Shell-less Heat Exchanger for Nuclear Component Cooling
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Solution Overview
Problem
Current nuclear reactor containment systems face challenges in efficiently managing thermal energy releases during accidents, relying on pumped heat rejection systems that are vulnerable to power outages and requiring expensive and difficult equipment changes, while component cooling water systems suffer from debris intrusion, biological fouling, and corrosion issues.
Innovation Solution
A nuclear reactor containment system with a double-walled structure featuring a water-filled annular reservoir for passive heat rejection, incorporating a shell-less heat exchanger and radial fins for efficient heat dissipation, and a component cooling water system that recirculates and evaporates water to cool the reactor, with an auxiliary air cooling system for continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If pumped heat rejection systems are used to reject heat from the containment structure, then heat rejection capability is improved, but reliability deteriorates due to vulnerability to power outages and dependency on robust power sources
Solution Approach 1:
The patent replaces the mechanical pumped heat rejection system with a passive natural convection system. The containment structure uses natural buoyancy-driven airflow to reject heat without requiring pumps or external power sources. Hot air rises naturally from the containment structure and is replaced by cooler ambient air, creating a continuous passive heat rejection cycle that maintains reliability during power outages.
Solution Approach 2:
The passive heat rejection system is self-regulating and requires no external control or power input. The natural convection current automatically adjusts to thermal conditions, drawing cool air in through lower openings and expelling hot air through upper openings based on temperature differentials, thereby serving itself without external intervention.
2Strength
If monolithic reinforced concrete containment structures are used to withstand aircraft impact, then strength is improved, but ease of manufacture deteriorates due to difficulty and expense of equipment removal and installation
Solution Approach 1:
The patent divides the containment structure into modular segments rather than using a monolithic design. This segmentation allows for pre-fabricated sections to be assembled around the reactor equipment, and enables equipment to be accessed and replaced by working from the outside of the modular sections without requiring costly and time-consuming cutting operations through thick concrete.
Solution Approach 2:
The containment structure is designed with nested modular sections that can be assembled around the reactor equipment. This nested configuration allows equipment to be installed or removed by accessing the nested layers from the exterior, maintaining structural integrity while facilitating equipment changes without penetrating the containment boundary.
3Temperature
If component cooling water system uses once-through flow from natural body of water, then cooling efficiency is improved, but object-affected harmful factors worsen due to debris intrusion, biological fouling, and corrosion
Solution Approach 1:
The patent uses a closed-loop cooling water system that recirculates treated water instead of drawing once-through flow from natural bodies of water. A replica or model of the natural cooling process is created using controlled evaporation cooling towers that simulate natural water cycle cooling while eliminating the harmful interactions with natural water sources. The recirculating system includes filtration and treatment components that prevent fouling and corrosion.
Solution Approach 2:
The patent introduces an intermediary closed-loop water system between the equipment to be cooled and the external environment. This intermediary system uses evaporation cooling towers to reject heat to the atmosphere without direct contact with natural water bodies, thereby mediating the cooling process to eliminate debris intrusion, biological fouling, and corrosion problems associated with once-through cooling systems.
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 enables passive, continuous heat rejection without pumps, withstands projectile impacts, and allows for easy equipment removal, while maintaining thermal performance and preventing equipment fouling, thus enhancing safety and operational efficiency.
Implementation Method 1
heat generated by the containment vessel is transferred to the water filled annular reservoir... thus cooling the containment vessel
Implementation Method 2
the water filled annular reservoir... configured to provide a heat sink for dissipating thermal energy
Implementation Method 3
Component cooling water from the plant flows through the tube bundle and is cooled by transferring heat to the annular water reservoir
Data Source
AI summary
A component cooling water system for a nuclear power plant. In one embodiment, the system includes an inner containment vessel housing a nuclear reactor and an outer containment enclosure structure. An annular water reservoir is formed between the containment vessel and containment enclosure structure which provides a heat sink for dissipating thermal energy. A shell-less heat exchanger is provided having an exposed tube bundle immersed in water held within the annular water reservoir. Component cooling water from the plant flows through the tube bundle and is cooled by transferring heat to the annular water reservoir. In one non-limiting embodiment, the tube bundle may be U-shaped.