meteorites, enstatite chondrite
meteorites contain most of their uranium in
the part of the meteorite that
corresponds to Earth's core.
It was one of the clues Herndon
needed, he said. Uranium is the heaviest
natural element. It makes sense that,
over time, solid uranium particles
would rain out from Earth's fluid
core at high temperatures. Because of
their high density, they could
collect at the very center of the Earth.
After enough uranium collected
together, a nuclear reaction would begin,
and that appears to be
what happened very soon after the formation of the planet.
In 1997, Herndon teamed up with
Hollenbach at Oak Ridge. The laboratory has
unique computer programs that can
analyze the performance of different
types of nuclear
reactors.
"Dan showed me those numerical
simulation programs could be applied to a
nuclear reactor at the center of the
Earth," Herndon said. "We used data
about the uranium content from the
meteorite discoveries to generate
simulations at varying power
levels."
A highly persuasive clue arrived in
the form of physical evidence of a
nuclear reactor at Earth's core.
Recently analyzed samples of lava rock
from deep-source volcanic "hot spots"
in Hawaii and Iceland contained tiny
amounts of the isotopes helium-3 and
helium-4.
Although scientists have known about
the helium-3 for some time, they have
thought it was left over from Earth's
formation some four-and-a-half
billion years ago. But no known
physical process could produce helium-3
except for nuclear fission, Herndon
said, and the proportion of the two
helium isotopes matches the
prediction of the Oak Ridge simulation. This is
strong evidence that the geo-reactor
is at work, he said.
Based on the simulations, and
the helium evidence, Herndon and
Hollenbach
theorize a five-mile-wide ball of
uranium has been operating as a nuclear
reactor for about 4.5 billion years.
Its output is an awesome 4 million
megawatts. Much of the energy it produces is heat, and that might be
what
powers the mechanism that produces
the geomagnetic field, Herndon said.
Perhaps more interesting, the Oak
Ridge programs suggest the reactor is a
breeder -- that is, it actually
produces more nuclear fuel than it
consumes, which is why it has been
able to operate over a time frame that
spans nearly the entire existence of
the planet. In addition, the reactor's
power level varies in intensity over
time and it shuts down periodically.
A nuclear reactor continuously
produces lighter elements, such as strontium
or barium, as the uranium fuel
fissions -- or splits apart. Those fission
fragments would begin to absorb
neutrons -- the subatomic particles
naturally emitted by the fissioning
uranium and responsible for the chain
reaction -- thereby preventing them
from splitting other atoms.
"One might imagine instances in which
the rate of production of fission
products exceeds their rate of
removal by gravitationally driven
diffusion," Herndon wrote in a recent
paper on the subject. If so, he
explained, "the power output of the
geo-reactor would decrease and the
reactor might eventually shut down,
thereby diminishing and ultimately
shutting down the Earth's magnetic
field."
Over time, as the lighter elements
moved away from the uranium core, the
reactor would restart.
The research is "certainly
going to be a major contribution to geophysics,"
Hatten S. Yoder, Jr.,
director emeritus of the Geophysical Laboratory of
the Carnegie Institution of
Washington, D.C., told UPI. "They have
developed an explanation for
(Earth's) magnetic field and the fact that you
can turn it on and
off."
One of the most remarkable
aspects of the planetary core reactor, Yoder
said, is "it only takes a
(five-mile) ball of uranium. That's only 65
percent of all the uranium on
Earth."
The reactor's existence, if
proven, solves the problem of delayed
geothermal cooling and
explains the observed heat flow, Yoder said. Without
a continuing power source, he
said, the heat dissipation would have ended
long ago. But "if you have a
ball of uranium at the center, it would
continue to put out
heat."
Herndon said he next plans to search
lava samples for traces of radioactive
elements that might have been
produced by the geo-reactor and be light
enough to have escaped the core and
reach Earth's surface. Lithium,
beryllium, boron and neon are
possibilities, he said.
"It's not an easy task because both
rock data and nuclear data are needed,
but it certainly is important,"
Herndon said.
Yoder agreed. "High-temperature and
high-pressure experiments are needed to
test the composition and melting
characteristics of the core," he said.
Copyright 2002 by United Press
International.