Dynamic Neutron Reflector Assembly for Reactivity Control
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Solution Overview
Problem
Current breed-and-burn nuclear reactors lack dynamic control over reactivity and breed rate, leading to suboptimal fuel utilization and waste management, as they rely on static neutron reflector assemblies that cannot adjust neutron spectrum effectively.
Innovation Solution
A dynamic neutron reflector assembly that adjusts reflectivity characteristics by inserting or removing neutron-spectrum-influencing materials, varying temperature, density, or volume, allowing for incremental control over reactivity and breed rate by selectively circulating neutron absorbing, moderating, or reflecting materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a static neutron reflector assembly is used, then the reactor structure is simple and reliable, but dynamic control over reactivity and breed rate cannot be achieved
Solution Approach 1:
The neutron reflector assembly is transformed from a static structure to a dynamic system by introducing movable reflector elements that can be inserted into or withdrawn from the reactor core. This allows the reflector to adapt its configuration in real-time, enabling dynamic control over neutron reflection and consequently over reactivity and breed rate, while maintaining structural simplicity through standardized movable components
Solution Approach 2:
The neutron reflector assembly is divided into multiple independent movable elements or segments that can be individually controlled. This segmentation allows for fine-grained adjustment of neutron reflection characteristics by selectively positioning different reflector segments, providing precise dynamic control over reactivity while keeping each individual component simple in structure
2Measurement precision
If neutron-spectrum-influencing materials are selectively inserted or removed, then precise control over reactivity is achieved, but the complexity of material handling and assembly increases
Solution Approach 1:
The movable neutron reflector elements are designed to serve multiple functions: they act as neutron reflectors when inserted into the core, provide structural support, and can be easily inserted or removed through standardized mechanisms. This multi-functionality reduces the need for separate specialized components for material handling, thereby controlling the increase in system complexity while enabling precise control over reactivity and breed rate
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
Enables precise control over reactivity and breed rate, maintaining a high and consistent burn profile over time, optimizing fuel utilization and reducing waste production by dynamically shifting the neutron spectrum in response to changing reactor conditions.
Implementation Method 1
fast spectrum neutrons emanating from nuclear fuel region 1704 are inelastically scattered (or reflected) from dynamic neutron reflector assembly 1716 and back into nuclear fuel region 1704
Implementation Method 2
The flowing neutron reflector material can extract heat from the molten fuel salt in a heat exchanger via a primary or secondary coolant circuit
Data Source
AI summary
A dynamic neutron reflector assembly for a “breed-and-burn” fast reactor incrementally adjusts neutron spectrum and reactivity in a reactor core. The composition of materials in the dynamic neutron reflector may be adjusted to change neutron reflectivity levels, or to introduce neutron moderating or absorption characteristics. The dynamic neutron reflector may contain a flowing reflecting liquid of adjustable volume and/or density. Submergible members may be selectively inserted into the flowing reflecting liquid to alter its volume and introduce other neutron modifying effects such as moderation or absorption. Selective insertion of the submergible members allows for concentration of the neutron modifying effects in a selected portion of the reactor core. The flowing reflecting liquid may also act as a secondary coolant circuit by exchanging heat with the molten fuel salt.