Radial In-Flow Particle Bed Nuclear Rocket Engine With Dynamic Neutron Control
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Solution Overview
Problem
Existing nuclear thermal rocket propulsion systems face challenges in efficiently managing neutron-neutron collisions within the reactor assembly, leading to inconsistent fission rates and thermal stress on components, which affects thrust production and longevity.
Innovation Solution
A radial in-flow particle bed reactor design with modifiable neutron reflectors and coolant channels that adjust neutron reflection and thermal management to control fission rates and temperature, using low-enriched uranium fuel particles and a moderator to regulate neutron availability and thermal energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If neutron reflectors are used to increase neutron availability, then fission rate increases, but thermal stress on components increases
Solution Approach 1:
The neutron reflectors are made movable rather than fixed, allowing them to be dynamically positioned to control neutron availability. The reflectors can be moved closer to or farther from the fuel particles, enabling dynamic adjustment of the fission rate and thermal output to manage thermal stress on components.
Solution Approach 2:
The system changes the physical position parameter of the neutron reflectors to control the density of neutron flux reaching the fuel particles. By adjusting the distance between reflectors and fuel, the system modulates the fission rate and corresponding thermal stress without changing the fundamental reactor design.
2Temperature
If coolant channels are added to manage thermal energy, then temperature control improves, but device complexity increases
Solution Approach 1:
The coolant channels serve multiple functions simultaneously: they cool the fuel particles, remove thermal energy from the reactor, and potentially serve as structural support elements. This multi-functionality reduces the need for separate dedicated cooling components, thereby limiting the increase in device complexity.
Solution Approach 2:
The coolant channels are integrated within the existing reactor structure, with channels positioned concentrically around fuel particle bundles. This nested arrangement allows thermal management without adding external complexity, as the cooling system is embedded within the natural geometric configuration of the fuel assembly.
3Reliability
If low-enriched uranium particles are used, then safety improves, but fission rate consistency decreases
Solution Approach 1:
Instead of relying on a single large fuel element, the system uses numerous small fuel particle copies distributed throughout the reactor. Each particle is low-enriched uranium, and collectively they provide consistent fission rates through statistical averaging, maintaining both safety and consistency.
Solution Approach 2:
The fuel bed is structured as a porous medium containing numerous small fuel particles with interstitial spaces for coolant flow. This porous configuration ensures uniform neutron distribution and consistent fission rates across all particles, while the large surface-area-to-volume ratio of individual particles enhances cooling efficiency and maintains safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves stable and efficient thrust production across temperature cycles, extending the rocket's lifespan by optimizing fission rates and thermal management, ensuring uniform neutron availability and temperature control across fuel elements.
Implementation Method 1
a moderator configured to slow neutrons released by the set of fuel particles
Implementation Method 2
a neutron reflector arranged on a perimeter of the reactor assembly and configured to reflect incident neutrons toward the set of fuel particles
Implementation Method 3
Each fuel element in the set of fuel elements includes a set of low enriched uranium fuel particles configured to release thermal energy via nuclear fission
Implementation Method 4
the propellant thereby cools the nuclear fuel particles within the fuel bed and absorbs thermal energy to produce thrust
Data Source
AI summary
A nuclear engine system includes: a pump configured to pump a propellant; a fuel element including a set of nuclear fuel particles; a moderator configured to surround the fuel element and defining a set of moderator coolant channels configured to cool the moderator; a reflector including a neutron-reflecting material and a reflector coolant channel arranged within the reflector to cool the reflector, the reflector configured to at a first time, operate in a closed configuration to reflect neutrons to the fuel element to increase an energy flux, and at a second time, operate in an open configured to leak neutrons out of the engine system to decrease the energy flux; and a thrust nozzle configured to outlet propellant from the fuel element to produce thrust including a nozzle coolant channel arranged within a wall of the thrust nozzle configured to cool the nozzle.