Passive Containment Cooling with Natural Circulation and Pressure Relief
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Solution Overview
Problem
Nuclear reactors face challenges in managing temperature and pressure excursions within containment environments due to limitations in heat transfer capabilities, requiring efficient cooling systems that do not rely on electrical power or operator intervention.
Innovation Solution
A passive containment cooling system is implemented, featuring a coolant reservoir, vertically extending coolant channels, and check valve assemblies that enable one-way flow of coolant fluid based on pressure thresholds, along with fusible plugs for temperature control, allowing for gravity-driven circulation and heat absorption without active pumping or operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If active cooling systems with pumps and control systems are used, then cooling effectiveness is improved, but electrical power consumption and operator intervention requirements increase
Solution Approach 1:
The cooling system utilizes natural buoyancy forces to drive coolant circulation without external power sources. Heated coolant naturally rises and cooler coolant sinks, creating self-sustaining convection currents that provide continuous cooling effectiveness while eliminating electrical power requirements
Solution Approach 2:
The patent replaces active mechanical pumping systems with passive thermal convection mechanisms. The mechanical energy input from pumps is substituted by thermal energy-driven natural circulation, maintaining cooling effectiveness while eliminating the need for powered mechanical components
2Temperature
If control systems with computer-implemented functionality are used, then temperature and pressure control precision is improved, but system complexity and operator intervention requirements increase
Solution Approach 1:
The system employs passive thermal convection that automatically responds to temperature differentials without requiring external control systems. The physics-based natural circulation self-regulates based on thermal conditions, eliminating complex computer control while maintaining effective temperature management
Solution Approach 2:
The system leverages changes in coolant density as a function of temperature to drive circulation. As coolant temperature changes, its density changes, creating natural buoyancy forces that automatically adjust flow rates according to thermal conditions without requiring active control intervention
3Power
If heat transfer capabilities are increased to manage heat rejection, then heat rejection effectiveness is improved, but the qualification temperature of the containment system may be exceeded
Solution Approach 1:
The cooling system divides heat rejection into multiple vertical zones along the containment structure. Coolant channels are distributed at different heights, allowing heat to be rejected progressively through segmented sections rather than concentrating thermal loads in a single location, thereby maintaining effective heat rejection while protecting structural integrity
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 effectively manages containment environment temperatures and pressures by circulating coolant fluid based on buoyancy changes and pressure thresholds, reducing the need for electrical power and operator intervention, enhancing nuclear reactor safety and efficiency.
Implementation Method 1
the coolant fluid rises through the coolant channel from the bottom of the coolant channel to the top of the coolant channel according to a change in coolant fluid buoyancy based on the coolant fluid absorbing heat rejected from the nuclear reactor
Implementation Method 2
the coolant supply conduit is configured to direct a flow of coolant fluid downwards out of the lower region of the coolant reservoir and into the bottom of the coolant channel via the coolant channel inlet according to gravity
Implementation Method 3
the coolant return conduit is configured to direct a flow of the coolant fluid to rise out of the top of the coolant channel via the coolant channel outlet and into the upper region of the coolant reservoir according to increased buoyancy of the coolant fluid at the top of the coolant channel over the buoyancy of the coolant fluid at the bottom of the coolant channel
Data Source
AI summary
A nuclear plant includes a nuclear reactor, a containment structure that at least partially defines a containment environment of the nuclear reactor, and a passive containment cooling system that causes coolant fluid to flow downwards from a coolant reservoir to a bottom of a coolant channel coupled to the containment structure and rise through the coolant channel toward the coolant reservoir due to absorbing heat from the nuclear reactor. A check valve assembly, in fluid communication with the coolant reservoir, selectively enables one-way flow of a containment fluid from the containment environment to the coolant reservoir, based on a pressure at an inlet being equal to or greater than a threshold magnitude. A fusible plug, in fluid communication with the coolant reservoir at a bottom vertical depth below the bottom of the coolant reservoir, enables coolant fluid to flow into the containment structure based on at least partially melting.