Underground Nuclear Plant Gravity Cooling and Evacuation
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Solution Overview
Problem
Conventional nuclear power plants face safety challenges due to uncontrolled reactor temperature increases, leading to potential meltdowns and radiation releases, exacerbated by failures in cooling systems, particularly when cooling water does not reach the reactor due to pump malfunctions or power supply issues.
Innovation Solution
A nuclear power plant design featuring a buried structure with a passive thermal fuse system that uses gravity-fed seawater for cooling, eliminating the need for pumps and minimizing electronic components, including thermal fuses that melt at set temperatures to allow borated water to flood the reactor and containment buildings, and a gravity elevator for safe operator evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling water tanks are located at a higher level than buildings to be cooled, then cooling water can enter without pumps, but the plant structure becomes more complex and requires significant vertical space
Solution Approach 1:
Instead of placing cooling water tanks at a higher level above the reactor, the patent inverts the approach by burying the reactor at a deeper level below the cooling water tanks. This allows gravity-fed cooling water flow to reach the reactor without requiring pumps, while avoiding the structural complexity of elevated tank installations.
Solution Approach 2:
The patent transitions from a vertical arrangement (tanks above reactor) to a horizontal/depth-based arrangement by burying the reactor underground at a sufficient depth below the cooling water tanks. This dimensional change enables gravity-fed cooling while simplifying the overall plant structure.
2Extent of automation
If thermal fuses are used to flood the reactor automatically, then operator intervention is minimized, but the system requires precise temperature sensing and control mechanisms
Solution Approach 1:
The thermal fuse system is designed to automatically melt and open floodgates when a predetermined temperature is reached, without requiring external control systems, sensors, or power sources. The system serves itself by utilizing the thermal energy present in the accident scenario to trigger the safety response.
Solution Approach 2:
The patent replaces complex electronic temperature sensing and control systems with a passive thermal fuse mechanism that directly responds to temperature increases through material phase change (melting). This mechanical/thermal direct-response system eliminates the need for sophisticated electronic controls.
3Object-affected harmful factors
If the power plant is buried underground, then protection from seismic and terrorist hazards is improved, but access for maintenance and emergency response becomes more difficult
Solution Approach 1:
The plant is divided into separate underground chambers or zones (reactor building, turbine building, control building, fuel storage) that can be independently accessed, maintained, or sealed. This segmentation allows targeted access to specific areas while maintaining overall underground protection.
Solution Approach 2:
Shafts, tunnels, and access corridors serve as intermediary pathways connecting the surface to underground components. These intermediaries enable maintenance personnel and emergency responders to reach buried equipment while the main reactor remains protected underground.
4Reliability
If gravity elevators are used for operator evacuation, then the system is simpler and more reliable, but evacuation capacity and speed are limited compared to powered elevators
Solution Approach 1:
Multiple gravity elevator shafts are distributed throughout the plant to provide parallel evacuation pathways. This segmentation increases total evacuation capacity while maintaining the simplicity and reliability of individual gravity-based systems.
Solution Approach 2:
Gravity elevators are pre-positioned and pre-configured in strategic locations throughout the plant before accidents occur. Operators can immediately evacuate to predetermined safe zones without requiring system activation or power supply during the emergency.
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 design significantly reduces the risk of reactor meltdowns by ensuring automatic cooling and isolating personnel from radiation, minimizing the impact of accidents and allowing for safe shutdown and decommissioning without dismantling, while reducing the probability of seismic and terrorist-related hazards.
Implementation Method 1
thermal fuses that melt at set temperatures to allow borated water to flood the reactor
Implementation Method 2
gravity elevator for safe operator evacuation
Implementation Method 3
uses gravity-fed seawater for cooling, eliminating the need for pumps
Data Source
AI summary
A nuclear power plant having buried buildings that include a containment building housing a nuclear reactor, a power generation building housing turbines, and a nuclear material storage building. A borated cooling water tank is located above the containment building and can gravity feed water thereto through cooling pipes. Steam exhaust pipes extend from the containment building to the bottom of the water tank. A float and valve arrangement provides seawater to keep the water tank at a constant water level. Horizontal tunnels have manually operated hatches to isolate the different buildings from one another. Vertical tunnels have gravity elevators.