Neutron Voltaics: Diamond-Based Direct Energy Conversion in Nuclear Reactors

The primary energy transformation in a nuclear power plant involves converting the energy of fission fragments and particles into thermal energy. The temperature of the reactor coolant, typically maintained between 300–400 °C, limits efficiency to around 30–35%. The average fission neutrons’ energy is approximately 2.0 MeV or 1.55∗10¹⁰K, is moderated toward 50 meV or 600 K. This study explores the potential of using diamond as both a neutron moderator and an energy converter in direct energy conversion (DEC) devices within nuclear reactors. By incorporating specific dopant isotopes into a diamond pn junction, these devices can withstand the challenging conditions present in nuclear reactors while maintaining excellent neutron moderation capabilities. Geometric considerations indicate positioning DEC devices optimally within the reactor for efficient energy collection. The reactor type and size of DEC device also play roles in maximizing energy harvesting efficiency. While primary charged fission particles cannot be harvested due to their limited range (≈80%offissionenergy), uncharged neutrons and gamma photons and their secondary charged particles, can be harvested effectively. Isotopes used as diamond dopants shows that boron-11 or nitrogen-14 to be neutronically compatible in both neutron moderation and low absorption. Diamond p-n junctions proposed as suitable configurations for DEC devices within nuclear reactors due to their high thermal and radiation tolerance. Graphite can serve as conductors for these devices. This research introduces a new direct energy conversion mechanism for part of the nuclear power which may also function as reactor monitoring tools. Further experimentation and testing on research are due.