![]() A more complex model involving a mechanism for fission product removal, which would allow the k eff of the system to fluctuate, is discussed below. ![]() Obviously, k eff could not remain over 1.0 for the last 4.5 billion years. ![]() The curve labeled Fission shows how the k eff of the system varies over time as a result of fission at a steady-state power of 3 TW, natural radioactive decay, and continuous removal of fission products. 1 show the calculated values of k eff over the entire period of geologic time as obtained from the geo-reactor numerical simulation with and without (Decay Only) fission power, made by using parameters set forth in Table 1. As the reactor increases in power, the geomagnetic field reestablishes itself, either in the same direction or in the reverse direction. As the fission products diffuse out of the reactor region to a region of lower density and the actinide fuel diffuses inward, the reactor restarts. In such an instance, 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. For example, one might imagine instances in which the rate of production of fission products exceeds their rate of removal by gravitationally driven diffusion. Unlike other globally significant energy sources, nuclear reactor output can be variable or intermittent, depending on changes in composition and/or the position of fuel, moderators, and neutron absorbers. The frequent, but irregular, variability in intensity and direction of the Earth's magnetic field may be understandable from a fissionogenic energy-production standpoint-a consequence of fission-product accumulation with concomitant nuclear fuel dilution and the subsequent gravitationally driven fission product separation with nuclear fuel reconcentration. Much of the uranium and some thorium occur in the alloy portion ( 4) of the Abee meteorite that corresponds to the Earth's core ( 23). Because of the highly reduced state of oxidation of the Abee meteorite, only part of its uranium is lithophile. Likewise, the constituents of the Earth's core, specifically the inner core and the “islands” of matter at the core boundary ( 21), are understandable in a causally related manner as precipitates from a highly reduced core gravitationally differentiated from enstatite-chondrite-like matter ( 14, 22). Moreover, the relative mass of the Earth's core is consistent with the Earth having been derived from highly reduced matter like that of certain enstatite chondrites ( 4, 17). The regolith of the planet Mercury, from reflectance spectroscopic investigations, appears to be highly reduced, essentially devoid of FeO-like the silicates of certain enstatite chondrites, such as the Abee meteorite ( 20). E-type asteroids (based on reflectance spectra, polarization, and albedo), the presumed source of enstatite meteorites, are radially from the sun, the innermost of the asteroids ( 19). There are reasons to associate the highly reduced matter of enstatite chondrites with the inner regions of the solar system and with the Earth.
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