Passive Emergency Feedwater System Natural Circulation
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Solution Overview
Problem
Conventional nuclear reactor designs face challenges such as high upfront costs, reliability concerns, and environmental impact, particularly in developing countries, and lack effective decay heat removal during a loss of site power, leading to extended shutdowns and inefficiencies.
Innovation Solution
A power module assembly with a sealed containment vessel and natural circulation-based secondary cooling system that draws emergency feedwater from a containment cooling pool, circulates it through a heat exchanger, and vents it back into the pool, enabling passive cooling without external power and minimizing environmental risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional active cooling systems are used, then cooling effectiveness is maintained during normal operation, but the system becomes unreliable during loss of site power conditions
Solution Approach 1:
The cooling system uses natural circulation driven by density differences between heated and cooled water to automatically circulate coolant through the heat exchanger without requiring external power sources or active pumping during emergency conditions
Solution Approach 2:
The patent replaces the mechanical pumping system with a passive natural circulation system that uses thermal buoyancy forces to drive coolant flow, eliminating the need for powered mechanical components during emergency operation
2Ease of manufacture
If active cooling systems with pumps are used, then cooling performance is controlled and maintained, but system complexity and cost increase
Solution Approach 1:
The patent extracts and removes the complex active pumping components and control systems from the emergency cooling arrangement, retaining only the essential heat exchanger and natural circulation pathways needed for passive cooling operation
Solution Approach 2:
The system uses the thermal energy already present in the reactor core and the density differences in the coolant to automatically drive the cooling circulation, eliminating the need for external power sources, pumps, and complex control systems
3Productivity
If feedwater is vented above the containment pool, then steam release is efficient, but natural circulation flow is reduced
Solution Approach 1:
The patent positions the vent outlet at a different elevation level within the containment structure, allowing steam to be discharged above the pool level while maintaining the submerged outlet configuration that drives natural circulation through elevation-based density differential
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
This solution provides a cost-effective, reliable, and environmentally friendly passive cooling system that maintains reactor core cooling during power losses, allowing for extended operation without operator intervention and quick reactor restart, while preventing radioactive material release.
Implementation Method 1
circulating the secondary coolant from the containment cooling pool through the heat exchanger via natural circulation
Implementation Method 2
The one or more outlets may be submerged in the containment cooling pool and may be configured to vent the secondary coolant into the containment cooling pool
Implementation Method 3
A heat exchanger may be configured to remove heat from the primary coolant, wherein the heat may be removed by circulating the secondary coolant from the containment cooling pool through the heat exchanger
Data Source
AI summary
A power module assembly may include a reactor vessel containing a primary coolant and one or more inlets configured to draw a secondary coolant from the containment cooling pool in response to a loss of power and/or a loss of coolant. One or more outlets may be submerged in the containment cooling pool and may be configured to vent the secondary coolant into the containment cooling pool. A heat exchanger may be configured to remove heat from the primary coolant, wherein the heat may be removed by circulating the secondary coolant from the containment cooling pool through the heat exchanger via natural circulation.