Assessing the feasibility and consequences of nuclear georeactors in the Earths core mantle boundary

TL;DR

This paper explores the possibility of nuclear georeactors at the Earth's core-mantle boundary, analyzing geochemical data and proposing that such reactors could explain mantle isotopic compositions, with implications for geoneutrino detection.

Contribution

It introduces a novel hypothesis that self-sustaining nuclear georeactors could exist at the CMB, supported by geochemical modeling and isotopic evidence.

Findings

A 5 TW georeactor could explain mantle helium and xenon isotopic data.

A small increase in U and Th concentration could ignite and sustain georeactors.

Geoneutrino tomography can test the presence of these georeactors.

Abstract

We assess the likelihood and geochemical consequences of the presence of nuclear georeactors in the core mantle boundary region (CMB) between Earths silicate mantle and metallic core. Current geochemical models for the Earths interior predict that U and Th in the CMB are concentrated exclusively in the mineral calcium silicate perovskite (CaPv), leading to predicted concentration levels of approximately 12 ppm combined U and Th, 4.5 Ga ago if CaPv is distributed evenly throughout the CMB. Assuming a similar behaviour for primordial 244Pu provides a considerable flux of neutrons from spontaneous fission. We show that an additional concentration factor of only an order of magnitude is required to both ignite and maintain self sustaining georeactors based on fast fission. Continuously operating georeactors with a power of 5 TW can explain the observed isotopic compositions of helium and xenon in the Earths mantle. Our hypothesis requires the presence of elevated concentrations of U and Th in the CMB, and is amenable to testing by direction sensitive geoneutrino tomography.