We propose to investigate a new approach to achieving high performance thermoelectric generators (TEGs) used in nuclear power environments that preliminary calculations suggest may result in a >20% conversion efficiency. This innovation employs the existing reactor neutron radiation coupled with boron based thermoelectric materials to significantly enhance their performance through effects that radiation is known to have on electrical conductivity of solids. The boron-10 material in a neutron field will react to create alpha particles and ionize the feet of the TEG to greatly improve material properties, resulting in an Advanced Thermoelectric Generator, or ATEG.
The major aspect of this innovation revolves around the tendency for ionizing radiation to excite the electrons in a material as it passes through. In doing so, the electrical conductivity of the material increases due to Radiation Induced Conductivity (RIC). However, it is known that the thermal and Seebeck properties of the material remain relatively unchanged. The figure of merit (ZT) for TEGs depends heavily on the electrical and thermal conductivity of the material, as well as the Seebeck coefficient. All three of these factors have been shown to improve when exposed to ionizing radiation. Based on effects seen from previous irradiation tests, the ZT of an ATEG can increase to the point where conversion efficiency can reach over 20%.
Previous work performed by Howe Industries has demonstrated the electrical conductivity change in boron nitride samples during tests at KSU. As boron based TEGs currently exist, adapting these for use with the Kilopower reactor will be the main focus of this project. Doing so will allow for an improved conversion efficiency, reliable power production, and minimal changes to the current designs. This project has the potential to not only increase the performance of the Kilopower reactor, but also decrease overall mass and design complications.
The ATEG system can be used for fission surface power with reactors as well as for high efficiency conversion with radioisotopes. Substituting the boron material with americium dopant allows for power generation uncoupled from a neutron source. Having a 20% efficient TEG would decrease the overall amount of radioisotope fuel required for deep space missions and enable larger missions or more missions per year to take place.
The ATEG system can be adapted for use on Earth for small modular reactors, full scale nuclear power plants, and waste head reclamation. Current estimates suggest that power can be generated in an ATEG SMR for $0.02/kWh and waste heat units can produce power at $0.003/kWh. Studies have found future market predictions for SMR and thermoelectrics to be $4.5B and $741M, respectively.