Nuclear Reflector Thermal Deformation for Load Following
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Solution Overview
Problem
Large nuclear reactors have complex and costly cooling systems due to numerous pipes, pumps, and heat exchangers, and lack efficient load following control systems, leading to increased size, complexity, and manufacturing costs.
Innovation Solution
A small nuclear reactor with a load following control system using thermal expansion of metallic members to control neutron reflection, employing metallic sodium, lead, or lead-bismuth as coolants, and eliminating the need for intermediate heat exchangers and steam generators, with a reflector system that adjusts neutron leakage and generation efficiency based on temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large nuclear reactors use conventional cooling systems with multiple loops, steam generators, and heat exchangers, then heat transfer between primary and secondary cooling systems is achieved, but the overall cooling system becomes large and complicated
Solution Approach 1:
The patent merges the primary and secondary cooling systems into a single integrated reactor vessel, eliminating the need for separate steam generators and heat exchangers. The liquid metal coolant directly contacts the fuel elements and transfers heat to the working fluid within the same vessel, simplifying the overall cooling system architecture while maintaining effective heat transfer.
Solution Approach 2:
The patent extracts and eliminates intermediate heat exchangers and steam generators from the conventional cooling system. By using liquid metal coolant with high heat transfer coefficients, the system achieves effective heat transfer without requiring these separate components, thereby reducing system complexity.
2Ease of operation
If large nuclear reactors use control rods positioned between fuel assemblies, then nuclear reaction rate control is achieved, but the structure becomes complicated and monitoring systems are required
Solution Approach 1:
The patent replaces mechanical control rods with a thermal field-based control mechanism. By controlling the temperature distribution and flow characteristics of the liquid metal coolant, the nuclear reaction rate is regulated through thermal feedback mechanisms rather than mechanical insertion or extraction of control rods, simplifying the reactor structure.
Solution Approach 2:
The patent implements a self-regulating cooling system where the liquid metal coolant automatically adjusts its flow and temperature distribution in response to nuclear reaction conditions. The system uses inherent thermal feedback to maintain stable operation without requiring complex external monitoring and control mechanisms.
3Stability of the object's composition
If conventional reactors use oxide fuel with low heat transfer characteristics, then fuel stability is maintained, but heat transfer efficiency decreases
Solution Approach 1:
The patent uses composite fuel elements consisting of uranium alloy cores surrounded by steel cladding. The uranium alloy provides high heat transfer characteristics and nuclear fuel properties, while the steel cladding maintains structural integrity and stability. This composite structure combines the advantages of both materials to achieve efficient heat transfer while maintaining fuel stability.
Solution Approach 2:
The patent changes the thermal parameters of the fuel system by using liquid metal coolant with high thermal conductivity and specific heat capacity. This parameter change enables efficient heat extraction from the fuel elements, overcoming the low heat transfer characteristics of conventional oxide fuels while maintaining fuel stability through controlled temperature gradients.
4Loss of energy
If multiple loops and heat exchangers are used in fast breeder reactors, then heat transfer is achieved, but the number of pipes, pumps, and components increases
Solution Approach 1:
The patent combines multiple cooling loops and heat exchanger functions into a single integrated reactor vessel. The liquid metal coolant circulates directly around the fuel elements and transfers heat to the working fluid within the same vessel, eliminating the need for separate pipes, pumps, and heat exchanger components while maintaining effective heat transfer.
Solution Approach 2:
The liquid metal coolant in the patent serves multiple functions simultaneously: it acts as the primary cooling medium, the heat transfer fluid, and the working fluid for power generation. This multi-functionality eliminates the need for separate systems for each function, reducing the quantity of components required.
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 a smaller, safer, and more cost-effective nuclear power generation with automatic reactivity control, reduced risk of accidents, and simplified maintenance, utilizing a closed-loop secondary coolant system with supercritical carbon dioxide for efficient power generation.
Implementation Method 1
heat deformation of reflector caused by thermal expansion phenomenon
Implementation Method 2
transfers the heat in the primary sodium system (primary cooling system) generated by cooling the reactor core to the secondary sodium system (secondary cooling system)
Implementation Method 3
closed-loop secondary coolant system with supercritical carbon dioxide for efficient power generation
Implementation Method 4
nuclear reaction in a small nuclear reactor
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The present invention provides a small nuclear power generation system being safe and easily controlled by load following, and allowing reductions in manufacturing costs and maintenance and management costs. The small nuclear power generation system has a small nuclear reactor employing a load following control method. The reactor includes: a fuel assembly reactor core 4 having metallic fuel containing one or both of uranium (235, 238) and plutonium-239; a reactor vessel 1 containing the fuel assembly reactor core 4; metallic sodium loaded into the reactor vessel 1 and heated by the fuel assembly reactor core 4; and a neutron reflector 2 for achieving criticality in the reactor core with effective multiplication factor of neutrons emitted from the fuel assembly reactor core 4 being maintained at or above about 1. The load following control method of the reactor allows a neutron effective multiplication factor to be controlled by coupling the neutron reflector to spring or spiral metallic members and utilizing heat deformation in the metallic members due to the temperature in coolant metallic sodium to control the fast neutron reflection efficiency of the neutron reflector