Natural Nuclear Fission Reactors

The mention of "nuclear reactor" might bring to mind names like Chernobyl or Three Mile Island or perhaps conjure images of complex mega-machines whose control rooms have more instrumentation than the cockpit of a 747. The complex instrumentation belies the elegant simplicity that is the basis of a nuclear reactor's operation.

Inside a nuclear reactor control room.

At its heart, a nuclear reactor is simply an accumulation of very heavy atoms, such as uranium, whose nuclei will split when hit with a neutron. When hit with a neutron, the very heavy atomic nucleus breaks into two parts in a process called nuclear fission, liberating energy plus a few more neutrons. These just-freed neutrons can strike another nucleus causing it to fission. This process can happen again and again as a chain reaction, which is what a nuclear reactor does. If too many neutrons come out of play, by escaping or by being absorbed, a chain reaction cannot be sustained.

Schematic representation of a nuclear fission chain reaction. Image by Jaroslav Franta.

Enrico Fermi formulated nuclear reactor theory and designed and built the world's first man-made nuclear reactor in 1942. In 1956, using Fermi's nuclear reactor theory, Paul K. Kuroda (1917-2001) showed that nuclear fission chain reactions could have occurred in uranium deposits two billion years ago and earlier. At the time this idea was very unpopular, but keep in mind that science is a logical process, not a democratic process.

Paul K. Kuroda

Fast forward 16 years to 1972 when I was a graduate student. One day Marvin W. Rowe, my thesis advisor, rushed into the lab to tell me that his former thesis advisor, Paul K. Kuroda, had just learned that French scientists had discovered the intact remains of a natural nuclear reactor in a uranium mine at Oklo in the Republic of Gabon. The reactor had functioned two billion years ago just as Kuroda had predicted. Other fossil reactors were later discovered in the region. I remember thinking at the time that the discovery must have huge implications, but there were just too many pieces missing from the puzzle to progress further. It was like looking out into a very, very dense fog. Over the next two decades, without consciously realizing it, I began to fill in the missing pieces.

I realized that in the Earth's core, density depends only on atomic number and atomic mass. Gravity provides a means for concentrating the densest substance, uranium, at the center of the Earth. I applied Fermi's nuclear reactor theory and in 1993 published the demonstration of the feasibility of a nuclear reactor at Earth's center as an energy source for the geomagnetic field. Later, in 2007, after discovering the physical impossibility of thermal convection in the Earth's fluid core, I published the basis for understanding that the georeactor, as it has come to be called, is both the energy source and production mechanism for the geomagnetic field.

Cut-away schematic of Earth's interiorand nuclear fission georeactor at its center (inset). The georeactor is one ten-millionth the mass of Earth's fluid core. The georeactor's radioactive-waste sub-shell, I posit, is a liquid or slurry and is situated between the nuclear fission heat source and inner-core heat sink. This assures the stable convection necessary for sustained geomagnetic field production by convection-driven dynamo action in the georeactor sub-shell.