Feasibility and parameterization of small-scale low-enriched Uranium nuclear thermal propulsion

Abstract

Low-enriched uranium nuclear thermal propulsion (LEU-NTP) has been experiencing a surge in support and investment over the past several years. Until recently, however, the range of potential applications has been limited to relatively large thrusts where the thermal-hydraulic requirements, rather than neutronic requirements, dictate the overall reactor size. Though no published studies exist, the unofficial consensus states that LEU-NTP at thrusts of 7.5klbf or lower is unachievable without an infeasible mass increase. Thus, this thesis attempts to disprove this claim officially by converting a previous 7.5klbf HEU-NTP design to a 7.5 klbf LEU-NTP one. In this work, Schnitzler's 7.5 klbf HEU reactor has been modified by introducing various design changes such as enhanced Zrhydride moderation and Zr-based structural materials and thicker radial reflector etc. All the neutronic analyses are done with the Serpent Monte Carlo code and the thermal hydraulic performance is analyzed with the SPOC code. Although this work required several modifications outside of those common to previous LEU-NTP conversion attempts, the author did obtain a critical configuration that did not require any increase in total reactor mass.