Passive Reactor Cooling with Two-Phase Emergency Heat Transfer
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Solution Overview
Problem
Existing nuclear reactors face challenges in efficiently cooling the reactor core during abnormal conditions without operator intervention, leading to potential accidents and environmental risks due to inadequate heat transfer rates and reliance on manual operation.
Innovation Solution
A passive cooling system that utilizes heat and pressure generated in the reactor to circulate cooling water through a two-phase heat transfer mechanism, incorporating a saturated vapor pressure cooling chamber and siphon recirculation pipes to enhance heat dissipation and minimize the need for external power and operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pool boiling heat exchange is used to cool the reactor, then the heat exchange capacity is limited, but the system size must be increased to compensate for the slow heat release rate
Solution Approach 1:
The patent employs two-phase heat transfer mechanisms where cooling water undergoes phase change from liquid to vapor and back, significantly enhancing heat exchange capacity. The cooling water is vaporized by reactor heat and then condensed to release heat externally, creating a high-efficiency thermal cycle that resolves the contradiction between heat exchange capacity and system size.
Solution Approach 2:
The system utilizes passive hydraulic circulation where heated cooling water rises and condensed water falls back to the reactor through gravity-driven flow paths. This natural circulation eliminates the need for large pump systems while maintaining effective heat transfer, reducing system size while preserving reliability.
2Ease of operation
If manual operation is required to operate the cooling system during emergencies, then the operator can control the system, but the operator may be injured, killed or evacuated, resulting in absence of operation
Solution Approach 1:
The cooling system is designed to operate autonomously during emergencies using passive safety mechanisms. The system automatically detects reactor overheating conditions and initiates cooling through natural circulation and phase change mechanisms without requiring operator intervention, ensuring operational continuity even when operators are unavailable.
Solution Approach 2:
The system is pre-configured with passive safety features and automatic control mechanisms that activate immediately upon detecting emergency conditions. Cooling water circulation paths and heat exchange systems are designed to function automatically, eliminating the need for manual operation during critical emergencies.
3Ease of operation
If complex manual procedures are provided for emergency cooling, then the system can be controlled, but the operator cannot block the accident due to complexity and training requirements
Solution Approach 1:
The system eliminates complex manual procedures by implementing self-regulating passive safety mechanisms. Automatic sensors and control systems monitor reactor conditions and adjust cooling parameters without operator intervention, simplifying the operational interface while maintaining precise control capability.
Solution Approach 2:
The patent replaces complex manual mechanical control systems with automated sensing and control mechanisms. Electronic sensors detect temperature and pressure conditions, and control systems automatically adjust cooling water flow and heat exchange parameters, reducing operational complexity while preserving control effectiveness.
4Productivity
If external power sources are required to operate the cooling system, then the system can function, but the system becomes dependent on external power availability
Solution Approach 1:
The cooling system utilizes passive safety mechanisms that operate independently of external power sources. Natural circulation driven by density differences, gravity-driven water flow, and thermally-driven phase changes enable the system to function during power outages, ensuring cooling productivity while achieving power independence.
Solution Approach 2:
The system is designed with passive cooling capabilities built-in from the outset, with cooling water circulation paths and heat exchange systems configured to operate automatically using thermal and gravitational forces. This preliminary design ensures the system maintains functionality without external power during emergencies.
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 rapid and efficient cooling by leveraging two-phase heat transfer, ensuring continuous operation even in the absence of external power or operator presence, thereby improving safety and reducing system size.
Implementation Method 1
the massive thermal energy generated as the reactor core 20 in the reactor 10 fissions is transferred to the cooling water
Implementation Method 2
the heated cooling water is converted to electrical energy through the generator 54 by turning the turbine 52 in the form of water vapor
Implementation Method 3
the heated cooling water is converted to electrical energy through the generator 54 by turning the turbine 52 in the form of water vapor
Implementation Method 4
then condensed back into water and circulated back into the reactor 10
Implementation Method 5
an infinite cooling circulation occurs by itself while cooling water is passively circulated without separate operation and control of an operator and supply of an external power source
Data Source
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AI summary
A passive cooling system for nuclear reactor includes an energy release space in which a nuclear reactor containing a reactor core is located; an energy absorbing space which is partitioned from the energy release space and which accommodates cooling water, and to which a pressure in the energy release space is transferred; an energy transfer space which is provided above the energy absorbing space and into which cooling water of the energy absorbing space flows, and which absorbs and cools heat transferred from the nuclear reactor vessel as the cooling water; an emergency cooling flow passage for transferring heat of the nuclear reactor to the energy transfer space; a reactor thermal insulation vessel spaced from the nuclear reactor and formed to surround an upper side and a circumference of the nuclear reactor; a pressure equalization pipe that communicates the reactor thermal insulation vessel and the energy absorbing space to transfer water vapor and pressure in the reactor thermal insulation vessel to the energy absorbing space; and a coolant spray pipe for flowing pressurized cooling water in the energy absorbing space by the pressure equalization pipe to the energy transfer space.