External Reflector Molten Salt Reactor Layout for Compact Neutronics
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Solution Overview
Problem
Existing low power, fast spectrum molten fuel reactors face challenges in managing neutronics, reactivity control, and heat dissipation, particularly in extra-terrestrial environments, where radiation exposure and heat sink conditions differ significantly from terrestrial settings.
Innovation Solution
Designs for low power, fast spectrum molten fuel reactors incorporating axial and radial neutron reflectors, active fuel circulation, and natural or pumped flow systems, with reactivity control via control drums and heat dissipation to external environments using thermoelectric generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If low power reactors are designed for experimental investigation, then novel designs can be pursued that would be unfeasible in commercial settings, but significant power generation is not achieved
Solution Approach 1:
The reactor system is divided into separate functional modules: a reactor core for fission, a fuel salt circulation system for heat transport, and a heat dissipation system for thermal management. This segmentation allows each component to be optimized for its specific function while maintaining overall low power output suitable for experimental purposes.
Solution Approach 2:
Molten fuel salt acts as an intermediary medium that circulates between the reactor core and heat dissipation systems, transferring thermal energy. This intermediary enables efficient heat removal while maintaining the low power characteristics needed for experimental investigation.
2Power
If molten fluoride fuel salts are used at high temperatures, then higher power densities are achieved, but fuel fabrication costs increase
Solution Approach 1:
The system operates with molten fluoride fuel salts at temperatures between 600°C and 860°C, optimizing the balance between achieving sufficient power density and controlling fuel fabrication costs. This temperature range allows the fuel to remain molten for efficient heat transfer while avoiding the highest cost associated with extreme temperature operations.
3Loss of energy
If active fuel circulation systems are implemented, then heat removal efficiency is improved, but system complexity increases
Solution Approach 1:
The fuel salt circulation system utilizes natural circulation driven by density differences between heated and cooled fuel salt, eliminating the need for external pumps. This self-service mechanism improves heat removal efficiency while minimizing system complexity by relying on the inherent thermal convection of the fuel salt itself.
Solution Approach 2:
The system employs hydraulic principles by using the fluidity and density variations of molten fuel salt to drive circulation. The thermal expansion and contraction of the fuel salt create natural flow patterns that efficiently transport heat without mechanical assistance.
4Object-affected harmful factors
If reactors are designed for extra-terrestrial use, then radiation exposure requirements are reduced, but heat sink conditions differ significantly from terrestrial settings
Solution Approach 1:
The heat dissipation system is designed with localized thermal management capabilities, including heat exchangers and radiators positioned to optimize heat transfer in extra-terrestrial environments. The system accounts for the specific thermal conditions of space, using phase change materials and radiative cooling surfaces adapted to vacuum and temperature gradients.
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
Facilitates stable operation and efficient heat removal in low-gravity conditions, enabling investigation of reactor phenomena and providing a reliable power source for extra-terrestrial applications.
Implementation Method 1
Heat generated from the fission in the reactor core is transferred from the molten fuel through the reactor vessel to a coolant
Implementation Method 2
The molten fuel may be actively pumped and/or the flow of the molten fuel may be driven by natural circulation caused by the density difference between high temperature molten fuel and low temperature molten fuel
Implementation Method 3
heated fuel salt flows from the reactor core through a duct between the radial neutron reflector and the reactor vessel and back into the reactor core
Implementation Method 4
Heat generated from the fission in the reactor core is transferred from the molten fuel through the reactor vessel to a coolant
Implementation Method 5
Heat may be dissipated directly to cold of space, for example, through a thermoelectric power generator attached to the exterior of the reactor vessel
Implementation Method 6
a reactor core volume defined by axial and radial neutron reflectors enclosed in a reactor vessel
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A simple nuclear reactor in which most of the reflector material is outside of the reactor vessel is described. The reactor vessel is a cylinder that contains all of the fuel salt and a displacement component, which may be a reflector, in the upper section of the reactor vessel. Other than the displacement component, the reflector elements including a radial reflector and a bottom reflector are located outside the vessel. The salt flows around the outside surface of the displacement component through a downcomer heat exchange duct defined by the exterior of the displacement component and the interior surface of the reactor vessel. This design reduces the overall size of the reactor vessel for a given volume of salt relative to designs with internal radial or bottom reflectors.