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The georeactor is a proposal by J. Marvin Herndon that a nuclear fission reactor may exist and operate at the Earth's core and serves as the energy source for the geomagnetic field. Herndon had earlier proposed the existence of fission reactors at the centers of large gaseous planets such as Jupiter and Saturn.

The georeactor hypothesis modifies the widely accepted dynamo theory. The georeactor hypothesis explains how convection can occur and power a dynamo, even though the solid rock of the crust insulates the core and should stop the convection. Georeactors may also explain apparent excess heat produced by the core of the Earth and certain gas giant planets. The evidence for georeactors depends on subtle measurements of heat loss and geologic helium emissions which are disputed because alternative explanations exist. Fission georeactors would depend upon the elemental abundance, concentration and dispersion of fissionable Uranium which is also disputed. Fusion georeactors can explain the same facts, but assume an undemonstrated form of high-pressure, low temperature fusion. The existence of such fusion is disputed, but could be called into question by geologic measurements of Tritium.

Both reactor hypotheses could be tested by observations of neutrino emissions. The experiment Borexino (2010) by observation of antineutrinos has set the upper limit on the possible power of the fission georeactor: P < 3 terawatt,[1] which is 14 times less than total heat flow from the Earth (~42 TW).

The disputed georeactor hypothesis refers specifically to the formation of a self-sustaining nuclear chain reaction[2] and not to the production of heat from the decay of radionuclides such as potassium-40, uranium-238 and thorium-232 which is more widely accepted [3][4]

Contents

Natural nuclear reactors

In the 1970s, geochemists documented the existence of naturally-occurring slow fission reactors in uranium-bearing geologic formations at Oklo in Gabon, Africa. The Oklo natural nuclear fission reactors operated approximately 1.5 to 2.0 billion years ago, when the natural occurrence of the uranium-235 isotope (required for the fission chain-reaction) was much higher.

The georeactor

Herndon's calculations also permitted the existence of a similar reactor at the Earth's core, depending on certain unconventional assumptions regarding the composition of the core, in particular the oxidation state of uranium and the likelihood of its precipitating to the center. He justifies these assumptions by comparison with the composition of enstatite chondrite meteorites, which do have the necessary highly reduced oxidation states and are the only chondrite meteorites which have sufficient iron metal-alloy to match the composition of the Earth with its massive core.

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The Earth's magnetic field in relation to the reactor

According to Herndon, the energy produced by the reactor is what sustains the magnetic field of the Earth. He says the energy produced maintains the field. The field has weakened in recent years to indicate a possible polarity switch of our planet's poles. In his theory the switches in the field are caused by the reactor turning on and off.

Dynamo theory

In 2007, Herndon suggested a modification of dynamo theory, in which the electrically conducting operant fluid, and thus region of dynamo action, may be contained within the geocentric nuclear fission reactor, called the georeactor, in its fluid sub-shell, rather than the in Earth’s iron-alloy core[2][5]. Herndon has pointed out the following reasons why long-term stable convection would not be favorable within the Earth’s fluid core[2][5]: Maintaining stable convection would require maintaining an adverse temperature gradient, which would require efficient removal of heat brought to the top of the core by convection , but the Earth’s core is insulated by a 2900 km thick blanket of silicate rock, the mantle, which has a much lower thermal conductivity, lower heat capacity, and higher viscosity than the core; all impediments to efficient removal of heat brought to the top of the core by convection. Herndon pointed out that these impediments would not be the case for convection within the georeactor sub-shell, which surrounds the actinide, heat producing sub-core, and which itself is surrounded by the inner core, acting as a heat sink, surrounded by another heat sink, the core, both of which are reasonably good conductors of heat. Moreover, radioactive decay of neutron-rich fission products in the georeactor sub-shell assures a continuous supply of charged particles for establishing a seed-field for dynamo initiation.

Planetary fission reactors

Large, gaseous planets, such as Jupiter or Saturn, radiate more energy into space than they receive from the Sun. (In the case of Jupiter, the radiated energy is almost twice the received energy.) The source of this energy was originally attributed to gravitational contraction, since gravitational potential energy conversion into heat seemed to be the heat source of sufficient magnitude to account for the quantity of energy released. In 1992, J. Marvin Herndon postulated that the excess energy could be explained by the existence of a central nuclear reactor. High-density fissile elements (i.e. uranium) would be concentrated at the core and could undergo sustained nuclear fission chain reactions. Herndon demonstrated the feasibility of a planetocentric nuclear reactor using Fermi's nuclear reactor theory, calculations similar to those used in nuclear-reactor design.

Currently active internally generated magnetic fields have been detected in six planets (Mercury, Earth, Jupiter, Saturn, Uranus, and Neptune) and in one satellite (Jupiter’s moon Ganymede). Magnetized surface areas of Mars and the Moon indicate the former existence of internally generated magnetic fields in those bodies.

Stellar fission reactors

Another possible instance of central nuclear fission may occur in protostars. Ignition of fusion reactions in the cores of stars and protostars requires tremendous temperatures and pressures, which are difficult to attain. Herndon suggests that the fusion reactions may, in fact, be ignited by a central fission reactor in the same manner that a fusion bomb is triggered by a fission bomb.

Planetary fusion reactions

In seemingly unrelated work, Steven E. Jones of Brigham Young University (BYU) has speculated on the existence of natural fusion reactions at planetary cores, continuing work initiated by Dr. Paul Palmer (also of BYU) in 1986. Their initial work was also focused on explaining the excess heat given off by Jupiter and then extended to include possible application to Earth. The term geo-fusion is used to describe their theory. Geo-fusion is a form of cold fusion, although not the type of room-temperature fusion described by Stanley Pons and Martin Fleischmann. Jones hypothesizes that geo-fusion is driven by the high pressures present at planetary cores. Jones has suggested that measurements of the levels of tritium released by volcanic processes may provide a possible confirmation of the theory.[6]

Criticism

Herndon's concepts are not accepted by the scientific community. However, Rob de Meijer and associates at the Nuclear Physics Institute in Groningen, the Netherlands, have proposed an experiment to measure the antineutrino flux from the Earth's core which they believe will validate Herndon's hypothesis. At present they are seeking funding for the project, which involves development of an underground laboratory in Curaçao.[7]

The following is taken from a San Francisco Chronicle article by Keay Davidson describing that test:

One of Herndon's leading critics is planetary scientist David Stevenson of the California Institute of Technology. He says in an e-mail: "Herndon is a solid and knowledgeable person when it comes to (nuclear) reactors. But the amount of attention this (georeactor) idea has received is out of proportion with its plausibility. ... It's not complete nonsense, but it's highly unlikely. There are many instances in science where this happens. This one has merely received more attention than most.
"The idea is based on two very dubious propositions: (a) That uranium (or any heavy element) would naturally go to the center of the Earth. This is almost certainly untrue. It is a misunderstanding of chemistry and statistical physics at a very fundamental level. (b) That there is something about Earth's heat flow or helium that is so wildly discordant with our usual ideas that it requires an outrageous hypothesis to explain it. This is incorrect."[7]

Herndon was asked to reply by the publisher of the critique, to which he responded:[8]

"...If a scientist has any serious disagreement, he/she should publish it in the literature, with all supporting documentation, in circumstances under which I might respond with full documentation. No one, including David Stevenson, has attempted to do that. If Stevenson truly believes that I have made some misunderstanding, he should provide the documentation. He won’t, because he can’t. My work is on solid footing."
"...Statistical physics is a fancy, important-sounding term that is completely irrelevant for the scientific considerations involved. A term more appropriate to the subject is metallurgical thermochemistry and that, I assure you, is a different animal entirely."

References

  1. ^ The Borexino collaboration. Observation of Geo-Neutrinos. arXiv:1003.0284.
  2. ^ a b c Herndon, J. M. (2007) Nuclear georeactor generation of Earth’s geomagnetic field. Curr. Sci. 93(11), 1485-1487
  3. ^ Sanders, Robert (2003). "Radioactive potassium may be major heat source in Earth's core". UCBerkleyNews. UC Berkley. http://www.berkeley.edu/news/media/releases/2003/12/10_heat.shtml. Retrieved 2009-01-30. 
  4. ^ Butler, S. L.; Peltier, W. R.; Costin, S. O. (2005). "Numerical models of the Earth’s thermal history: Effects of inner-core solidification and core potassium". Physics of the Earth and Planetary Interiors, Volume 152, Issue 1-2, p. 22-42. NASA ASD. http://adsabs.harvard.edu/abs/2005PEPI..152...22B. Retrieved 2009-01-30. 
  5. ^ a b http://www.ias.ac.in/currsci/dec102007/1485.pdf
  6. ^ [1] Walter Sullivan New York Times, 25 April 1989
  7. ^ a b Scientific maverick's theory on Earth's core up for a test Keay Davidson, San Francisco Chronicle, November 29, 2004
  8. ^ The Naysayer

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