Multi-disciplinary Modelling and Simulation of the High Temperature Test Reactor (HTTR) and Small Nuclear Rocket Engine (SNRE)
File(s)
Author(s)
Stewart, Emma
Type
Thesis
Abstract
Nuclear powered propulsion systems have been identified as a viable method for achieving a mission to Mars. These systems can achieve almost double the efficiency of chemical combustion rockets, which reduces travel time, and the radiation dose received by astronauts in space.
Historically, NTP systems, using High Enriched Uranium (HEU), were tested during the Rover/NERVA programs but little information is available to support high fidelity modelling with modern numerical methods. Literature relating to the Small Nuclear Rocket Engine (SNRE) provides the most complete set of information.
Nuclear Thermal Propulsion (NTP) systems derived from High Temperature Gas-cooled Reactors (HTGRs), in the use of TRISO particles and graphite moderation. Whilst later designs in the NERVA program diverged from a conventional HTGR, more recent efforts in NTP development have revisited the possibility of using TRISO particle fuel, along with Low Enriched Uranium (LEU).
The High Temperature Test Reactor (HTTR) is included in the International Handbook of Reactor Physics Benchmark Experiments (IRPhE) and provides extensive benchmark data which can be used as a reference for modelling.
This thesis provides a multi-disciplinary study of the SNRE and HTTR. Reactor physics, thermal-hydraulic and thermal stress analysis of the HTTR is performed, which draws on previous work in the IRPhE. A key takeaway from this work is the suitability of the multi-cell method within WIMS deterministic software, where it is often difficult to calculate the multiplication factor of a heterogeneous system.
Included within the reactor physics study of the SNRE is an assessment of the neutron source due to spallation of the Galactic Cosmic Ray (GCR) proton flux, which is key when analysing nuclear systems in space.
Finally a Uncertainty Quantification (UQ) analysis of the SNRE is performed, demonstrating the suitability of Gaussian Process Regression (GPR) as a surrogate model for Monte Carlo (MC) neutronics software.
Historically, NTP systems, using High Enriched Uranium (HEU), were tested during the Rover/NERVA programs but little information is available to support high fidelity modelling with modern numerical methods. Literature relating to the Small Nuclear Rocket Engine (SNRE) provides the most complete set of information.
Nuclear Thermal Propulsion (NTP) systems derived from High Temperature Gas-cooled Reactors (HTGRs), in the use of TRISO particles and graphite moderation. Whilst later designs in the NERVA program diverged from a conventional HTGR, more recent efforts in NTP development have revisited the possibility of using TRISO particle fuel, along with Low Enriched Uranium (LEU).
The High Temperature Test Reactor (HTTR) is included in the International Handbook of Reactor Physics Benchmark Experiments (IRPhE) and provides extensive benchmark data which can be used as a reference for modelling.
This thesis provides a multi-disciplinary study of the SNRE and HTTR. Reactor physics, thermal-hydraulic and thermal stress analysis of the HTTR is performed, which draws on previous work in the IRPhE. A key takeaway from this work is the suitability of the multi-cell method within WIMS deterministic software, where it is often difficult to calculate the multiplication factor of a heterogeneous system.
Included within the reactor physics study of the SNRE is an assessment of the neutron source due to spallation of the Galactic Cosmic Ray (GCR) proton flux, which is key when analysing nuclear systems in space.
Finally a Uncertainty Quantification (UQ) analysis of the SNRE is performed, demonstrating the suitability of Gaussian Process Regression (GPR) as a surrogate model for Monte Carlo (MC) neutronics software.
Version
Open Access
Date Issued
2025-03-31
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Eaton, Matthew
Bluck, Michael
Duan, Yu
Lampunio, Lisa
Publisher Department
Department of Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)